A  HANDBOOK  OF 

SUGAR  ANALYSIS 


A   PRACTICAL  AND  DESCRIPTIVE  TREATISE 
FOR  USE  IN 

RESEARCH,  TECHNICAL   AND   CONTROL 
LABORATORIES 


BY 

C.    A.    BROWNE,   PH.D. 

Chemist  in  charge  of  the  New  York  Sugar  Trade  Laboratory 

{Formerly  Chief  of  the  Sugar  Laboratory,  U.  8.  Bureau  of  Chemistry, 

Washington,  D.C.,  and  Research  Chemist  of  the  Louisiana 

Sugar  Experiment  Station,  New  Orleans,  La.) 


SECOND  EDITION 

FIRST    THOUSAND 


NEW   YORK 
JOHN  WILEY  &  SONS 

LONDON:   CHAPMAN  &   HALL,  LIMITED 
1912 


COPYRIGHT,  1912, 

BY 
C.   A.    BROWNE 

Copyright,  1912,  in  Great  Britain 


Stanbepe  iprcss 

F.    H.  GILSON   COMPANY 
BOSTON,  U.S.A. 


TP.3Z2 


AGRIC. 
LIBRARY 


DEDICATED 
TO   HIS  TEACHER, 

GEH.-RATH  PROF.  DR.  B.  TOLLENS, 

OF  GOTTINGEN  UNIVERSITY, 

AS  A  TOKEN  OF  GRATITUDE  AND  ESTEEM, 

BY  THE  AUTHOE 


PREFACE 


THE  subject  of  sugar  analysis,  which  a  generation  ago  was  limited 
to  determinations  of  density,  specific  rotation  and  reducing  power, 
has  greatly  expanded  within  the  past  twenty-five  years.  Instru- 
ments of  greater  accuracy  have  been  devised,  old  methods  have  been 
improved  and  new  methods  have  been  discovered.  In  the  present 
volume  the  purpose  of  the  author  has  been  to  give  a  rather  wide, 
but  a  by  no  means  complete,  selection  of  the  more  recent  methods  of 
sugar  analysis  and  at  the  same  time  to  retain  the  more  important 
features  of  the  older  textbooks. 

The  range  of  sugar  analysis  is  so  broad  that  in  the  selection  of 
methods  the  author  has  been  guided  largely  by  his  own  experience  in 
various  research,  technical  and  control  laboratories.  While  the  par- 
ticular methods  chosen  for  description  may  not  in  all  cases  meet  with 
general  approval  it  is  hoped  that  the  underlying  principles  of  sugar 
analysis  have  been  covered  sufficiently  to  enable  the  chemist  to  make 
his  own  applications  and  modifications.  References  to  special  works 
and  original  articles  will  assist  the  chemist  in  case  he  desires  to  follow 
some  special  line  of  investigation  more  fully. 

Next  to  the  knowledge  of  a  method  the  most  important  fact  which 
the  student  of  sugar  analysis  must  acquire  is  the  knowledge  of  this 
method's  limitations.  The  great  susceptibility  of  the  sugars  to 
chemical  changes  and  to  variations  in  specific  rotation,  reducing  power 
and  other  "constants"  is  a  factor  which  the  sugar  chemist  must  al- 
ways bear  in  mind.  The  prescribed  methods  of  analysis  are  usually 
too  silent  upon  these  points,  and  the  inexperienced  chemist  often  pro- 
ceeds to  make  general  use  of  a  formula  or  method  which  has  only  a 
limited  applicability.  The  author  has  endeavored  to  correct  this 
tendency  by  including  with  the  description  of  each  method  a  brief 
account  of  its  applicability  and  limitations. 

In  the  examination  of  sugar-containing  materials  the  problems  of 
analysis  are  much  simplified  by  a  knowledge  of  what  one  may  expect 
to  find.  The  author  has  felt  that  a  work  upon  sugar  analysis  is  not 
complete  without  some  description  of  the  sugars  themselves.  In 
Part  II  of  the  present  volume,  he  has  therefore  included  a  brief 


Vi  PREFACE 

account  of  the  occurrence,  methods  of  preparation,  properties  and 
reactions  of  the  different  sugars  and  their  allied  derivatives.  Brief 
references  are  also  made  to  methods  of  sugar  synthesis;  the  latter  play 
such  an  important  part  in  the  separation  and  isolation  of  the  rarer 
sugars  that  the  sugar  analyst  is  not  fully  equipped  without  some  knowl- 
edge of  synthetic  processes. 

The  principal  textbooks  and  journals  which  have  been  consulted 
in  preparing  the  present  volume  are  named  in  the  Bibliography. 
The  author's  obligations  to  these  are  indicated  in  most  cases  by  the 
footnotes.  In  reviewing  original  papers,  the  abstracts  and  references 
contained  in  Lippmann's  "Chemie  der  Zuckerarten"  and  his  "Berichte 
liber  die  wichtigsten  Arbeiten  aus  dem  Gebiete  der  reinen  Zucker- 
chemie,"  published  semiannually  in  "Die  Deutsche  Zuckerindustrie," 
have  been  of  invaluable  service. 

In  concluding  his  task,  which  has  extended  with  many  interrup- 
tions over  a  period  of  five  years,  the  author  desires  to  thank  the  many 
friends  and  coworkers  who,  by  their  help  and  encouragement,  have 
greatly  lightened  his  labors. 

Special  obligations  are  due  to  Dr.  C.  S.  Hudson  for  reviewing  the 
section  upon  mutarotation  and  to  Prof.  H.  C.  Sherman  for  suggestions 
upon  methods  for  determining  diastatic  power.  Acknowledgement  is 
also  made  of  courtesies  extended  by  Mr.  A.  H.  Bryan  and  by  Mr. 
G.  W.  Rolfe. 

For  the  use  of  cuts  contained  in  Dr.  G.  L.  Spencer's  "Handbook 
for  Cane  Sugar  Manufacturers"  and  in  A.  E.  Leach's  "Food  Inspec- 
tion and  Analysis"  the  author  owes  an  acknowledgment  to  the 
authors  of  these  books  and  to  his  publishers  Messrs.  John  Wiley  & 
Sons.  To  the  latter  also  he  would  express  his  appreciation  of  the 
hearty  support  which  has  been  given  and  of  the  generous  considera- 
tion which  has  been  shown  for  the  many  delays  incident  to  the  com- 
pletion of  the  work. 

NEW  YORK,  N.  Y.,  August,  1912. 


BIBLIOGRAPHY 


SPECIAL  WORKS 


Author  or  Editor 


Abderhalden . 
Abderhalden . 

Allen 

Armstrong . . . 

Basset 

Browne .  . 


Bryan .... 


Bujard   and    Baier 

Claassen  (Hall  and  Rolfe) 

Cross  and  Bevan 

Cross  and  Bevan 

Czapek 

Deerr 

Emmerling 


Fischer,  E .  .  . 
Fischer,  F. . 
Fribourg 
Friihling.... 


Gange 


Geerligs . 
Geerligs . 


Gredinger 

Jago 

Konig.... 


Lafar.  .  . 
Landolt . 


Leach 

Lippmann 


Title 


Biochemisches  Handlexikon,  Vol.  II  (1911). 
Handbuch  der  Biochemischen  Arbeitsmeth- 

oden,  Vol  II  (1909).. 
Commercial    Organic     Analysis,     Vol.    I 

(1901). 
The  Simple  Carbohydrates  and  the  Gluco- 

sides  (1910). 
Guide    pratique    du    Fabricant    de    Sucre 

(1872). 
Chemical    Analysis    and    Composition    of 

American  Honeys   (1908).      Bull.   110, 

U.  S.  Bureau  of  Chemistry. 
Analyses   of   Sugar  Beets,    1905   to   1910, 

together  with  Methods  of  Sugar   De- 
termination (1911).      Bull.   146,  U.  S. 

Bureau  of  Chemistry. 
Hilfsbuch     fur      Nahrungsmittelchemiker 

(1900). 

Beet  Sugar  Manufacture  (1906). 
Cellulose  (1895). 

Researches  on  Cellulose,  1895-1900  (1901). 
Biochemie   der    Pflanzen,    Vol.    I    (1905). 
Cane  Sugar  (1911). 
Die  Zersetzung  stickstofffreier  organischer 

Substanzen  durch  Bakterien  (1902). 
Untersuchungen  uber  Kohlenhydrate  und 

Fermente  (1884-1908),  (1909). 
Handbuch    der    chemischen    Technologic, 

Vol.  II  (1902). 
L' Analyse  chimique  en  Sucreries  et  Raf- 

fineries  de  Cannes  et  Betteraves  (1907). 
Anleitung  zur  Untersuchung  der  fiir  die 

Zuckerindustrie  in   Betracht  kommen- 

den  Rohmaterialien,  Produkte,  Neben- 

produkte  und  Hilfssubstanzen  (1903). 
Lehrbuch  der  Angewandten  Optik  in  der 

Chemie.    Spectralanalyse,  Mikroskopie, 

Polarisation  (1886). 

Cane  Sugar  and  its  Manufacture  (1909). 
Methods    of    Chemical    Control    in    Cane 

Sugar  Factories  (1905). 
Die  Raffination  des  Zuckers  (1909). 
The  Technology  of  Bread  Making  (1911). 
Die  Untersuchung  landwirtschaftlich  und 

gewerblich  wichtiger  Stoffe  (1898). 
Technische  Mykologie  (1897-1907).   - 
Das    optische    Drehungsvermogen    organ- 
ischer   Substanzen    und    dessen    prak- 

tische  Anwendungen  (1898). 
Food  Inspection  and  Analysis  (1911). 
Die  Chemie  der  Zuckerarten  (1904).    i^ 


Vlll 


BIBLIOGRAPHY 


Author  or  Editor 
Maquenne 


Mittelstaedt  (Bourbakis) 


Pavy 

Plimmer 


Preston 
Rolfe.. 


Riimpler.  .  .  . 
Sherman .... 
Sidersky 


Sidersky , 

Sidersky, 
Spencer . 


Sykes  and  Ling. 
Tervooren . . 


Tollens. 


Tucker 

Van't  Hoff  (Marsh) . . . 

Walker 

Ware.. 


Wein  (Frew) 


Wiechmann 

Wiedemann  and  Ebert , 


Wiley.... 
Wiley.. 


Title 

Les  Sucres  et  leurs  principaux  Derives 
(1900). 

Technical  Calculations  for  Sugar  Works 
(1910). 

Physiology  of  the  Carbohydrates  (1894). 

The  Chemical  Changes  and  Products  Re- 
sulting from  Fermentations  (1903). 

The  Theory  of  Light  (1901). 

The  Polariscope  in  the  Chemical  Labora- 
tory (1905). 

Die  Nichtzuckerstoffe  der  Ruben   (1898). 

Methods  of  Organic  Analysis   (1912). 

Les  Densites  des  Solutions  Sucrees  a  dif- 
ferentes  Temperatures  (1908). 

Manuel  du  Chimiste  de  Sucrerie,  de  Raf- 
finerie  et  de  Glucoserie  (1909). 

Polarisation  et  Saccharimetrie  (1908). 

A  Handbook  for  Cane-Sugar  Manufac- 
turers and  their  Chemists  (1906). 

The  Principles  and  Practice  of  Brewing 
(1907). 

Methoden  van  Onderzoek  der  bij  de  Java 
Rietsuiker-Industrie  voorkomende  Pro- 
ducten  (1908). 

Kurzes  Handbuch  der  Kohlenhydrate 
(1895-8). 

A  Manual  of  Sugar  Analysis  (1905). 

Chemistry  in  Space  (1891) 

Introduction  to  Physical  Chemistry  (1903). 

Beet  Sugar  Manufacture  and  Refining 
(1905-7). 

Tables  for  the  Quantitative  Estimation  of 
the  Sugars  (1896). 

Sugar  Analysis  (1898). 

Physikalisches  Praktikum  mit  besonderer 
Beriicksichtigung  der  Physikalisch- 
Chemischen  Methoden  (1899). 

The  Principles  and  Practice  of  Agricultural 
Analysis,  Vol.  Ill  (1897). 

Official  and  Provisional  Methods  of  Analy- 
sis, Association  of  Official  Agricultural 
Chemists.  Bull.  107  (Revised)  U.  S. 
Bureau  of  Chemistry. 


PERIODICALS 


Abbreviation 

Am.  Chem.  Jour 

Am.  Sugar  Ind 

Analyst 

Ann 

Ann.  chim.  phys 

Archief  Java  Suiker  Ind.. 
Archiv  Pharm. . . 


Biochem.  Zeitschrift 

Bull,  assoc.  chim.  sucr.  dist. 


Title 

American  Chemical  Journal. 
American  Sugar  Industry. 
Analyst. 

Annalen  der  Chemie  (Liebig's). 
Annales  de  chimie  et  de  physique. 
Archief  voor  de  Java  Suiker  Industrie. 
Archiv  der  Pharmazie. 
Berichte  der  deutschen  chemischen  Gesell- 

schaft. 

Biochemische  Zeitschrift. 
Bulletin  de  I'association  des  chimistes  de 

sucrerie  et  de  distillerie  de  France  et 

des  colonies. 


BIBLIOGRAPHY 


Abbreviation 

Bull.  soc.  chim 

Centralblatt 

Centrbl.  Zuckerind 

Chem.  News 


Chemiker-Ztg. 
Compt.  rend.. 


Deut.  Zuckerind 

Dingier 's  Poly  tech.  Jour. 

Int.  Sugar  Jour 

J.  Am.  Chem.  Soc 

J.  Chem.  Soc 

J.  fabr.  sucre 

Jour,  f .  Landwirtsch 
J.  Ind.  Eng.  Chem 


J.  pharm 

J.  pharm.  chim. .  . 
J.  prakt.  Chem.  . 
J.  Soc.  Chem.  Ind. 

La.  Planter 

Land.  Vers.-Stat.. 


Monatshefte 

Mon.  scient 

Neue  Zeitschrif t 

Oest.-Ung.  Z.  Zuckerind. 

Pfliiger's  Archiv 


Pogg.  Ann 

Proceedings  A.  O.  A.  C 


Proceedings  Int.  Cong.  App.  Chem. 

Rec.  trav.  Pays-Bas 

Sitzungsber.  Wiener  Akad 

Stammer's  Jahresbericht . . 


Sucrerie  Beige 

West  Indian  Bull 

Wochenschr.  f.  Brauerei. .  , 

Z.  analyt.  Chem 

Z.  angew.  Chem 

Z.  Instrument 

Z.  physik.  Chem 

Z.  physiol.  Chem 

Z.  Spiritusind 

Z.  Unters.  Nahr.  Genussm. 


Z.  Ver.  Deut.  Zuckerind. 
Z.  Zuckerind.  Bohmen.. 


Title 

Bulletin  de  la  societe  chimique  de  France. 

Chemisches  Centralblatt. 

Centralblatt  fur  die  Zuckerindustrie. 

Chemical  News  and  Journal  of  Physical 
Science. 

Chemiker-Zeitung . 

Comptes  rendus  hebdomadaires  des  seances 
de  1'academie  des  sciences. 

Die  Deutsche  Zuckerindustrie 

Dingier 's  Polytechniches  Journal. 

The  International  Sugar  Journal. 

Journal  of  the  American  Chemical  Society. 

Journal  of  the  Chemical  Society  (London). 

Journal  des  fabricants  de  sucre. 

Journal  fur  Landwirtschaft. 

Journal  of  Industrial  and  Engineering 
Chemistry. 

Journal  de  pharmacie. 

Journal  de  pharmacie  et  de  chimie. 

Journal  fur  prakt  ische  Chemie. 

Journal  of  the  Society  of  Chemical  In- 
dustry. 

The  Louisiana  Planter-  and  Sugar  Man- 
ufacturer. 

Die  landwirthschaftlichen  Versuchs-Sta- 
tionen. 

Monatshefte  fiir  Chemie. 

Moniteur  scientifique. 

Neue  Zeitschrif  t  fiir  Riibenzuckerindustrie. 

Oesterreichisch-Ungarische  Zeitschrift  fiir 
Zuckerindustrie  und  Landwirthschaft. 

Pfliiger's  Archiv  fiir  die  gesammte  Physiol- 
ogic der  Menschen  und  der  Thiere. 

Poggendorff's  Annalen. 

Proceedings  of  the  Association  of  Official 
Agricultural  Chemists. 

Proceedings  of  the  International  Congress 
of  Applied  Chemistry. 

Recueil  des  travaux  chimiques  des  Pays- 
Bas. 

Sitzungsberichte  der  kaiserlichen  Akademie 
der  Wissenschaften,  Wien. 

Stammer's  Jahresbericht  iiber  die  Unter- 
suchungen  und  Fortschritte  auf  dem 
Gesamtgebiete  der  Zuckerfabrikation. 

La  Sucrerie  Beige. 

West  Indian  Bulletin. 

Wochenschrift  fiir  Brauerei. 

Zeitschrift  fiir  analytische  Chemie. 

Zeitschrift  fiir  angewandte  Chemie. 

Zeitschrift  fiir  Instrumentenkunde. 

Zeitschrift  fiir  physikalische  Chemie. 

Zeitschrift  fiir  physiologische  Chemie. 

Zeitschrift  fiir  Spirit usindustrie. 

Zeitschrift  fur  Untersuchung  der  Nahrungs- 
und  Genussmittel. 

Zeitschrift  des  Vereins  der  Deutschen 
Zuckerindustrie. 

Zeitschrift  fiir  Zuckerindustrie  in  Bohmen. 


TABLE   OF   CONTENTS 


PAGE 

PREFACE v 

BIBLIOGRAPHY vjj 

PART   I 

PHYSICAL  AND  CHEMICAL  METHODS  OF  SUGAR  ANALYSIS 1 

CHAP. 

I.   SAMPLING  OF  SUGAR  AND  SUGAR  PRODUCTS 3 

II.   DETERMINATION  OF  MOISTURE  IN  SUGARS  AND  SUGAR  PRODUCTS  BY 

METHODS  OF  DRYING 15 

III.  DENSIMETRIC  METHODS  OF  ANALYSIS 27 

IV.  PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER 50 

V.   POLARIZED  LIGHT,  THEORY  AND  DESCRIPTION  OF  POLARIMETERS  . . .  76 

VI.   THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS 108 

VII.   POLARISCOPE  ACCESSORIES 146 

VIII.   SPECIFIC  ROTATION  OF  SUGARS 172 

'    IX.   METHODS  OF  SIMPLE   POLARIZATION 194 

X.   METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION 263 

XI.   SPECIAL  METHODS  OF  SACCHARIMETRY 287 

XII.   MISCELLANEOUS  PHYSICAL  METHODS  AS  APPLIED  TO  THE  EXAMINA- 
TION OF  SUGARS 307 

XIII.  QUALITATIVE  METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS 333 

XIV.  REDUCTION  METHODS  FOR  DETERMINING  SUGARS 388 

XV.   SPECIAL  QUANTITATIVE  METHODS 449 

XVI.   COMBINED  METHODS  AND  THE  ANALYSIS  OF  SUGAR  MIXTURES.  ...  472 

XVII.   MISCELLANEOUS  APPLICATIONS 494 

PART  II 

THE  OCCURRENCE,  METHODS  OF  PREPARATION,  PROPERTIES  AND  PRINCIPAL 

REACTIONS  OF  THE  SUGARS  AND  ALLIED  DERIVATIVES 525 

XVIII.    CLASSIFICATION  OF  THE  SUGARS  AND  THEIR  FORMATION  IN  NATURE.  527 

XIX.   THE  MONOSACCHARIDES 535 

XX.   THE  DISACCHARIDES 643 

XXI.   THE  TRISACCHARIDES  AND  TETRASACCHARIDES 731 

XXII.   THE  AMINO  SUGARS  AND  THE  CYCLOSES 751 

XXIII.   THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 764 

APPENDIX  OF  SUGAR  TABLES 789 

INDEX..                                                                                xiii 


PAET   I 

PHYSICAL  AND   CHEMICAL  METHODS   OF 
SUGAK  ANALYSIS 


ANALYSIS 


CHAPTER  I 

SAMPLING   OF   SUGAR  AND   SUGAR  PRODUCTS 

IN  the  analysis  of  sugars  and  sugar  products,  special  stress  must  be 
laid  upon  the  correctness  of  sample.  Accuracy  in  analytical  details  is 
of  no  value  unless  the  portion  of  substance  weighed  out  for  examina- 
tion is  an  accurate  sample  of  the  entire  lot  of  product  in  question. 
While  the  chemist  is  not  always  charged  with  the  supervision  of  sam- 
pling, he  should,  nevertheless,  acquaint  himself  so  far  as  possible  with 
the  history  of  his  product  before  it  is  received..  In  this  way  he  may 
often  explain  differences  which  might  otherwise  be  attributed  to  mis- 
takes of  analysis.  A  few  introductory  pages  devoted  to  the  general 
subject  of  sampling  may,  therefore,  not  be  amiss. 

The  best  illustration  of  methods  of  sampling,  and  of  the  errors  con- 
nected therewith,  is  furnished  by  raw  cane  sugar.  The  sampling  of  this 
commodity  is  selected  first  and  discussed  in  somewhat  fuller  detail. 

SAMPLING  OF  RAW  SUGARS 

The  raw  sugar  imported  from  the  various  sugar-producing  countries 
comes  in  a  great  variety  of  forms.  Centrifugal  sugar,  from  Cuba, 
Porto  Rico,  and  most  of  the  West  Indian  Islands,  comes  in  300-lb. 
jute  bags;  sugar  from  the  Hawaiian  Islands  comes  in  125-lb.  bags; 
sugar  from  Java  comes  either  in  bags  or  large  cylindrical  baskets 
weighing  from  500  to  700  Ibs.;  sugar  from  the  Philippines  comes  in 
small  wicker  mats  weighing  about  50  Ibs.;  Muscovado  sugars,  which 
are  purged  by  draining  and  contain  much  molasses,  come  usually  in 
large  hogsheads.  In  addition  to  the  above  forms  of  package,  sugars 
come  occasionally  in  boxes,  barrels,  grass  mats,  ceroons,  and  other 
receptacles. 

The  need  for  carefully  prescribed  rules  in  sampling  sugar  becomes 
at  once  self-evident  when  we  consider  the  different  forms  of  the  package 
and  the  exceedingly  variable  character  of  the  sugar  which  may  be  con- 

3 


4  SUGAR  ANALYSIS 

tained  therein.  The  sugar,  for  example,  may  contain  lumps  of  higher 
or  lower  polarization  than  the  finer  part  of  the  product;  the  sugar  may 
also  retain  considerable  amounts  of  molasses,  sometimes  as  high  as 
30  per  cent,  which  drain  during  transit  or  storage  and  form  the  "  foots  " 
at  the  bottom  of  the  package.  The  difference  in  composition  between 
the  top  and  bottom  layers  of  a  hogshead  of  Muscovado  sugar,  which 
is  a  kind  that  " foots"  easily,  is  very  marked.  In  addition  to  the 
differences  in  composition  of  sugar  within  the  single  packages  are 
the  differences  in  composition  between  different  packages  of  the  same 
lot.  These  differences  may  be  the  result  of  manufacture;  they  may 
also  result  when  no  dunnage  is  used  for  covering  the  bottom  of  the 


Fig.  1.  —  Trier  for  sampling  sugar. 

holds  of  the  ships  used  for  transport,  with  the  result  that  the  bottom 
tiers  of  sugar  may  be  damaged  through  absorption  of  bilge  water.  In 
many  cases  the  top  tiers  of  sugar  suffer  the  damage,  as  when  sugars 
sweat  beneath  the  hatches;  the  vapors  from  the  warm  sugar  rise,  con- 
dense, and  then  drop  back  upon  the  upper  layers  of  the  cargo.  If  the 
packages  of  sugar  run  unevenly  it  is  difficult  to  secure  a  representative 
fraction  unless  every  container  is  sampled.  The  most  approved  method 
of  sampling  at  present  is  to  take  a  specimen  of  sugar  so  far  as  possible 
from  every  package.* 

Sugar  is  sampled  in  the  same  way  as  fertilizers  and  many  other 
commodities, — by  means  of  a  trier.  This  implement  (Fig.  1)  consists  of 
a  long  pointed  rod  of  steel  with  a  groove  or  spoon  upon  one  side.  A 

*  For  a  discussion  of  this  and  other  points  pertaining  to  methods  of  sampling 
raw  sugar  in  different  countries  see  paper  by  F.  G.  Wiechmann  (Int.  Sugar  Journ., 
9,  18-28)  read  before  the  Fifth  Meeting  of  the  International  Commission  for  Uni- 
form Methods  of  Sugar  Analysis,  Bern,  1906. 


SAMPLING  OF  SUGAR  AND  SUGAR  PRODUCTS 


thrust  of  the  trier  into  the  package  forces  the  sugar  along  its  pathway 
tightly  into  the  bowl  of  the  spoon;  the  sugar  thus  adhering,  after  the 
trier  is  withdrawn,  is  removed  by  the  thumb,  or  by  means  of  a  scraper, 
into  a  covered  bucket,  and  the  process  is  continued  until  a  sufficient 
number  of  packages  have  been  sampled  to  constitute  a  mix;  this 
number  may  vary,  according  to  the  size  of  lot  and  kind  of  sugar,  from 
one  package  to  several  thousand.  The  practice  of  the  New  York  Sugar 
Trade  is  to  mix  twice  daily,  and  in  no  case  is  a  sample  to  remain  un- 
mixed over  night. 

It  is  of  course  important  that  the  triers  of  the  different  workmen 
who  are  sampling  a  given  lot  of  sugar  should  be  exactly  alike,  es- 
pecially as  regards  the  dimensions  of  the  spoons.  The  specifications 
of  the  United  States  Treasury  Department  Regulations*  are  very  ex- 
plicit upon  this  point  and  give  the  following  dimensions  of  the  short, 
long,  and  barrel  triers. 

TABLE  I 

Giving  Dimensions  of  Triers  for  Sampling  Sugar 


Short  trier. 

Long  trier. 

Barrel  trier. 

Length  over  all 

Centimeters. 
40  6 

Centimeters. 

152  4 

Centimeters. 

104  0 

Length  of  spoon 

22  9 

132  1 

91  4 

Length  of  shank        ... 

17  8 

20  3 

12  7 

Length  of  handle     

26  7 

38  1 

30  5 

Width  of  spoon    

2  7 

2  5 

2  5 

Depth  of  spoon  

0  8 

1.3 

1.1 

Diameter  of  handle  

3.8 

3.8 

3.8 

According  to  the  United  States  Treasury  Department  Regulations,! 
"sugar  in  hogsheads  and  other  wooden  packages  shall  be  sampled  by 
putting  the  long  trier  diagonally  through  the  package  from  chime  to 
chime,  one  trierful  to  constitute  a  sample,  except  in  small  lots,  when  an 
equal  number  of  trierfuls  shall  be  taken  from  each  package  to  furnish 
the  required  amount  of  sugar  necessary  to  make  a  sufficient  sample. 
In  the  sampling  of  baskets,  bags,  ceroons,  and  mats  the  short  trier 
shall  be  used,  care  being  exercised  to  have  each  sample  represent  the 
contents  of  the  package." 

It  is  necessary  in  sampling  to  keep  the  triers  always  clean;  the  stick- 
ing of  sugar  to  the  bowl  of  the  spoon  is  especially  annoying  with  some 

*  Regulations  governing  the  weighing,  taring,  sampling,  classification,  and  polari- 
zation of  imported  sugars  and  molasses.  U.  S.  Treasury  Department,  Division  of 
Customs,  Document  No.  2470,  Art.  5. 

t  Loc.  cit.,  Art.  6. 


6  SUGAR  ANALYSIS 

kinds  of  sugar  under  certain  atmospheric  conditions  of  humidity. 
The  surface  of  the  metal  should  be  smooth  and  bright;  the  United 
States  Treasury  Regulations  attach  a  penalty  in  case  of  samplers  who 
neglect  this  precaution.  When  ready  for  making  the  composite  sample, 
the  contents  of  the  sugar  bucket  are  thoroughly  mixed;  the  cans  and 
bottles  to  receive  the  sample  are  compactly  filled,  labeled,  and  sealed, 
after  which  they  are  sent  to  the  chemists  who  are  to  make  the  polariza- 
tions. 

The  general  rule  in  sampling  sugar  is  that  the  package  shall  be 
stabbed  at  the  middle  to  the  center,  and  if  this  practice  is  conscien- 
tiously followed  it  will  give  no  doubt  as  fair  a  sample  as  can  be  secured 
under  the  hurried  conditions  of  discharging  a  cargo.  There  are  times, 
however,  when  it  is  impossible  to  follow  this  rule.  Sugar  which  has 
remained  for  a  long  time  in  storage  will  sometimes  solidify  upon  the 
approach  of  cold  weather  to  a  hard  mass  of  material  resembling  con- 
crete, a  circumstance  due  to  the  evaporation  of  moisture  and  cement- 
ing together  of  the  grain.  A  trier  is  almost  useless  under  these  con- 
ditions and  such  sugar  is  rarely  sampled  properly.  The  sugar  broken, 
or  chipped  off,  by  the  trier  from  the  outside  of  the  package  is  not  a 
correct  sample.  A  pickaxe  is  sometimes  resorted  to  with  hard  sugar  in 
order  to  open  a  passage  for  the  trier;  this  is  much  better  than  just 
skimming  the  outside,  but  is  far  from  satisfactory. 

To  eliminate  so  far  as  possible  the  errors  of  personal  equation  in 
sampling,  the  practice  of  the  New  York  Sugar  Trade  is  for  the  samplers 
of  buyer  and  seller  to  work  alternately  hour  by  hour;  the  one  party  in 
the  interval  of  rest  exercising  a  control  upon  the  operations  of  the 
other.  The  tendencies  to  draw  too  high  and  too  low  from  the  package 
are  thus  counterbalanced  and  the  personal  errors  equalized.  This 
method  seems  as  good  as  any  that  can  be  devised. 

The  liability  of  change  in  composition  of  the  product  during  sampling 
is  an  exceedingly  important  factor  in  the  valuation  of  any  commodity, 
and  more  important  perhaps  in  the  case  of  sugar  than  almost  any 
other  staple.  Raw  cane  sugar  upon  exposure  to  the  air  may  either 
absorb  or  lose  moisture  according  to  the  conditions  of  atmospheric 
humidity.  If  the  latter  be  very  high  or  low,  and  the  sugar  be  exposed 
to  the  air  for  any  great  length  of  time  during  drawing  or  mixing  the 
sample,  a  considerable  error  may  be  introduced  into  the  composition 
of  the  product.  The  buckets,  which  hold  the  samples  for  mixing, 
should  always  be  kept  tightly  covered;  this  precaution  will  reduce  the 
errors  from  absorption  and  evaporation  to  a  large  extent,  although  with 
present  methods  of  sampling  the  errors  from  this  source  will  never  be 


SAMPLING  OF  SUGAR  AND  SUGAR  PRODUCTS  7 

completely  eliminated.  On  rainy  days  sugar  is  rarely  sampled  at  the 
pier,  and  this  is  a  wise  precaution,  considering  the  rapidity  with  which 
sugar  absorbs  moisture  from  a  saturated  atmosphere.  No  matter  how 
pure  the  sugar,  there  will  be  absorption  under  such  conditions,  the 
amount  of  moisture  taken  up  depending  upon  the  initial  dryness  of  the 
sugar,  the  fineness  of  the  grain  and  the  hygroscopic  character  of  the  im- 
purities present. 

If  a  layer  of  sugar  be  placed  in  a  dish  over  water  under  a  closed 
bell  jar,  it  will  soon  absorb  moisture  enough  to  liquefy,  and,  according 
to  the  phase  rule,  this  absorption  of  moisture  will  continue  until  the 
pressures  of  water  vapor  for  solution  and  atmosphere  are  the  same. 
Theoretically  this  limit  is  infinity,  and  if  the  dish  under  the  bell  jar  be 
weighed  from  day  to  day  it  will  be  found  that  the  liquefied  sugar  will  con- 
tinue to  attract  moisture  as  long  as  one  cares  to  follow  the  experiment. 

If  the  atmosphere  is  not  completely  saturated,  the  absorption  of 
moisture  by  the  sugar  is  less  rapid,  and  with  further  decrease  in  humidity 
a  point  of  equilibrium  is  soon  reached  where  there  is  neither  absorption 
nor  evaporation.  This  point  of  equilibrium,  which  represents  equality 
of  vapor  pressure  between  the  moisture  of  the  sugar  and  the  air,  is 
different  for  different  sugars.  With  still  further  decrease  in  humidity 
the  sugar  begins  to  give  up  moisture,  the  rate  of  loss  increasing  as  the 
percentage  of  saturation  in  the  air  becomes  less  and  less. 

In  the  following  table  the  percentages  of  moisture  which  different 
sugars  gain  or  lose  at  100  per  cent  relative  humidity  and  at  60  per  cent 
relative  humidity  are  given,  and  the  changes  in  moisture  content  at 
the  point  of  equilibrium.  Two  grams  of  sugar  were  spread  in  a  thin 
layer  upon  a  watch  glass  and  the  change  in  weight  noted  after  regular 
intervals  of  time  in  one  case  over  water  under  a  bell  jar,  and  in  the 
other  case  upon  exposure  to  the  open  air.  The  temperature  of  experi- 
ments was  20°  C. 

TABLE  II 

Showing  Variations  in  Moisture  Content  of  Sugars 


Gain 

Change 

first 

first 

W        'f\ 

Residual 

Kind  of  sugar. 

Grain. 

Polar- 
ization. 

Mois- 
ture in 
sugar. 

hour, 
100  per 
cent 

hour, 
60  per 
cent 

Total  change  at 
point  of  equilib- 
rium. 

ityat 
equilib- 

mois- 
ture at 
equilib- 

humid- 

humid- 

rium. 

ity. 

ity. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Granulated  

Fine 

99.85 

0.10 

.78 

+0.03 

+0.01  (2  hours) 

56 

0.11 

Peruvian  
Porto  Rico  

Large 
Medium 

98.40 
96.40 

0.35 
1.31 

.09 
.40 

-0.09 
-0.54 

-0.14  (4  hours) 
-0.73  (2  hours) 

56 
62 

0.21 
0.58 

Philippine  mats. 
Cuban  molasses 

Fine 
Large 

87.45 
82.75 

3.12 
4.85 

.80 
.12 

-0.68 
-1.00 

-1.25  (6  hours) 
-2.42  (24  hours) 

56 

59 

1.87 
2.43 

8  SUGAR  ANALYSIS 

After  the  point  of  equilibrium  was  reached  upon  exposure  of  the 
above  sugars  to  the  air,  no  change  in  weight  was  noted  as  long  as  the 
temperature  and  relative  humidity  remained  unchanged;  with  fluctua- 
tions in  the  latter  corresponding  gains  and  losses  were  always  observed 
in  the  weight  of  the  sugars. 

As  to  the  absorption  of  moisture  by  sugars  under  excessive  humidity, 
no  relationship  can  be  traced  in  the  above  table  between  composition 
and  rate  of  absorption.  The  refined  granulated  sugar  and  the  low- 
grade  mats  have  equally  high  absorptive  powers  and  the  high-grade 
Peruvian  crystals  and  the  Cuban  molasses  sugar  equally  low  absorptive 
powers.  If  the  grain  of  these  sugars  is  compared,  however,  it  will  be 
seen  that  the  Peruvian  crystals  and  molasses  sugar  of  low  absorptive 
power  have  the  largest  grain  and  that  the  granulated  sugar  and  mat 
sugar  of  highest  absorptive  power  have  the  smallest  grain,  so  that  the 
physical  condition  of  the  sugar  is  a  very  important  factor  in  the  in- 
fluences which  bear  upon  absorption. 

As  to  the  evaporation  of  moisture  from  sugars  under  diminished 
humidity,  the  table  shows  a  very  definite  relationship  between  compo- 
sition and  rate  of  evaporation,  this  rate  being,  as  would  be  supposed, 
roughly  proportional  to  the  initial  moisture  content  of  the  sugar.  The 
percentage  of  residual  moisture  in  a  sugar  at  the  point  of  equilibrium  is  a 
function  of  the  hygroscopic  power  of  the  non-sugars,  and  is  greatest 
with  the  sugars  of  lowest  purity  (highest  molasses  content). 

The  point  of  greatest  importance,  in  the  bearing  which  these  re- 
sults have  upon  the  changes  in  composition  of  sugar  during  sampling, 
is  that  the  gain  or  loss  in  weight  through  absorption  or  evaporation  of 
moisture  is  most  rapid  at  the  beginning.  A  comparison  recently  made 
by  the  author  of  the  changes  in  moisture  content  which  sugars  undergo 
upon  exposure  to  the  air  shows  that  the  relationship  between  time  and 
loss  or  gain  in  moisture  follows  approximately  the  well-known  equation 

for  slow  reactions,  k  =  -  log  —    — ,  in  which  a  is  the  total  change  in 

t          CL        3J 

moisture  content  at  the  point  of  equilibrium,  x  the  loss  or  gain  in  weight 
at  the  end  of  any  given  time  t,  and  k  the  coefficient  of  velocity,  which 
is  a  constant  quantity  for  each  kind  of  sugar  under  fixed  conditions  of 
temperature  and  humidity. 

The  assumption  is  frequently  made  by  samplers  of  sugar  that  the 
errors  from  absorption  and  evaporation  of  moisture  by  the  sample  will 
equalize  one  another  in  the  long  run.  This,  however,  is  far  from  being 
the  case.  The  percentage  of  moisture  in  the  ordinary  grades  of  raw 
cane  sugar  is  considerably  above  the  equilibrium  point  for  the  average 


SAMPLING  OF  SUGAR  AND  SUGAR  PRODUCTS  9 

relative  humidity  at  the  port  of  New  York.  It  should  be  stated,  how- 
ever, that  the  loss  from  evaporation  under  the  prescribed  conditions  of 
sampling  is  nowhere  near  as  great  as  that  in  the  above  experiments, 
where  the  sugars  were  exposed  to  the  open  air  in  a  thin  layer.  The 
error,  however,  does  exist,  and  unless  due  care  is  exercised  by  the 
sampler  there  will  be  a  very  noticeable  difference  in  the  test. 

Another  occasional  source  of  error  in  the  sampling  of  sugar  is  the 
introduction  into  the  sample  of  particles  of  bag,  basket,  mat,  shavings 
of  barrels,  etc.,  which  are  introduced  from  the  package  by  the  trier. 
The  error  from  this  cause  is  usually  trifling;  there  are  times,  however, 
when  it  may  be  considerable.  Such  fragments  of  extraneous  matter 
do  not  belong  to  the  sugar,  and  it  devolves  upon  the  chemist  to  elimi- 
nate these  as  far  as  possible  before  weighing  out  the  sugar  for  polariza- 
tion. In  removing  foreign  material  from  sample  sugar  the  chemist 
must  carefully  discriminate,  however,  between  trash  which  belongs  to 
the  sugar  and  refuse  which  is  introduced  during  sampling. 

In  addition  to  removing  trash,  the  chemist  must  complete  the  mix- 
ing of  the  sample.  Lumps  must  be  crushed  and  thoroughly  incorporated 
with  the  rest  of  the  sample.  Even  samples  of  sugar,  which  are  well 
mixed  at  the  point  of  sampling,  must  be  mixed  again  at  the  laboratory 
owing  to  the  segregation  of  foots  at  the  bottom  of  the  can  or  bottle. 
A  neglect  of  such  mixing  of  the  sample  in  the  laboratory  is  a  cause  of 
frequent  differences  between  the  results  of  different  chemists.  This 
mixing  of  the  sample  must  be  done  with  the  utmost  dispatch  in  order 
to  avoid  the  errors  due  to  absorption  or  evaporation  already  mentioned. 
Mixing  of  the  sample  upon  paper  or  other  porous  substance  which 
would  absorb  moisture  is  especially  to  be  avoided.  The  method  of 
mixing  followed  by  the  New  York  Sugar  Trade  Laboratory  is  as  follows: 

When  samples  are  brought  into  the  laboratory  during  freezing 
weather,  the  cans  or  bottles  are  first  allowed  to  come  to  approximately 
the  room  temperature  before  opening  and  mixing.  This  is  done  to 
guard  against  condensation  of  moisture  upon  the  cold  sugar,  which 
would  lower  the  polarization.  The  sugar  is  poured  out  from  the  can 
upon  a  clean  sheet  of  plate  glass,  all  pieces  of  bagging,  baskets,  mats, 
etc.,  are  removed,  and  the  sample  is  thoroughly  mixed  with  a  clean 
steel  spatula.  Lumps  are  reduced  by  means  of  a  porcelain  roller  and 
incorporated  with  the  rest  of  the  sample.  The  plate  glass  and  porce- 
lain roller  are  cleaned  and  wiped  perfectly  dry  each  time  before  using. 
The  reduction  of  lumps  is  of  greatest  importance  in  securing  uniformity 
of  sample;  the  difference  in  polarization  between  the  lumps  and  the 
fine  portion  of  some  sugars  has  been  found  to  vary  several  per  cent. 


10  SUGAR  ANALYSIS 

The  can  from  which  the  sugar  was  taken  is  then  filled  about  three- 
fourths  full,  the  excess  of  sugar  upon  the  plate  being  discarded.  By 
leaving  a  little  empty  space  in  the  can,  the  weighing  out  of  the  sample 
by  the  chemist  is  facilitated. 

SAMPLING  OF  JUICES,  SIRUPS,  MOLASSES,  AND  LIQUID  SUGAR  PRODUCTS 

The  sampling  of  juices,  sirups,  molasses,  and  other  liquid  sugar 
products  involves  no  special  difficulties  provided  the  material  be  of  even 
composition  throughout  the  body  of  the  container.  A  large  glass  or 
metal  tube  may  serve  for  withdrawing  samples  of  molasses,  etc.,  from 
the  bungholes  of  hogsheads,  barrels,  and  casks,  when  other  means  are 
not  available.  Containers  of  different  capacity  should  be  sampled 
separately,  and  in  making  composite  samples  each  individual  fraction 
should  be  proportionate  to  the  total  amount  of  material  from  which  it 
was  drawn. 

The  regulations  of  the  United  States  Treasury  Department*  govern- 
ing the  sampling  of  molasses  are  as  follows:  "In  drawing  samples  of 
molasses,  care  shall  be  taken  to  secure  a  fair  representation  and  an 
equal  amount  of  the  contents  from  each  package.  Packages  of  the 
same  size  shall  be  sampled  in  groups  of  not  more  than  25;  samples 
from  all  of  the  packages  of  each  group  being  put  into  a  bucket.  An 
accurate  tally  shall  be  kept  and  with  each  bucket  shall  be  reported  the 
number  of  packages  the  samples  therein  represent.  The  dock  list 
accompanying  the  sample  buckets  shall  convey  the  same  information 
and  account  for  every  package  of  the  mark.  Packages  of  different  size, 
although  invoiced  and  permitted  under  the  same  mark,  shall  be  sepa- 
rately sampled,  tested,  and  returned  for  classification.  Molasses  dis- 
charged from  tank  vessels  shall  be  sampled  as  it  is  pumped  from  the 
tanks,  a  sample  of  uniform  quantity  being  drawn  at  either  regular 
intervals  of  approximately  fifteen  minutes  or  for  every  5000  gallons 
discharged." 

In  sampling  the  juices  from  mills  and  diffusion  batteries  in  sugar 
factories,  various  automatic  sampling  devices  have  been  devised  for  the 
purpose  of  securing  a  sample  of  the  main  body  of  juice  at  each  instant 
of  tune.  Coomb's  drip  sampler  (Fig.  2)  is  an  illustration  of  such  a  de- 
vice. A  defect  of  such  automatic  contrivances  is  that  they  do  not  always 
give  a  flow  of  sample  proportionate  to  the  total  amount  of  juice,  f 

*  Loc.  cit.,  Art.  16. 

t  A  very  efficient  automatic  liquid  sampler  is  described  by  G.  L.  Spencer  in  the 
J.  Ind.  Eng.  Chem.,  2,  253;  3,  344. 


SAMPLING  OF  SUGAR  AND  SUGAR  PRODUCTS 


11 


In  grinding  sugar  cane,  when  it  is  desired  to  test  the  work  of  macera- 
tion or  to  determine  the  relative  efficiency  of  each  mill,  the  juices  from 
the  several  sets  of  rollers  are  sampled  and  analyzed  separately,  the 
results  of  the  work  enabling  the  chemist  to  calculate  the  composition 
of  the  so-called  "normal"  juice  or  to  determine  the  extracting  power 


JUICE  PIPE 


A. — |  TO  |  INCH  VALVE. 
B,— STRONG  RUBBER  TUBE  CON- 
NECTING PIPE  LEADING  FROM"A"WITH 

C, —  A  GLASS  T-TUBEjTO  CINCHES 
INSIDE  DIAMETER. 

D,  — SHORT  ARM  OF  T,  FROM  WHICH 
THE  SAMPLE  IS  TO  BE  LED  INTO  AN 
APPROPRIATE  RECEIVER. 


Fig.  2.  —  Coomb's  apparatus  for  sampling  sugar  juices. 

of  each  mill.  This  phase  of  sampling  belongs,  however,  to  the  subject 
of  sugar-house  control,  and  the  chemist  is  referred  to  the  special  treatises 
by  Spencer,  Prinsen  Geerligs,  Deerr,  and  others. 

ERRORS  OF  SAMPLING  DUE  TO  SEGREGATION  OF  SUGAR  CRYSTALS 

A  serious  error  in  the  sampling  of  liquid  sugar  products  is  often 
occasioned  by  the  crystallization  and  separation  of  sugar  within  the 
container.  The  deposition  of  sucrose  crystals  from  molasses,  and  from 
maple,  cane,  and  sorghum  sirups,  is  an  example  of  this;  the  granula- 
tion of  strained  honey  through  separation  of  crystallized  glucose  is 
another  illustration.  Containers  of  molasses,  sirup,  and  honey  fre- 
quently have  a  compact  layer  of  crystals  upon  the  bottom.  Samples 
taken  from  the  liquid  surface  and  from  the  crystalline  deposits  of  such 
products  will  show  the  greatest  difference  in  composition.  It  is  there- 
fore necessary  to  mix  thoroughly  the  contents  of  a  container  before 
sampling.  In  the  laboratory  the  crystallized  sugar  in  a  sample  of 
sirup,  molasses,  or  honey  should  be  redissolved  by  gentle  warming 


12  SUGAR  ANALYSIS 

before  beginning  the  analysis.  This  is  impracticable,  however,  in 
sampling  these  products  in  bulk  from  casks  or  hogsheads,  and  the  most 
that  the  sampler  can  do  is  to  mix  the  contents  as  well  as  possible  by 
shaking  and  stirring. 

The  sampling  of  leaky  containers,  which  allow  the  escape  of  liquid 
but  retain  all  crystallized  solids,  is  a  fruitful  cause  of  wide,  and  often 
puzzling,  discrepancies  in  analytical  results. 

ERRORS  OF  ANALYSIS  DUE  TO  CHANGE  IN  COMPOSITION  OF  SAMPLES 

Owing  to  the  liability  of  sugar  products  to  change  in  composition 
through  evaporation  or  absorption  of  moisture  and  through  decomposi- 
tion by  the  action  of  enzymes  or  microorganisms,  it  is  important  that 
analyses  be  begun  as  soon  as  possible  after  samples  are  received.  It 
happens,  however,  in  many  cases  that  samples  must  be  sent  for  a  long 
distance,  or  stored  for  a  considerable  time,  before  examination  can  be 
made;  the  long  storage  of  products  is  often  necessary,  as  in  the  case  of 
reserve  samples  which  are  retained  for  the  purpose  of  confirming  an 
original  analysis  in  the  event  of  doubt  or  dispute.  The  sources  of  error 
from  change  in  composition  of  samples  will  be  briefly  considered. 

Changes  in  Composition  of  Samples  through  Evaporation  or 
Absorption  of  Moisture.  —  Changes  in  composition  due  to  this 
cause  are  prevented  by  hermetically  sealing  the  samples  in  a  perfectly 
tight  container.  If  cans  are  employed  all  joints  and  connections  should 
be  soldered;  cans  of  swaged  metal,  free  from  seams,  are  very  desirable, 
but  it  has  not  been  found  possible  as  yet  to  manufacture  these  in  large 
sizes.  The  covers  should  fit  the  cans  closely  and  the  space  between 
the  two  should  be  sealed  by  means  of  melted  paraffin  or  by  a  band  of 
adhesive  tape.  In  many  respects  wide-mouth  glass  bottles  or  jars  are 
the  best  containers  for  samples;  the  stoppers  or  corks  of  these  should 
be  sealed  by  melted  paraffin  or  wax. 

In  a  series  of  experiments  by  Stanek  *  upon  the  drying  out  of  sam- 
ples of  raw  beet  sugar  in  unsealed  cans,  the  average  daily  evaporation 
of  moisture  for  1  month  was  0.0115  per  cent;  when  the  covers  of  the 
cans  were  sealed  with  adhesive  tape  (leucoplast)  the  average  daily  evap- 
oration for  1  month  was  reduced  to  0.0006  per  cent.  This  loss  from 
evaporation  is  of  course  not  evenly  distributed,  but  is  greatest  during 
the  first  few  days.  Samples  of  raw  cane  sugar  kept  in  covered  but 
unsealed  cans  frequently  show  a  daily  increase  in  polarization,  through 
loss  of  moisture,  of  from  0.05  to  0.10  sugar  degrees  during  the  first  days 
of  storage. 

*  Z.  Zuckerind.     Bohmen,  34,  155. 


SAMPLING  OF  SUGAR  AND  SUGAR  PRODUCTS  13 

Changes  in  Composition  of  Samples  through  Action  of  Enzymes.  — 

Changes  in  composition  due  to  this  cause  are  frequently  noted  during 
the  storage  of  plant  substances,  such  as  grains,  seeds,  fruits,  tubers,  etc. 
The  change  may  consist  in  an  inversion  of  sucrose  by  action  of  invertase, 
in  a  conversion  of  starch  by  action  of  diastase,  in  a  modification  of 
gums,  hemicelluloses,  etc.,  by  action  of  other  enzymes,  or  in  a  loss  of 
sugars  through  respiration.  It  is  impossible  to  preserve  untreated 
plant  materials  of  the  above  description  for  any  length  of  time  without 
change  in  composition,  although  the  rate  of  change  may  be  greatly 
retarded  by  cold  storage.  Heating  the  samples  before  storing  will 
destroy  enzymes,  but  has  the  disadvantage  in  some  cases  of  causing 
inversion  or  of  liquefying  and  saccharifying  starch.  Freezing  the 
material  may  suspend  enzyme  action  for  the  time,  but  may  on  the  other 
hand  incite  changes  of  a  different  character,  as  in  the  production  of 
sucrose  from  starch  in  frozen  potatoes. 

When  samples  of  fresh  plant  materials,  which  are  liable  to  undergo 
enzymic  decomposition,  cannot  be  analyzed  immediately,  an  effective 
method  of  preventing  change  is  to  weigh  out  a  quantity  of  the  finely 
reduced  substance  and  preserve  in  a  stoppered  jar  or  bottle  by  the 
addition  of  alcohol.  An  excess  of  alcohol  (over  50  per  cent)  destroys 
the  action  of  enzymes,  and  samples  thus  preserved  do  not  undergo  any 
change  in  composition  after  many  months'  standing. 

Changes  in  composition  through  enzyme  action  may  also  occur  in 
cold-strained  honey.  It  has  happened  in  the  author's  experience  that 
a  bottle  of  such  honey,  which  contained  over  20  per  cent  sucrose  at  the 
time  of  sampling,  contained  after  4  months'  storage  less  then  10  per  cent; 
in  a  second  sample  of  the  same  honey,  which  was  kept  in  a  warm  labora- 
tory during  the  same  period,  the  sucrose  was  almost  completely  in- 
verted. The  inversion  was  probably  due  to  an  invertase  secreted  by 
the  bees.  The  action  of  enzymes  in  such  products  as  honey  may  be 
destroyed  by  heating  the  sample  to  a  temperature  of  80°  C. 

Changes  in  Composition  of  Samples  through  Action  of  Micro- 
organisms. —  The  effect  of  yeasts,  moulds,  and  bacteria  in  changing 
the  composition  of  sugar  products  is  well  known.  While  the  conditions 
for  the  development  of  microorganisms  are  most  favorable  in  such 
dilute  media  as  juices  and  musts,  they  may  also  cause  deterioration  in 
such  concentrated  products  as  molasses  and  sugar.  The  fermentation 
of  such  a  thick  menstruum  as  molasses,  however,  is  confined  entirely  to 
the  surface,  which,  through  the  attraction  of  hygroscopic  moisture,  be- 
comes dilute  enough  to  favor  microorganic  growth.  The  same  is  true 
of  raw  sugars;  the  film  of  molasses  coating  the  crystals  undergoes  a 


14 


SUGAR  ANALYSIS 


gradual  fermentation,  with  the  result  that  the  underlying  sucrose  is 
slowly  dissolved  and  inverted. 

The  changes  which  may  occur  as  a  result  of  fermentation  in  stored 
samples  of  raw  cane  sugar  may  be  seen  from  the  following  polarizations 
made  by  Browne*  at  the  Louisiana  Sugar  Experiment  Station  upon 
several  samples  of  Cuban  Centrifugal  sugars  after  keeping  9  months  in 
the  can. 

TABLE  III 
Showing  Deterioration  of  Sugar  Samples  in  Storage 


Number. 

April,  1904. 

January,  1905. 

Decrease. 

Polarization. 

Polarization. 

1 

96.50 

95.60 

0.90 

2 

96.05 

95.00 

1.05 

3 

95.50 

93.20 

2.30 

4 

94.20 

91.70 

2.50 

5 

97.15 

94.60 

2.55 

6 

93.95 

91.10 

2.85 

7 

94.70 

91.20 

3.50 

8 

95.00 

91.20 

3.80 

9 

95.90 

91.50 

4.40 

10 

96.80 

90.70 

6.10 

11 

96.20 

89.00 

7.20 

Average 

95.63 

92.25 

3.38 

The  preservation  of  sugars  and  sugar  products  against  micro- 
organisms by  sterilization  is  not  always  desirable  on  account  of  the 
changes  which  the  high  temperature  may  produce  in  the  physical  and 
chemical  properties  of  the  sample.  Sterilization  of  sugar  products  in 
order  to  be  effective  must  be  repeated  upon  several  successive  days 
owing  to  the  extreme  resistance  of  many  spores  to  a  single  heating. 

The  preservation  of  liquid  sugar  products  such  as  juices,  musts, 
sirups,  etc.,  is  sometimes  effected  by  adding  0.05  per  cent  of  formalde- 
hyde solution  (40  per  cent  strength)  or  0.02  per  cent  of  mercuric  chloride. 

The  preservation  of  succulent  plant  substances,  such  as  pulp  of 
fruits,  etc.,  is  best  accomplished  by  treating  a  weighed  portion  of  the 
sample  with  alcohol  in  a  stoppered  jar  or  bottle,  in  the  manner  pre- 
viously described. 

Other  essentials  pertaining  to  the  sampling  of  sugar-containing 
materials  will  be  described  elsewhere. 


*  Bull.  91,  Louisiana  Sugar  Expt.  Station,  p.  103. 


CHAPTER  II 

DETERMINATION   OF   MOISTURE  IN   SUGARS  AND   SUGAR  PRODUCTS 
BY  METHODS   OF  DRYING 

THE  accurate  determination  of  moisture,  in  some  respects  the 
most  simple  of  analytical  operations,  is  frequently  one  of  the  most 
difficult  determinations  which  the  sugar  chemist  is  called  upon  to 
make.  Among  the  chief  difficulties  which  confront  the  chemist  in  de- 
termining the  moisture  content  of  sugar  products  by  the  ordinary 
methods  of  drying,  may  be  mentioned:  (1)  the  very  hygroscopic  nature 
of  many  sugar-containing  materials  and  the  retention  of  water  by  ab- 
sorption or  occlusion;  (2)  the  extreme  sensitiveness  of  some  sugars, 
notably  fructose,  to  decomposition  at  temperatures  between  80°  and 
100°  C.,  with  splitting  off  of  water  and  other  volatile  products;  (3) 
the  liability  of  many  impure  sugar-containing  substances  to  absorb 
oxygen  during  drying,  with  formation  of  acids  and  other  decomposition 
products.  The  moisture  determination  is  further  complicated  by  the 
fact  that  many  sugars,  as  maltose,  lactose,  and  raffinose,  retain  variable 
amounts  of  water  of  crystallization  under  different  conditions  of  drying, 
so  that  the  chemist  is  not  always  certain  —  even  when  no  further  loss 
of  weight  occurs  in  the  oven  —  as  to  the  exact  amount  of  moisture 
which  may  be  retained  in  a  hydrated  form. 

In  the  following  description  of  processes  for  determining  moisture, 
methods  will  be  given  for  a  number  of  typical  substances.  The  first 
class  of  methods  to  be  described  is  intended  only  for  products  which 
are  stable  at  100°  to  110°  C.  The  determination  of  moisture  in  cane 
sugar  is  taken  as  an  illustration. 

DETERMINATION  OF  MOISTURE  IN  CANE  SUGAR 

Refined  sugar,  raw  beet  sugar,  and  the  superior  grades  of  raw  cane 
sugar  are  dehydrated  successfully  by  drying  2  to  5  gms.  of  the  finely 
powered  sample  in  a  thin  layer  for  2  to  3  hours  in  a  boiling-water  oven 
and  then  heating  in  a  special  oven  for  1  hour  at  105°  to  110°  C.  The 
sugar  is  cooled  in  a  desiccator,  and,  after  determining  the  loss  in  weight, 
reheated  at  105°  to  110°  C.  for  another  hour.  The  process  is  con- 
tinued until  successive  heatings  cause  no  further  loss. 

15 


16  SUGAR  ANALYSIS 

For  weighing  out  the  sugar  flat-bottomed  aluminum,  nickel,  or 
platinum  dishes  may  be  used;  clipped  watch  glasses  are  also  con- 
venient. (See  Figs.  3  and  4.)  With  lower-grade  sugars,  which  con- 
tain hygroscopic  salts  and  other  impurities,  the  dish  should  be  covered 
during  weighing.  For  many  purposes  of  dehydration  low  glass- 


Fig.  3  Fig.  4  Fig.  5 

Receptacles  for  drying  sugar. 

stoppered  weighing  bottles  (Fig.  5)  are  well  suited,  and  prevent  loss  of 
moisture  in  weighing  out  the  sample  and  absorption  of  moisture  in 
weighing  the  dry  residue. 

The  official  method*  of  the  Association  of  Official  Agricultural 
Chemists  for  determining  moisture  in  sugars  prescribes  drying  in  a  hot- 
water  oven  for  10  hours.  With  some  sugars,  more  especially  those  of 
large  grain,  there  is  danger  of  occlusion  and  retention  of  water,  and  the 
last  traces  of  moisture  may  not  be  expelled  at  98°  to  100°  C.  The 
method  of  the  International  Commission  f  upon  Unification  of  Methods 
for  Sugar  Analysis  prescribes  in  case  of  normal  beet  sugars  drying  at 
105°  to  110°  C.;  this  temperature  is  sufficient  to  expel  the  last  traces 
of  occluded  water  and  is  not  attended  with  sufficient  decomposition 
to  affect  the  weight  of  product.  The  temperature  of  drying  by  this 
method  should  not  exceed  110°  C. 

For  maintaining  a  uniform  temperature  of  105°  to  110°  C.  a  glycerin 
or  salt-water  bath  may  be  used.  The  Soxhlet  drying  oven,  shown 
in  Fig.  6,  is  favored  by  many  for  rapid  drying.  The  bath  is  filled 
with  a  salt  solution  of  the  desired  boiling  point,  and  closed  with 
the  condenser  B.  The  material  is  placed  in  the  oven  and  the  door 
tightly  clamped  at  A.  Upon  lighting  a  gas  flame  in  the  chimney  C  a 
current  of  air  is  generated  through  the  flues  at  F,  and,  after  being 
heated  by  the  boiling  salt  solution,  passes  forward  from  the  back  of 
the  drying  chamber  over  the  material  to  be  dried.  The  thermometer 
T  indicates  the  temperature  of  the  drying  chamber.  By  raising  the 

*  Bull.  107  (revised),  U.  S.  Bureau  of  Chem.,  p.  64. 
t  Proceedings,  Paris  Convention,  1900. 


DETERMINATION  OF  MOISTURE  IN  SUGARS  17 


Fig.  6.  —  Soxhlet  drying  oven. 


Fig.  7.  —  Wiesnegg  hot-air  oven  with  Reichert  gas  regulator. 


18  SUGAR  ANALYSIS 

temperature  gradually  to  100°  C.  and  then  to  105°  C.  for  the  final  dehy- 
dration, the  time  of -drying  by  the  Soxhlet  oven  may  be  reduced  hi 
many  cases  to  less  than  an  hour.    A  mixture  of  glycerine  and  water  of 
the  desired  boiling  point  is  less  liable  to  corrode  the  metal  of  the  oven 
than  the  salt  solution,  and  is  preferred  by  many  for  this  reason. 

In  case  a  hot-air  oven  is  used  for  drying  at  105°  to  110°  C., 
the  temperature  should  be  governed  by  means  of  a  gas  regulator.  A 
Wiesnegg  hot-air  oven  with  porcelain  inner  chamber  and  glass  door  is 
a  very  suitable  type.  Illustration  with  Reichert  gas  regulator  is  shown 
in  Fig.  7.  In  using  hot-air  ovens,  where  considerable  variations  in 
temperature  are  liable  to  occur  through  unequal  distribution  of  heat, 
the  exact  temperature  of  drying  should  be  determined  by  a  thermom- 
eter placed  near  the  material  under  examination. 

DETERMINATION  OF  MOISTURE  IN  SIRUPS,  MOLASSES,  MASSECUITES, 
ETC.,  WHEN  FRUCTOSE  is  ABSENT  OR  PRESENT  ONLY  IN  TRACES 

For  dehydrating  sirups,  molasses,  massecuites,  and  other  sugar- 
containing  substances,  which  contain  but  little  or  no  fructose,  the 
method  of  drying  previously  described  may  be  used.  The  material, 
however,  should  first  be  absorbed  upon  dry  sand,  pumice  stone,  or 
asbestos  in  order  to  facilitate  the  removal  of  the  large  excess  of  water. 
The  following  provisional  methods*  of  the  Association  of  Official  Agri- 
cultural Chemists  are  recommended  for  drying  the  semiliquid  products 
of  this  class: 

Drying  upon  Pumice  Stone.  —  "Prepare  pumice  stone  in  two  grades 
of  fineness.  One  of  these  should  pass  through  a  1-mm.  sieve,  while 
the  other  should  be  composed  of  particles  too  large  for  a  millimeter 
sieve,  but  sufficiently  small  to  pass  through  a  sieve  having  meshes 
6  mm.  in  diameter.  Make  the  determination  in  flat  metallic  dishes  or 
in  shallow,  flat-bottom  weighing  bottles.  Place  a  layer  of  the  fine 
pumice  stone  3  mm.  in  thickness  over  the  bottom  of  the  dish  and  upon 
this  place  a  layer  of  the  coarse  pumice  stone  from  6  to  10  mm.  in  thick- 
ness. Dry  the  dish  thus  prepared  and  weigh.  Dilute  the  sample  with 
a  weighed  portion  of  water  in  such  a  manner  that  the  diluted  material 
shall  contain  from  20  to  30  per  cent  of  dry  matter.  Weigh  into  the 
dish,  prepared  as  described  above,  such  a  quantity  of  the  diluted  sample 
as  will  yield,  approximately,  1  gm.  of  dry  matter.  Use  a  weighing 
bottle  provided  with  a  cork  through  which  a  pipette  passes  if  this 
weighing  cannot  be  made  with  extreme  rapidity.  Place  the  dish  in. 

*  Bull.  107  (revised),  U.  S.  Bureau  of  Chem.,  p.  64. 


DETERMINATION  OF  MOISTURE  IN  SUGARS  19 

a  water  oven  and  dry  to  constant  weight  at  the  temperature  of  boil- 
ing water,  making  trial  weighings  at  intervals  of  2  hours.  In  case  of 
materials  containing  much  levulose  or  other  readily  decomposable 
substances,  conduct  the  drying  in  vacuo  at  about  70°  C." 

Drying  upon  Quartz  Sand.  —  "  In  a  flat-bottom  dish  place  6  to  7  gms. 
of  pure  quartz  sand  and  a  short  stirring  rod.  Dry  thoroughly,  cool  in 
a  desiccator,  and  weigh.  Then  add  3  or  4  gms.  of  the  molasses,  mix 
with  the  sand,  and  dry  at  the  temperature  of  boiling  water  for  from 
8  to  10  hours.  Stir  at  intervals  of  an  hour,  then  cool  in  a  desiccator, 
and  weigh.  Stir,  heat  again  in  the  water  oven  for  an  hour,  cool,  and 
weigh.  Repeat  heating  and  weighing  until  loss  of  water  in  one  hour 
is  not  greater  than  3  mgs. 

"  Before  using,  digest  the  pure  quartz  sand  with  strong  hydrochloric 
acid,  wash,  dry,  ignite,  and  keep  in  a  stoppered  bottle." 

In  order  to  prevent  the  occlusion  or  retention  of  water  in  the  dried 
residue,  an  hour  of  drying  at  105°  to  110°  C.  is  advisable  as  under 
the  determination  of  moisture  in  sugar. 

Pellet's  Method  of  Determining  Moisture.*  —  In  a  method  of 
drying  considerably  employed  in  France,  Pellet  nickel  capsules,  85  mm. 


3 


Fie;.  8  Fig.  9 

Pellet  capsule  for  drying  liquid  sugar  products. 

wide  and  20  mm.  deep,  are  used.  The  capsule  has  a  circular  depression 
in  the  center  as  shown  in  Fig.  8.  Each  capsule  is  provided  with  a 
cover  having  a  small  notch  at  the  edge  for  the  passage  of  a  small  stirring 
rod. 

The  raised  border  of  the  capsule  is  filled  with  fine  particles  (about 
1  mm.  diameter)  of  freshly  ignited  pumice  stone,  employing  an  inverted 
funnel  as  shown  in  Fig.  9.  The  funnel  is  then  removed,  the  cover  and 
stirring  rod  put  in  place,  and  the  capsule  weighed.  Three  grams  of 
the  substance  to  be  dried  are  then  weighed  in  the  central  depression  of 
the  capsule;  5  c.c.  of  hot  distilled  water  are  then  added,  and  after 
*  Fribourg's  "  Analyse .chimique"  (1907),  pp.  90-94. 


20 


SUGAR  ANALYSIS 


stirring  to  dissolve  all  soluble  matter,  the  capsule  is  slightly  inclined 
on  different  sides  to  permit  absorption  of  the  solution  by  the  pumice 
stone.  The  process  is  repeated  with  3  c.c.  more  of  hot  water  and  then 
with  2  c.c.  The  contents  of  the  capsule  are  then  spread  evenly  over 
the  entire  bottom  and  dried  in  any  suitable  oven  at  a  final  temperature 
of  102°  to  105°  C. 

In  case  of  products  containing  even  traces  of  free  acid,  a  drop  or 
two  of  strong  ammonia  is  added.  The  excess  of  ammonia  is  expelled 
and  the  amount  retained  in  the  combined  form  is  usually  too  small 
to  be  regarded.  If  the  free  acid  is  not  neutralized,  inversion  of  sucrose 
may  result,  with  the  introduction  of  a  considerable  error  in  the  deter- 
mination. 

DETERMINATION  OF  MOISTURE  IN  PRODUCTS  WHICH  CONTAIN  FRUCTOSE 

Owing  to  the  susceptibility  of  fructose  to  decomposition  in  presence 
of  water  at  temperatures  much  above  70°  C.,  the  methods  previously 
described  are  not  applicable  to  the  determination  of  moisture  in  such 
products  as  honey,  sugar-cane  molasses,  jams,  fruit  products,  and 
other  similar  substances.  The  error  which  may  result  from  this  source 
may  be  seen  from  the  following  experiment  by  Carr  and  Sanborn  upon 
dehydrating  a  solution  containing  17.75  per  cent  of  fructose.  The 
solution  was  dried  upon  pumice  stone  in  flat-bottomed  dishes  at  100°  C. 
in  air. 


Hours  of  drying. 

Per  cent  of  solids. 

1 

19.02 

2 

18.53 

3 

18.57 

4 

18.16 

5 

17.42 

6 

17.34 

8 

16  90 

It  is  seen  that  the  per  cent  of  solids  after  5  hours'  drying  is  lower 
than  the  actual  amount  of  fructose  taken. 

Methods  of  Drying  in  Vacuum.  —  The  susceptibility  of  many 
sugar  products  to  decomposition  at  100°  C.  in  the  air  induced  Scheibler 
in  1876  to  propose  drying  in  vacuum.  Weisberg*  in  1894,  and  Carr 
and  Sanborn f  in  1895,  further  emphasized  the  necessity  of  vacuum 
drying;  and  at  present  dehydration  at  low  temperature  under  reduced 

*  Bull,  assoc.  chim.  sucr.  dist.,  11,  524. 

t  Bull.  47,  U.  S.  Bureau,  of  Chem.,  pp.  134-151. 


DETERMINATION  OF  MOISTURE  IN  SUGARS  21 

atmospheric  pressure  is  the  only  recognized  method  for  the  accurate 
determination  of  moisture  in  fructose-containing  materials. 

Carr  and  Sanborn's  Method.  —  Many  methods  have  been  devised 
for  drying  sugar  solutions  in  vacuum.  The  following  process  is  the 
one  described  by  Carr  and  Sanborn,*  who  have  employed  their  method 
successfully  upon  the  widest  range  of  materials,  such  as  fructose  solu- 
tions, honey,  molasses,  sorghum  and  maize  juices,  etc. 

"  Select  clean,  fine-grained  pumice  stone  and  divide  into  fragments 
the  size  of  No.  4  shot.  Pass  the  dust  through  a  40-mesh  sieve  and 
treat  separately  from  the  larger  particles.  Digest  hot  with  2  per  cent 
sulphuric  acid  and  wash  until  the  last  trace  of  acid  disappears  from  the 
wash  water.  Owing  to  the  ready  subsidence  of  the  material,  the  wash- 
ing may  be  accomplished  rapidly  by  decantation.  After  complete 
washing,  place  the  material,  wet,  in  a  Hessian  crucible,  and  bring  to 
redness  in  a  monitor  or  other  convenient  furnace.  When  complete 
expulsion  of  water  is  assured,  place,  hot,  in  a  desiccator,  or  direct  into 
the  drying  dishes  if  desired  for  use  immediately.  In  loading  the  dishes 
place  a  thin  layer  of  the  dust  over  the  bottom  of  the  dish  to  prevent 
contact  of  the  material  to  be  dried  with  the  metal;  over  this  layer 
place  the  larger  particles,  nearly  filling  the  dish.  If  the  stone  has  been 
well  washed  with  the  acid,  no  harm  may  result  from  placing  the  dish 
and  stone  over  the  flame  for  a  moment  before  placing  in  the  desiccator 
preparatory  to  weighing. 

"  If  the  material  to  be  dried  is  dense,  dilute  until  the  specific  gravity 
is  in  the  neighborhood  of  1.08  by  dissolving  a  weighed  quantity  in  a 
weighed  quantity  of  water.  (Alcohol  may  be  substituted  in  material 
not  precipitable  thereby.)  Of  this,  2  to  3  gms.  may  be  distributed 
over  the  stone  in  a  dish,  the  area  of  which  is  in  the  neighborhood  of 
3  sq.  in.,  or  1  gm.  for  each  square  inch  of  area.  Distribute  this  material 
uniformly  over  the  stone  by  means  of  a  pipette  weighing  bottle  (weigh- 
ing direct  upon  the  stone  will  not  answer),  ascertaining  the  weight 
taken  by  difference. 

"  Place  the  dishes  in  a  vacuum  oven,  in  which  may  be  maintained  a 
pressure  of  not  more  than  5  in.  mercury,  absolute.  The  form  of  oven 
is  not  material  so  long  as  the  moisture  escapes  freely  by  passing 
a  slow  current  of  air  (dried)  beneath  the  shelf  supporting  the  dishes. 
The  temperature  must  be  maintained  at  70°  C.  and  the  vacuum  at 
25  in. 

"  All  weighings  must  be  taken  when  the  dish  is  covered  by  a  ground 
plate,  and  the  open  dish  must  not  be  exposed  to  the  air  longer  than 
*  Bull.  47,  U.  S.  Bureau  of  Chem.,  pp.  134-151. 


22 


SUGAR  ANALYSIS 


absolutely  necessary.     Weighings  should  be  made  at  intervals  of  2  or 
3  hours." 

The  following  triplicate  series  of  experiments  were  made  by  Carr 
and  Sanborn  upon  a  solution  containing  17.10  per  cent  fructose.  The 
solution  was  dried  on  pumice  stone  in  flat-bottomed  dishes  at  70°  C. 
under  a  vacuum  of  25  in. 


Hours. 

Number  1. 

Number  2. 

Number  3. 

Means. 

4.. 

8  

Per  cent. 
17.12 
17.11 

Per  cent. 
17.09 
17.09 

Per  cent. 
17.06 
17.08 

Per  cent. 

17.09 
17.09 

12 

17  06 

17  05 

17  06 

17  06 

17 

17  09 

17  07 

17  07 

17.08 

Fig.  10.  —  Carr  vacuum  oven. 

It  is  seen  that  constancy  in  weight  is  secured  after  4  hours,  and 
that  no  further  appreciable  loss  takes  place  even  after  17  hours'  drying. 

An  illustration  of  the  Carr  vacuum  oven  is  shown  in  Fig.  10.  The 
oven  is  provided  with  openings  for  attachment  of  manometer,  insertion 


DETERMINATION  OF  MOISTURE  IN  SUGARS 


23 


of  thermometer,  and  for  inlet  and  exit  of  air.  A  gas  drier  contain- 
ing concentrated  sulphuric  acid  may  be  used  for  removing  moisture 
from  the  slow  current  of  entering  air.  The  detachable  plate  at  the  end 
of  the  oven  is  provided  with  a  rubber  gasket  and  is  fastened  into 
position  by  four  screws  which  secure  a  perfectly  air-tight  joint. 

Browne's  Method  of  Vacuum  Drying.  —  When  one  of  the  specially 
constructed  types  of  vacuum  drying  oven  is  not  available,  the  author 
has  found  the  following  arrangement  (Fig.  11),  which  is  easily  con- 
structed from  ordinary  laboratory  materials,  to  be  perfectly  efficient. 

I 


->To  Vacuum  Pump 


W 


Fig.  11.  —  Browne's  method  of  vacuum  drying. 

The  vacuum  chamber  consists  of  a  large-mouth  bottle  (B)  of  heavy 
glass,  which  is  supported  by  the  shelf  (S)  of  an  ordinary  water  oven 
(0).  The  mouth  of  the  bottle  is  closed  by  a  tight-fitting  rubber  stopper 
(R)  whose  3  holes  permit  the  insertion,  through  the  top  opening  of  the 
oven,  of  the  tubes  I  and  E  and  the  thermometer  T.  The  bottle  is 
easily  fitted,  and  detached  from  the  stopper  by  first  withdrawing  the 
shelf,  the  latter  being  shoved  into  position  again  when  the  bottle  is  in 
place.  The  current  of  air  entering  by  tube  /  to  the  bottom  of  the 


24  SUGAR  ANALYSIS 

vacuum  bottle  is  controlled  by  a  clamp  pinchcock  (C)  and  freed  of 
moisture  by  a  gas  drier  (D).  The  exit  air  from  the  vacuum  bottle 
passes  by  the  tube  E  to  the  vacuum  pump  or  aspirator. 

For  absorbing  the  sugar-containing  liquid,  asbestos  in  perforated 
brass  or  copper  tubes  is  used.  The  tubes  measure  9  cm.  long  by  2  cm. 
in  diameter,  and  are  nearly  filled  with  freshly  ignited  asbestos,  the 
latter  being  tightly  packed  with  a  rod  against  the  sides  in  the  upper 
half  of  the  tube,  so  as  to  leave  a  central  cavity. 

Each  tube  thus  prepared  is  placed  in  a  glass-stoppered  weighing 
bottle  of  sufficient  size,  and  the  whole  weighed.  About  5  c.c.  of  the 
liquid  to  be  analyzed  are  then  delivered  from  a  pipette  into  the  cavity 
in  the  asbestos,  the  object  of  the  cavity  being  to  secure  a  rapid  ab- 
sorption and  even  distribution  of  the  liquid  through  the  asbestos. 
The  weighing  bottle  is  then  immediately  stoppered  and  reweighed,  the 
increase  in  weight  being  the  amount  of  substance  taken.  After  re- 
moving the  stopper  the  weighing  bottle  with  tube  is  placed  in  the 
vacuum  bottle,  as  shown  by  W  in  the  diagram,  and  the  temperature 
raised  to  70°  C.  During  the  first  few  hours  of  drying  a  brisk  current 
of  air  is  drawn  through  the  vacuum  bottle  in  order  to  remove  the 
large  excess  of  moisture  first  given  off.  In  the  last  stages  of  the  dry- 
ing the  air  current  is  decreased  and  the  vacuum  kept  at  about  25  in. 
At  the  end  of  a  few  hours  the  weighing  bottle  is  removed,  allowed  to 
cool  in  a  desiccator,  and  then  restoppered  and  weighed.  The  bottle  is 
then  redried  for  a  second  short  period  to  determine 
if  all  moisture  has  been  expelled. 

In  the  weighing  out  of  juices,  sirups,  sugar  solu- 
tions, etc.,  for  absorption  upon  pumice  stone,  sand, 
or  asbestos,  a  small  flask  provided  with  a  stopper 
and  a  rubber-bulbed  pipette  or  medicine  dropper 
will  be  found  convenient  (Fig.  12).  The  bottle  is 
filled  about  two-thirds  full  with  the  sugar  solution, 
which  should  not  contain  over  25  per  cent  solids, 
and  then  closed  with  the  stopper  and  pipette. 
Fig.  12.  —  Bottle  for  After  weighing  the  bottle  and  contents,  about  5  c.c. 

~  °f  Uquid  are  conveyed  by  means  of  the  bulb  P^ette 
to  the  absorbent  material,  and  the  flask  restoppered 
and  weighed.  The  difference  in  weight  is  the  amount  of  sample  taken. 
Honeys,  molasses,  jellies,  and  other  water-soluble  substances  of  high 
density  should  be  diluted  before  this  method  is  employed,  by  dissolv- 
ing a  weighed  amount  of  substance  in  a  weighed  amount  of  water. 
The  above  method  of  weighing  samples  is  precluded,  however,  when 


DETERMINATION  OF  MOISTURE  IN  SUGARS  25 

insoluble  matter  is  present,  as  with  jams,  sauces,  and  similar  products. 
In  such  cases  a  weighed  amount  of  the  well-mixed  sample  is  stirred 
with  a  little  water  until  all  soluble  matter  is  dissolved  and  then  com- 
pletely transferred  to  the  absorbent  material  in  the  drying  dish  with 
help  of  a  fine  jet  of  water.  The  Pellet  method  of  drying  is  especially 
convenient  for  products  of  this  class. 

DETERMINATION  OF  MOISTURE  IN  SUGAR  MATERIALS  WHICH  CON- 
TAIN WATER  OF  HYDRATION 

Difficulty  is  sometimes  experienced  in  dehydrating  sugars  such  as 
glucose,  lactose,  maltose,  and  raffinose,  which  crystallize  with  one  or 
more  molecules  of  water  of  crystallization.  The  principal  precaution 
to  be  observed  in  drying  such  sugars  is  not  to  raise  the  temperature  in 
the  first  stages  of  the  process  above  the  melting  point  of  the  hydrate, 
otherwise  the  sugar  will  liquefy  to  a  thick  viscous  mass  from  which  it 
is  difficult  to  expel  the  last  traces  of  water  without  decomposition. 

For  drying  glucose  hydrate,  C6Hi2O6  +  H20,  the  sugar  is  spread  in 
a  thin  layer  and  gently  warmed  at  50°  to  60°  C.  for  several  hours, 
when  most  of  the  water  will  be  removed  without  melting  of  the  crystals. 
The  sugar  is  then  gradually  heated  to  about  105°  C.,  when  the  last 
traces  of  water  will  be  expelled,  with  no  evidence  of  liquefaction. 

For  drying  raffinose  hydrate,  Ci8H32Oi6  +  5  H2O,  the  finely  powdered 
sugar  is  first  warmed  to  80°  C.  for  several  hours  and  then  the  tempera- 
ture gradually  raised  to  about  105°  C.  The  preliminary  drying  may 
be  hastened  greatly  by  heating  the  sugar  in  a  vacuum  oven. 

Maltose  hydrate,  Ci2H22On  +  H2O,  gives  off  its  water  very  incom- 
pletely at  100°  C.  under  atmospheric  pressure,  and  vacuum  dehydra- 
tion is  necessary.  The  sugar  is  gently  heated  under  a  strong  vacuum 
at  90°  to  95°  C.,  and  then  after  a  few  hours  the  temperature  is  raised 
to  between  100°  and  105°  C. 

Lactose  hydrate,  Ci2H22On  +  H2O,  retains  its  water  of  crystalliza- 
tion unchanged  at  100°  C.  under  atmospheric  pressure.  It  is  therefore 
customary  in  analytical  work  to  estimate  lactose  as  the  hydrate.  Lac- 
tose may  be  dehydrated,  however,  by  gently  heating  the  finely  pulver- 
ized sugar  in  a  strong  vacuum  to  a  temperature  of  125°  to  130°  C. 

The  method  of  drying  devised  by  Lobry  de  Bruyn  and  van  Laent,* 
and  used  by  Brown,  Morris,  and  Millar,f  and  also  by  Walker,t  is  to 
weigh  the  finely  powdered  sugar  in  a  small  flask  and  connect  the  latter 

*  Rec.  trav.  chim.  Pays-Bas,  13,  218. 
t  J.  Chem.  Soc.  Trans.,  71,  76. 
j  J.  Am.  Chem.  Soc.,  29,  541. 


26  SUGAR  ANALYSIS 

by  a  T  tube  to  a  bottle  containing  phosphorus  pentoxide,  P205,  as  a 
dehydrating  agent.  The  open  branch  of  the  T  tube  is  connected  with 
a  strong  vacuum;  the  flask  containing  the  sugar  is  then  placed  in 
an  oil  bath  and  the  temperature  gently  raised  to  the  point  desired. 
Walker  found  that  lactose  under  these  conditions,  after  heating  1  hour 
at  80°  C.  and  then  1  hour  at  130°  C.,  remained  perfectly  white,  but 
upon  heating  to  140°  C.  the  sugar  became  tinged  with  brown,  show- 
ing signs  of  decomposition. 

The  method  of  Lobry  de  Bruyn  and  van  Laent  has  also  been  suc- 
cessfully employed  by  Rolfe  and  Faxon  *  for  determining  the  total  car- 
bohydrates in  acid-hydrolyzed  starch  products.  In  the  modified  appa- 
ratus of  Rolfe  and  Faxon  the  T  tube  is  provided  with  a  three-way 
stop-cock,  which  allows  the  great  excess  of  water  first  given  off  to  be 
removed  without  coming  in  contact  with  the  phosphorus  pentoxide. 
*  J.  Am.  Chem.  Soc.,  19,  698. 


CHAPTER  III 

DENSIMETRIC   METHODS   OF  ANALYSIS 

THE  quantity  of  matter  in  a  unit  volume  of  substance  is  called  the 
absolute  density  of  that  substance.  If  m  be  the  mass  and  V  the  volume 

of  a  given  substance,  its  absolute  density  D  will  be  D  =  •=•     The 

ratio  between  the  masses  of  equal  volumes  of  a  substance  and  of  some 
standard  material  is  the  relative  density  of  that  substance.  Since, 
however,  the  masses  of  two  bodies  at  any  one  place  are  proportional  to 
their  weights,  the  relative  density  S  of  a  given  substance  may  be  ex- 

w 
pressed  S  =  ^>  where  w  and  W  are  the  weights  respectively  of  equal 

volumes  of  the  substance  and  standard  material.  Relative  density  is 
commonly  known  as  specific  gravity,  and,  since  the  standard  substance 
of  comparison  is  nearly  always  water,  specific  gravity  is  commonly 
defined  as  a  number  indicating  how  much  heavier  a  substance  or  solu- 
tion is  than  an  equal  volume  of  water. 

The  determination  of  specific  gravity  is  one  of  greatest  importance 
in  the  analysis  of  sugars;  its  great  value  consists  in  the  fact  that  solu- 
tions of  different  sugars  of  equal  concentration  have  very  nearly  the 
same  specific  gravity.  The  following  specific  gravities  are  given  for 
10  per  cent  solutions  of  nine  different  sugars  at  20°  C.  with  reference 
to  water  at  4°C.:  Arabinose  1.0379,  glucose  1.0381,  fructose  1.0385, 
galactose  1.0379,  sorbose  1.0381,  sucrose  1.0381,  maltose  1.0386,  lactose 
1.0376,  raffinose  1.0375.  It  will  be  noted  that  the  specific  gravity  of 
each  sugar  solution  is  but  little  removed  from  the  average  1.0380,  which 
is  almost  the  same  as  that  of  sucrose.  It  is  possible,  therefore,  by  means 
of  specific  gravity  tables  established  for  solutions  of  pure  sucrose  to 
determine  very  closely  the  percentage  of  dissolved  substance  for  any 
sugar  or  mixture  of  sugars  in  aqueous  solution. 

Units  of  Volume.  The  unit  of  volume  universally  employed  in 
sugar  analysis  is  the  cubic  centimeter.  This  unit  is  differently  defined 
and  the  chemist  must  distinguish  carefully  between  (1)  the  metric  or 
true  cubic  centimeter,  (2)  the  Mohr  cubic  centimeter,  and  (3)  the 
reputed  cubic  centimeter. 

27 


28  SUGAR  ANALYSIS 

The  Metric  Cubic  Centimeter  is  defined  as  the  volume  occupied  by 
one  gram  of  water  weighed  in  vacuo  at  4°  C.,  the  temperature  of  maxi- 
mum density  (D  =  1.000000).  At  20°  C.  the  metric  or  true  cubic  centi- 
meter is  equivalent  to  the  volume  occupied  by  0.998234  gram  of  water 
weighed  in  vacuo,  or  0.997174  gram  of  water  weighed  in  air  with  brass 
weights. 

The  Mohr  Cubic  Centimeter  is  defined  as  the  volume  occupied  by  one 
gram  of  water  weighed  in  air  with  brass  weights  at  17.5°  C.  One  Mohr 
cubic  centimeter,  as  thus  defined,  is  equivalent  to  1.00234  metric  cubic 
centimeters. 

The  Reputed  Cubic  Centimeter,  a  term  introduced  by  Brown,  Morris, 
and  Millar,*  is  defined  as  the  volume  at  15.5°  C.  of  one  gram  of  water 
weighed  in  air  with  brass  weights.  One  reputed  cubic  centimeter,  as 
thus  defined,  is  equivalent  to  1.00198  metric  cubic  centimeters. 

The  true  or  metric  cubic  centimeter  was  adopted  as  the  standard 
unit  of  volume  by  the  International  Commission  for  Uniform  Methods 
of  Sugar  Analysis  at  its  meeting  in  Paris,  1900. 

SPECIFIC  GRAVITY  TABLES  FOR  SUGAR  SOLUTIONS 
Various  tables  have  been  established  by  different  observers  which 
give  the  specific  gravity  (sp.  gr.)  of  cane-sugar  solutions  for  different 
concentrations.  These  tables  are  expressed  in  several  ways;  they  vary 
according  to  the  temperature  which  is  selected  for  the  determination, 
15°  C.,  17.5°  C.,  or  20°  C.  being  usually  taken,  and  also  as  to  whether  the 
weight  of  water  at  4°  C.  (true  specific  gravity)  is  used  for  comparison, 
or  water  at  15°C.,  17.5°C.,  and  20°  C.  (relative  specific  gravity).  In 
expressing  specific  gravity  it  is  customary  to  indicate  the  system  em- 
ployed by  writing  the  temperature  of  the  solution  above  that  of  the 
water;  thus,  ^>  ^-,  j£f0.  f£,  etc. 

In  Table  IV  the  specific  gravities  of  sucrose  solutions  at  several 
concentrations  are  given  according  to  the  calculations  of  different 
authorities. 

Various  formulae  have  been  worked  out  for  expressing  the  relation- 
ship between  the  specific  gravity  and  percentage  by  weight  of  dissolved 
sucrose.  Gerlach  for  specific  gravity  ]££!  has  expressed  the  relation- 
ship by  the  equation 

y  =  1+  0.00386571327 Z  +  0.00001414091906  z2 

+  0.0000000328794657176  z3, 

in  which  y  is  the  specific  gravity  and  x  the  per  cent  of  sugar. 
*  J.  Chem.  Soc.,  71,  78  (1897). 


DENSIMETRIC  METHODS  OF  ANALYSIS 


29 


Scheibler  has  recalculated  Gerlach's  equation  for  sugar  solutions 
of  different  temperatures  with  the  following  results: 

Temperature. 

0  °  y=l  +  0. 003976844  x  +  0 . 0000142764  x2  +  0 . 000000029120  x3 

10  y  =  1  +  0 . 003915138  x  +  0 . 0000139524  x2  +  0 . 000000032728  z3 

15  y  =  l  +  0. 003884496  x  +  0 . 0000139399  z2  +  0 . 000000033806  z3 

20  0  =  1  +  0. 003844136  x  +  0 . 0000144092  x2  +  0 . 000000030912  x3 

30  0  =  1+0. 003796428  x  +  0 . 0000145456  x2  +  0 . 000000030664  x3 

40  0  =  1  +  0. 003764028  x  +  0 . 0000143700  x2  +  0 . 000000035192  x3 

50  0=1  +  0. 003722992  x  +  0 . 0000148088  x2  +  0 . 000000032440  x3 

60  0  =  1  +  0. 0036831 12  x  +  0 . 0000155904  x2  +  0 . 000000026368  x3 


TABLE  IV 
Specific  Gravity  of  Sucrose  Solutions  by  Different  Authorities 


Sucrose,  per  cent 
by  weight. 

Balling-Brix, 
17.5° 

d!7T°C- 

Gerlach, 
,17.5° 
d!7^C- 

Gerlach- 
Scheibler, 

*&* 

German  Imperial  Commission. 

rf15°r 
dl5~°c' 

,20° 

dToc. 

0 

1.00000 

1.00000 

1.00000 

.00000 

0.99823 

5 

1.01970 

1.01969 

1.01978 

.01973 

.01785 

10 

1.04014 

1.04010 

1.04027 

.04016 

.03814 

15 

1.06133 

1.06128 

1.06152 

.06134 

.05917 

20 

1.08329 

1.08323 

1.08354 

.08328 

.08096 

25 

1  .  10607 

1  .  10600 

1  .  10635 

.  10604 

.10356 

30 

1  .  12967 

1  .  12959 

1  .  12999 

.  12962 

.12698 

35 

1.15411 

1  .  15403 

1  .  15448 

.  15407 

1.15128 

40 

1  .  17943 

1.17936 

1.17985 

.17940 

1  .  17645 

45 

.20565 

1.20559 

1.20611 

.20565 

1.20254 

50 

.23278 

1.23275 

1.23330 

.23281 

1.22957 

55 

.26086 

1.26086 

1.26144 

.26091 

1.25754 

60 

.28989 

1.28995 

1.29056 

.28997 

1.28646 

65 

.31989 

1.32005 

1.32067 

.31997 

1.31633 

70 

.35088 

1.35117 

1.35182 

.35094 

1.34717 

75 

1.38287 

1.38334 

1.38401 

.38286 

1.37897 

One  of  the  best-known  tables  for  the  specific  gravity  of  sugar  solu- 
tions is  that  of  Balling*  (jfj),  published  in  1854,  and  which  served 
as  a  basis  for  the  better-known  and  more  complete  table  of  Brix,  whose 
name  is  now  almost  universally  given  to  the  percentages  of  sugar  or 
dissolved  solids  (degrees  Brix)  derived  by  densimetric  means.  Another 
well-known  table  is  that  of  Gerlach  f  (}££)>  published  in  1863-64,  and 
which  served  as  a  basis  for  Scheibler'st  table  calculated  to  jp-  The 

*  Z.  Ver.  Deut.  Zuckerind.,  4,  304. 
t  Dingler's  Polytech.  Jour.,  172,  31. 
|  Neue  Zeitschrift,  26,  37,  185. 


30 


SUGAR  ANALYSIS 


most  recent  and  most  accurately  established  tables  are  those  of  the 
German  Imperial  Commission*  upon  Standards,  based  upon  the  deter- 
minations of  Plato,  and  published  in  1898  and  1900.  These  tables 
give  the  percentages  of  sucrose  for  specific  gravities  at  y^'  15*  >  and 
^r°.  The  ^?  table,  which  was  established  according  to  the  require- 
ments of  the  Fourth  International  Congress  of  Applied  Chemistry 
(Paris,  1900),  is  given  in  the  Appendix  (Table  1). 

The  specific  gravity  tables  of  the  German  Imperial  Commission 
have  since  been  enlarged  by  Sidersky,f  so  as  to  give  the  grams  of  sugar 
for  100  gms.,  and  also  for  100  c.c.,  of  solution  for  ^  and  ^  between 
10°  and  30°  C.  and  for  concentrations  between  0°  and  30°  Brix.  For 
their  limited  range  Sidersky's  tables  are  the  most  complete  of  any 
which  have  been  compiled. 

Influence  of  Temperature  upon  the  Specific  Gravity  of  Sugar 
Solutions.  —  With  increase  of  temperature,  sugar  solutions  expand  in 
volume  and  the  specific  gravity  becomes  correspondingly  less.  The 
coefficient  of  cubical  expansion  of  sugar  solutions  varies  according  to 
concentration.  Josse  and  RemyJ  give  the  following  coefficients  for 
different  sugar  solutions  between  15°  and  25°  C.: 

TABLE  V 

Coefficients  of  Cubical  Expansion  for  Sugar  Solutions 


d!5°C. 

d25°C. 

Concentration. 

Coefficient. 

1.02425 

.02211 

6.32 

0.0002052 

1.05100 

.04365 

12.75 

0.0002100 

1  .  10025 

.09744 

23.88 

0.0002250 

1.14782 

.14452 

33.71 

0.0002574 

1.19875 

.19500 

43.81 

0.0002896 

.   1.25110 

.24718 

5,3.37 

0.0003153 

1.30384 

1.29962 

62.39 

0.0003262 

1.33025 

1.32591 

.       66.74 

0.0003289 

The  mean  coefficient  of  expansion  (7)  of  a  solution  containing  p  per 
cent  of  sucrose  for  temperatures  between  10°  and  27°  C.  can  be  found 
by  Schonrock's  §  formula  with  a  probable  error  of  only  =b  0.000006. 

7  =  0.000291  +  0.0000037  (p  -  23.7)  +  0.0000066  (t  -  20) 

-  0.00000019  (p  -  23.7)  (t  -  20). 

*  Z.  ang.  Chem.  (1898),  774;  Z.  Ver.  Deut.  Zuckerind.,  50,  982  to  1079. 

t  "  Les  Densit6s  des  Solutions  sucre"es  &  diflterentes  Temperatures,"  Paris,  1908. 

%  Bull,  assoc.  chim.  sucr.  dist.,  19,  302. 

§  Z.  Ver.  Deut.  Zuckerind.,  60,  419. 


DENSIMETRIC  METHODS  OF  ANALYSIS  31 

Knowing  the  value  of  7,  the  specific  gravity  dt  at  temperature  t 
can  be  calculated  from  the  specific  gravity  dt0  at  temperature  to  by  the 
equation 

dt  = 


In  the  employment  of  temperature  corrections  in  densimetric 
methods  of  analysis,  it  is  more  customary  to  apply  the  correction  to  the 
percentage  of  sugar  (degrees  Brix)  rather  than  to  the  specific  gravity. 
The  correction  is  to  be  added  in  case  the  temperature  is  above,  and 
to  be  subtracted  in  case  the  temperature  is  below,  the  standard  degree 
of  the  table  (17.5°  C.  for  the  old  Brix  tables  and  20°  C.  for  the  new 
tables  of  the  German  Commission).  Lists  of  such  corrections  are 
affixed  to  the  standard  tables  of  specific  gravities.* 

Determination  of  Dissolved  Solids  by  Use  of  Solution  Factors.  — 
In  the  investigation  of  starch-conversion  products  the  percentage  of 
solids  in  100  c.c.  of  solution  is  frequently  calculated  from  the  specific 
gravity  by  means  of  a  "  solution  factor."  This  method  was  introduced 
in  1876  by  O'Sullivan,  f  who  found  that,  when  10  gms.  of  maltose  or 
dextrin  were  dissolved  at  60°  F.  (15.5°  C.)  to  100  c.c.,  a  solution  of 
1.0385  sp.  gr.  (jf^)  was  obtained.  Assuming  that  the  percentage  of 
dissolved  substance  is  always  proportional  to  the  specific  gravity  of  the 
solution  (which  is  only  approximately  true),  a  solution  containing  1 
gm.  of  maltose  or  dextrin  in  100  c.c.  should  have  a  specific  gravity 
of  1.00385  at  15.5°  C.  A  solution  of  specific  gravity  d  should  contain 

KKOr,    1000  (d-  1.000)  ,     r, 

at  15.5   C.  -  -  gms.  of  solids. 

o.oO 

Brown,  Morris,  and  Millar  J  determined  the  solution  factors  of  a 

number  of  different  sugars  for  a  uniform  specific  gravity  of  1.055  {575-0 
with  the  following  results: 

TABLE  VI 

Solution  Factors  of  Sugars  and  Starch  Conversions 

Anhydrous  glucose  .....................................  3  .  825 

Anhydrous  sucrose  ....................................  '•  3  859 

Anhydrous  invert  sugar  ................................  3  .  866 

Anhydrous  fructose  ....................................  3  .  907 

Anhydrous  maltose  ....................................  3  .  916 

Low  starch  conversion  ([«]/>  =  +149.7)   ..........  -  ......  3.947 

Medium  starch  conversion  ([a]D  =  +173.9)  ..............  3.985 

High  starch  conversion  ([a]D  =  +188.6)    ................  4.000 

Dextrin  ................................................  4.206 

*  Appendix,  Tables  2  and  4.  t  J-  Chem.  Soc.  (1876),  129. 

J  J.  Chem.  Soc.  (1897),  71,  72. 


32 


SUGAR  ANALYSIS 


The  solution  factors  of  glucose,  fructose,  and  maltose  have  recently 
been  determined  by  Ling,  Eynon,  and  Lane  *  with  practically  the  same 
results  as  Brown,  Morris,  and  Millar. 

For  ordinary  purposes  Brown,  Morris,  and  Millar  recommend  the 
use  of  the  sucrose  factor  3.86.  A  comparison  of  the  actual  grams  of 
sucrose  per  100  c.c.  of  solution  with  those  calculated  by  means  of  this 
solution  factor  is  given  in  the  following  table: 

TABLE  VII. 


,  15.5° 
15T0' 

Sucrose  in  100  c.c. 
of  solution. 

-  Sucrose  by  formula, 
1000  (d-  1.0000) 

3.86 

Grams. 

Grams. 

1.0039 

1.00 

1.01 

1.0193 

5.00 

5.00 

1.0386 

10.00 

10.00 

1.0578 

15.00 

14.97 

1.0770 

20.00 

19.95 

1.0959 

25.00 

24.84 

1.1149 

30.00 

29.76 

It  is  seen  that  the  employment  of  solution  factors,  while  sufficiently 
accurate  for  dilute  solutions,  is  attended  with  considerable  error  upon 
liquids  of  high  concentration.  The  factor  3.86  is  not  exactly  the  same 
for  all  sugars,  so  that  this  method  of  estimating  solids  is  only  useful  for 
approximate  purposes. 

If  the  sugar  solution  be  reduced  to  a  uniform  specific  gravity  of 
about  1.05  and  a  correction  be  made  for  the  true  density  factor,  the 
constant  3.86  can  be  employed  without  serious  error.  The  correction 
is  made  by  multiplying  the  results  (percentages,  specific  rotation,  re- 
ducing power,  etc.)  obtained  by  using  the  factor  3.86  by  the  value 

o  o£» 

-W- 1  in  which  F  is  the  true  solution  factor,  according  to  Table  VI,  of 

the  sugar  in  question. 

Contraction  in  Volume  of  Sucrose  and  Water  Mixtures.  —  A 

phenomenon,  which  has  a  most  important  bearing  upon  the  specific 
gravity  of  solutions  of  sugars  and  other  substances,  is  that  of  con- 
traction. If  a  definite  quantity  of  sucrose,  for  example,  be  dissolved 
in  a  definite  quantity  of  water,  the  volume  of  solution  is  always  less 
than  the  sum  of  the  volumes  of  sucrose  and  water  taken.  The  same  is 
also  true,  but  to  a  less  extent,  of  the  mixture  of  sucrose  solutions  of 
different  concentration  and  of  sucrose  solutions  with  water.  The  phe- 
*  J.  Soc.  Chem.  Ind.,  28,  730. 


DENSIMETRIC  METHODS  OF  ANALYSIS  33 

nomenon  of  contraction  in  volume  during  solution  of  sucrose  and 
water  has  long  been  known.  It  was  first  observed  by  Reaumur  and 
Petit  le  Medecin  in  1733,  and  has  been  repeatedly  studied  by  many 
subsequent  observers.*  The  extent  of  this  contraction  has  been  vari- 
ously estimated.  If  x  is  the  per  cent  of  dissolved  sucrose,  the  change 
in  volume  v  according  to  Brixf  is  represented  by  the  equation 

v  =  0.0288747  x  -  0.000083613  z2  -  0.0000020513  x*. 
Scheibler  J  gives  the  equation 

v  =  0.0273731  x  -  0.000114939  x*  -  0.00000158792  x3, 

according  to  which  the  maximum  contraction  is  0.8937  c.c.  for  55.42 
gms.  sucrose  and  44.58  gms.  water  at  17.5°  C.  Gerlach  gives  the  maxi- 
mum contraction  as  0.9946  c.c.  for  56.25  gms.  sucrose  and  43.75  gms. 
water,  and  Ziegler  §  as  0.9958  c.c.  for  56  gms.  sucrose  and  44  gms.  water. 
According  to  Matthiessen  and  others,  ||  the  maximum  contraction  is 
reached  at  about  40  per  cent  sucrose;  beyond  this  there  is  a  decrease 
until  at  60  per  cent  sucrose  the  contraction  is  0;  with  concentrations 
above  60  per  cent  sucrose  there  is  an  expansion  in  volume.  This  view 
of  the  question  is  due,  according  to  Plato,  1f  to  the  mistaken  idea  that 
dissolved  sucrose  has  the  same  specific  gravity  as  the  crystallized  solid 
(1. 59103  |p  for  chemically  pure  powdered  sucrose,  1.5892 1£  for  chemi- 
cally pure  sucrose  crystals).  If  we  take  Plato's  calculated  value  for 
the  specific  gravity  of  dissolved  sucrose  in  aqueous  solution,  1.55626,  the 
following  results  (Table  VIII)  are  obtained  which  are  in  close  concord- 
ance with  those  of  Gerlach  and  Ziegler.  The  apparent  change  in 
specific  gravity  of  dissolved  sucrose  is  due  to  the  phenomenon  of  con- 
traction, for  which  no  satisfactory  explanation  has  as  yet  been  offered. 

*  In  contradiction  to  the  results  of  all  previous  experimenters,  Olizy  (Bull. 
assoc.  chim.  sucr.  dist.,  27,  60)  claims  to  have  demonstrated  by  numerous  experi- 
ments that  absolutely  no  contraction  takes  place  during  the  solution  of  sucrose  in 
water. 

t  Z.  Ver.  Deut.  Zuckerind.,  4,  308. 

|  Neue  Zeitschrift,  26,  37. 

§  Oest.  Ung.  Z.  Zuckerind.,  12,  760. 

II  Lippmann,  "Chemie  der  Zuckerarten,"  1081. 

If  Z.  Ver.  Deut.  Zuckerind.,  50,  1098. 


34 


SUGAR  ANALYSIS 


TABLE  VIII 

Showing  Contraction  in  Volume  of  Sucrose- 
Water  Mixtures 


Per  cent 
sucrose. 

Contraction  of  mixture. 

For  1  kilo. 

For  1  liter. 

0 

c.c. 

0.0 

c.c. 
0.0 

5 

1.5 

1.5 

10 

2.9 

3.0 

15 

4.2 

4.5 

20 

5.4 

6.0 

25 

6.5 

7.4 

30  ' 

7.5 

8.7 

35 

8.4 

9.9 

40 

9.1 

11.0 

45 

9.7 

12.0 

50 

10.1 

12.8 

55 

10.3 

13.4 

60 

10.3 

13.7 

65 

10.0 

13.7 

70 

9.6 

13.4 

75 

8.8 

12.6 

80 

7.7 

11.5 

85 

6.2 

9.8 

90 

4.6 

7.5 

95 

2.4 

4.3 

100 

0.0 

0.0 

The  effect  of  mixing  sucrose  solutions  and  water  is  shown  in  the 
following  table  which  gives  the  calculated  contraction  of  mixtures  of 
60  per  cent  sucrose  solutions  with  water  to  make  100  gms. 

TABLE  IX 

Showing  Contraction  in  Volume  of  a  60  Per  Cent  Sucrose  Solution  and  Water 


A 

B 

c 

D 

E 

F 

Solution 
taken. 

Volume  of 
solution, 
17.5°. 

Water 
taken. 

Volume  of 
water, 
17.5°. 

Volume  before 
mixing, 
B+D. 

Volume  after 
mixing. 

Contraction 

(E-F). 

Grams. 

c.c. 

Grams. 

c.c. 

c.c. 

c.c. 

c.c. 

0 

0.000 

100 

100.126 

100.126 

100.126 

0.000 

5 

3.876 

95 

95.120 

98.996 

98.840 

0.156 

10 

7.752 

90 

90.113 

97.865 

97.682 

0.183 

20 

15.504 

80 

80.101 

95.605 

95.372 

0.233 

40 

31.008 

60 

60.076 

91.084 

90.789 

0.295 

50 

38  760 

50 

50.063 

88.823 

88.521 

0.301 

60 

46.512 

40 

40.050 

86.562 

86.273 

0.289 

80 

62  016 

20 

20.025 

82.041 

81.845 

0.196 

90 

69.768 

10 

10.013 

79.781 

79.670 

0.111 

95 

73.644 

5 

5.006 

78.650 

78.595 

0.055 

100 

72.526 

0 

0.000 

72.526 

72.526 

0.000 

DENSIMETRIC  METHODS  OF  ANALYSIS 


35 


The  Specific  Gravity  of  Impure  Sugar  Solutions.  —  While  the 

application  of  specific  gravity  tables  established  for  sucrose  to  the  esti- 
mation of  dissolved  substance  in  solutions  of  other  sugars  and  car- 
bohydrates is  fairly  accurate,  their  use  in  the  case  of  impure  sugar 
solutions  may  lead  to  serious  errors,  owing  to  the  fact  that  the  per- 
centage of  dissolved  impurities  for  the  same  specific  gravity  differs 
from  the  corresponding  percentage  of  sucrose.  The  errors  resulting 
from  this  cause  may  be  seen  in  Table  X,  which  gives  the  concentrations 
of  sucrose,  tartaric  acid,  sodium  potassium  tartrate,  and  potassium 
carbonate  for  different  specific  gravities.  When  the  specific  gravity  is 
determined  after  dilution  with  a  definite  amount  of  water,  as  is  neces- 
sary with  very  thick  sirups,  the  error  in  estimation  of  dissolved  sub- 
stance is  still  further  intensified,  owing  to  the  difference  in  contraction 

TABLE  X 

Concentrations  of  Aqueous  Solutions  of  Organic  and  Inorganic  Com- 
pounds Compared  with  Those  of  Sucrose  at  15°  C.  for 
the  Same  Specific  Gravity 


Specific  gravity. 

Sucrose. 

Tartaric  acid. 

NaK  tartrate. 

'  K2C03. 

1.0039 

Per  cent. 
1 

Per  cent. 
0.87 

Per  cent. 
0.57 

Per  cent. 
0.43 

1.0078 

2 

1.73 

1.14 

0.86 

1.0118 

3 

2.62 

1.71 

1.29 

1.0157 

4 

3.49 

2.28 

1.72 

1.0197 

5 

4.40 

2.87 

2.15 

1.0402 

10 

8.67 

5.87 

4.40 

1.0833 

20 

17.52 

12.16 

9.00 

1  .  1296 

30 

26.29 

18.38 

13.78 

1.1794 

40 

35.33 

24.73 

18.72 

1.2328 

50 

44.22 

31.10 

23.76 

TABLE  XI 

Contraction  on  Diluting  Mixtures  of  Solutions  of  Above  Substances  with  Water  to 

Reduce  Degrees  Brixfrom  50  to  10.     Solution  Taken,  100  gms.,  1.2328  sp.  gr.,  or 

81.49  c.c.     Specific  Gravity  after  Dilution,  1.0402.     Temperature  15°  C. 


Substance. 

Dissolved  substance, 
per  cent. 

Water  added. 

Volume 
before  mix- 
ing. 

tf  =(£+81.49) 

Actual 
volume 
after  mixing. 

(100+C) 

Con- 
traction 

(E-F). 

Before 
dilution. 
A 

After 
dilution. 
B 

(*r)-* 

C 

D 

(1.0402) 

Sucrose 

50.00 

44.22 
31.10 
23.76 

10.00 
8.67 

5.87 
4.40 

Grams. 

400.00 
410.04 
429.81 
440.00 

c.c. 
400.34 
410.38 
430.17 
440.37 

c.c. 

481.83 
491.87 
511.66 
521.86 

c.c. 

480.67 
490.32 
509.34 
519.13 

c.c. 
1.16 
1.55 
2.32 
2.73 

Tartaric  acid  . 
NaK  tartrate. 
K2CO3  

36 


SUGAR  ANALYSIS 


between  sugar  and  dissolved  impurities  in  aqueous  solution.  This  can 
be  seen  by  reference  to  Table  X;  it  is  also  shown  in  Table  XI,  which 
gives  the  calculated  differences  in  contraction  obtained  by  diluting 
solutions  of  sucrose,  tartaric  acid,  sodium  potassium  tartrate,  and 
potassium  carbonate  with  water  to  reduce  degrees  Brix  from  50  to  10. 

Additional  comparisons  showing  the 
differences  between  true  dry  substance 
and  dry  substance  as  calculated  from 
specific  gravity  are  given  for  a  number 
of  compounds  in  Table  XVII. 

METHODS    OF    DETERMINING    SPECIFIC 
GRAVITY  OF  SUGAR  SOLUTIONS 

In  the  estimation  of  dissolved  sugars 
by  means  of  specific  gravity,  the  tem- 
perature of  the  laboratory  is  not  always 
the  same  as  that  prescribed  by  the  table. 
It  is  then  necessary  either  to  bring  the 
solution  to  the  required  temperature  by 
artificial  means  or  else  to  apply  a  fixed 
correction  from  a  conversion  table.  The 
latter  method  is  the  more  convenient 
and  for  ordinary  purposes  is  sufficiently 
exact;  in  cases,  however,  where  great 
accuracy  is  required  the  determination 
must  be  conducted  under  absolutely  the 
same  temperature  conditions  as  speci- 
fied in  the  tables. 

Specific  Gravity  Bottle  or  Pycnom- 
eter.  —  The  most  accurate  method  for 
the  determination  of  specific  gravity  is 
the  direct  comparison  of  the  weights  of 
equal  volume  of  water  and  sugar  solu- 
tion. In  this  method  some  form  of 
specific  gravity  bottle  or  pycnometer  is  used,  various  types  of  which 
are  shown  in  Figs.  13  to  16. 

Before  using  the  instrument  the  pycnometer  is  calibrated  by  de- 
termining the  weight  of  distilled  water  which  it  contains  at  the  tem- 
perature of  comparison.  The  bottle  is  first  thoroughly  cleaned  by 
means  of  dilute  caustic  soda  and  hydrochloric  acid;  it  is  then  washed 
with  distilled  water  and  dried  in  an  air  bath.  In  case  of  pycnometers 


Fig.    13.  —  Specific   gravity  bottle 
with  thermometer. 


DENSIMETRIC  METHODS  OF  ANALYSIS 


37 


constructed  with  a  thermometer  stem,  the  latter  should  never  be 
warmed  beyond  the  limit  of  graduation,  which  is  frequently  only 
40°  C.,  otherwise  the  expansion  of  the  mercury  may  break  the  in- 
strument. After  drying  and  cooling  the  pycnometer  is  weighed.  The 
bottle  is  next  filled  with  distilled  water,  recently  boiled  and  cooled  to 
expel  dissolved  air.  The  temperature  adjustment  is  best  effected  by 
filling  the  bottle  with  water  a  degree  or  so  lower  than  the  temperature 
desired;  the  stopper  is  then  inserted,  taking  care  to  prevent  the  intro- 
duction of  air  bubbles,  and  the  bottle  placed  in  a  bath  of  water  kept 
exactly  at  the  desired  temperature.  After  about  10  minutes,  or  as 


Fig.  14 


Fig.  15 
Types  of  specific  gravity  bottles. 


Fig.  16 


soon  as  the  thermometer  of  the  instrument  has  risen  to  the  right  de- 
gree, the  excess  of  water,  exuding  from  the  stem,  or  above  the  gradua- 
tion mark,  is  removed  with  a  thin  piece  of  filter  paper,  the  cap  is  fitted, 
and  the  bottle  wiped  perfectly  dry  and  reweighed.  The  increase  in 
weight  is  the  water  capacity  of  the  bottle  at  the  desired  temperature. 
The  process  is  repeated  and  the  average  of  several  determinations  used 
as  a  constant  in  all  subsequent  work. 

The  pycnometer,  after  redrying  or  rinsing  repeatedly  with  the  liquid 
to  be  examined,  is  next  filled  with  the  sugar  solution  (observing  the 
same  precautions  as  to  temperature  as  before)  and  reweighed.  The 
weight  of  solution  divided  by  the  water  capacity  of  the  bottle  gives  the 
specific  gravity. 

Since  20°  C.  has  been  adopted  as  the  standard  temperature*  for 

*  At  the  sixth  session  of  the  International  Commission  for  Uniform  Methods 
of  Sugar  Analysis  (London,  May  31,  1909)  it  was  "voted  unanimously  to  accept 
a  single  specific  gravity  table  as  standard,  at  the  temperature  of  20°  C.,  which  is  to 
be  based  upon  the  official  German  table.  From  this,  other  tables  may  be  calculated 
at  other  temperatures,  for  instance,  at  15°  C.,  17.5°  C.,  30°  C.,  etc." 


38    ,  SUGAR  ANALYSIS 

all  processes  of  sugar  analysis,  it  is  best  to  make  the  determination  of 
specific  gravity  when  possible  at  this  temperature.  For  the  specific 
gravity  ^  the  value  for  |j-0  must  be  multiplied  by  the  density  of  water 
at  20°  C.,  or  0.998234. 

For  very  exact  work  the  calculation  of  specific  gravity  must  be 
made  upon  the  weights  in  vacuo,  in  which  case  a  correction  for  the 
density  of  the  air  must  be  introduced.  The  method  of  making  the  cal- 
culation is  as  follows  :  Let  A  =  apparent  weight  of  pycnometer,  B  =  ap- 
parent weight  of  pycnometer  and  water  at  t°  C.,  C  =  apparent  weight 
of  pycnometer  and  sugar  solution  at  t°  C.,  d  =  density  of  water  at 
t°  C.,  and  s  =  density  of  air  at  t°  C.  and  the  observed  atmospheric 
pressure;  then  the  corrected  specific  gravity  S  will  be 

C~A         B~C 


If  the  temperature  of  the  laboratory  is  much  above  that  of  adjust- 
ment, the  specific  gravity  bottle  and  contents  must  remain  at  rest 
until  they  acquire  the  surrounding  atmospheric  temperature,  otherwise 
moisture  will  condense  upon  the  instrument  and  interfere  with  the 
weighing.  It  is  needless  to  add  that  the  cap  of  the  bottle  must  be  suffi- 
ciently tight  to  prevent  leakage  of  liquid  displaced  by  expansion  through 
increase  of  temperature.  Pycnometers  whose  stems  are  to  be  filled 
to  mark  and  hence  allow  room  for  expansion,  as  Fig.  13,  are  gener- 
ally to  be  preferred.  For  certain  kinds  of  work  (as  for  densities  of 
very  dilute  sugar  solutions)  Sidersky*  recommends  Boot's  pycnometer 
(Fig.  15),  which,  having  a  double  wall  with  vacuum,  keeps  the  tempera- 
ture of  the  solution  constant  for  a  long  time. 

For  highly  concentrated  sugar  solutions,  such  as  molasses,  masse- 
cuites,  or  other  viscous  substances,  the  method  must  be  somewhat 
modified,  if  the  specific  gravity  of  the  undiluted  material  is  desired. 
For  this  purpose  a  pycnometer  with  rather  wide  neck,  of  the  form  in 
Fig.  16,  is  chosen,  and  filled  nearly  to  the  mark  with  the  hot  material 
to  be  examined.  To  remove  occluded  air  bubbles  the  bottle  is  placed 
for  a  short  time  in  an  oil  or  salt-water  bath,  the  boiling  point  of  which 
is  sufficiently  high  to  keep  the  material  in  a  liquid  condition.  After 
cooling  to  20°  C.  and  weighing,  the  space  between  the  substance  and 
the  graduation  mark  is  filled  with  distilled  water  and  the  bottle  re- 
weighed.  The  method  of  calculation  is  illustrated  by  the  following 
example  upon  a  molasses: 

*  "  Les  Densit^s  des  Solutions  sucrees,"  p.  17. 


DENSIMETRIC  METHODS  OF  ANALYSIS 


39 


A,  water  capacity  of  pycnometer 

B,  weight  of  molasses 

C,  weight  of  molasses  and  water 
C  —  B  =  weight  of  water  added 
A  —  (C  —  B)  =  weight  of  water 

occupying  space  of  molasses 
56.348 


=  50.124  gms. 
=  56.348  gms. 
=  66.536  gms. 
=  10.188  gms. 

=  39.936  gms. 


39.936 


=  1.411  sp.  gr.  of  molasses. 


Reich*  has  modified  the  above  method  by  filling  the  pycnometer 
to  mark  directly  from  a  burette  divided  into  0.05  c.c.  and  noting  the 


Fig.  17.  —  Determining  specific  gravity  by  means  of  analytical  balance. 

volume  of  water  added.  If  the  burette  has  50  instead  of  0  as  the  top 
graduation,  the  actual  cubic  centimeters  of  molasses,  etc.,  in  the  pyc- 
nometer is  read  off  directly  when  the  latter  is  calibrated  to  hold  exactly 
50  c.c.  This  of  course  obviates  a  second  weighing  of  the  pycnometer, 
and,  while  not  as  accurate  as  the  method  of  weighing,  is  sufficiently  close 
for  many  purposes: 

A  second  method  for  determining  the  specific  gravity  of  sugar 
solutions  is  based  upon  the  well-known  principle  of  Archimedes,  —  that 
*  Deut.  Zuckerind.,  34,  38. 


40  SUGAR  ANALYSIS 

a  body  immersed  in  a  liquid  loses  the  same  weight  as  that  of  the  volume 
of  liquid  displaced.  It  is  therefore  only  necessary  to  compare  the 
losses  in  weight  which  the  same  body  undergoes  in  water  and  in  a  given 
solution,  in  order  to  determine  the  specific  gravity  of  the  latter.  The 
process  may  be  carried  out  in  a  variety  of  ways;  a  common  method 
is  by  means  of  the  analytical  balance. 

A  sinker  of  heavy  glass,  or  a  bulb  of  glass  containing  mercury,  is 
attached  to  a  silk  thread  and  weighed  first  in  air,  then  in  distilled  water, 
and  finally  in  the  sugar  solution.  The  method  of  conducting  the 
weighing  is  shown  in  Fig.  17. 

The  method  of  calculation  is  shown  by  the  following  example: 

A,  weight  of  sinker  in  air  =  25.345  gms.  at  20°  C. 

B,  weight  of  sinker  in  water  =  22.302  gms.  at  20°  C. 

C,  weight  of  sinker  in  sugar  solution,  =  21.504  gms.  at  20°  C. 

Specific  gravity  of  sugar  solution,  S  =  -   —  =  ^^  =  1.2622 ~ 

To  convert  to  true  density  with  reference  to  weights  in  vacuo,  the 
above  equation  becomes  S  $>  =  (d  —  s)  -: ~  +  s,  in  which  d  =  den- 
sity of  water  at  t°,  and  s  =  density  of  air  at  t°  and  the  observed  atmos- 
pheric pressure. 

Mohr's  Specific  Gravity  Balance.  —  The  specific  gravity  balance 
of  Mohr,  as  improved  by  Westphal,  and  hence  frequently  called  the 
Westphal  balance,  makes  use  of  the  principle  of  the  sinker  described  in 
the  previous  section.  The  construction  and  operation  of  the  balance 
are  best  understood  from  Fig.  18.  The  beam  (AC)  of  the  balance  is 
pivoted  at  B  and  between  the  pivot  and  point  of  suspension  (C)  is 
divided  by  notches  into  10  equal  parts.  The  distance  between  each 
division  of  the  beam  is  ordinarily  made  exactly  1  cm.  The  balance, 
as  usually  supplied,  has  a  specially  constructed  thermometer  sinker  . 
(Reimann's  thermometer  body)  which  by  careful  grinding  of  the  lower 
end  is  made  to  displace  exactly  5  gms.  of  distilled  water  at  15°  C. 
The  sinker  is  attached  by  means  of  a  fine  platinum  wire  to  the  brass 
hanger  H,  the  combined  weight  of  sinker,  wire,  and  hanger  being  made 
to  equal  exactly  15  gms.  Before  using,  the  balance  is  first  adjusted 
by  hanging  the  sinker  from  the  arm  and  regulating  the  screw  S  until, 
when  the  beam  is  at  rest,  the  pointers  of  the  arm  and  support  at  A 
exactly  coincide.  If  the  sinker  be  now  submerged  in  distilled  water 
at  15°  C.,  it  will  require  5  gms.  at  the  point  of  suspension  C  to  re- 
store equilibrium.  The  standard  weight  for  Reimann's  thermometer 


DENSIMETRIC  METHODS  OF  ANALYSIS 


41 


body  is  therefore  5  gms.,  and  in  determining  the  specific  gravity  of 
solutions  heavier  than  water  this  weight  must  always  be  hung  from 
the  point  C.  To  obtain  the  decimal  figures  of  the  specific  gravity, 
weights  are  added  to  the  notches  on  the  beam  until  the  pointers  indicate 
equilibrium.  The  first  decimal  figure  is  obtained  by  means  of  a  dup- 
licate 5-gm.  weight,  which  is  moved  from  notch  to  notch  on  the  beam 


Fig.  18.  —  Mohr's  specific  gravity  balance  (indicating  1.1267  sp.  gr.). 

until  the  correct  decimal  is  secured;  the  second  decimal  figure  is  ob- 
tained by  means  of  a  0.5-gm.  weight,  the  third  decimal  figure  by  a 
0.05-gm.  weight,  and  the  fourth  decimal  figure  by  a  0.005-gm.  weight. 
The  specific  gravity  is  then  read  from  the  scale  divisions  of  the  beam 
in  the  order  of  the  diminishing  weights.  The  method  of  reading  is 
easily  understood  from  Fig.  19. 

In  using  the  Westphal  balance  the  temperature  of  the  solution  is 
read  from  the  thermometer  of  the  sinker.     In  case  of  turbid  or  dark- 


42 


SUGAR  ANALYSIS 


colored  solutions  which  render  the  reading  of  this  thermometer  difficult 
or  impossible,  the  temperature  is  read  either  by  carefully  drawing  up 
the  thermometer  body  until  the  top  of  the  mercury  column  is  visible, 
or,  better,  by  means  of  a  larger  thermometer  immersed  in  the  solution. 
Thermometers  and  cylinders  of  special  form  have  been  constructed  for 
taking  specific  gravities,  a  type  of  which  is  shown  in  Fig.  20. 


0.9570 


1.2646 


1.4826 


Fig.  19.  —  Method  of  reading  West- 
phal  balance. 


Fig.  20.  —  Special  cylinder  and  ther- 
mometer for  Westphal  balance. 


Hydrometers.  —  A  third  method  of  determining  the  specific  grav- 
ity of  sugar  solutions,  and  the  one  most  commonly  employed  in  technical 
operations,  is  by  means  of  the  hydrometer.  In  its  usual  form  (Fig.  21), 
this  instrument  consists  of  a  hollow  glass  body  terminating  at  its  lower 
extremity  in  a  bulb  (which  can  be  weighted  with  mercury  or  shot) 
and  at  its  upper  extremity  in  a  hollow  slender  stem,  inside  of  which 
a  paper  scale  is  sealed.  If  this  instrument  is  allowed  to  float  in  a 
solution,  the  weight  of  liquid  displaced  is  equal  to  the  weight  of  the 


DENSIMETRIC  METHODS  OF  ANALYSIS 


43 


floating  hydrometer.  If  placed  in  solutions  of  different  concentration, 
the  stem  will  sink  to  varying  depths;  that  point  upon  the  scale  which 
is  level  with  the  surface  of  the  liquid  indicates  the  density  or  percentage 
for  the  given  concentration  and  temperature.  It  is  in  this 
manner  that  hydrometers  are  calibrated  and  standardized. 

In  actual  practice  a  hydrometer  scale  is  standardized 
at  only  a  few  of  its  points,  the  intermediary  divisions 
being  determined  by  interpolation.  The  method  of  inter- 
polation will  depend  upon  whether  the  scale  is  to  indicate 
specific  gravity  or  direct  percentages. 

The  specific  gravity  D  of  a  solution  is  equal  to  the 
weight  W  of  the  hydrometer  divided  by  the  volume  V  of 


Then  V 


W 


-~  -    If  the  scale  is  to  be 


the  part  submerged. 

graduated  for  specific  gravity  the  numerical  divisions  will 
proceed  in  arithmetical  progression,  such  as  1.00;  1.05; 
1.10;  1.15;  1.20,  etc.  The  difference  between  the  volumes 
of  the  hydrometer  for  any  two  scale  divisions  will  give 
the  volume  v  between  these  divisions;  letting  r  =  half  the 

diameter  of  the  stem,  then  — ^  =  the  distance  between  the 

two  divisions.  The  relationship  between  the  stem  divi- 
sions of  a  hydrometer  weighing  20  gms.  and  with  a  cross 
area  of  stem  (irr2)  equal  to  0.2  sq.  cm.  can  be  seen  from 
the  following  table : 

TABLE  XII 
Showing  Hydrometer  Scale  Divided  According  to  Specific  Gravity 


Specific  gravity 
(D). 

Volume  of  part 
submerged 

(-}• 

\D) 

Volume  between 
divisions 

(»). 

Distance  between 
divisions 

(o-2)' 

c.c. 

c.c. 

cm. 

1.00 

20.000 

0.952 

4.76 

1.05 

19.048 

0.866 

4.33 

1.10 

18.182 

0.791 

3.96 

1.15 

17.391 

0.725 

3.63 

1.20 

16.666 

0.666  . 

3.33 

1.25 

16.000 

0.615 

3.08 

1.30 

15.385 

Fig.  21.— 
Hydrometer. 


44 


SUGAR  ANALYSIS 


It  will  be  noted  that  as  the  specific  gravity  increases  the  distance 
between  the  scale  divisions  decreases.  Owing  to  the  great  labor  in- 
volved in  the  making  of  calculations  and  measurements,  the  division 
of  a  hydrometer  scale  harmonically  is  accomplished  in  practice  by  means 
of  a  dividing  engine. 

In  the  graduation  of  a  hydrometer  scale  for  indicating  direct  per- 
centages of  sugar,  the  distance  between  the  scale  divisions  is  much  more 
uniform.  The  relationship  is  best  seen  from  the  following  table,  where 
a  hydrometer  of  20  gm.  weight  and  0.2  sq.  cm.  cross  area  of  stem  (wr2) 
was  used  as  before. 

TABLE  XIII 
Showing  Hydrometer  Scale  Divided  According  to  Sugar  Percentage 


Percentage  sugar. 

Specific  gravity. 

Volume  of  part 
submerged 

Volume  between 
divisions 

w. 

Distance  between 
divisions 

C-V 

\Q.2j 

0.00 

1.00000 

c.c. 

20.000 

c.c. 

cm. 

0.772 

3.86 

10.00 

1.04014 

19.228 

0.766 

3.83 

20.00 

1.08329 

18.462 

0.758 

3.79 

30.00 

1  .  12967 

17.704 

0.747 

3.74 

40.00 

1  .  17943 

16.957 

0.733 

3.67 

50.00 

1.23278 

16.224 

0.719 

3.60 

60.00 

1.28989 

15.505 

The  maximum  difference  between  the  length  of  the  scale  divisions 
in  Table  XII  is  1.68  cm.,  while  for  the  same  range  of  specific  gravity 
the  maximum  difference  of  Table  XIII  is  only  0.26  cm.  For  a  hydrom- 
eter graduated  to  read  direct  percentages  of  sugar,  it  is  customary  in 
practice  to  establish  only  a  few  points  upon  the  scale  by  means  of 
sugar  solutions  of  known  concentration,  and  then  divide  the  intervals 
between  these  points  into  equal  subdivisions.  While  this  method  is 
not  absolutely  accurate,  the  errors  of  division  are  less  .than  the  probable 
errors  of  observation. 

The  construction  of  a  hydrometer  to  read  direct  percentages  of 
sucrose  is  first  due  to  Balling.  The  scale  of  this  instrument,  as  after- 
wards recalculated  by  Brix,  constitutes  the  form  at  present  in  most 
general  use.  The  divisions  of  the  scale  are  usually  called  degrees 
Balling  or  degrees  Brix,  as  the  case  may  be;  the  differences  between 


DENSIMETRIC  METHODS  OF  ANALYSIS 


45 


the  two  scales  are  so  slight  that  they  have  no  significance  in  practical 
work. 

The  Brix  hydrometer*  or  spindle  is  supplied  in  a  variety  of  forms. 
For  approximate  work  spindles  are  used  with  graduation  of  0-30, 
30-60,  and  60^90,  and  divided  either  into  0.5  or  0.2  degree.  The  forms 
in  most  common  use,  however,  have  only  a  range  of  10  degrees,  0-10, 
10-20,  20-30,  30-40,  etc.,  graduated  into  0.1  degree.  For  greater 
accuracy  a  third  form  of  spindle  has  been  made  with  a  range  of  only 
5  degrees,  0-5,  5-10,  10-15,  15-20,  etc.,  and  graduated  into  0.05  degree. 
With  the  help  of  a  spindle  for  only  approximate  work,  the  choice  of 


Fig.  22.  —  Floating  Brix 
spindle. 


Fig.  23.  —  Winter's  cylinder  for  taking 
specific  gravity. 


the  particular  hydrometer  for  the  finer  reading  will  be  facilitated. 
The  accuracy  of  the  spindle  is  of  course  the  greater,  the  smaller  the 
diameter  of  the  stem  and  the  consequently  larger  interval  between  the 
scale  divisions. 

In  determining  specific  gravity  by  means  of  the  hydrometer,  a  tall, 
narrow  cylinder  is  usually  employed  for  holding  the  liquid  to  be  ex- 
amined. The  spindle  is  carefully  lowered  into  the  solution  in  such  a 

*  The  term  saccharometer,  which  is  sometimes  applied  to  a  hydrometer  indi- 
cating percentages  of  sucrose,  is  unfortunate,  owing  to  the  confusion  with  the  word 
saccharimeter,  of  entirely  different  meaning. 


46 


SUGAR  ANALYSIS 


10 


°BRIX. 

10 


H 


15 


115 


17 


18 


way  that  the  surface  of  the  stem  above  the  liquid  is  not  moistened. 

Care  should  also  be  exercised  that  the  instrument  floats  freely  and  does 
not  touch  the  bottom  or  walls  of  the  cylinder.  The 
reading  is  made  by  bringing  the  eye  upon  a  level  with 
the  surface  of  the  solution  and  noting  where  the  border 
line  intersects  the  scale;  the  film  of  liquid  drawn  up 
around  the  stem  by  capillarity  should  be  disregarded. 
The  reading  of  the  spindle,  for  example,  in  Fig.  22,  is  20 
and  not  17.  The  scale  of  the  hydrometer  is  read  with 
greater  ease  when  the  surface  of  the  liquid  is  level  with 
the  brim  of  the  cylinder.  Cylinders  of  the  form  designed 
by  Winter  (Fig.  23)  are  convenient  for  this  purpose;  any 
overflow  of  liquid  displaced  by  the  spindle  is  caught  in 
the  circular  trough. 

The  same  attention  must  be  paid  to  temperature 
when  the  hydrometer  is  employed  as  in  other  methods 
of  determining  specific  gravity.  The  Brix  spindle  is  cal- 
ibrated at  17.5°  C.,  and  unless  the  solution  be  of  this 
temperature  a  correction  must  be  applied.  A  table  of 
temperature  corrections  for  degrees  of  the  Brix  scale  is 
given  in  Table  4  of  the  Appendix;  these  corrections  are 
to  be  added  to  readings  made  above  17.5°  C.  and  sub- 
tracted from  those  made  below. 

Brix  hydrometers  are  sometimes  fitted  with  ther- 
mometers, a  form  of  which  modification  is  shown  in 
Fig.  24,  The  advantages  of  this  construction  disappear 
somewhat  when  working  with  turbid  liquors,  which  ren- 
der the  reading  of  the  thermometer  difficult  or  impos- 
sible. For  general  purposes  the  temperature  of  the 
solution  is  best  taken  by  means  of  an  accurately  stand- 
ardized special  thermometer. 

Volquartz*  has  constructed  a  Brix  spindle  with  a 
correction  scale,  the  mercury  of  the  thermometer  in  the 
stem  indicating,  instead  of  temperature,  the  correction 
necessary  to  be  added  to  the  scale  reading.  The  method 

Fig.  24. —  Brix  of  operation  may  be  seen  from  Fig.  25.  The  spindle  in 
spindle  with  the  illustration  indicates  10.0  Brix;  the  mercury  of  the 
thermometer,  thermometer  marks  2.7;  the  reading  corrected  to  17.5°  C. 

is,  then,  10.0  +  2.7  =  12.7  Brix.     If  the  mercury  is  below  the  0  mark 

(17.5°  C.),  the  correction  must  be  subtracted. 

*  Z.  Ver.  Deut.  Zuckerind.,  46,  392. 


\ 


23 


DENSIMETRIC  METHODS  OF  ANALYSIS 


47 


80°  0. 


Vos^tka*  has  constructed  a  Brix  spindle  with  movable  scale,  which 
after  adjustment  to  the  temperature  of  the  sugar  solution  gives  the 
true  reading  directly. 

For  determining  the  Brix  of  dilute  sugar  solutions,  an  operation  of 
considerable  importance  in  exhausting  filter-press  cake  ("sweetening 
off"),  a  variety  of  spindles  known  as  " sweet- water  "  ^-^ 

spindles  has  been  constructed.  These  hydrometers 
have  a  large  body  with  a  thin  stem,  so  that  the  read- 
ings can  be  easily  made  to  0.1  degree.  The  sweet 
water  as  it  comes  from  the  filters  has  usually  a  tem- 
perature of  60°  to  80°  C.,  and,  to  prevent  the  delay 
incident  to  cooling  the  solution  to  17.5°  C.,  sweet- 
water  spindles  are  often  calibrated  at  high  tempera- 
tures. One  form  of  such  spindle  is  graduated  to  read 
0  degree  Brix  in  water  at  75°  C.,  and  5  Brix  in  a 
5  per  cent  sugar  solution  of  the  same  temperature; 
such  a  spindle  cannot  of  course  be  employed  at  other  17  5- 
temperatures,  so  that  its  usefulness  is  somewhat 
limited. 

Another  form  of  sweet-water  spindle  (Fig.  26)  is 
graduated  from  0  to  5  Brix  in  the  normal  way.  Be-  jj 
low  the  0  mark  the  divisions  are  continued  in  the 
same  manner,  the  result  being  a  double  scale  with 
the  0  division  in  the  middle.  At  17.5°  C.  the  read- 
ings of  the  upper  scale  give  the  true  Brix;  at  temper- 
atures above  17.5°  C.,  sweet  waters  will  read  less  than 
the  true  Brix.  At  70°  C.  a  5  per  cent  sugar  solution 
reads  0  on  the  spindle,  a  4  per  cent  solution  —1,  a 


perature    correc- 


3  per  cent  solution  —2,  a  2  per  cent  solution—  3,  a  Fig.  25.—  Volquartz 
1  per  cent  solution  -4,  and  pure  water  -5.     The      spindle  with  tem- 

.   „  , 

true  Brix  can  be  determined  for  any  temperature  by 

means  of  a  correction  table;  determinations  by  this 
instrument  can  always  be  controlled  by  cooling  the  solution  to  17.5°  C. 
Still  another  form  of  sweet-water  spindle  has  been  devised  by 
Langen.  This  spindle  (Fig.  27)  contains  within  its  body  a  thermom- 
eter graduated  from  30°  to  70°  C.  The  graduated  scale  in  the  stem 
of  Langen's  spindle  differs  from  other  forms,  however,  in  not  giv- 
ing Brix  degrees,  but  in  simply  indicating  the  thermometer  reading 
for  each  division  to  which  the  hydrometer  will  sink  in  pure  water. 
If  placed,  for  example,  in  distilled  water  of  30°  C.,  the  instrument 
*  Z.  Zuckerind.  Bohmen,  27,  689. 


48 


SUGAR  ANALYSIS 


GO 


50 


40 


will  sink  to  the  division  30  on  the  stem,  and  in  water  of  70°  C.  to 
the  division  70;    in  other  words,  the  thermometer  and  scale  of  the 
spindle  will  give  the   same  readings  between  30   and  70  when  the 
instrument    is    floated    in    distilled    water.       When    the 
spindle  is  placed  in  a  sweet  water,  the  reading  of  ther- 
mometer and  scale  will  no  longer  agree.     The 
spindle  necessarily  sinks  to  a  lesser  depth  than 
in  water,  and  the  scale  of  the  stem  gives  a  dif- 
ferent reading  from  that  of  the  thermometer, 
the  difference  between  the  two  being  propor- 
tional to  the  concentration  of   solution.     In 
sweetening  off,  it  is  only  necessary  to  observe 
the  readings  of  thermometer  and  scale;  the 
differences  between  these  decrease  as  the  ex- 
traction proceeds,  until  with  the  coincidence 
of  the  two  readings   complete  exhaustion  is 
indicated. 

Another  form  of  hydrometer  which  is  fre- 
quently used  in  the  sugar  factory,  but  to  a 
much  less  extent  in  the  sugar  laboratory,  is 
that  of  Baume.     This  instrument  is  standard- 
ized by  means  of  common  salt;  the  0  point  at 
the  top  of  the  stem  is  obtained  by  means  of 
distilled  water,   and  the   15-degree   mark  by 
means  of  a  15  per  cent  salt  solution.     The 
interval  between  these  two  divisions  is  then 
divided  into  15  equal  parts,  this  graduation 
being  extended  downwards  on  the  scale  as  far 
as  desired.    Unfortunately,  in  the  early  instru- 
ments the  temperature  of  the  water  and  the 
specific  gravity  of  the  salt  solution  were  not 
correctly  obtained,  so  that  the  values  of  the 
Baume'  scale  divisions  have  been  variously  re- 
ported by  different  authorities.     The  so-called 
Fig.  26.—     "old"  Baume  degrees,  as  calculated  by  Brix, 
Sweet-water   are  stiU  used  in   European   countries   in  the 
e>       commercial   analysis   of    molasses  *    notwith- 
standing the  fact  that  Gerlach  as  long  ago  as 
1870  showed  the  incorrectness  of  the  formulae  employed  by  Brix  in  his 
calculations. 

*  Friihling's  "  Anleitung,"  p.  74. 


Fig.  27.— 

Langen's 

sweet-water 

spindle. 


I 


DENSIMETRIC  METHODS  OF  ANALYSIS  49 


Gerlach  found  as  the  specific  gravity  of  a  15  per  cent  salt  solution 
at  17.5°  C.,  1.11383.  The  volume  of  a  Baume"  spindle  up  to  the  0 
mark,  in  terms  of  the  volume  of  a  single  scale  division,  is  then  equal 

1  11383  X  15 
to  -T  r  =  146.78.     The  specific  gravity  S  corresponding  to  any 

J..J.IGOO  —  1 

scale  division  N  of  the  Baume  scale  can  then  be  calculated  by  the 
formula  S  =  '  ^  •  It  is  by  use  of  this  formula  that  the  so- 

called  "  new  "  Baume  degrees  have  been  determined.  The  relationship 
between  percentages  of  sugar,  or  degrees  Brix,  specific  gravity  and  the 
new  and  old  degrees  Baume,  is  shown  in  Table  3  in  the  Appendix. 


CHAPTER  IV 

PRINCIPLE  AND  USES   OF  THE  REFRACTOMETER 

A  SECOND  method  of  estimating  the  percentage  of  sugars  in  solution 
is  by  means  of  the  refractive  index.  The  general  applicability  of  this 
method,  as  in  the  case  of  specific  gravity,  depends  upon  the  fact  that 
solutions  of  all  sugars  of  equal  concentration  have  nearly  the  same 
index  of  refraction. 

Law  of  Refraction.  —  If  a  beam  of  light  from  one  medium,  such  as 
air,  fall  at  an  inclined  angle  upon  the  surface  of  a  second  medium,  such 
as  water,  it  will  be  found  that  the  beam  upon  entering  the  second 
medium  is  bent  or  deflected  from. its  original  course.  A  good  example 
of  this  phenomenon,  which  is  called  refraction,  is  the  bent  appearance 
of  the  oar  of  a  boat  when  seen  obliquely  under  water.  There  is  a 
general  law  of  refraction  for  all  transparent  liquids  and  solids  which 
may  be  stated  as  follows:  For  two  given  media  and  the  same  ray  of 
light  (same  wave  length),  the  ratio  of  the  sine  of  the  angle  of  incidence 
to  the  sine  of  the  angle  of  refraction  is  always  a  constant  quantity  for 
the  same  temperature. 

In  Fig.  28  m  and  m'  are  two  media;  PPf  is  drawn  perpendicular  to 
the  dividing  surface  FF'.  Let  a  beam  of  light  pass  through  m  in  the 
direction  LO;  a  part  of  the  beam  at  the  point  0  of  the  surface  is  re- 
flected in  the  direction  OL';  another  part  of  the  beam  entering  m'  is 
refracted  in  the  direction  OS.  The  angle  LOP  which  the  falling  ray 
makes  with  the  perpendicular  is  the  angle  of  incidence,  or  i;  the  angle 
SOP'  which  the  refracted  ray  makes  with  the  perpendicular  is  the 

angle  of  refraction,  or  r.     The  ratio  — —  =  n  is  called  the  index  of 

smr 

refraction.     This  ratio  in  Fig.  28  is  represented  by  -r- 


line  cd 


sin  i 


The  ratio  -     -   is  also  that  of  the  velocities  of  light  in  the  two 
smr 

media.     If  v  is  the  velocity  of  light  in  m  and  v'  the  velocity  in  mf,  then 

S1T1  ?  W 

n  =  -   -  —  —  -     If  the  refracted  ray  is  bent  toward  the  perpendicular 
sin  i       v 

as  in  Fig.  28,  the  velocity  v'  is  smaller  than  v,  and  the  medium  m'  is 
called  of  greater  optical  density  than  m.    Optical  density  must  not  be 

50 


. 

nnnfiiser 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         51 

confused  with  material  density,  since  the  two  expressions  do  not  at 
all  correspond. 

If  the  ray  of  light  in  Fig.  28  pass  from  a  denser  medium  m!  into  a 
rarer  medium  m  in  the  direction  SO,  it  will  be  refracted  in  m  in  the 

direction  OL.     In  this  case  the  index  of  refraction  is  -  — .)  which  is  the 

sin  i 

reciprocal  of  the  index  for  light  passing  in  the  opposite  direction.    The 
refractive  index  varies  with  the  wave  length  of  the  light,  increasing 


Fig.  28.  —  Illustrating  law  of  refraction. 

from  the  red  towards  the  violet  end  of  the  spectrum.  From  this  it 
follows  that  when  ordinary  light  is  refracted  it  is  decomposed  into  light 
of  the  different  prismatic  colors;  this  unequal  refraction  for  light  of 
different  wave  lengths  is  called  dispersion. 

Measurement  of  Refractive  Index.  —  The  refractive  index  of  a 
solution  can  be  measured  in  a  variety  of  ways.  One  of  the  simplest 
methods,  which  is  of  more  value  for  demonstration  than  for  accuracy, 
is  by  means  of  the  refractometer  trough.  This  apparatus,  shown  in 
Fig.  29,  consists  of  a  semicircular  trough,  the  inner  curved  surface  of 
which  is  divided  into  degrees.  The  side  of  the  trough  corresponding 
to  the  diameter  of  the  circle  consists  of  a  plate  of  glass  which  is  made 
nontransparent,  excepting  a  narrow  perpendicular  slit  at  the  center  c. 
If  the  trough  be  filled  partly  with  a  solution  and  a  beam  of  light  fall 
upon  the  glass,  that  part  of  the  beam  passing  through  the  slit  above 


52 


SUGAR  ANALYSIS 


the  surface  of  the  liquid  will  mark  the  angle  of  incidence  and  that  part 
passing  below  the  surface  will  mark  the  angle  of  refraction.     In  the 


Fig.  29.  —  Measuring  refractive  index  by  refractometer  trough. 

illustration,  where  water  is  used,  these  angles  are  60  degrees  and  40 
degrees  respectively. 

sin  60°      0.8660 


sin  40°      0.6428 


=  1.34  or  n,  the  approximate  index  of  refraction. 


Fig.  30.  —  Illustrating  principle  of  total  reflection. 

In  the  construction  of  refractometers  for  more  accurate  measure- 
ments, instrument  makers  generally  employ  the  method  of  total  re- 
flection. The  principle  of  this  method  can  be  understood  from  Fig.  30. 

Let  m  and  mi  be  two  media,  such  as  glass  and  water,  of  which  m  is 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         53 

the  more  optically  dense,  the  dividing  surface  being  SF.  The  beams 
of  light  which  fall  from  the  source  L  upon  SF  at  various  angles  are 
refracted,  in  mi  in  different  directions.  The  beam  LO  J_  SF  is  not  re- 
fracted and  proceeds  in  the  same  direction;  the  beam  Lo,  making  the 
angle  of  incidence  i,  is  refracted  in  the  direction  ot,  making  the  angle  of 
refraction  r;  in  the  same  way  Loi  is  refracted  to  Oiti,  and  Loz  to  O-&L. 
As  the  angle  of  incidence  for  the  falling  beam  increases,  there  finally 
comes  a  point  at  o3  where  the  refracted  ray  o3Z3  coincides  with  the  sur- 
face SF,  and  the  angle  of  refraction  r3  =  90  degrees.  If  the  angle  of 
incidence  be  increased  beyond  i3  to  it,  the  beam  which  previously  was 
only  partly  reflected  is  totally  reflected  in  the  direction  24,  and  there  is 

no  refraction  in  m\.     Since  — — - ,  the  index  for  the  beam  before  total 

smr3 

a     .-  i   sin  1*2  sini  ,    .         .  ^o 

reflection,  equals-; >  etc.,  =  -: —  =  n,  and  since  sin  r3  =  90  =  1,  it  is 

sin  r2  sin  r 

evident  that  for  the  border  line  of  total  reflection  sin  i  =  n.  In  other 
words,  the  sine  of  the  angle  of  incidence  for  the  border  line  of  total  re- 
flection is  equal  to  the  refractive  index.  It  is  seen  from  the  diagram  that 
total  reflection  can  only  take  place  when  light  passes  into  an  optically 
rarer  medium. 

For  absolute  measurements  the  refractive  index  of  a  substance  is 
referred  to  a  vacuum.  Since,  however,  the  absolute  index  of  air  is 
only  1.000294,  refractive  indices  referred  to  air  are  sufficiently  exact 
for  most  purposes.  In  the  case  of  three  media  such  as  air,  glass,  and  a 
liquid,  if  the  index  from  air  to  glass  be  Nag  and  from  glass  to  liquid  Ngi, 
then  the  index  from  air  to  liquid  Nai  —  Nag  X  Ngi.  The  sine  of  the 
angle  of  incidence  for  the  border  line  of  total  reflection  between  glass 
and  a  given  liquid,  multiplied  by  the  index  of  refraction  between  air 
and  glass,  will  give  the  index  of  refraction  for  the  liquid  with  reference 
to  air. 

ABBE  REFRACTOMETER 

The  best  general  instrument  for  determining  the  refractive  index  of 
sugar  solutions  is  that  of  Abbe  (Fig.  31).  The  essential  part  of  the 
Abbe  refractometer  consists  of  two  flint-glass  prisms  A  and  B  of  refrac- 
tive index  nD  =  1.75,  each  cemented  into  a  metal  mounting.  To  open 
the  prisms  the  latter  are  rotated  on  their  bearings  to  a  horizontal  posi- 
tion with  the  prism  B  uppermost;  the  clamp  v  is  then  released  and  prism 
B  swung  open  on  its  hinge  C.  A  few  drops  of  the  solution  to  be  ex- 
amined are  then  placed  upon  the  polished  inner  surface  of  the  fixed 
prism  A  next  to  the  telescope,  and  prism  B,  whose  inner  surface  is 


54 


SUGAR  ANALYSIS 


Fig.  31.  —  Abbe  refractometer. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         55 

ground,  brought  slowly  back  and  clamped  as  before.  The  instrument 
is  then  swung  into  an  upright  position  and  light  reflected  from  the 
mirror  R  upon  the  surface  of  the  lower  prism. 

In  the  following  diagram  (Fig.  32)  FDE  and  ABC  are  longitudinal 
sections  of  the  two  prisms  in  an  Abbe  refractometer  between  whose 
hypotenuse  surfaces  FE  and  AB  (separated  by  about  1.5  mm.)  is  the 


P' 


Fig.  32.  —  Illustrating  principle  of  Abbe  refractometer. 

film  of  liquid  to  be  examined.  The  beams  of  light  passing  from  L 
through  the  lower  prism  to  the  surface  of  the  solution  AB  are  re- 
fracted or  totally  reflected,  according  to  the  refractive  index  of  the 
liquid.  As  shown  in  the  diagram  the  beams  which  fall  upon  the  hypot- 
enuse surface  AB  at  a  less  inclination  than  the  line  10  undergo  re- 
fraction in  the  liquid,  and,  passing  through  the  upper  prism,  the  sets 
of  parallel  rays  s,  s',  s",  .  .  .  ,u,u',  u",  .  .  .  ,  etc.,  are  condensed  by 
the  objective  K  of  the  telescope  upon  the  field  XY.  The  beams  in  the 


56  SUGAR  ANALYSIS 

prism  parallel  to  10  are  refracted  along  the  surface  BA  and  the  beams 
of  greater  inclination  totally  reflected;  since  these  beams  do  not  reach 
the  surface  of  the  upper  prism,  a  part  of  the  field  XY  remains  in 
shadow. 

The  telescope  of  the  refractometer  (F  in  Fig.  31)  is  attached  to  a 
sector  S  and  the  prisms  to  a  movable  arm  J  (the  alidade)  which  carries  a 
magnifying  lens  L.  By  moving  the  alidade  until  the  intersection  of  the 
reticule  in  the  telescope  field  (Fig.  32)  cuts  the  dividing  line  between 
the  bright  and  dark  portions  of  the  field,  the  refractive  index  can  be 
read  directly  upon  the  scale  of  the  sector  by  means  of  the  lens. 

The  relation  between  the  angles  of  incidence  and  refraction  of  light 
between  air  and  prism,  and  prism  and  liquid,  in  the  Abbe  refractometer 
may  be  understood  from  Fig.  32.  Let  PP'  be  drawn  J_  to  the  end  planes 
BC  and  DE  of  the  double  prism,  and  hhf  be  drawn  J_  to  the  hypotenuse 
planes  AB  and  EF. 

Let  a  =  angle  of  incidence  from  air  and 
b  =  angle  of  refraction  in  glass;  then 

— r  =  n  for  prism,  which  for  the  flint  glass  of  the  Abbe  mstru- 
sm  b 

ment  is  about  1.75. 
Let  r  =  angle  of  prism. 

a!  =  angle  of  incidence  in  glass  upon  surface  AB  and 

br  =  angle  of  refraction  in  liquid  =  90  degrees  for  border  line  of 

total  reflection. 

In  A  BOIZ.  r  +  Z  BOI  +  Z  BIO  =  2rt.  Z's; 
Z  BOI  +  Z  a'  +  Z  BIO  +  Z  b  =  2  rt.  Z's; 
whence  r  =  a'  +  b. 

By  way  of  illustration  the  following  values  are  given  for  a,  b,  and  r, 
with  water  as  the  liquid  between  the  prisms: 
a  =  18°  32'. 
b  =  10°  28'. 
r  =  60°  00'. 
sin  a      0.3179 

E&  =  al8l7  =  L75  =  * for  air  to  pnsm' 

a'  =  60°  -  10°  28'  =  49°  32'. 

sin  a'      0.76 

— — T7  =  — =—  =  0.76  =  n  for  glass  of  prism  to  water. 

1.75  X  0.76  =  1.33  =  n  for  air  to  water. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         57 

Each  division,  therefore,  upon  the  sector  of  the  refractometer  rep- 
resenting refractive  index  is  equal  to  the  sine  of  the  angle  of  incidence 
in  the  prism  for  the  border  line  of  total  reflection  multiplied  by  the  re- 
fractive index  of  the  prism.  Since  total  reflection  can  take  place  only 
when  light  passes  from  an  optically  denser  to  a  rarer  medium,  the 
capacity  of  the  refractometer  is  necessarily  limited  to  solutions  of 
smaller  refractive  index  than  1.75. 

A  second  important  feature  of  the  Abbe  refractometer  is  the  com- 
pensator. The  function  of  this  is  to  correct  the  dispersion  which  white 
light  undergoes  in  the  double  prism.  Without  the  compensator  the 
border  line  between  the  light  and  dark  parts  of  the  field,  owing  to  the 
unequal  refraction  of  light  of  different  wave  lengths,  assumes  the  ap- 
pearance of  a  band  of  prismatic  colors,  which  it  is  impossible  to  use  for 
purposes  of  adjustment. 

The  compensator  of  the  refractometer  is  placed  in  the  prolongation 
of  the  telescope  tube  between  the  objective  and  the  double  prism.  It 
consists  of  two  similar  Amici  prisms,  such  as  are  used  in  a  direct-vision 
spectroscope,  and  which  give  no  divergence  for  the  yellow  D  line  of  the 
spectrum  (i.e.,  the  emergent  D  rays  are  parallel  with  the  optical  axis). 
The  two  prisms  are  rotated  simultaneously  in  opposite  directions  by 
means  of  the  screw  head  M  (Fig.  31). 

Trapezoidal  sections  of  the  two  Amici  prisms  are  shown  in  Fig.  33. 
Each  prism  consists  of  a  combination  of  two  crown-glass  prisms,  with 


Fig.  33.  —  Illustrating  principles  of  compensator. 

a  third  right-angled  flint-glass  prism  between  them  in  the  manner 
shown.  If  a  beam  of  white  light  LT  fall  upon  the  surface  of  the  first 
prism  AB,  it  is  decomposed  into  its  colored  constituents,  as  shown  by 
the  divergent  broken  lines.  In  their  passage  through  the  prism  the  red 
rays  are  refracted  least  and  emerge  at  r,  the  yellow  rays  emerge  at  y, 
and  the  violet  rays,  which  are  refracted  most,  emerge  at  v.  If  the  light 
emerging  from  the  prism  ABDE  now  enter  a  second  prism  A'B'D'E' 
similarly  placed  to  the  first  prism  (their  refracting  edges  A  and  A'  being 
parallel  and  on  the  same  side  of  the  optical  axis  LL'),  the  colored  rays 
will  emerge  from  the  second  prism  at  the  points  r',  y',  and  v'  respectively, 
the  angle  of  dispersion  for  any  two  differently  colored  rays  being  twice 
that  for  the  single  prism  ABDE. 


58  SUGAR  ANALYSIS 

If  the  two  Amici  prisms  be  now  rotated  in  opposite  directions 
around  the  optical  axis  LL',  the  dispersion  of  the  compensator  will 
diminish  until,  when  each  prism  has  rotated  90  degrees  (the  difference 
from  the  previous  position  being  180  degrees),  the  dispersions  of  the 
two  prisms  neutralize  one  another  and  the  dispersion  of  the  compen- 
sator is  zero.  In  this  position  the  refracting  edges  A  and  Af  of  the 
two  prisms  will  again  be  parallel,  but  on  opposite  sides  of  the  optical 
axis  LL'.  If  we  now  imagine  the  direction  of  the  colored  rays  through 
the  two  prisms  to  be  reversed,  we  have  an  exact  representation  of  the 
work  performed  in  the  compensator.  The  band  of  colored  light  from 
the  double  prism  of  the  refractometer,  passing  in  the  direction  L'L, 
emerges  at  T  as  a  colorless  beam,  and  the  bright  and  dark  halves  of  the 
field  are  sharply  divided.  By  rotating  the  screw  head  the  compen- 
sator can  be  given  an  equal  but  opposite  dispersion  to  that  of  the  liquid 
examined  for  any  value  from  zero  up  to  twice  the  dispersion  of  a  single 
Amici  prism. 

After  setting  the  compensator  to  the  point  where  the  colored  bands 
disappear,  the  reading  of  the  scale  upon  its  drum  (T,  Fig.  31)  enables 
one  to  calculate  the  dispersion  of  the  liquid  examined  for  the  F  and  C 
rays  of  the  spectrum,  the  mean  dispersion  np  —  nc  (difference  in  refrac- 
tive index  for  the  F  and  C  rays)  being  determined  with  the  help  of  a 
special  table  supplied  with  the  instrument. 

Duplicate  readings  upon  the  Abbe  refractometer  with  a  sharp  defi- 
nition of  the  border  line  should  agree  within  two  places  of  the  fourth 
decimal.  After  each  determination  the  prisms  should  be  cleaned  with 
wet  filter  paper  and  then  wiped  dry  with  a  piece  of  soft  linen. 

Illumination  of  Abbe  Refractometer.  —  For  illuminating  the  refrac- 
tometer ordinary  daylight  may  be  used,  in  which  case  the  instrument 
should  not  be  placed  in  the  direct  light  of  the  sun.  Since,  however, 
daylight  (especially  in  winter)  is  of  variable  intensity,  and  upon  dark 
days  not  strong  enough  for  the  examination  of  deep-colored  solutions, 
it  is  better  on  the  whole  to  use  artificial  light  of  constant  intensity. 
An  incandescent  electric  lamp  or  Welsbach  gas  burner  is  a  most  con- 
venient method  of  illumination.  A  large  sheet  of  cardboard,  placed  in 
front  of  the  instrument  so  as  to  shield  the  light  from  the  upper  prism 
and  from  the  eye  of  the  observer,  will  protect  the  field  of  vision  from 
the  disturbing  influences  of  extraneous  light  and  increase  to  a  marked 
extent  the  sensibility  of  adjustment. 

Regulation  of  Temperature  in  Abbe  Refractometer.  —  The  re- 
fractive index  of  sugar  solutions,  as  of  all  other  substances,  varies  with 
the  temperature,  the  index  decreasing  as  the  temperature  rises.  It  is 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         59 

therefore  important  in  all  refractometer  work  that  the  temperature  be 
kept  constant  during  the  course  of  observation.  In  the  Abbe  refrac- 
tometer shown  in  Fig.  31  water  of  constant  temperature  is  allowed  to 
circulate  in  the  direction  of  the  arrow  through  the  metal  casings  which 
surround  the  prisms;  a  thermometer  screwed  into  the  upper  casing 
indicates  the  temperature. 

Zeiss  Spiral  Heater  and  Water-pressure  Regulator.  —  A  conven- 
ient piece  of  apparatus  for  controlling  the  temperature  of  refractom- 
eters  is  the  Zeiss  spiral  heater  and  water-pressure  regulator.  This 
apparatus  shown  in  Fig.  34  consists  of  a  constant-level  reservoir  A 
connected  by  rubber  tubing  to  the  water  supply  and  attached  to  a 
sliding  frame  which  can  be  adjusted  to  different  heights.  The  water 
passes  from  the  reservoir  to  the  spiral  heater,  which  is  placed  upon  a 
level  below  the  refractometer.  The  heater  consists  of  about  12  feet 
of  copper  tubing  wound  in  a  spiral  and  inclosed  in  a  metal  jacket  which 
is  heated  by  a  Bunsen  burner.  The  water  flows  from  the  heater  upward 
to  the  prisms  of  the  refractometer  and  thence  to  a  constant-level  vessel 
B,  from  which  the  overflow  escapes  to  a  drain.  The  water,  which 
should  not  flow  too  slowly,  is  first  warmed  to  the  approximate  tem- 
perature by  regulating  the  flame  of  the  burner;  the  exact  adjustment 
is  then  made  by  varying  the  speed  of  the  flow,  which  is  done  by  raising 
or  lowering  the  pressure  reservoir  on  its  sliding  frame.  In  this  manner 
the  temperature  can  be  maintained  for  hours  within  0.1°  C.,  provided 
of  course  that  no  variations  take  place  in  the  temperature  of  the  main 
water  supply. 

Instead  of  the  Zeiss  heater  a  large  insulated  heatable  tank  holding 
50  to  100  liters  of  water  may  be  used. 

Testing  the  Adjustment  of  the  Abbe  Refractometer.  —  The  ad- 
justment of  the  Abbe  refractometer  can  be  tested  by  means  of  liquids 
or  glass  test  plates  of  known  refractive  power.  Freshly  distilled  water 
free  from  air  (n™°  =  1.33298)  is  convenient  for  testing  the  lower  divi- 
sions of  the  sector  scale;  monobromonaphthalene  (n™°=  1.658)  is  con- 
venient for  testing  the  upper  part  of  the  scale;  the  latter  substance 
unless  freshly  prepared  usually  requires  to  be  redistilled  (boiling  point 
277°  C.).  The  Abbe  instrument  is  supplied  with  a  glass  test  plate 
whose  index  is  marked  upon  the  upper  ground  surface.  The  method 
of  using  the  plate,  which  can  be  applied  to  any  transparent  solid,  is 
that  of  grazing  incidence  (explained  in  detail  under  the  immersion 
refractometer). 

In  using  the  test  plate  the  instrument  is  reversed  as  shown  in  Fig.  35, 
the  double  prism  spread  open,  and  the  polished  surface  of  the  plate 


60 


SUGAR  ANALYSIS 


[51 


Befractometer  X, 
Prisms 


Fig.  34.  —  Zeiss  spiral  water-heater  with  pressure  regulator. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER          61 

attached  to  the  upper  prism  by  the  capillary  action  of  a  drop  of  mono- 
bromonaphthalene;  the  polished  end  surface  of  the  test  plate  is  directed 
downwards  to  receive  the  reflected  rays  from  the  bright  inner  surface 
of  the  metal  casing  surrounding 
the  lower  prism.  The  average 
of  several  readings  is  taken,  the 
prism  being  wiped  clean  and  the 
plate  reattached  after  each  meas- 
urement. Care  must  be  exer- 
cised not  to  confuse  the  reading 
in  the  reversed  position  of  the 
sector  scale.  The  average  of  the 
readings  should  not  differ  more 
than  two  points  in  the  fourth 
decimal  from  the  value  marked 
upon  the  plate.  Should  greater 
differences  than  this  occur,  the 
refractometer  should  be  adj  usted. 
In  some  of  the  instruments  the 

adjustment  is  made  by  moving 
, ,       .     ,  .    ,,  ,&     Fig.  35.  —  Verifying  adjustment  of  refrac- 

the  index   of  the   sector   scale  tometer  by  test  plate, 

with    a    setpin    until    it    corre- 
sponds to  the  value  marked  upon  the  test  plate.     The  border  line  of 
the  field  must  remain  meanwhile  upon  the  intersection  of  the  reticule, 
so  that  care  must  be  exercised  not  to  ^disturb  the  alidade  while  making 
the  adjustment. 

In  more  recent  forms  of  the  Abbe  refractometer  the  adjustment  is 
made  by  moving  the  reticule  instead  of  the  index.  The  process  is  the 
reverse  of  that  previously  described.  The  alidade  is  first  moved  until 
the  index  of  the  scale  corresponds  to  the  reading  of  the  test  plate;  then 
by  means  of  a  key  the  screw  K  (Fig.  31),  which  moves  the  reticule,  is 
turned  until  the  intersection  of  the  cross  threads  coincides  with  the 
border  line. 


REFRACTOMETER  TABLES  FOR  SUGAR  SOLUTIONS 

A  number  of  tables  have  been  constructed  which  give  the  refractive 
indices  of  sugar  solutions  for  different  concentrations.  The  first  of 
such  tables  was  published  in  1883  by  Strohmer,*  who  showed  also  that 
a  fixed  relation  existed  between  the  refractive  index  and  specific  gravity 


Oest.  Ung.  Z.  Zuckerind.,  12,  925;  13,  185. 


62 


SUGAR  ANALYSIS 


of  sugar  solutions.  Using  the  method  of  least  squares,  Strohmer  cal- 
culated this  relation  to  be  n£5°=  1.00698  +  0.32717  d,  in  which  d  is  the 
specific  gravity  of  the  solution  at  17.5°  C. 

In  1901  Stolle,*  using  a  Pulfrich  ref lactometer,  constructed  tables 
for  sucrose,  glucose,  fructose,  and  lactose,  a  comparison  of  which  showed 
that  but  very  little  variation  existed  in  the  refractive  index  of  solutions 
of  different  sugars  for  the  same  concentration.  The  following  table 
is  made  up  from  the  observations  of  Stolle  upon  sucrose  solutions  of 
different  concentrations. 

TABLE  XIV 

Giving  Index  of  Refraction  of  Sugar  Solutions 


Concentration, 

Specific  gravity  (d) 

Per  cent  sucrose 

Refractive  index  (n) 

Refractive  constant 

17  5° 

n  •    1 

4° 

(n*+2)  d 

0.9979 

1.00241 

1.00 

1.33465 

0.20612 

4  0073 

1.01406 

3.95 

1.33889 

0.20615 

12.0052 

1.04484 

11.49 

1.35044 

0.20617 

17.9385 

1.06736 

16.81 

1.35891 

0.20621 

25.0120 

1.09420 

22.87 

1.36891 

0.20617 

35.0219 

1  .  13194 

30.94 

1.38306 

0.20610 

45.8381 

1  .  17246 

39.10 

1.39873 

0.20619 

55.0266 

1.20651 

45.61 

1.41150 

0.20602 

The  average  value  for  the  refractive  constant  (calculated  by  the 
formula  of  Lorenz  and  Lorentz)  is  0.20614;  from  this  it  follows  that 
the  specific  gravity  (d)  of  sugar  solutions  may  be  calculated  from  the 

n2  —  1 
refractive  index  (n)  by  the  equation  d  =      2          x  02Q614' 

In  1906  Tolman  and  Smith,f  using  an  Abbe  refractometer  of  latest 
construction,  showed  that  "the  refractometer  is  a  satisfactory  instru- 
ment for  determining  the  soluble  carbohydrates  in  solution  under  the 
same  conditions  as  those  under  which  specific  gravity  can  be  used,  and 
in  fact  gives  the  same  results;  that  it  has  many  advantages  over  the 
specific  gravity  method  in  speed,  ease  of  manipulation,  and  amount  of 
sample  required  for  the  determination,"  and  that  the  refractometer  can 
be  used  for  a  great  deal  of  work  where  quickness  and  approximate 
accuracy  only  are  necessary.  Tolman  and  Smith  give  the  following 
table  showing  index  of  refraction  at  20°  C.  and  percentage  of  various 
carbohydrates  in  solution. 


*  Z.  Ver.  Deut.  Zuckerind.,  51,  469. 
t  J.  Am.  Chem.  Soc.,  28,  1476. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER 


63 


TABLE  XV 

Giving  Index  of  Refraction  of  Various  Sugar  Solutions  of  Different  Concentration 
(Dried  in  vacuum  at  70°  C.  to  constant  weight.) 


Index  of  refraction, 
20°  C. 

Sucrose. 

Maltose. 

Commercial 
glucose. 

Lactose. 

Dextrin. 

1.3343 
1.3357 
1.3402 
1.3477 
.3555 
.3637 

Per  cent. 

1.00 
2.00 
5.00 
10.00 
15.00 
20.00 

Per  cent. 

1.00 
2.07 
5.07 
10.07 
15.12 
20.17 

Per  cent. 
1.00 

2.00 
5.00 
10.07 
15.06 
20.06 

Per  cent. 
1.00 
2.00 
5.13 

10.13 
15.13 

Per  cent. 
1.00 
1.93 

4.87 
9.60 
14.13 
18  94 

3722 

25  00 

25  00 

23  71 

3810 

30  00 

30  02 

28  78 

.3902 

35.00 

35.03 

.3997 

40.00 

40.05 

1.4096 

45.00 

45.04 

1  4200 

50  00 

50  03 

1  4306 

55  00 

55  02 

1  4419 

60  00 

60  01 

1  4534 

65  00 

65  01 

1  4653 

70  00 

70  00 

1  .  4776 

75  00 

75.00 

1.4903 

80.00 

80.00 

1  .  5034 

85.00 

85.00 

1.5170 

90.00 

90.00 

It  will  be  seen  from  the  above  table  that  dextrin  alone  of  the  carbo- 
hydrates examined  differs  appreciably  from  sucrose  in  its  index  of 
refraction.  Comparing  the  specific  gravity  ^r  of  the  above  sucrose 
solutions  with  their  refractive  indices  the  method  of  least  squares  shows 
that  nl°=  0.9509  +  0.3818  d^°. 

Tolman  and  Smith  also  studied  the  effects  of  temperature  upon  the 
refractive  index  of  sugar  solutions,  and  their  results  "show  that  the 
temperature  correction  for  the  specific  gravity  and  the  index  of  refrac- 
tion are  practically  the  same,  and  the  table  as  given  for  Brix  can  be 
used  for  the  index  of  refraction.  The  manner  of  using  the  table  is  the 
same.  The  reading  of  index  of  refraction  is  made  at  room  temperature 
and  this  reading  calculated  to  per  cent  of  sugar,  then  the  proper  correc- 
tion from  the  table  calculated  and  applied." 

Following  the  work  of  Tolman  and  Smith  was  that  of  Main*  in 
1907.  Main  was  the  first  to  demonstrate  the  practical  utility  of  the 
Abbe  refractometer  in  sugar-house  work,  and  showed  that  the  refractive 
index  was  an  accurate  measure  of  the  moisture  and  total  solids  in  all 

*  Int.  Sugar  Jour.,  9,  481. 


64 


SUGAR  ANALYSIS 


refinery  products  except  the  very  lowest.  The  table  of  Main  (Table  5, 
Appendix),  which  agrees  almost  exactly  with  that  of  Tolman  and  Smith, 
is  the  one  employed  by  most  sugar  chemists  at  present.  The  indices  give 
the  percentage  of  water  to  0.1  per  cent  from  100  per  cent  to  15  per  cent; 
the  percentage  of  water  subtracted  from  100  gives  the  corresponding 
percentage  of  total  solids.  Stanek  *  has  prepared  a  table  of  tempera- 
ture corrections  for  the  table  of  Main,  the  figures  of  which  show,  as 
was  indicated  by  Tolman  and  Smith,  that  the  temperature  corrections 
for  specific  gravity  and  refractive  index  are  virtually  the  same  (Table  6, 
Appendix) . 

Schonrock  f  of  the  Physikalisch-Technische  Reichsanstalt  in  Berlin 
has  made  the  most  recent  measurements  of  the  refractive  indices  of 
sugar  solutions.  A  preliminary  report  of  Schonrock's  determinations, 
which  as  regards  attention  to  scientific  detail  are  probably  the  most 
carefully  conducted  of  any  measurements  thus  far  made,  is  given  in 
Table  XVI,  in  which  n  is  the  refractive  index  at  20°  C.  for  the  two  D 
lines  of  sodium  light  (589.3  ///*)  and  w  the  water  content  of  the  solution. 

TABLE  XVI 
Giving  Refractive  Index  and  Water  Content  of  Sugar  Solutions 


< 

W 

< 

W 

< 

W 

-v,20° 

nD 

w 

1.3330 
1.3344 
.3359 
.3374 
.3388 
.3403 
.3418 
3433 

100 
99 
98 
97 
96 
95 
94 
93 

1.3639 
1.3655 
1.3672 
1.3689 
.3706 
.3723 
1.3740 
1  3758 

80 
79 
78 
77 
76 
75 
74 
73 

1.3997 
1.4016 
1.4036 
1.4056 
1.4076 
1.4096 
1.4117 
1  4137 

60 
59 
58 
57 
56 
55 
54 
53 

.4418 
.4441 
.4464 
.4486 
.4509 
.4532 
.4555 

40 
39 
38 
37 
36 
35 
34 

3448 

92 

1  3775 

72 

1  4158 

52 

3464 

91 

1  3793 

71 

1  4179 

51 

3479 

90 

1  3811 

70 

1  4200 

50 

3494 

89 

1  3829 

69 

1  4221 

49 

3510 

88 

1  3847 

68 

1  4242 

48 

3526 

87 

1  3865 

67 

1  4264 

47 

3541 

86 

1  3883 

66 

1  4285 

46 

1  3557 

85 

1  3902 

65 

1  4307 

45 

1  3573 

84 

1  3920 

64 

1  4329 

44 

1.3590 

83 

1  3939 

63 

1  4351 

43 

1.3606 

82 

1  3958 

62 

1  4373 

42 

1.3622 

81 

1.3978 

61 

1  4396 

41 

The  above  table  shows  no  greater  deviation  at  any  reading  than 
in  the  fourth  decimal  place  from  the  previous  work  of  Main. 

*  Z.  Zuckerind.  Bohmen,  33,  153. 
t  Z.  Ver.  Deut.  Zuckerind.,  61,  421. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         65 


The  use  of  the  Abbe  refractometer  was  extended  to  raw  sugar  cane 
products  by  Prinsen  Geerligs  and  van  West*  who  made  a  special  study 
of  the  effect  of  impurities  upon  the  refractive  index  of  sugar  solutions. 
Their  results,  in  connection  with  observations  upon  low-grade  Java 
molasses,  show  that  the  refractive  index  of  impure  sugar  solutions  is  a 
much  truer  measure  of  the  actual  amount  of  dry  substance  present  than 
the  specific  gravity.  The  refractometer  table  (Table  7,  Appendix)  of 
Geerligs  f  is  established  at  28°  C.  and  is  the  one  best  adapted  for  tropi- 
cal countries;  the  temperature  corrections  which  accompany  the  table 
have  a  range  from  20°  to  35°  C.  When  corrected  to  20°  C.,  Geerligs's 
results  are  identical  with  those  of  Tolman  and  Smith,  and  Main. 

The  use  of  the  refractometer  in  the  examination  of  sugar-beet 
products  has  been  studied  by  Lippmann,  Htibener,  Lange,  and  many 
others.  As  in  the  case  of  sugar-cane  products,  the  refractometer  gives 
values  for  solid  matter  much  closer  to  the  true  dry  substance  than 
specific  gravity. 

The  percentage  of  moisture  or  dry  matter  in  sugar  products  which 
have  partly  crystallized,  such  as  massecuites,  moist  sugars,  etc.,  can 
be  made  upon  the  refractometer  after  dissolving  all  soluble  matter 
with  a  known  amount  of  water. 

Example.  —  10  gms.  of  massecuite  were  dissolved  in  10  c.c.  of  hot  distilled 
water,  the  weight  of  mixture  after  cooling  to  20°  C.  being  brought  to  20  gms. 
by  addition  of  distilled  water  of  20°  C.  The  refractive  index  of  the  mixture 
was  1.4107,  which  according  to  Main's  table  indicates  54.45  per  cent  water. 
54.45  per  cent  of  20  gms.  =  10.89  gms.  water  in  mixture.  10.89  -  10  (gms. 
water  added)  =  0.89  gm.  water  in  original  massecuite,  or  8.90  per  cent. 

Hardin  has  made  comparative  determinations  of  the  moisture  in 
different  grades  of  sugar  by  drying  and  by  the  refractometer  with  the 
following  results: 


Grade  of  sugar. 

Refractive  index, 
20°  C.  (1  part  sugar 
+1  part  distilled 
water). 

Per  cent  of  water. 

By  refractometer. 

By  drying  to 
constant  weight. 

Refined  sugar 

1.4200 
1.4199 
1.4197 
.4190 
.4189 
.4181 
.4179 
.4172 
.4139 

Per  cent. 
0.10 
0.20 
0.40 
1.00 

1.10 
1.90 
2.10 
2.70 
5.90 

Per  cent. 
0.05 
0.45 

0.82 
0.82 
1.05 
1.93 
2.40 
2.83 
5.54 

Hawaiian  centrifugal     

Philippine  mats  (dried  out)  
Java  centrifugal 

Louisiana  centrifugal 

Cuban  centrifugal                

Muscovado                

IVIolasses  sugar 

Molasses  sugar 

*  Archief  Java  Suikerind.  (1907),  15,  487.         t  Int.  Sugar  Jour.,  10,  69-70. 


66  SUGAR  ANALYSIS 

The  variations  in  the  results  by  the  two  methods  are  in  both  direc- 
tions, and  may  have  been  due  either  to  the  presence  of  trash  in  the 
sugar  or  to  the  influence  of  non-sugars.  Since  the  refractometer  only 
indicates  the  percentage  of  dissolved  solids,  any  insoluble  matter 
which  is  present  in  the  weighed  sample  will  introduce  an  error  in  the 
calculation. 

Insoluble  suspended  matter  in  sugar  solutions,  if  present  in  large 
amounts,  will  darken  the  field  of  the  refractometer  and  interfere  with 
the  adjustment  of  the  border  line.  In  such  cases  the  solution  must 
be  filtered. 

Examination  of  Dark-colored  Sugar  Solutions  with  the  Re- 
fractometer. —  In  the  examination  of  dark-colored  sugar  solutions, 
molasses,  sirups,  extracts,  etc.,  by  means  of  the  refractometer,  it  is  not 
always  possible  for  the  compensator  to  eliminate  completely  the  effects 
of  dispersion;  the  border  line  of  the  field  is  then  more  or  less  blurred 
and  a  sharp  adjustment  to  the  intersection  of  the  reticule  becomes  a 
matter  of  some  difficulty.  In  solutions  which  are  not  too  strongly 
colored  this  trouble  may  be  remedied  by  bringing  the  border  line  to 
the  point  of  intersection  alternately  from  each  side  of  the  field;  the 
average  of  the  readings  thus  obtained  will  correct  to  a  large  extent  the 
errors  of  faulty  adjustment.  Some  authorities  have  recommended 
with  dark  solutions  to  adjust  the  compensator  to  a  colored  border, 
selecting  the  color  most  sensitive  to  the  observer's  eye;  this,  however, 
is  not  very  satisfactory,  and  if  the  blurring  of  the  border  line  is  excessive, 
the  color  of  the  solution  must  be  reduced  by  some  method  of  dilution 
or  clarification. 

In  the  dilution  of  impure  sugar  products  with  water  an  error  will  be 
introduced  in  the  refractometer  reading  in  the  same  manner  as  in  the 
determination  of  specific  gravity,  owing  to  the  difference  in  contrac- 
tion between  solutions  of  sugar  and  of  the  accompanying  impurities 
(page  35). 

A  study  of  the  errors  resulting  from  unequal  contraction,  when 
dilution  is  employed  in  densimetric  and  refractometric  methods  of 
analysis,  has  been  made  by  Stanek.*  Fifty  per  cent  solutions  of  betaine 
and  of  various  organic  salts  of  sodium  and  potassium  were  prepared. 
These  solutions  were  then  diluted  with  known  weights  of  water  and  the 
per  cent  of  dry  substance  determined  from  the  degrees  Brix,  from  the 
refractive  indices  according  to  Main's  table,  and  by  drying  on  sand 
in  a  Soxhlet  oven  at  102°  C.  A  few  of  the  results  are  given  in  the 
following  table: 

*  Z.  Zuckerind.    Bohmen,  34,  5. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER 


67 


TABLE  XVII 
Comparative  Determinations  of  Solids  by  Brix,  Refractometer  and  Drying  at  102° 


True  dry 

I 

)ry  substance  by 

SubststncG  t&KGii. 

substance. 

Degrees  Brix. 

Refractometer. 

Drying  at  102°. 

c 

Per  cent. 
5 

Per  cent. 
2.2 

Per  cent. 
5.10 

Per  cent. 
5.05 

Betaine  (anhydrous)  .      .  .  .  \ 

10 

4.3 

10.20 

10.01 

25 

10.8 

24.15 

25.03 

( 

5 

8.1 

4.60 

4.99 

Sodium  formate       \ 

10 

15.6 

8.85 

10.04 

25 

37.7 

20.55 

25.05 

( 

5 

7.3 

3.60 

5.00 

Potassium  formate  < 

10 

14.28 

7.20 

9.97 

25 

35.7 

17.20 

25.09 

( 

5 

6.7 

5.00 

4.97 

Sodium  acetate                      \ 

10 

13.1 

9.70 

9.99 

25 

31.1 

22.70 

25.00 

, 

5 

6.6 

5.00 

5.00 

Potassium  acetate  ...       .  s 

10 

12.8 

8.25 

10.07 

25 

30.4 

19.75 

25.15 

( 

5 

4.75 

4.90 

4.90 

Sodium  butyrate  < 

10 

9.4 

10.25 

9.89 

25 

22.9 

24.35 

24.94 

( 

5 

6.3 

5.00 

5.10 

Sodium  lactate  ] 

10 

12.3 

10.00 

10.07 

25 

30.2 

24.05 

25.05 

jf 

5 

6.3 

4.85 

5.18 

Potassium  lactate                   j 

10 

12.5 

9.10 

10.13 

25 

30.3 

21.65 

25.20 

, 

5 

6.8 

6.40 

5.05 

Sodium  glutaminate  < 

10 
25 

13.2 
31.1 

12.50 
30.05 

10.23 
26.41 

( 

5 

6.7 

5.90 

5.03 

Potassium  glutaminate  .  .  .  .  \ 

10 
25 

13.1 
30.65 

11.50 
27.70 

10.24 
25.27 

It  will  be  noted  from  the  above  that  the  refractometer  gives  a 
much  closer  approximation  to  the  true  dry  substance  than  the  degrees 
Brix,  the  refractometer  yielding  usually  lower  results  and  the  degrees 
Brix  higher.  It  is  also  seen  that  the  sodium  salts  of  organic  acids  give 
higher  results  by  both  methods  than  potassium  salts.  Contraction 
upon  dilution  is  noted  in  every  case,  the  results  corrected  for  dilution 


68  SUGAR  ANALYSIS 

being  higher  according  to  the  amount  of  water  added.  The  usual 
effect  of  this  contraction  is  to  make  the  error  in  estimating  non-sugars 
less  by  the  refractometer  and  greater  by  degrees  Brix.  Neither  of 
these  methods  for  estimating  non-sugars  approaches  in  point  of  ac- 
curacy the  method  of  actual  drying. 

The  errors  in  determining  the  refractive  index  of  dark  impure 
sugar  solutions,  resulting  from  dilution  with  water,  may  be  largely 
eliminated  by  employing  the  method  of  Tischtschenko,*  which  con- 
sists in  reducing  the  color  of  the  product  by  means  of  a  solution  of  pure 
sucrose  of  about  the  same  density  as  the  liquid  to  be  examined.  The 
disturbing  influences  of  color  dispersion  in  the  refractometer  field  are 
in  this  way  overcome  without  the  errors  of  contraction.  The  method 
of  operation  is  as  follows:  A  known  weight  (a)  of  the  molasses,  sirup, 
etc.,  is  intimately  mixed  with  a  known  weight  (6)  of  pure  sugar  solution, 
whose  sugar  content  (p)  has  been  previously  determined  by  means  of 
the  refractometer.  The  refractive  index  of  the  mixed  solution  is  then 
determined  and  the  corresponding  percentage  (P)  of  dry  substance  found 
from  the  table.  The  percentage  of  dry  substance  (x)  in  the  molasses, 
sirup,  etc.,  is  then  calculated  by  the  formula  ax  +  bp  =  (a  +  6)P, 

(a  +  b)P-bp 

whence  x  =  -          -• 

a 

Example.  —  Weight  of  beet  molasses  (a)  =  14.1028  gms. 
Weight  of  sugar  sirup  (6)  =  13.2438  gms. 
Sugar  in  sirup  (p)  =  51.3  per  cent. 

ng°of  mixture  =  1.4538  =  34.87  per  cent  water 

(Main's  table). 
Solids  of  mixture  (P)  =  100-34.87  =  65.13  per  cent. 

Substituting  these  values  in  the  formula,  x  —  78.12  per  cent  solids  in  molasses. 
The  method  by  water  dilution  gave  79.11  per  cent.  Direct  determination  by 
drying  gave  77.80  per  cent. 

If  a  sugar  sirup  of  greater  density  had  been  used  for  mixing,  the  value  of  x 
would  have  been  more  close  to  the  result  by  direct  determination. 

If  equal  weights  of  molasses  and  sugar  solution  are  used  in  Tischt- 
schenko's  method,  then  a  =  b  .in  the  formula,  whence  x  =  2P  —  p; 
the  labor  of  calculation  is  thus  considerably  reduced.  In  using  the 
method,  the  mixture  of  molasses  and  sugar  solution  must  be  perfectly 
homogeneous.  Care  must  also  be  exercised,  as  in  all  cases,  that  no 
air  bubbles  are  inclosed  with  the  liquid  between  the  prisms.  A  com- 

*  Z.  Ver.  Deut.  Zuckerind.,  69,  103. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         69 

parison  of  results  in  determining  dry  substance  in  different  samples 
of  beet  molasses  by  various  methods  is  given  by  Lippmann*  in  the 
following  table: 

TABLE  XVIII 

Comparative  Determinations  of  Solids  in  Beet  Molasses  by  Drying,  Specific  Gravity,  and 

Refractometer 


Number. 

By  direct 
determination. 

By  degrees 
Brix. 

By  refractometer. 

Water  dilution. 

Tischtschenko's 
method. 

1 

76.78 
77.95 
76.22 
77.85 
77.05 
77.55 
77.97 
77.32 
77.50 
77.31 
76.58 
76.94 
77.43 
76.53 
77.82 
77.90 

78.90 

79.80 
78.60 
79.30 
79.40 
79.20 
79.90 
79.30 
79.30 
79.60 
78.90 
79.20 
79.60 
78.90 
80.00 
80.20 

77.90 

78.50 
77.00 
78.60 
78.20 
78.10 
78.60 
78.20 
78.60 
78.40 
77.70 
77.90 
78.50 
77.70 
79.00 
78.90 

76.80 
78.00 
76.10 
77.90 
77.30 
77.80 
78.30 
77.70 
77.88 
77.70 
77.00 
77.40 
77.90 
77.00 
78.30 
77.40 

2 

3          .    . 

4  

5  

6  

7  

8  

9 

10 

11 

12 

13.    ..    . 

14  

15  

16  

Average  

77.29 

79.38 

78.24 

77.53 

It  will  be  noted  from  the  above  that  the  average  error  of  estimating 
dry  substance  in  the  16  samples  of  beet  molasses  was,  by  degrees  Brix, 
+2.09  per  cent;  by  refractometer,  using  water  dilution,  +0.95  per  cent; 
and  by  refractometer,  using  Tischtschenko's  method,  only  +0.24  per 
cent. 

Another  method  of  correcting  the  disturbances  in  refractometer 
work  due  to  color  of  solution  is  by  clarification.  Lead  subacetate  is 
the  reagent  most  generally  employed  for  this  purpose.  The  use  of 
this  and  similar  salts  must  be  limited,  however,  to  the  greatest  possible 
minimum,  since  the  excess  of  salt  remaining  in  the  clarified  solution 
causes  an  increase  in  the  refractive  index.  In  the  following  experiments 
made  by  Rosenkranzf  at  the  Berlin  Institute  for  Sugar  Industry,  the 
effect  of  increasing  the  quantity  of  subacetate  is  shown  upon  the  re- 
fractive index  of  a  molasses  containing  78.59  per  cent  dry  substance 
and  diluted  1:1,  inclusive  of  the  lead  solution  added. 

*  Deut.  Zuckerind.,  34,  402. 

t  Z.  Ver.  Deut.  Zuckerind.,  68,  195. 


70 


SUGAR  ANALYSIS 


Lead  subacetate. 

Specific  gravity, 
dilute  solution, 
20°. 

Calculated 
Brix  of  original 
molasses. 

Refractive 
index,  dilute 
solution. 

Dry  substance, 
dilute  solution 
(Main's  table). 

Calculated 
dry  substance, 
original 
molasses. 

c.c. 

"5 
10 
12.5 

1.1813 

1.1865 
1.1912 
1.1951 

81.9 
84.0 

85.7 
87.2 

1.3994 
1.4003 
1.4009 
1.4022 

39.85 
40.3 
40.6 
41.3 

79.70 
80.60 
81.2 
82.6 

Another  material  recommended  by  Lippmann  for  decolorizing  dark 
sirups,  etc.,  for  the  refractometer  is  "Decrolin,"  the  zinc  salt  of  formal- 
dehyde sulphoxylic  acid,  CH2OH.O.SO.Zn.OH.  One  to  two  per  cent  of 
Decrolin  is  used  and  the  liquid  heated  to  about  55°  C.  to  hasten  solution 
and  decolorization. 

For  the  refractometric  examination  of  turbid  beet  juices,  etc., 
Herzfeld*  has  recommended  the  addition  of  a  few  drops  of  10  per 
cent  acetic  acid,  heating  for  2  minutes  at  80°  C.  to  coagulate  albu- 
minoids, and  filtering.  With  beet  juices  the  effect  of  dilution  (1  to  5 
per  cent)  is  compensated  by  the  greater  refractive  index  of  the  10  per 
cent  acetic  acid  used,  as  shown  in  the  following  experiment: 


10  c.c.  beet  juice. 

Refractive 
index,  rc*°- 

Dry  substance 
by  Main's 
table. 

+0.5    c.c.  water  

1.3583 

16.75 

H-0.5    c.c.  acetic  acid  (10  per  cent)  
+0.25  c.c.  water  

1.3595 
1.3588 

17.45 
16.95 

+0.25  c.c.  acetic  acid  (10  per  cent)  .... 
+0  10  c.c.  water 

1.3591 
1  35905 

17.20 
17  15 

+0.10  c.c.  acetic  acid  (10  per  cent).  .  .  . 

1.35905 

17.15 

THE  IMMERSION  REFRACTOMETER 

A  second  form  of  instrument  which  is  used  for  determining  the  re- 
fractive power  of  sugar  solutions  is  the  immersion  refractometer,  the 
Zeiss  model  of  which  is  shown  in  Fig.  36.  While  this  instrument  has  a 
narrower  range  than  the  Abbe  apparatus,  the  scale  being  adapted  only 
for  solutions  containing  from  0  to  21.7  per  cent  sugar,  it  gives  a  much 
sharper  border  line,  thus  allowing  a  greater  magnification  in  the  tele- 
scope, with  a  corresponding  increase  in  the  accuracy  of  observation. 
In  the  immersion  refractometer  there  is  no  sector;  the  scale  is  placed 
below  the  eyepiece  of  the  telescope,  the  latter,  unlike  the  Abbe  re- 
fractometer, being  rigidly  connected  with  the  prism. 

*  Z.  Ver.  Deut.  Zuckerind.,  68,  197. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         71 

The  principle  of  the  immersion  refractometer  is  the  same  as  that  of 
the  Abbe  instrument,  being  based  upon  an  observation  of  the  border 
line  of  total  reflection.  In  Fig.  37,  G  is  a  cylindrical  glass  prism  with 
its  refracting  surface  DE  immersed  in  the  liquid  W  contained  in  the 
glass  beaker  V.  If  we  suppose  light  to  pass  through  the  top  of  the 
prism  from  the  surface  A B,  the  parallel  rays  sP5  s'P',  s"P",  etc.,  will 


• 


Fig.  36.  —  Zeiss  immersion  refractometer. 

be  refracted  in  the  liquid  in  the  direction  PM,  P'M',  P"M",  etc.  By 
increasing  the  angle  of  incidence  for  the  parallel  rays  upon  the  surface 
DE,  a  point  is  reached  where  the  parallel  rays  rP,  r'P' ,  r"P",  etc.,  are 
refracted  along  the  surface  of  the  prism  towards  D.  This  is  the  bor- 
der line  of  total  reflection  as  explained  under  Fig.  30,  where  the  angle 
•  of  refraction  is  90°.  In  the  use  of  the  immersion  refractometer  the 
course  of  the  light  is  in  the  reversed  direction  to  that  just  described, 
being  reflected  from  the  mirror  HK  through  the  bottom  of  the  beaker 
V  so  as  to  pass  as  nearly  parallel  as  possible  to  the  oblique  surface  of 
the  prism.  The  rays  of  light  which  coincide  with  the  surface  DE  form 


72 


SUGAR  ANALYSIS 


the  border  line  for  total  reflection  and  are  refracted  upward  through  the 
prism  as  the  parallel  rays  Pr,  PV,  P"r",  etc.,  which,  being  condensed 
by  the  objective  0  of  the  refractometer  telescope  upon  the  point  x  of 

the  scale  S,  form  the  border 
line  for  observation;  the  rays  of 
light  which  may  strike  the  prism 
surface  obliquely,  as  MP,  M'P', 
M"P" ,  etc.,  are  refracted  in  the 
direction  Ps,  PY,  P'Y',  etc., 
and  being  condensed  by  the  ob- 
jective between  x  and  y  cause 
this  part  of  the  scale  to  be  illu- 
minated. There  being  no  pos- 
sible angle  of  refraction  for  light 
in  the  prism  greater  than  that 
for  the  border  line  of  total  re- 
flection, the  part  of  the  scale 
between  x  and  z  remains  in 
shadow. 

As  in  the  Abbe  refractom- 
eter, the  border  line  on  account 
of  differences  in  dispersion  is 
fringed  with  color  and  must  be 
corrected  by  a  compensator  in 
the  manner  described  on  p.  57. 
The  compensator  is  placed  at  A 
(Fig.  38)  between  the  objective 
0  and  the  prism  P  and  is  ro- 
tated by  the  milled  ring  R  until 
the  border  line  upon  the  scale 

becomes  sharp  and  colorless.  The  position  of  the  border  line  upon  the 
scale  marks  the  reading  for  the  whole  division;  the  fractional  division 
is  determined  by  rotating  the  micrometer  screw  Z,  which  controls  the 
scale,  until  the  whole  division  previously  noted  is  brought  into  contact 
with  the  border  line.  The  reading  of  the  micrometer  drum  shows  the 
fractional  division  which  remains  to  be  added.  Readings  can  be  made 
by  careful  observers  to  agree  within  0.1  scale  division,  which  cor- 
responds to  3.7  of  the  fifth  decimal  of  the  refractive  index.  This  ex- 
ceeds considerably  in  accuracy  the  reading  of  the  Abbe  refractometer. 
The  adjustment  of  the  Zeiss  immersion  refractometer  scale  is  made 
by  means  of  distilled  water,  which  should  give  a  reading  of  15  at 


Fig.  37.  —  Illustrating  principle  of  immer- 
sion refractometer. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER 


73 


17.5°  C.     The  adjustment,  however,  can  be  made  at  other  tempera- 
tures according  to  the  following  table. 

The  correctly  adjusted  refract ometer  should  show  for  distilled  water: 


At  a  temperature  of  

10°  C. 

11 

12 

13 

14 

15 

16 

17 

17.5 

18 

19°  C. 

The  scale  division  

16.3 

16.15 

16.0 

15.85 

15.7 

15.5 

15.3 

15.1 

15.0 

14.9 

14.7 

At  a  temperature  of  

20°  C. 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30°  C. 

The  scale  division               

14.5 

14.25 

14.0 

13.75 

13.5 

13.25 

13.0 

12.7 

12.4 

12.1 

11.8 

Fig.  38.  —  Showing  inner  construction  of  immersion  refractometer. 

Should  the  average  of  several  careful  readings  differ  by  more  than 
0.1  division  from  the  reading  in  the  above  table  for  the  temperature  of 
testing,  the  scale  should  be  readjusted.  This  is  done  by  first  setting 
the  micrometer  at  10;  then  by  inserting  a  setpin  in  the  hole  of  an 


74 


SUGAR  ANALYSIS 


adjusting  screw  inside  the  micrometer  drum  and  turning  anticlockwise, 
the  border  line  of  the  field  is  made  to  agree  with  the  whole  scale  division 
corresponding  to  the  temperature  of  the  water.  The  loosened  microm- 
eter drum  is  now  turned  until  its  index  marks  the  proper  decimal; 
holding  it  firmly  in  this  position,  the  nut  which  governs  the  micrometer 
is  retightened.  The  new  adjustment  should  be  controlled  by  repeated 
readings. 

The  readings  of  the  Zeiss  immersion  scale  extend  from  —5  to  +105, 
and  are  converted  into  refractive  indices  or  into  percentages  of  sugar 


Fig.  39.  —  Tempering  bath  for  immersion  refractometer. 

by  means  of  special  conversion  tables  which  accompany  the  instrument. 
Sugar  tables  for  the  immersion  refractometer  have  been  prepared  by 
Hiibener;  *  these  give  the  sucrose  values  of  the  scale  from  15  to  106 
with  percentages  of  sucrose  from  0.00  to  21.71.  Each  0.1  division  of 
the  scale  corresponds  to  about  0.02  per  cent  sucrose  or  other  sugar, 
and  readings  can  be  made  with  this  degree  of  exactness.  (See  Table  8, 
Appendix.) 

For  controlling  the  temperature  of  the  water  bath,  containing  the 
*  Dent.  Zuckerind.,  33,  108. 


PRINCIPLE  AND  USES  OF  THE  REFRACTOMETER         75 

beakers  of  solution  for  the  immersion  refractometer,  the  spiral  heater 
and  water-pressure  regulator  previously  described  may  be  used.  A 
tempering  bath  holding  10  liters  of  water  and  with  a  revolving  frame 
for  12  beakers  (shown  in  Fig.  39)  is  also  recommended.  When  the 
proper  temperature  has  been  reached  in  the  beakers  the  solutions  are 
read  in  sequence,  the  refractometer  prism  being  wiped  dry  after  each 
immersion.  When  large  numbers  of  solutions  are  to  be  tested,  each 
solution  as  soon  as  read  is  replaced  by]a  beaker  of  fresh  solution,  thus 
giving  sufficient  time  for  regulation  of  temperature  without  interruption 
of  work. 

When  only  a  few  cubic  centimeters  of  solution  are  available  or  when 
the  liquids  to  be  examined  consist  of  dark-colored  sirups,  molasses, 
extracts,  etc.,  the  immersion  prism  is  fitted  with  an  auxiliary  prism 
held  in  position  by  means  of  a  metal  beaker  and  cover.  The  method 
of  use  is  somewhat  similar  to  that  of  the  Abbe  refractometer;  the  hy- 
potenuse surface  of  the  auxiliary  prism  is  covered  with  a  few  drops  of 
solution  and  then  inserted  in  the  beaker  against  the  face  of  the  immer- 
sion prism  so  that  a  thin  layer  of  liquid  is  spread  between  the  two. 

The  remarks  upon  illumination  under  the  Abbe  refractometer  also 
apply  to  the  immersion  instrument. 

As  to  the  particular  choice  of  refractometer  for  the  sugar  laboratory, 
the  chemist  must  be  guided  by  his  requirements.  The  Abbe  refractom- 
eter has  the  widest  range,  is  adapted  to  smaller  quantities  of  solution, 
and  is  more  convenient  to  operate.  The  immersion  refractometer, 
however,  is  more  accurate  in  adjustment  and  much  less  expensive.  For 
general  work  the  Abbe  instrument  will  be  found  more  useful;  for  more 
limited  operations  upon  solutions  below  20°  Brix,  such  as  beet  and 
cane  juices,  sweet  waters,  etc.,  the  immersion  instrument  possesses 
certain  advantages. 


CHAPTER  V 

POLARIZED  LIGHT,    THEORY  AND   DESCRIPTION   OF   POLARIMETERS 

IN  order  to  arrive  at  a  sufficiently  clear  understanding  of  the  optical 
principles  which  underlie  the  construction  and  manipulation  of  polari- 
scopes,  a  brief  reference  must  be  made  to  the  physical  theories  of  light. 

According  to  the  undulatory  theory  of  Huyghens,  light  consists  of 
vibrations  or  wave  motions  of  the  luminiferous  ether,  the  imponder- 
able medium  which  pervades  all  space  and  penetrates  all  matter. 

Waves  of  light,  contrary  to  those  of  sound,  vibrate  transversally 
instead  of  longitudinally.  In  Fig.  40  a  graphic  representation  is  given 


o 


D 
Fig.  40.  —  Illustrating  principle  of  a  light  wave. 

of  a  light  wave  vibrating  transversally  to  the  direction  of  motion  LM. 
The  plane  of  vibration  of  ordinary  light  takes  all  possible  positions 
about  this  line  of  motion.  The  distance  OB  or  OfD  from  the  middle  to 
the  extremity  of  an  oscillation  is  known  as  the  amplitude  of  the  wave. 
The  distance  from  A  to  E  (points  in  the  same  phase)  is  known  as  the 
wave  length  (X),  which  for  light  is  expressed  in  millionths  of  a  milli- 
meter GU/X).  The  number  of  waves  per  second  is  called  the  rate  of 
vibration  (N).  If  the  velocity  of  light  through  a  homogeneous  medium 

be  V,  then  N  =  ^- 

A 

According  to  Maxwell's  electromagnetic  theory,  which  has  since 
been  confirmed  by  the  work  of  Hertz,  there  are  two  sets  of  transverse 
vibrations  in  the  transmission  of  a  ray  of  light,  the  one  an  electric  dis- 
placement of  the  ether,  and  the  other  a  magnetic  displacement,  the 
planes  of  these  being  perpendicular  to  each  other. 

The  intensity  of  a  ray  of  light  is  proportional  to  the  square  of  the 

76 


flTYIT 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


77 


amplitude;  the  color  depends  upon  the  rate  of  vibration  of  the  ether 
wave.  The  color  of  light  may,  therefore,  be  expressed  mathematically 
in  terms  of  the  rate  of  vibration  N  or  of  its  wave  length  X.  The  values 
of  N  and  X  for  the  average  ray  in  each  color  of  the  spectrum  are  given 
in  the  following  table : 

TABLE  XIX. 


Color. 

Rate  of  vibration 
per  second  (N). 

Wave  length  (X) 
in  millionths  of  a 
millimeter  (jin). 

Red            

Billions. 
437 

683 

Orange  

485 

615 

Yellow  

534 

559 

Green  

582 

512 

Blue  

631 

473 

Indigo  

679 

439 

Violet  

728 

410 

The  human  eye  is  sensitive  to  light  of  vibration  periods  between 
about  366  and  804  billion  per  second,  and  of  wave  lengths  between 
about  820  MM  and  373  pp.  Ether  waves  of  greater  length  than  820  MM 
constitute  the  so-called  infra-red  or  heat  rays,  and  those  of  shorter 
length  than  373  MM  the  so-called  ultra-violet  or  chemical  rays. 

Light  of  definite  wave  length  is  exceedingly  important  in  making 
polariscopic  measurements,  and  this  is  secured  by  using  incandescent 
salts  of  certain  metals,  as  sodium  or  lithium,  which  give  bright  spectral 
lines  whose  wave  lengths  are  absolutely  defined.  The  prominent  lines 
of  the  different  elements  are  usually  designated  by  the  letters  of  the 
alphabet,  which  have  been  adopted  to  mark  their  positions  in  the  solar 
spectrum.  For  the  sodium  line  *  D,  to  which  nearly  all  polariscopic 
measurements  are  referred,  X  =  589.3  MM- 

The  vibrations  of  ordinary  light  proceed  in  an  infinite  number  of 
planes.  By  means  of  various  special  contrivances  it  is  possible,  how- 
ever, to  affect  a  beam  of  light  so  that  the  electric  and  magnetic  vibrations 
will  each  proceed  in  a  single  plane.  Such  light  is  said  to  be  plane- 
polarized;  the  plane  to  which  the  electric  vibration  of  the  waves  is 
perpendicular  is  called  the  plane  of  polarization. 

The  polarization  of  light  was  first  noticed  by  Huygens  in  1678, 
while  studying  the  refraction  of  light  in  a  crystal  of  Iceland  spar.  No 
satisfactory  explanation  of  the  phenomenon  was  made,  however,  until 

*  The  sodium  line  is  double;  the  component  Z>i  has  a  wave  length  of  589.6  MM 
and  the  brighter  component  D2  a  wave  length  of  589.0  MM-  The  average  wave  length 
of  the  two  lines,  589.3  /*/*  (more  exactly  589.25  MM),  is  the  value  taken  for  D. 


78  SUGAR   ANALYSIS 

Malus,  in  1808,  discovered  that  the  polarization  noticed  by  Huygens  in 
Iceland  spar  could  also  be  produced  by  reflection. 

Polarization  by  Reflection.  —  If  a  beam  of  light  (as  LO  in  Fig.  28) 
fall  upon  the  smooth  surface  of  a  transparent  substance,  it  is  decomposed 
into  reflected  and  refracted  rays.  The  reflected  rays  at  a  definite 
angle  of  incidence  are  completely  polarized,  the  plane  of  the  lines  of 
incidence  and  reflection  being  the  plane  of  polarization.*  These  obser- 
vations, according  to  Fresnel  and  Arago,  could  be  explained  only  by 
supposing  that  the  vibrations  in  a  light  wave  are  tran verse  to  the  direc- 
tion of  motion,  and  that  during  reflection  these  vibrations  are  reduced  to 
a  single  plane,  which  is  perpendicular  to  the  plane  of  polarization. 

The  angle  of  incidence  at  which  reflected  light  is  completely  polar- 
ized is  called  the  polarizing  angle,  and  varies  according  to  the  refractive 
power  of  the  reflecting  substance.  This  relationship  is  expressed  by 
Brewster's  law,  viz. :  The  tangent  of  the  polarizing  angle  is  equal  to  the 
index  of  refraction  for  the  reflecting  substance,  or  tan  i  =  n.  The 
polarizing  angle  of  glass  (n  =  1.54)  is  accordingly  about  57  degrees. 

The  Norrenberg  Apparatus.  —  A  simple  apparatus  for  producing 
and  studying  polarized  light  is  that  of  Norrenberg,  shown  in  Fig.  41. 
A  and  B  are  two  mirrors  of  black  glass;  the  upper  mirror  B  can  be 
rotated  by  the  crank  D  around  the  vertical  axis  of  the  instrument,  the 
angular  displacement  being  indicated  upon  a  divided  circle  S.  The 
planes  of  the  two  mirrors  are  first  placed  parallel,  at  an  angle  of  45 
degrees  to  the  vertical,  and  a  beam  of  light  is  allowed  to  fall  upon  the 
mirror  A  at  an  angle  of  incidence  of  57  degrees.  The  reflected  beam  is 
then  completely  polarized  and,  passing  upward,  is  reflected  from  mirror 
B  upon  the  screen  C,  where  it  appears  as  a  bright  spot.  With  the 
mirrors  parallel,  the  planes  of  incidence  and  reflection,  and  hence  of 
polarization,  coincide  for  each  surface.  Without  changing  its  inclina- 
tion, the  mirror  B  with  its  screen  C  is  rotated  by  the  crank  D  around  the 
vertical  axis.  The  plane  of  incidence  and  reflection  for  the  beams  of 
polarized  light  at  mirror  B  no  longer  coincide  with  that  at  mirror  A; 
the  intensity  of  the  spot  of  light  upon  the  screen  accordingly  begins  to 
diminish  until,  after  a  revolution  of  90  degrees,  the  screen  is  perfectly 
dark,  all  the  light  being  refracted  and  absorbed  in  the  mirror  B.  In 
the  latter  position  the  planes  of  incidence,  and  hence  of  polarization,  for 
the  light  of  the  two  mirrors  are  at  right  angles,  and  the  mirrors  are 
said  to  be  crossed.  By  turning  D  in  the  same  direction  the  spot  of  light 

*  The  refracted  rays  of  light  are  also  polarized,  but  not  completely;  most  of  the 
refracted  rays,  however,  are  polarized  in  one  direction,  their  plane  of  polarization 
being  perpendicular  to  that  of  the  reflected  rays. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


79 


reappears  upon  the  screen,  and  after  180  degrees  again  reaches  maxi- 
mum brilliancy,  in  which  position  the  planes  of  incidence  and  of  polar- 
ization again  coincide  in  both  mirrors;  at  270  degrees,  when  these 
planes  are  again  at  right  angles,  the  spot  of  light  is  reextinguished. 


Fig.  41.  —  Norrenberg's  polarizing  apparatus. 

If  at  one  of  the  points  of  extinguishment  of  light  upon  the  screen 
the  glass  cylinder  F  containing  a  solution  of  sucrose  or  other  optical 
active  sugar  be  inserted  in  the  path  of  the  light  rays  reflected  from  A, 


80  SUGAR  ANALYSIS 

the  illumination  upon  the  screen  will  reappear.  The  plane  of  polariza- 
tion of  the  light  reflected  from  A  must,  therefore,  have  been  rotated  by 
the  sugar  solution  through  a  certain  angle  in  order  that  reflection  could 
take  place  from  B\  by  turning  D  until  the  plane  of  polarization  for  the 
light  upon  B  is  again  brought  perpendicular  to  the  plane  of  incidence, 
the  point  of  maximum  darkness  is  reestablished.  By  measuring  upon 
S  the  positions  of  maximum  darkness,  before  and  after  inserting  the 
cylinder,  the  angle  through  which  the  sugar  solution  has  rotated  the 
plane  of  polarized  light  can  be  measured.  In  the  Norrenberg  ap- 
paratus the  mirror  A  for  polarizing  the  light  is  called  the  polarizer  and 
the  mirror  B  for  measuring  rotation  the  analyzer. 

Polarization  by  Double  Refraction.  —  Of  the  several  contrivances 
available  for  producing  plane  polarized  light,  a  modified  crystal  of  Ice- 
land or  calc  spar  is  the  only  one  used  in  the  construction  of  polariscopes 
and  saccharimeters.  Calc  spar  is  a  clear,  transparent  mineral  which 
cleaves  readily  into  rhombohedra.  If  a  small  object  be  viewed  through 
such  a  rhombohedron,  the  image  will  be  doubled.  Rays  of  light  in? 
passing  through  the  crystal  undergo  "double  refraction."  The  phe- 
nomenon is  noticeable  in  any  position  of  the  calc-spar  rhombohedron 
except  in  a  direction  parallel  to  the  diagonal  joining  the  two  opposite 


c  D  » > 

Fig.  42.  —  Calc  spar  rhom-  Fig.  43.  —  Illustrating  double  refraction  of 

bohedron.  light  in  calc  spar. 


obtuse  corners,  known  as  the  optical  axis.  Any  plane  including  the 
optical  axis  and  perpendicular  to  the  face  of  the  crystal  is  called  an 
axial  plane  or  principal  section. 

In  the  rhombohedron  of  calc  spar,  in  Fig.  42,  the  direction  AH  is 
the  optical  axis.  The  plane  ABHG  (or  any  parallel  plane)  perpendicu- 
lar to  the  face  AFGD  is  an  axial  plane  or  principal  section  to  that 
face. 

If  a  beam  of  light  LA  fall  upon  the  surface  of  such  a  rhombohedron 
(Fig.  43),  it  is  resolved  into  two  rays,  the  ordinary  ray  ABO  and  the 
extraordinary  ray  ACE.  Both  of  these  rays  emerging  from  the  crystal 
are  polarized,  their  planes  of  polarization  being  perpendicular  to  each 
other. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


81 


I 


The  Nicol  Prism.  —  Before  a  crystal  of  calc  spar  can  be  utilized 
for  polariscope  construction  it  must  be  modified  so  as  to  eliminate  one 
set  of  the  component  rays.  The  best  known  method  (that  of  Nicol) 
is  the  following:  A  rhombohedron  ABCD  (Fig.  44)  is  selected  whose 
length  is  about  three  times  the  width.  At  each 
end  of  the  crystal,  wedge-shaped  sections  BFC 
and  ADE  are  removed  so  as  to  reduce  the  acute 
angles  DAB  and  BCD  of  the  axial  plane  from 
71  degrees  to  68  degrees.  The  crystal  is  then 
divided  by  the  plane  FGEH  perpendicular  to 
the  two  modified  end  faces.  The  cut  surfaces 
are  then  polished  and  reunited  with  Canada 
balsam.*  The  sides  of  the  prism  thus  obtained 
are  afterwards  blackened  and  the  whole  is 
mounted  by  means  of  cork  and  wax  in  a  metal 
tube. 

Let  AFCE  represent  a  principal  section  of 
the  Nicol  prism  (Fig.  45).  A  beam  of  light  LT 
entering  parallel  to  the  long  sides  of  the  prism  is  resolved  into  two 
component  rays;  the  component  most  refracted  (the  ordinary  ray) 
meets  the  film  of  balsam  EF  at  such  an  angle  that  it  is  completely 
reflected  to  the  side  of  the  prism,  where  it  is  absorbed  by  the  dark 
coating.  The  other  component  (the  extraordinary  ray),  whose  vibra- 
tions are  in  the  plane  of  the  principal  section,  is  less  refracted  and, 
passing  through  the  film  of  balsam,  emerges  in  a  polarized  condition 


C 

Fig.  44.  —  Illustrating 
construction  of  Nicol 
prism. 


Fig.  45.  —  Illustrating  polarization  of  light  by  a  Nicol  prism. 

from  the  end  surface  of  the  Nicol  at  the  point  e.  With  respect  to  the 
end  surface  of  the  Nicol  FCLM  (Fig.  44),  the  electric  vibrations  of  the 
emergent  light  are  in  the  plane  of  the  principal  section,  i.e.,  in  the  direc- 
tion of  the  short  diagonal  FC;  the  plane  of  polarization  is  in  the  direc- 
tion of  the  long  diagonal  LM. 

"Iceland  spar  is  rather  friable,  and  in  practice  it  is  found  easier  to  grind  away 
half  of  the  rhomb  instead  of  cutting  it,  as  generally  described.  The  remaining  halves 
of  two  rhombs  thus  ground  are  then  cemented  together."  —  Preston,  "  Theory  of 
Light,"  third  edition,  p.  319. 


82 


SUGAR  ANALYSIS 


In  the  discussion  of  polarized  light,  it  makes  no  difference  which 
plane  is  taken  for  reference,  provided  it  be  always  the  same.  In  future 
pages  the  terms  vibrate,  vibration,  plane  of  vibration,  etc.,  refer  entirely 
to  the  electric  displacements  in  the  transmission  of  light.  With  this 
understanding,  the  statement  of  Fresnel,  which  is  followed  in  nearly 
all  works  upon  polarimetry,  —  that  the  plane  of  vibration  of  light  is 
perpendicular  to  the  plane  of  polarization,  —  can  be  retained  without 
confusion. 

The  Glan  Prism.  —  The  type  of  Nicol  prism  which  is  the  most 
scientifically  perfect  and  the  one  most  used  at  present  in  constructing 

polariscopes  and  saccharimeters  is  that 
of  Glan.  In  constructing  this  prism  the 
opposite  obtuse  corners  of  a  calc-spar 
rhombohedron  (as  ABCDEF,  Fig.  46) 
c  are  cut  off  by  planes  PQR  and  STF 
perpendicular  to  the  optical  axis  which 
passes  through  the  point  X.  From  this 
section  a  rectangular  prism  LMNO  is 
sawed  out,  which  is  then  cut  in  half 
along  a  plane  through  MN.  After  pol- 
ishing, the  cut  halves  are  cemented  to- 
gether again  by  Canada  balsam  am 
mounted  as  in  an  ordinary  Nicol.  Th< 

great  advantages  of  the  Glan  prism  ovei 
Fie.  46.  —  Illustrating  construction  ,.  ,.  XT.     ,  ,,        ,, 

of  a  Glan  prism.  the  ordmarv  Nlco1  are  that  the  rays  oi 

light  enter  the  prism  perpendicular 

the  end  surface  and  at  right  angles  to  the  optical  axis,  thus  securii 
the  greatest  amount  of  light  capacity  per  unit  of  length. 

PRINCIPLE  AND  CONSTRUCTION  OF  POLARIMETERS 

Polarizer  and  Analyzer.  —  A  combination  of  two  Nicol  prisms, 
called  the  polarizer  and  analyzer,  constitutes  the  essential  feature  of 
every  polariscope.  The  function  which  these  two  parts  play  can  b( 
be  understood  from  the  following  diagram  (Figs.  47  and  48). 

The  polarizer,  which  is  stationary,  is  represented  by  the  pris 
ABCDEFGH,  whose  axial  plane  lies  through  ACEG.  A  beam  of  light 
entering  from  L  at  the  point  x  is  doubly  refracted;  the  ordinary  rays 
are  eliminated  at  o,  while  the  extraordinary  rays  emerge  at  e,  vibratii 
in  the  axial  planes  of  the  prism,  with  the  plane  of  polarization  parallel 
with  the  plane  BDFH.  If  the  emergent  polarized  light  now  enter 
second  prism  A'B'C'D'E'F'G'H'  (the  analyzer),  which  can  be  rotat 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


83 


about  its  long  axis,  its  course  will  remain  unimpeded  only  so  long  as  it 
can  continue  to  vibrate  in  the  same  axial  plane.  If  the  analyzer  be 
rotated  about  its  long  axis,  the  light  which  enters  from  the  polarizer 
is  doubly  refracted  and  only  that  component  which  vibrates  in  the 


Crossed 
Nicols 


Analyzer  Fig.48  Polarizer 

Figs.  47  and  48.  —  Illustrating  principle  of  polarizer  and  analyzer. 

plane  of  the  principal  section  emerges.  As  the  analyzer  is  rotated  the 
intensity  of  the  emergent  light  diminishes  until  after  a  quarter  revo- 
lution it  is  completely  extinguished;  in  this  position  the  axial  planes 
of  polarizer  and  analyzer  are  perpendicular  to  one  another  and  the  two 
prisms  are  said  to  be  crossed  (Fig.  48).  If  the  rota- 
tion of  the  analyzer  be  continued,  light  will  again 
begin  to  emerge,  until  after  a  half  -re  volution,  when 
the  axial  planes  are  again  parallel,  the  original  in- 
tensity will  be  restored. 

The  amount  of  light  which  will  pass  through  the 
analyzer  for  any  position  of  its  axial  plane  with  ref- 
erence to  the  polarizer  may  be  readily  calculated  by 
referring  to  Fig.  49. 

Let  AB  be  the  axial  plane  of  the  polarizer  (always 
stationary)  and  CD  any  given  position  of  the  axial 
plane  of  the  analyzer,  the  two  planes  forming  the 
angle  DOB.  From  0  lay  off  any  distance  OP  as  the 
amplitude  of  the  light  emerging  from  the  polarizer, 
From  P  erect  PL  perpendicular  to  CD;  then  the 
line  OL  represents  the  amplitude  of  the  light  emerg- 
ing  from  the  analyzer  and  PL  the  amplitude  of  the 
light  extinguished  in  the  analyzer.  As  regards  the  relation  in  intensity, 
this  is  proportional  to  the  squares  of  the  amplitudes:  OP 


extinguished  by 
analyzer. 


OL  +  PL  . 


84  SUGAR  ANALYSIS 

If  we  erect  LM  perpendicular  to  AB  and  call  the  intensity  of  the  light 
emerging  from  the  polarizer  OP,  then  the  intensity  of  the  light  emerging 
from  the  analyzer  will  be  represented  by  OM  and  the  intensity  of  the 
light  extinguished  in  the  analyzer  by  MP  (OM  :  MP  ::  OL2 :  PL2). 
The  intensities  OM  and  OP  are  equal  when  the  planes  CD  and  AB 
coincide  (parallel  prisms) ;  the  intensity  OM  is  zero  when  the  planes  CD 
and  AB  are  perpendicular  (crossed  prisms). 

The  construction  and  principle  of  the  simplest  form  of  polariscope 
can  now  be  understood  from  the  following  diagram  (Fig.  50).  P  is  the 
polarizer  consisting  of  a  stationary  Nicol  and  A  is  the  analyzer  con- 
sisting of  a  movable  Nicol  mounted  in  a  revolving  sleeve;  the  angular 


Fig.  50.  —  Showing  arrangement  of  parts  in  a  simple  polariscope. 

rotation  of  A  is  measured  upon  a  graduated  scale  S.  L  is  the  source 
of  monochromatic  light  which  passes  through  the  instrument  to  the 
eye  of  the  observer  at  E.  We  will  suppose  the  Nicol  A  to  be  crossed 
with  reference  to  P,  the  point  of  light  extinction  marking  the  zero  point 
on  the  scale  S.  If  a  tube  T  filled  with  a  solution  of  some  optically 
active  substance,  such  as  cane  sugar,  be  now  placed  between  P  and  A, 
the  plane  of  polarized  light  emergent  from  P  will  be  rotated  from  its 
original  position  and  the  light  will  no  longer  be  entirely  extinguished 
in  A.  By  rotating  the  analyzer  until  its  axial  plane  is  perpendicular 
to  the  vibration  plane  of  the  light  emergent  from  T,  the  point  of  ex- 
tinction is  again  reached.  The  angular  rotation  of  the  solution  in  T  is 
then  determined  upon  the  graduated  scale.  By  continuing  the  revo- 
lution of  the  analyzer,  light  will  again  emerge  from  the  latter,  to  become 
reextinguished  at  a  point  180  degrees  from  the  first  reading.  Owing 
to  the  fact  that  light  rays  of  different  wave  lengths  are  rotated  to  a 
different  extent  by  optically  active  substances  (a  phenomenon  known 
as  rotation  dispersion),  it  is  necessary  that  the  light  used  in  this  type  of 
polariscope  be  monochromatic. 

Blot's  Polariscope.  —  The  original  polariscope  of  Biot*  (Fig.  51), 
constructed  in  1840,  had  an  adjustable  mirror  (M)  of  black  glass  for 

*  Ann.  chim.  phys.  [2],  74,  401  (1840). 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS  85 

the  polarizer  and  a  modified  prism  of  calc  spar  for  the  analyzer  (A). 
The  essential  features  of  this  early  instrument  are  still  retained  in 
modern  polarimeters,  although  in  a  greatly  modified  form. 


Fig.  51.  —  Biot's  polariscope. 

Mitscherlich' s  Polariscope.  —  Mitscherlich*  in  1844  modified  the 
Biot  apparatus  by  discarding  the  polarizing  mirror  and  arranging  the 
optical  parts  of  his  instrument  as  shown  in  Fig.  50.  In  the  Biot  polari- 
scope the  end  point  was  marked  by  total  light  extinction.  But  in  the 
Mitscherlich  apparatus  a  vertical  black  band  with  shaded  margins 
marked  .the  zero  point.  By  rotating  the  analyzer  gently  to  and  fro 
until  the  vertical  band  appears  exactly  in  the  center  of  the  field,  a  zero- 
point  adjustment  can  be  secured  with  a  probable  error  of  ±6  minutes. 
The  Biot-Mitscherlich  polariscope,  with  position  of  its  optical  parts,  is 
shown  in  Fig.  52. 

Sections  of  the  circular  scales  used  upon  the  Mitscherlich  and  other 
polarimeters  for  measuring  the  angular  rotation  of  the  plane  of  polar- 
ized light  are  shown  in  Figs.  53  and  54.  The  scale  in  Fig.  53  for  a 
small  polariscope  indicates  0.1  degree  and  is  immovable,  the  rotation 
being  indicated  by  the  position  of  the  zero  mark  of  the  movable  ver- 
nier V.  In  the  illustration  the  zero  mark  of  the  vernier  lies  between  the 
*  "  Lehrbuch  der  Chemie"  (1844),  1,  361. 


80 


SUGAR  ANALYSIS 


2-degree  and  3-degree  division  of  the  scale;  to  obtain  the  fractions  of  a 
degree,  one  proceeds  from  the  zero  mark  of  the  vernier  and,  moving 
upward  along  the  divisions  of  the  main  scale,  comes  finally  to  a  divi- 
sion which  exactly  coincides  with  one 
of  the  divisions  of  the  vernier.  In 
the  illustration  this  vernier  division 
is  0.4,  which,  added  to  the  reading 
on  the-  main  scale,  makes  the  angular 
rotation  2.4  degrees.  For  the  larger 
polariscopes  indicating  0.01  degree  the 
main  scale  is  movable,  the  circular 
rim  divided  into  0.25  degree  rotating 
against  the  fixed  vernier,  which  gives 
the  readings  to  0.01  degree.  In  the 
illustration  (Fig.  54)  the  zero  of  the 
vernier  falls  between  13.50  degrees 
and  13.75  degrees;  the  0.18  mark  of 
the  vernier  is  in  coincidence  with  a 
division  on  the  main  scale.  13.50°  -f 
0.18°  =  13.68°,  which  is  the  angular 
rotation  indicated. 

Robiquet's  Polariscope.  —  Robi- 
quet  increased  the  sensibility  of  the 
Biot-Mitscherlich  polariscope  by  in- 
troducing a  Soleil  double  quartz  plate 
as  the  end-point  device.  The  general 
appearance  of  this  instrument,  with 
position  of  optical  parts,  is  shown  in 
Fig.  55. 

Principle  of  the  Soleil  Double  Quartz 
Plate.  —  The  Soleil  double  quartz  plate 
consists  of  two  plates  of  quartz  of 
equal  thickness,  one  of  which  rotates  the  plane  of  polarized  light  to  the 
right  and  the  other  to  the  left.  The  plates,  which  are  cut  perpendicu- 
lar to  the  optical  axis  of  the  crystal,  are  cemented  together  at  their 
edges  and  carefully  ground  and  polished.  If  white  polarized  light  pass 
through  such  a  plate,  the  rays  of  different  wave  length  and  color  will 
be  rotated  to  a  different  degree  (rotation  dispersion),  the  rays  of  less 
wave  length  being  rotated  the  most.  For  a  piece  of  quartz  1  mm.  thick, 
cut  as  above  described,  the  rotation  will  be  15.75  degrees  for  the  red  B 
ray,  21.72  degrees  for  the  yellow  D  ray  of  sodium,  and  32.76  degrees  for 


Fig.  52. —  The  Biot-Mitscherlich 
polariscope. 

a  =  position  of  polarizer 
6  =  position  of  analyzer 
c  =  lever  for  rotating  analyzer 
I  =  condensing  lens. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS  87 


Fig.  53  Fig.  54 

Sections  of  circular  scales  of  polariscopes. 


Fig.  55.  —  Robiquet's  polariscope. 

d  =  polarizer 
e  =  condensing  lens 
/  =  Soleil  double  quartz  plate 
g  =  analyzer 
h-i  =  telescope 
k  =  lever  for  rotating  analyzer. 


88  SUGAR  ANALYSIS 

the  blue  F  ray.  For  the  average  ray  in  the  middle  of  the  yellow  spec- 
trum the  rotation  is  24  degrees.  The  thickness  of  the  Soleil  plate  is  so 
chosen  that  this  average  yellow  ray  is  extinguished  in  the  analyzer. 
This  corresponds  to  a  rotation  of  90  degrees,  or  to  a  thickness  of  3.75 
mm.  (90°  -5-  24  =  3.75)  for  the  double  plate,  when  the  end  point  is  taken 

for  parallel  Nicols.  If  a  plate  of  the 
above  description  be  inserted  between 
two  parallel  Nicols  and  examined  with 
white  light,  the  color  of  the  two  halves 
will  be  of  a  uniform  rose  color,  the 
blending  of  the  spectral  colors  minus 
the  yellow.  The  relationship  of  the 
_j_60  •  angular  rotations  for  red,  yellow,  and 

blue  in  the  two  halves  of  a  3.75  mm. 

CYellow-90J  +  90)  Extinguished  Plate  at  the   transition   point   may  be 

seen  from   Fig.   56.     By  rotating  the 

Blue— 120  j  +120  analyzer  to  the  right  or  left  the  uniform 

rose  color  of  the  plate  will  change,  one- 
Fig.  56.  —  Showing  principle  of     half  to   blue   and  the   other  to  red>   or 
Soleil  double  quartz  plate.         vice  versa.     If  a  solution  of  an  optical 

active  substance  be  placed  in  the  tube 

before  the  analyzer,  the  equilibrium  in  color  of  the  transition  tint  will 
be  destroyed  and  the  two  halves  of  the  field  will  be  differently  colored. 
Rotating  the  analyzer  to  the  point  where  the  transition  tint  is  again 
produced  will  give  the  angular  rotation  of  the  solution. 

The  Robiquet  polariscope,  which  has  a  sensibility  of  about  db  4  min- 
utes, is  of  course  only  adapted  for  white  light.  The  rotation  angle  (a) 
of  a  substance  for  extinction  of  the  mean  yellow  ray  was  expressed 
by  Biot  as  «/  (j  =  French,  jaune;  yellow).  The  fact  that  the  point  j 
corresponds  to  no  well-defined  line  of  the  spectrum  makes  it  a  difficult 
one  to  verify,  and  some  confusion  has  resulted  from  this  cause.  Landolt 
gives  for  1  mm.  quartz,  a/  =  24.5  degrees  instead  of  24  degrees.  The 
value  a.j  is  always  greater  than  aD  (the  rotation  angle  for  the  D  ray  of 

24  5 

sodium).    The  relationship  given  by  Landolt  is  «,-  =  0    ictaD  =  1.128  aD ; 

Zi.iZ    ' 

using  the  value  24  degrees  «/ =  l.W5aD.  Many  authorities  employ 
the  factor  1.111. 

In  the  examination  of  colored  solutions,  the  transition  tint  of  the 
Soleil  double  plate  is  affected  to  such  a  degree  that  a  considerable  error 
is  introduced  in  the  observation.  The  use  of  this  end-point  device  is 
valueless  for  the  color-blind.  For  these  reasons  the  transition-tint 
polariscopes  are  at  present  but  little  used. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS          89 

Jellefs  Half-shadow  Polariscope.  —  Efforts  to  obtain  a  polariza- 
tion apparatus  which  would  be  free  from  the  defects  of  those  previously 
named  led  Jellet*  in  1860  to  the  construction  of  the  first  half -shadow 
polariscope.  In  this  type  of  end-point  adjustment,  which  can  be 
secured  in  a  variety  of  ways,  the  field  of  vision  is  divided  into  two  or 
more  parts,  which  at  the  zero  position  of  the  analyzer  have  a  uniform 
shade.  Rotating  the  analyzer  to  the  right  will  cause  one  section  of 
the  field  to  become  darker  and  the  other  lighter;  rotation  to  the  left 
will  produce  the  opposite  effect. 

The  half-shadow  device  of  Jellet  consists  of  a  rhombohedron  of 
calc  spar  with  its  ends  cut  square  and  bisected  lengthwise  by  a  plane 
forming  a  small  angle  with  the  axial  plane  of  the  prism;  the  two  halves 
are  then  cemented  together  in  the  reversed  position,  the  result  being 
that  the  axial  planes  of  each  part  are  no  longer  parallel  but  are  tilted 
toward  one  another  at  a  slight  angle.  This  reunited  prism,  placed 
between  the  polarizer  and  analyzer  with  its  line  of  union  bisecting  the 
field,  causes  the  planes  of  vibration  of  light  proceeding  from  the  polar- 
izer to  be  slightly  inclined  towards  one  another  in  each  half  of  the 
field.  Rotating  the  analyzer  until  it  is  crossed  with  the  polarizer  will 
not  produce  extinction,  but  a  uniform  shadow  or  penumbra  whose  depth 
will  depend  upon  the  inclination  of  the  axial  planes  in  the  two  halves 
of  the  Jellet  prism. 

Jellet-Cornu  Prism.  —  The  Jellet  polarizer  was  modified  by 
Cornuf  by  taking  an  ordinary  Nicol  prism  and  dividing  it  length- 
wise by  a  plane  passing  through  the  shorter  diagonal  of  the  end.  A 
small  wedge-shaped  section  is  then  removed  from  each  cut  surface  and 
the  two  halves  reunited  (see  Figs.  57  and  58).  This  "split"  or  "twin" 
prism  combines  the  effect  of  an  ordinary  Nicol  and  Jellet  prism. 

The  Jellet-Cornu  prism  was  still  further  simplified  by  bisecting 
only  one-half  of  the  Nicol  prism  in  the  way  described.  The  three 
pieces  are  then  cemented  together  and  the  prism  squared  and  mounted, 
with  the  split  half  turned  toward  the  analyzer.  This  form  of  prism, 
sometimes  called  the  Schmidt  and  Haensch  polarizer,  was  formerly 
much  used  in  the  construction  of  half-shadow  saccharimeters.t 

The  principle  of  the  half-shadow  device  of  Jellet  and  its  modifica- 
tions may  be  seen  from  Fig.  59. 

Let  GO  and  HO  represent  the  directions  of  the  axial  planes  in  each 
half  of  the  Jellet  prism,  forming  with  each  other  the  angle  GOH  (the 

*  Rep.  Brit.  Assoc.,  29,  13  (1860). 

t  Bull.  soc.  chim.  [2],  14,  140  (1870). 

t  Landolt,  "  Das  optische  Drehungsvermogen  "  (1898),  p.  307. 


90 


SUGAR  ANALYSIS 


half-shadow  angle  designated  by  a  and  made  usually  not  to  exceed 
10  degrees).  It  will  be  seen  that  with  the  axial  plane  of  the  analyzer 
perpendicular  to  PO  the  light  from  the  polarizer  will  not  be  completely 
extinguished  in  the  analyzer;  a  small  amount  of  light  will  emerge 


End  of  Nicol  prism 

before  and  after 

splitting. 


Showing  construction  of  a  Jellet-Cornu  prism. 

BDE  and  BDF,  wedge  sections  removed. 

GE  and  H F,  directions  of  axial  plane  before  cutting. 

GK  and  HK,  directions  of  axial  planes  after  uniting  cut  surfaces. 

from  each  half  of  the  field  proportional  to  the  amplitudes  OM  and  ON 
(see  Fig.  49).  The  equality  of  light  in  the  two  divisions  of  the  field 
constitutes  the  end  point.  By  rotating  the  analyzer  to  the  position 
A'L'  perpendicular  to  HO,  the  light  in  the  right  half  of  the  field  will  be 


Fig.  59.  —  Illustrating  principle  of  Jellet's  half-shadow  polariscope. 

completely  extinguished,  and  that  in  the  left  half  will  be  increased 
from  OM  to  OM1 ';  similarly,  with  A"L"  perpendicular  to  GO  the  light 
in  the  left  half  of  the  field  is  extinguished  and  that  in  the  right  half  in- 
creased from  ON  to  ON']  it  is  evident  from  the  above  that  the  half- 
shadow  angle  GOH  can  be  measured  by  the  angle  A'OA"  through  which 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS  91 

the  analyzer  is  rotated  between  the  points  of  extinction  in  the  two 
halves  of  the  field.  (For  appearance  of  field  at  the  several  points  see 
Fig.  61.) 

There  are  several  types  of  polariscopes  which  use  the  Jellet-Cornu 
polarizer  for  an  end  point.  All  of  these  have  the  advantage  that  they 
can  be  used  with  either  mixed  or  homogeneous  light,  but  the  disadvan- 
tage that  the  half-shadow  angle  is  fixed  and  cannot  be  changed  to  suit 
the  requirements  demanded  by  different  kinds  of  work.  The  sensi- 
bility of  the  instrument  to  slight  changes  of  rotation  becomes  greater 
as  the  half-shadow  angle  of  the  polarizer  is  made  smaller;  but,  on  the 
other  hand,  the  loss  of  light  at  the  end  point  produced  by  decreasing 
the  inclination  of  the  planes  in  the  two  halves  of  the  field  lessens  the 
usefulness  of  the  instrument  in  polarizing  dark-colored  solutions. 

Laurent's  Half-shadow  Apparatus.  —  To  overcome  the  last- 
named  defect  of  the  Jellet-Cornu  polarizer,  Laurent  *  in  1877  con- 
trived an  end-point  device  in  which  the  half-shadow  angle  could  be 
changed  to  suit  varied  requirements.  The  Laurent  polariscope  has 
the  ordinary  arrangement  of  Nicol  prisms  for  polarizer  and  analyzer, 
the  only  difference  being  that  the  polarizer  is  attached  to  a  small  lever 
by  which  it  can  be  rotated  through  a  small  angle  to  the  right  or  left. 
The  essential  part  of  the  end-point  device  is  a  thin  plate  of  quartz  cut 
perfectly  plane  and  exactly  parallel  to  its  optical  axis.  This  plate, 
which  must  be  of  specially  prepared  thickness,  is  mounted  upon  glass 
in  such  a  way  that  it  covers  one-half  of  the  field  of  vision.  The  rays 
of  light  from  the  polarizer  on  entering  the  plate  are  resolved  into  two 
components,  one  (the  ordinary)  vibrating  in  the  plane  of  the  optical 
axis,  and  the  other  (the  extraordinary)  in  a  plane  perpendicular  thereto. 
The  extraordinary  component,  being  less  refracted,  is  transmitted  more 
rapidly,  and  the  thickness  of  the  quartz  plate  is  so  regulated  that  when 
the  two  components  emerge,  the  extraordinary  one  is  in  advance  of  the 
ordinary  by  half  a  wave  length.  The  thickness  of  the  plate  depends 
upon  the  wave  length  X  of  the  light,  which  must  necessarily  be  homo- 
geneous. The  component  rays  which  emerge  from  the  quartz  plate 
with  half  a  wave  length's  (or  uneven  multiple  thereof)  difference  in  vibra- 
tion are  resolved  by  the  analyzer  into  light  which  at  the  end  point 
is  of  the  same  amplitude  and  intensity  as  that  in  the  uncovered  half 
of  the  field  (the  loss  of  light  in  the  quartz  plate  by  reflection  and  ab- 
sorption being  negligible).  The  two  planes  of  vibration,  which  are  in- 
clined towards  each  other  equally  and  symmetrically  with  reference  to 
the  optical  axis  of  the  plate,  form  the  angle  of  the  half  shadow.  The 
*  Dingler's  Polytech.  Jour.,  223,  608  (1877). 


92 


SUGAR  ANALYSIS 


principle  of  the  Laurent  plate  can  be  better  understood  from  the 
following  diagram  (Fig.  60). 

Let  LMNK  represent  the  quartz  plate  with  the  edge  MK  bisecting 
the  circular  field,  MK  being  assumed  for  convenience  to  coincide  with 
the  optical  axis  of  the  plate.  Let  A  A'  represent  the  plane  of  the 
analyzer  at  the  end  point  and  PPf  the  plane  of  the  polarizer,  the  latter 
being  set  at  the  angle  POM  with  the  optical  axis  MK.  Lay  off  OB  as 


Fig.  60.  —  Showing  principle  of  Laurent's  half-wave  plate. 

the  amplitude  of  the  homogeneous  light  emerging  from  the  polarizer 
and  draw  BC  A.AA',  then  OC  will  represent  the  amplitude  of  the 
light  emergent  from  the  analyzer  for  the  uncovered  half  of  the  field 
(Fig.  49).  The  light  of  amplitude  OB  upon  entering  the  quartz  plate 
is  resolved  into  two  components,  one  of  which  OF  (the  ordinary  ray) 
vibrates  in  the  plane  of  the  optical  axis  MK,  and  the  other  OC  (the  ex- 
traordinary ray)  vibrates  in  the  plane  OS  _L  MK.  The  quartz  plate  is 
of  such  thickness  that  the  extraordinary  component  entering  at  the  phase 
o>  is  accelerated  in  its  passage  one-half  wave  length  and  emerges  at  the 
opposite  phase  «'.  The  amplitude  OC'  being  equal  to  OC,  the  resultant 
OB',  between  OC'  and  OF,  is  equal  to  OB,  and  the  angle  B'OM  equal 
to  the  angle  BOM,  the  two  together  being  the  angle  of  the  half-shadow. 
The  light  emergent  from  the  analyzer  in  both  halves  of  the  field  will 
therefore  be  equal  in  amplitude  and  intensity  for  any  angle  at  which 
PP'  may  be  set  with  reference  to  MK.  On  rotating  the  analyzer 
from  its  position,  the  equilibrium  in  shade  between  the  two  halves  will 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS  93 

be  destroyed  (Fig.  61),*  the  effect  being  the  same  as  that  described 
under  Fig.  59. 

The  Laurent  polariscope,  which  is  the  standard  instrument  in 
France,  has  the  great  advantage,  over  other  forms,  of  adjustable  sen- 
sibility without  change  in  zero  point,  but  the  great  disadvantage  of 
being  adapted  to  only  monochromatic  light.  It  cannot  be  used  with 


TI 


Fig.  61.  —  Showing  divisions  of  double  field  of  a  half -shadow  polariscope. 

I,  analyzer  crossed  with  left  half  of  field; 
II,  analyzer  crossed  with  right  half  of  field; 
III,  end  point. 

white  light  except  when  adapted  to  bichromate  filtered  light  for  a 
quartz  wedge  saccharimeter.  With  intense  illumination  and  a  small 
half-shadow  angle  (the  conditions  of  greatest  sensibility  for  all  half- 
shadow  instruments),  the  average  error  of  observation  according  to 
Landolt  is  less  than  1  minute. 

Concentric  Half -wave  Plate. — Pellin  has  modified  the  Laurent  polari- 
scope by  using  a  half-wave  plate  of  quartz  cut  in  circular  or  annular 
form.  The  field  of  vision  is  in  this  way  divided  concentrically  as  shown 
in  Figs.  62  and  63.*  While  the  concentric  field  may  secure  a  more  correct 


O 


Fig.  62  Fig.  63 

Concentric  double  field.  Concentric  triple  field. 

alignment  of  the  eye  with  the  optical  axis  of  the  polariscope,  it  is  much 
more  fatiguing  to  the  eye  than  the  ordinary  bisected  field.  The  prin- 
ciple of  the  concentric  half-wave  plate  is  the  same  as  that  of  the 
Laurent  plate. 

*  In  Figs.  61,  62,  63,  and  67b  the  dividing  lines  of  the  fields  at  end  point  are 
much  intensified.  With  a  properly  adjusted  instrument  the  dividing  lines  com- 
pletely disappear  at  end  point  leaving  a  plain  disk  of  uniform  shade. 


94 


SUGAR  ANALYSIS 


Lippich's  Half -shadow  Polarimeter. — In  1880  Lippich*  davised  a 
form  of  polarizer  which  combines  the  advantages  of  adjustable  half- 
shadow  and  of  adaptability  to  all  kinds  of  light. 
The  Lippich  polarizer  consists  of  two  Nicol  prisms, 
one  large  Nicol,  which  can  be  rotated  about  its 
long  axis  according  to  the  needs  of  sensibility, 
and  one  smaller  Nicol,  known  as  the  " half-prism," 
which  is  mounted  in  front  of  the  large  Nicol  so 
as  to  cover  one-half  of  the  field.  The  half-prism 
is  slightly  tilted  so  that  its  inner  vertical  edge 
forms  a  sharply  dividing  line,  which  can  easily 
be  focused  by  the  eyepiece  of  the  instrument 
(Fig.  64). 

The  principle  of  the  Lippich  polarizer  can  be 
understood  by  referring  to  the  opposite  diagram 
(Fig.  65) : 

Let  OP  be  the  plane  of  the  large  Nicol  and  OH 
the  plane  of  the  half-prism,  the  included  angle 
POH  being  that  of  the  half-shadow  a.    Let  OB  = 
the  amplitude  of  the  light  emergent  from  the  large 
Nicol.    Draw  BG  _L  OH.    Then  OG  will  represent 
the  amplitude  of  the  light  emergent  from  the  half- 
prism.     It  can  readily  be  seen  that  with  a  loss  of 
Fig.  64.  —  Showing  con-  a  part  of  the  light  in  the  half -prism  the  ampli- 
struction  of  a  Lippich  tudeg  QQ>  and  QD>  in  the  two  halves  of  the  field 
polarizer     for     double    -.  *.      ,       ^  A ,  ,      ,, 

do  not  agree  when  the  perpendicular  OA   to  the 


half 


N  =  large  Nicol; 
n  =  small  Nicol  or 
prism; " 


plane  of  the  analyzer  bisects  the  half-shadow  a. 

By  rotating  the  analyzer  slightly  from  L'M'  to 

LM  the  amplitudes  OC  and  OD  are  made  equal, 

Z>=  margin  of  diaphragm;  m  which  position  the  perpendicular  OA  no  longer 
F  =  projection  of  field.       bisects  a.     The  angle  d  which  the  perpendicular 

OA  makes  with  the  bisector  OA '  will  vary  accord- 
ing to  the  size  of  the  half-shadow  angle  a.  The  Lippich  polarizer  is 
therefore  not  symmetrical,  which  is  a  disadvantage,  since  by  chang- 
ing the  half-shadow  a  to  vary  the  sensibility  there  is  also  a  change 
in  the  zero  point  of  the  analyzer.  The  latter  must  accordingly  be  re- 
adjusted for  each  change  in  sensibility. 

The  relation  of  intensities  in  the  light  emerging  from  the  large 
and  small    prisms    of    the    Lippich    polarizer    is    found    as    follows: 


*  Z.  Instrument.,  2,  167;  14,  326. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


95 


OG 

^  =  cos  Z  BOG  —  cos  a.    If  /  and  /'  are  the  intensities  for  the  large 

and  small  prisms  respectively,  then 

T/  f)C^ 

-j  = o  =  cos2  a     and     I'  —  I  cos2  a.  (1) 

2       OB 


C  O  Dr~ 

Fig.  65.  —  Illustrating  principle  of  Lippich  polarizer. 


-M' 


The  relation  between  the  angle  of  the  half-shadow  a  and  that  of 
the  change  in  zero  point  5  may  be  calculated  as  follows :  When  the  two 
halves  of  the  field  are  matched  the  amplitudes  OC  =  OD  and  the  inten- 
sities OC  = 

OC 
OB 


sin  Z  CBO  =  sin  Z  POA  =  sin  ( £  - 


gg  =  sinOOD  =  sin  Z  #04 

§— s-> 


-sin(f  +  «). 


(2) 


OB 


(3) 


96  SUGAR  ANALYSIS 

Substituting  /  and  I'  for  OB  and  OG  ,  we  obtain 


OD2  =  sin2fe  +  A  I';  since  OC*  =  ~6T)   for  the  matched  field,  we 
obtain 


(4) 

sin2  (f  ~  ^)  =  sin2  (|  +  «)  j  =  sin2  (|  +  «)  cos2  a.  (5) 

sin  »  cos  5  —  cos  -  sin  8  =  sin  •=  cos  5  cos  a  +  cos  ^  sin  5  cos  a. 
Dividing  by  cos  ~  cos  8,  we  obtain 

tan  =  —  tan  5  =  tan  -  cos  a.  +  tan  5  cos  a. 

-  2 

a  1  —  COS  a  ,  a 

tan  6  =  tan  ^  -=—. =  tan3  ^  •  (6) 

2  1  +  cos  a  2 

In  the  above  calculation  only  the  light  extinguished  in  the  small 
Nicol  has  been  considered.  There  are  other  factors,  however,  which 
must  be  taken  into  account  in  the  calculation  of  the  true  zero-point 
correction.  Schonrock*  has  shown  that  7.5  per  cent  of  the  light  is  lost 
by  reflection  from  the  surface  of  the  small  Nicol,  and  that  this  amount 
is  increased  to  8  per  cent  or  more  by  the  loss  through  absorption. 
Equation  1  for  intensity  would  then  become 

WO     Cl  \J»  \J      •  \  '    / 

The  value  of  8  thus  modified  would  be  expressed  by 

1  -  cos  a  A/O92  ,      a 

tan  6  =  -. tan  -.  (8) 

l+cosaVo.92         2 

Bates  f  has  shown,  however,  that  a  part  of  the  light  lost  by  reflection 
from  the  sides  of  the  small  Nicol  is  again  restored  in  the  analyzer,  and 
that  when  all  factors  such  as  depolarization,  size,  shape,  and  inclination 
of  the  small  prism,  etc.,  are  taken  into  account  the  true  value  of  8  is 
between  those  calculated  by  equations  6  and  8,  the  exact  figure  depend- 
ing upon  the  construction  of  each  individual  Lippich  system. 

Apart  from  the  disadvantage  that  the  zero  point  must  be  corrected 

*  Z.  Ver.  Deut.  Zuckerind.,  68,  111. 
t  Ibid.,  68,  821. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


97 


for  changes  in  sensibility,  the  Lippich  polarizer  is  the  best  for  general 
use  and  the  one  most  sensitive  to  minute  changes  in  rotation.     The 
average  error  of  adjustment,  according  to  Landolt, 
with  bright  illumination  and  a  half-shadow  angle  of 
1  degree,  is  only  about  15  seconds  (0.004  degree). 

Lippich  Polarizer  with  Triple  Field.  —  The  sensibil- 
ity of  the  Lippich  polarizer  has  been  almost  doubled 
by  using  two  half-prisms  in  place  of  one,  the  system 
being  so  arranged  that  the  field  of  vision  is  divided  into 
three  parts  (Figs.  66  and  67).  ^The  principle  of  the 
triple  field  can  be  understood  by  referring  to  Fig.  67a. 

Let  AC,  ac,  and  a'c'  represent  planes  of  the  large 
Nicol  N,  and  ab  and  a'b'  planes  of  the  half-prisms  n 
and  n'  respectively.  It  will  be  seen  that  ab  and  a'b' 
must  be  perfectly  parallel  in  order  that  the  half- 
shadow  angles  a  and  a'  be  equal  for  both  half-prisms, 
an  absolute  essential  if  perfectly  uniform  illumination 
is  to  be  obtained  at  the  end  point.  It  sometimes  hap- 
pens that  the  two  half-prisms  get  out  of  parallelism 
through  jarring  of  the  instrument  or  expansion  and 

contraction  of  the  mountings.     There  will  then  be  Fjg  6g Showing 

two  end  points   for  the  half-shadow,   according  to      construction     of 
which  side  the  middle  of  the  field  is  made  to  agree.      Lippich  polarizer 
The  observer  is  then  obliged  either  to  take  but  one      for  triPle  fielch 
of  these  end  points,  which  is  equivalent  to  reducing  A,  large  Nicol; 
the  instrument  to  an  imperfect  double  field,  or  else  to  #  and  C,  small  half- 
readjust  the  planes  of  the  half-prisms  to  parallelism,  p^™8'^  Of  ^ia 
a  most  delicate  as  well  as  time-consuming  operation,      phragm; 
For  instruments  requiring  constant  use  the  increase  E  and  F,  inner  edges 
in  sensibility  of  the  triple  field  can  hardly  be  said  to      of  half-prism 
offset  the  increased  sensitiveness  of  the  polarizer  to 
disarrangement.     The  more  simple  double-field  end- 
point  device  is  much  to  be  preferred  for  ordinary  lab- 
oratory conditions.* 

Lippich  Polarizer  with  Quadruple  Field.  —  Lummerf  has  constructed 
a  polarizer  with  quadruple  field  (Fig.  68)  by  placing  before  the  larger 

*  Many  chemists  wrongly  use  the  expressions  half-shade  and  triple-shade  in  place 
of  the  terms  double  field  and  triple  field.  The  term  half-shade  or  half-shadow,  (Ger- 
man, Halbschatten;  French,  penombre),  refers  to  the  depth  of  shade  in  the  field  at 
the  end  point  and  not  to  the  division  of  the  field.  The  expression  triple  shade  is 
meaningless. 

t  Z.  Instrument.,  16,  209. 


which  form  the 
divisions  H,  J, 
and  K  of  the  triple 
field. 


SUGAR  ANALYSIS 


i  n 

a  b 

Fig.  67.  —  Illustrating  principle  of  Lippich  polarizer  for  triple  field. 
I,  analyzer  crossed  with  outer  divisions  of  field; 
II,  analyzer  crossed  with  inner  division  of  field; 
III,  end  point. 

Nicol  A  one  large  half-prism  B,  and  before  the  latter  two  smaller  half- 
prisms  C  and  D.  The  increased  complica- 
tion of  this  form  of  polarizer  has  prevented 
its  general  introduction. 

Wild's  Polaristrobometer.  —  Another 
form  of  polarizing  apparatus,  whose  pecu- 
liarities of  construction  place  it  in  a  class 
by  itself,  is  the  jpolaristrobometer  invented 
by  Wild*  in  1864.  In  this  instrument, 
shown  in  Fig.  69,  the  polarizer  (/)  is  at- 
tached to  a  divided  circle,  K,  both  being 
rotated  by  a  rod  and  pinion  from  the  screw 
C  around  the  longitudinal  axis  of  the  Nicol 
prism.  The  end-point  device  placed  at  e 
consists  of  a  Savart  double  plate  made  up 
of  two  sections  of  calc  spar  each  3  mm. 
thick,  cut  at  an  angle  of  45  degrees  to  the 
optical  axis  of  the  crystal,  and  cemented 
together  so  that  their  principal  sections 
cross  at  right  angles.  A  diaphragm  c  with 
cross  threads  is  placed  in  the  focus  of  the 
objective  lens  d  of  the  telescope.  The  an- 
alyzer at  a  is  stationary,  being  usually 
mounted  with  its  principal  section  hori- 
zontal and  forming  an  angle  of  45  degrees 
Fig.  68.—  Showing  construction  with  the  crossed  sections  of  the  Savart 

of  Lippich  polarizer  for  quad-    plate 

ruple  field. 

*  "  Ueber  em  neues  Polaristrobometer,"  Bern,  1865. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS 


99 


To  determine  the  zero  point  of  the  polaristrobometer,  which  is  first 
illuminated  at  D  with  a  sodium  flame,  a  tube  of  water  is  placed  in  the 
instrument  and  the  ocular  of  the  telescope  focused  sharply  upon  the 
cross  threads;  the  field,  except  near  the  end  point,  consists  of  a  series  of 
dark  horizontal  parallel  bands,  the  so-called  interference  fringes,  which 


Fig.  69.  —  Wild's  polaristrobometer. 

upon  rotation  of  the  polarizer  increase  and  decrease  in  intensity;  at 
certain  points  of  rotation  the  bands  gradually  become  paler  until,  at 
the  maximum  point  of  brightness,  they  are  suddenly  extinguished  in 
the  center  of  the  field,  leaving  only  a  slightly  shaded  border  at  each 
edge  (see  Figs.  70  and  71).  The  point  at  which  the  shaded  borders 
and  the  extinguished  part  of  the  field  are  symmetrically  distributed 
with  reference  to  the  cross  threads  constitutes  the  end  point.  In  this 


100  SUGAR  ANALYSIS 

position  the  plane  of  the  polarizer  is  parallel  with  one  of  the  crossed 
planes  of  the  Savart  plate,  so  that  the  end  point  reoccurs  every  90  de- 
grees. In  case  the  extinguished  part  of  the  fringes  is  too  wide  for 
accurate  adjustment,  the  intensity  of  the  light  should  be  diminished 
until  the  borders  of  the  fringes  are  brought  sufficiently  close  to  the 
reticule.  The  fringes  haye  usually  a  different  appearance  at  each  of 
the  end  points,  and  also  with  colored  solutions,  so  that  a  beginner  must 
familiarize  himself  with  the  various  characters  of  the  field  before  making 


Fig.  70  Fig.  71 

Showing  field  of  Wild's  polaristrobometer. 

Fig.  70.  —  Interference  fringes  before  end  point. 
Fig.  71.  —  Interference  fringes  at  end  point. 

readings.  In  case  the  zero  points  of  the  scale  and  vernier  do  not  coin- 
cide at  the  end  point,  the  deviation  may  be  noted  and  applied  to  the 
readings  as  a  correction,  or  else  they  may  be  set  at  zero  and  the  instru- 
ment brought  into  adjustment  by  gently  turning  the  screw  G  until  the 
proper  end  point  is  secured. 

If  the  polarizer  is  set  at  one  of  the  four  zero  points  and  a  tube  of 
sucrose  solution  be  placed  in  the  trough,  the  interference  fringes  will 
reappear.  The  polarizer  must  then  be  rotated  to  the  left  (opposite  to 
the  rotation  of  the  sugar  solution)  until  the  fringes  again  disappear. 
The  angular  displacement  of  the  polarizer  to  the  left  gives  the  angular 
rotation  of  the  sucrose  solution  to  the  right.  The  readings  are  made 
through  a  telescope  P  which  is  focused  upon  the  fixed  vernier  J;  the 
latter  is  illuminated  by  a  flame  at  Q.  The  average  error  of  adjustment 
according  to  Landolt  is  about  ±  3  minutes. 

The  divisions  of  the  scale  upon  the  Wild  polaristrobometer  are  made 
usually  in  both  circular  degrees  and  in  degrees  of  a  sugar  scale  giving 
percentages  of  sucrose.  The  sugar  scale  is  constructed  by  dividing 
53.134  circular  degrees  into  400  equal  parts.  Each  of  these  sugar 
divisions  corresponds  to  the  rotation  of  1  gm.  of  sucrose  dissolved  to 
1000  c.c.  and  polarized  in  a  200-mm.  tube;  10  gms.  of  pure  sucrose  dis- 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS         101 

solved  to  100  c.c.  will  indicate  the  100-degree  point  of  Wild's  scale, 
20  gms.  sucrose  dissolved  to  100  c.c.  will  indicate  the  200-degree  point, 
30  gms.  the  300-degree  point,  and  40  gms.  the  400-degree  point.  The 
normal  weight  of  the  sugar  scale  of  the  Wild  polaristrobometer  can 
therefore  be  varied  according  to  the  concentration  of  the  product  to 
be  examined,  the  readings  obtained  with  the  20-gm.,  30-gm.,  and  40-gm. 
normal  weights  being  divided  by  2  or  3  or  4,  as  the  case  may  be. 

The  Wild  polaristrobometer,  although  formerly  used  in  many 
European  laboratories,  finds  at  present  but  limited  application  in  tech- 
nical sugar  analysis. 

DESCRIPTION  OF  STANDARD  MODERN  POLARIMETERS 

The  concluding  parts  of  this  chapter  will  be  devoted  to  descriptions 
of  a  few  standard  forms  of  modern  polarimeters. 

Laurent's  Polarimeter.  —  As  a  type  of  instrument  of  French  manu- 
facture the  Laurent  polarimeter  is  shown  in  Fig.  72. 


Fig.  72.  —  Laurent's  polarimeter. 

A.  A  duplex  Laurent  sodium  burner  placed  200  mm.  from  B. 

B.  Illuminating  lens. 

C.  Quadrant  whose  outer  circle  is  divided  into  circular  degrees  and  whose  inner 

circle  is  divided  into  sugar  degrees. 

D.  Diaphragm  containing  half -wave  plate  of  quartz. 

E.  Light  filter  consisting  of  a  crystal  of  potassium  bichromate. 


102  SUGAR  ANALYSIS 

F.  Screw  for  adjustment  of  zero  point. 

G.  Geared  screw  for  rotating  the  analyzer  and  the  arm  supporting  the  verniers. 

The  upper  vernier  on  the  right  is  for  reading  circular  degrees  and  the  lower 
vernier  upon  the  left  for  reading  sugar  degrees. 

L.   Bronze  trough  600  mm.  long  for  holding  observation  tubes. 

M.   Mirror  for  illuminating  scale. 

N.    Magnifying  glass  for  reading  scale. 

R.  Tube  section  containing  polarizer;  the  latter  can  be  moved  through  a  small 
angle  by  the  arm  K,  which  is  moved  by  the  crank  J  through  the  rod  X  by  means 
of  the  lever  U.  If  the  solution  to  be  examined  is  but  little  colored,  the  lever  U 
is  raised,  which  decreases  the  half-shadow  angle.  With  colored  solutions  U  is 
lowered  until  the  half-shadow  is  increased  to  the  point  of  greatest  sensibility. 
The  zero  point  should  be  redetermined  after  each  change  in  the  position  of 
the  polarizer. 


The  100-degree  point  of  the  sugar  scale  of  the  Laurent  polarimeter 
corresponds  to  an  angular  rotation  of  21.67  degrees  (21°  40'),  which 
is  the  value  given  by  French  authorities  to  the  angular  rotation  of  the 
1  mm.  thick  plate  of  quartz  cut  perpendicular  to  the  optical  axis  (see 
page  112).  The  normal  weight  of  sucrose  corresponding  to  this  rota- 
tion is  given  as  16.29  gms.  dissolved  to  100  c.c.  and  polarized  in  the 
200-mm.  tube.  The  sugar  scale  extends  400  divisions  to  the  right  and 
200  divisions  to  the  left,  thus  giving  ample  range  for  polarizing  all 
dextro-  and  levo-rotatory  sugars.  If  desired,  the  sugar  scale  of  the 
Laurent  polarimeter  is  adjusted  according  to  the  so-called  Interna- 
tional saccharimetric  scale  of  20  gms.  The  value  of  the  100-degree 
division  of  the  International  scale  in  circular  degrees  would  equal 

21  67  X  20 

'          —  =  26.605  degrees;  this  is  a  trifle  more  than  the  circular  value 
lo.^y 

of  the  Wild  20-gm.  scale,  viz.,  26.567  degrees,  the  difference  being  due 
presumably  to  the  adoption  of  a  slightly  different  standard  value  for 
the  specific  rotation  of  sucrose. 

Pellin's  Polarimeter.  —  Another  type  of  French  polariscope  is  the 
half-shadow  polarimeter-saccharimeter  made  by  Pellin,  shown  in  Fig. 
73.  The  polarizer  of  this  instrument  consists  of  a  modified  Jellet-Cornu 
prism;  the  half-shadow  angle  is  therefore  fixed.  The  division  of  the 
quadrant  into  circular  and  sugar  degrees  is  identical  with  that  of  the 
Laurent  polarimeter. 

The  Pellin  polarimeter  with  variable  half-shadow  angle  (Fig.  74) 
makes  use  of  a  half-wave  plate  of  quartz  for  the  end  point,  which  is 
constructed  for  either  divided  or  concentric  fields.  The  arrangement 
of  optical  parts  and  method  of  manipulation  are  the  same  as  in  the 
Laurent  polarimeter. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS         103 


Fig.  73.  —  Pellin's  polarimeter  with  Jellet-Cornu  prism. 


Fig.  74.  —  Pellin's  polarimeter  with  half -wave  plate. 


104  SUGAR  ANALYSIS 

Lippich's  Polarimeter.  —  A  simple  form  of  Lippich's  polarimeter 
adapted  for  general  chemical  use  is  shown  in  Fig.  75.  Angular  rotations 
can  be  measured  with  this  instrument  to  about  0.015  degree. 


Fig.  75.  —  Simple  form  of  Lippich's  polarimeter. 

h.  Lever  for  moving  large  Nicol  of  polarizer  and  regulating  sensibility.     The  half- 
shadow  angle  which  is  read  by  the  scale  can  be  varied  from  0  degrees  to  20  de- 


K.  Divided  circle  for  measuring  rotation.  The  circle  with  analyzer  in  A  and 
telescope  at  F  is  rotated  by  the  screw  T.  The  readings  of  the  scale  are  made 
on  each  side  of  the  circle  through  the  lenses  I,  which  are  focused  upon  the  fixed 
verniers  at  n. 

P.  Location  of  Lippich  polarizer. 

S.  Detachable  end  for  holding  light  filter. 

A  form  of  the  Lippich  apparatus  devised  by  Landolt  for  more  general 
use  is  shown  in  Fig.  76.  This  instrument  presents  an  advantage  in 
that  any  form  of  tube  or  container  may  be  used  for  holding  the  solution 
or  substance  to  be  polarized. 

The  trough  D  of  the  polariscope  for  holding  ordinary  tubes  can  be 
removed  and  the  support  T  employed.  The  latter  is  raised  or  lowered 
by  the  screw  q  and  moved  laterally  upon  the  tracks  c.  For  polarizing 
materials  in  hot  or  cold  condition,  the  apparatus  G,  consisting  of  a 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS         105 


Fig.  76.  —  Landolt's  polarimeter  for  general  use. 

g.   Lever  for  rotating  circle  R',  the  final  adjustment  is  made  by  means  of  the  microm- 
eter screw  m  after  fixing  the  clamp  k. 
P.   Position  of  Lippich  polarizer  with  two  half-prisms  giving  triple  field. 


Fig.  77.  —  Large  model  Landolt  polarimeter. 


106  SUGAR  ANALYSIS 

polariscope  tube  in  an  asbestos-jacketed  bath,  is  employed.  The  plate 
T  is  then  removed  and  the  bath  placed  directly  upon  the  tracks  c.  The 
burner  for  heating  the  bath  is  placed  upon  the  adjustable  stand  under- 
neath. The  center  narrow  tube  projecting  through  the  replaceable  top 
of  the  bath  receives  the  overflow  from  the  observation  tube;  the  other 
tubes  serve  for  a  thermometer  and  stirrer  for  the  liquid  of  the  bath. 
For  polarizing  at  low  temperature  a  cooling  medium  is  used  in  the  bath, 
in  which  case  the  ends  of  the  observation  tubes  must  be  covered  with 
desiccating  caps  to  prevent  condensation  of  moisture  upon  the  cover 
glasses. 

A  type  of  more  elaborate  polarimeter,  which  can  be  read  to  0.01 
degree,  is  the  large  Landolt  instrument  shown  in  Fig;  77.  The  divided 
circle  (driven  by  the  wheel  T  and  micrometer  screw  m)  is  covered  by  a 
cap  K.  Small  mirrors  Si  and  S2  reflect  light  from  the  observation 
lamp  through  openings  in  the  cap  to  illuminate  the  scale.  A  feature  of 
this  instrument  is  the  double  trough  by  which  different  tubes  of  solu- 
tion can  be  brought  into  the  field  by  movement  of  the  large  lever  H. 

VERIFICATION  OF  SCALE  READING  OF  POLARIMETERS 

The  graduations  of  the  divided  circle  upon  a  polarimeter  should  be 
verified  by  taking  check  readings  at  different  points  upon  opposite 
sides  of  the  disk.  The  division  and  mounting  of  the  circle  in  the  best 
instruments  is  made  with  great  accuracy,  and,  unless  the  disk  has  been 
warped  or  bent,  check  readings  on  opposite  sides  of  the  circle  will  agree 
much  closer  than  the  observer  can  set  the  scale  for  a  matched  field. 

Polariscope  readings  should  always  be  verified  upon  the  opposite 
scale.  It  is  also  well  to  reverse  the  circle  180  degrees  and  repeat  the 
readings  each  way  from  the  other  side.  By  so  doing  the  observer  will 
have  4  sets  of  readings,  the  mean  of  which  will  practically  eliminate  all 
errors  due  to  faulty  scale  division  or  eccentricity.  The  example  on  page 

107  of  readings  made  upon  a  sugar  solution  will  illustrate  the  method. 
The  adjustment  of  the  halt-shadow  angle  is  made  to  the  point  of 

greatest  sensibility,  the  angle  being  small  for  light-colored  solutions  and 
larger  for  dark  liquids.  Since  altering  the  half-shadow  of  the  Lippich 
system  produces  a  change  in  zero  point  (p.  95),  the  adjusting  lever 
should  never  be  disturbed  during  a  set  of  observations.  The  analyzer, 
if  desired,  can  be  brought  back  to  the  0  of  the  scale  for  any  change  in 
the  half-shadow  angle  by  means  of  a  small  regulating  screw  (shown  at 
a,  Fig.  77).  The  better  method,  however,  is  to  establish  the  zero  point 
upon  the  scale,  as  in  the  following  example,  and  subtract  this  from  the 
scale  reading. 


THEORY  AND  DESCRIPTION  OF  POLARIMETERS         107 


Zero  point. 

Sugar  solution. 

Right. 

Left. 

Right. 

Left. 

r 

3.07 

183.07 

29.30 

209.295 

>> 

3.09 

183.085 

29.28 

209.28 

3.11 

183.11 

29.295 

209.29 

* 

3.08 

183.075 

29.27 

209.28 

Half-shadow 

fln0.1p  _  «o^ 

3.10 

183.10 

29.285 

209.29 

Temperature 
"     20°  C 

Average  . 

3.09 

183.088 

29.286 

209.287 

3.090 

183.088 

[ 

26.196 

26.199 

, 

( 

183.075 

3.08 

209.270 

29.265 

1 

183.10 

3.10 

209.285 

29.28 

183.08 

3.085 

209.28 

29.28 

Reversing 
the  circle  •< 

183.09 
183.09 

3.09 
3.095 

209.27 
209.285 

29.27 
29.285 

Temperature 

r     21  °  C 

180°. 

183.087 

3.090 

209.278 

29.276 

183.087 

3.090 

^ 

26.191 

26.186 

J 

Average  of  4  readings,  26.193°  for  20.5°  C. 


CHAPTER  VI 

THEORY  AND   DESCRIPTION   OF  SACCHARIMETERS 

WHILE  the  instruments  described  in  the  previous  chapter  are 
adapted  to  the  examination  of  all  optically  active  substances,  sac- 
charimeters  are  designed  solely  for  polarizing  sugars.  For  convenience 
the  scale  expressing  angular  rotation  is  replaced  upon  the  saccharimeter 
by  one  graduated  according  to  the  decimal  system  indicating  percent- 
ages. 

THE  QUARTZ-WEDGE  COMPENSATION 

Owing  to  the  many  difficulties  and  inconveniences  connected  with 
the  use  of  sodium  or  other  monochromatic  light  in  practical  work,  the 
French  physicist  Soleil  was  led  in  1848  to  devise  a  means  by  which 
ordinary  daylight  or  lamplight  could  be  used  for  measuring  the  optical 
rotation  of  sugar  solutions.  This  invention,  known  as  the  quartz- 
wedge  compensation,  is  the  characteristic  feature  of  all  saccharimeters. 

In  the  quartz-wedge  saccharimeter  the  polarizer  and  analyzer  are 
both  stationary;  the  rotation  of  the  sugar  solution  is  measured  by 
shifting  a  wedge  of  optically  active  quartz  between  the  solution  and 
analyzer  until  the  rotation  of  the  wedge  system  at  a  certain  thickness 
exactly  neutralizes  or  compensates  the  rotation  of  the  sugar  solution. 
By  means  of  a  scale  attached  to  the  quartz  wedge  the  rotation  of  the 
sugar  in  solution  is  measured  in  percentage. 

The  selection  of  quartz  for  compensation  is  based  upon  the  fact 
that  it  has  almost  exactly  the  same  rotation  dispersion  as  cane  sugar; 
i.e.,  a  section  of  quartz  and  a  cane-sugar  solution  of  equal  rotation  for 
light  of  one  wave  length  will  have  very  nearly  equal  rotations  for  light 
of  all  other  wave  lengths  (see  Table  XX).  The  small  disturbances 
due  to  the  slight  difference  in  rotation  dispersion  between  sugars  and 
quartz  are  eliminated  by  a  bichromate  light  filter. 

Single-wedge  System.  —  The  quartz  wedges  used  in  the  con- 
struction of  saccharimeters  are  cut  perpendicularly  to  the  optical  axis 
of  the  quartz  crystal;  they  may  be  either  of  dextrorotatory  or  levo- 
rotatory  quartz,  the  method  of  mounting  the  wedge  depending  upon 
the  character  of  the  rotation.  This  can  be  seen  more  clearly  by  in- 
specting the  following  diagrams  (Fig.  78). 

108 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      109 


In  diagram  I,  A  is  a  fixed  plate  of  levorotatory  quartz,  and  R  and 
C  two  wedges  of  dextrorotatory  quartz,  of  which  B  is  movable  and  C 
stationary.  The  two  wedges,  wljich  though  of  different  size  must  have 
equal  angular  dimensions,  may  be  considered  to  form  together  a  single 
section  with  sides  parallel  to  the  plate  A  and  perpendicular  to  the 
axis  of  light  through  the  instrument.  The  thickness  of  the  two  wedge 
sections  can  be  increased  or  diminished  by  moving  wedge  B  to  the 
right  or  left.  At  the  zero  point  of  the  instrument  the  right  rotation  of 


Dextro-rotatory  wedge 
system 


Levo-rotatory  wedge 
system 


u 


II  0 

Fig.  78.      Showing  construction  of  single  wedge  quartz  compensation. 

the  section  Imno  of  the  two-wedge  system  exactly  neutralizes  the  left 
rotation  of  the  quartz  plate  A.  If  a  tube  of  dextrorotatory  sugar 
solution  be  now  placed  in  the  instrument  between  the  polarizer  and  the 
compensation  plate  A,  the  optical  neutrality  is  destroyed,  and  it  will 
be  necessary  to  decrease  the  thickness  of  the  two-wedge  section  by 
sliding  B  from  o>  towards  «'  until  the  excess  of  left  rotation  in  A  over  B 
and  C  exactly  neutralizes  the  right  rotation  of  the  sugar  solution.  If  the 
solution  of  sugar  is  left-rotating,  it  will  be  necessary  to  slide  B  in  the 
opposite  direction  until  the  excess  of  right  rotation  in  B  and  C  over  A 
equals  the  left  rotation  of  the  sugar.  In  a  levorotatory  wedge  system 
(diagram  II)  the  compensation  plate  A  is  dextrorotatory  and  the  wedges 
B  and  C  levorotatory,  the  compensating  motion  of  wedge  B  being  the 
reverse  of  that  in  diagram  I. 

Owing  to  the  lateral  refraction  of  light  from  the  inclined  surfaces 
of  the  wedges  through  the  intervening  air  space  (as  shown  by  the 
dotted  line  efg),  the  planes  of  quartz  are  separated  only  just  sufficiently 
to  allow  free  movement  of  the  parts  without  friction.  The  circum- 
stance that  the  field  is  not  exactly  at  the  end  point,  when  the  thickness 
of  the  two-wedge  section  agrees  with  that  of  the  compensating  plate, 
is  due  to  this  lateral  refraction.  The  shifting  of  zero  point  due  to  re- 
fraction depends  upon  the  wave  length  of  light;  the  difference  in  zero 


110 


SUGAR  ANALYSIS 


point  between  red  light  of  760  MM  wave  length,  and  violet  light  of  396.8 
WJL  wave  length  was  found  by  Schonrock  to  be  0.059  degree  for  the 
Ventzke  sugar  scale. 

The  scale  of  the  saccharin) eter  is  attached  to  the  large  or  movable 
wedge,  and  is  read  by  means  of  a  vernier  scale  attached  to  a  regu- 
lating screw.  In  case  the  zero  marks  of  the  two  scales  do  not  agree, 
when  the  two  halves  of  the  field  correspond  in  shade,  they  can  be 
brought  into  coincidence  by  shifting  the  vernier  slightly  to  the  right  or 
left  by  means  of  a  key  which  fits  the  regulating  screw.  The  vernier 
is  never  to  be  moved  except  for  making  this  adjustment,  and  when  the 
two  scales  are  once  set  has  rarely  to  be  disturbed.  Owing  to  the  in- 
evitable slight  fluctuations  in  the  zero  point  of  saccharimeters,  it  is  best 
to  correct  the  reading  by  the  zero-point  error  and  not  to  adjust  the 
scale  unless  there  be  a  persistent  difference  of  the  zero  point  in  one 
direction  greater  than  0.1  degree.  The  method  of  reading  the  sac- 
charimeter  scale  can  be  seen  from  Figs.  80  and  81. 

Double-wedge  System.  —  An  elaboration  of  the  quartz-wedge 
system  just  described  is  the  double- wedge  compensation  introduced 

by   Schmidt   and   Haensch.     The 
arrangement  of  the  parts  in  the 
double-wedge  system  is  shown  in 
A    Fig.  79. 

In  the  double- wedge  system  the 
B    compensation  plate  is  lacking,  this 
being  supplied  by  one  or  the  other 
c    of  the  pair  of  wedges,  which  are 
of  opposite  rotation.     The  smaller 
D    wedges  A  and  D  are  stationary  and 
the  larger  wedges  B  and  C  mova- 
ble.   B  and  C  are  usually  mounted 

•p.    -n  f  ,    , ,     with  their  points  in  the  same  direc- 

Fig.  79.  —  Showing  construction  of  double  r 

wedge  quartz  compensation.  tlon  m  order  to  equalize  the  refrac- 

tion of  the  light  rays  in  the  air 

spaces  between  the  inclined  surfaces  of  quartz  (as  indicated  by  the 
dotted  line) ;  for  this  reason  also  the  corresponding  wedges  of  each  sys- 
tem are  made  as  near  alike  as  possible.  Each  of  the  large  wedges  is 
provided  with  a  scale.  These  may  be  read  through  the  same  telescope 
as  upon  the  Schmidt  and  Haensch  saccharimeter  (Fig.  80),  or  by  sepa- 
rate telescopes  as  in  the  Fric  instruments  (Fig.  81). 

In  using  the  double-wedge  system  for  dextrorotatory  substances, 
the  scale  K  (Fig.  80)  is  set  at  zero  with  its  vernier,  and  the  optical  rota- 


THEORY  AND  DESCRIPTION  OF  SACCHARI METERS      111 


tion  measured  upon  the  scale  A;  for  levorotatory  solutions,  A  is  set 
at  zero  and  the  scale  K  employed.  An  additional  advantage  of  the 
double-wedge  system  consists  in  the  fact  that  any  reading  obtained  upon 


PATENT 
JOSEF  &  JAN  ERIC 


Fig.    80.  —  Scale   of    double   wedge 
Schmidt  and  Haensch  saccharimeter. 
K,  control  scale; 

A,  working  scale  indicating  85.5  de- 
grees Ventzke. 


Fig.  81.  —  Scale  of  Fric  saccharimeter 
with  double  vernier  indicating  97.7 
degrees  Ventzke .  (The  division  be- 
tweenscale  and  vernier  is  intensified ; 
in  reality  no  dividing  line  is  seen.) 


the  working  wedge  can  be  immediately  verified  by  removing  the  tube 
of  solution  and  moving  the  control  wedge  to  the  point  of  compensation. 
The  control  wedge  under 'such  conditions  gives  the  true  reading  directly, 
even  though  the  working  wedge  have  a  zero-point  correction. 


Zero-point  determination. 


Polarization  of  mat  sugar. 


Control-wedge 

scale. 

Working-wedge 
scale. 

Difference. 

Control-wedge 
scale. 

Working-wedge 
scale. 

Difference. 

0.00 

0.10 

+0.10 

0.00 

89.40 

89.40 

11.55 

11.65 

+0.10 

0.75 

90.15 

89.40 

20.75 

20.80 

+0.05 

2.15 

91.50 

89.35 

32.20 

32.30 

+0.10 

2.90 

92.30 

89.40 

43.75 

43.80 

+0.05 

3.85 

93.25 

89.40 

52.50 

52.55 

+0.05 

5.45 

94.85 

89.40 

61.85 

61.95 

+0.10 

6.55 

96.00 

89.45 

70.50 

70.60 

+0.10 

7.95 

97.30 

89.35 

81.15 

81.30 

+0.15 

9.10 

98.45 

89.35 

91.15 

91.25 

+0.10 

10.15 

99.55 

89.40 

Average  zero  point               +0.09 

Average  polarization  un-  )       89  .  39 

corrected                          ( 

Zero-point  correction  =            0.09 

Corrected  polarization  =          89.30 

112  SUGAR  ANALYSIS 

Zero-point  Determination.  —  The  zero-point  correction  of  the  work- 
ing wedge  can  be  determined  very  accurately  by  taking  check  readings 
at  different  parts  of  the  scale  upon  the  control.  By  making  polariza- 
tions in  the  same  way,  the  local  defects  of  scale  or  wedge  will  be  almost 
wholly  eliminated.  The  readings  in  this  case  are  made  without  re- 
moving the  tube,  the  difference  between  the  two  scales  being  the 
uncorrected  polarization.  The  preceding  table,  giving  the  readings  upon 
the  working-wedge  scale  for  various  positions  of  the  control,  will  illus- 
trate the  method. 

THE  SUGAR  SCALE  AND  NORMAL  WEIGHT  OF  SACCHARIMETERS 

The  100-degree  point  of  a  saccharimeter  scale  is  usually  based  upon 
the  rotation  of  a  definite  weight  (the  so-called  normal  weight)  of  chemi- 
cally pure  sucrose  dissolved  in  water  to  100  c.c.  at  a  specified  temperature 
and  polarized  at  the  same  temperature  in  a  200-mm.  tube.  The  greatest 
confusion  has  prevailed  in  saccharimetry  in  the  past,  and  unfortunately 
still  prevails,  not  only  as  to  the  size  of  the  normal  weight  of  sugar  to  be 
taken  for  a  specified  scale,  but  also  as  to  the  conditions  of  volume  and 
temperature  under  which  this  normal  weight  is  to  be  polarized. 

French  Sugar  Scale.  —  The  100-degree  point  of  the  sugar  scale 
employed  upon  saccharimeters  of  French  manufacture  is  based  upon 
the  rotation  in  sodium  light  of  a  plate  of  dextrorotatory  quartz  1  mm. 
in  thickness  and  cut  exactly  perpendicular  to  the  optical  axis.  The 
choice  of  quartz  as  a  standard  proved  to  be  unfortunate,  for,  owing 
either  to  mistakes  of  polarimetric  measurement  or  to  defects  in  the 
quartz  (through  natural  imperfection  or  mistakes  in  cutting),  the 
rotation  of  the  1-mm.  plate  has  been  given  a  different  value  from  time 
to  time,  the  results  ranging  from  +20.98  degrees,  the  early  figure  of 
Biot,  to  +22.67  degrees.  Most  French  authorities  at  present  employ 
the  value  +21.67  degrees.  The  figure,  regarded  usually  as  the  most 
exact,  is  that  of  Landolt,  who,  for  spectral  pure  Na  light  of  mean  wave 
length  589.3  MM,  found  the  value  +21.723  degrees.  The  grams  of 
sucrose  necessary  to  give  the  same  rotation  in  100  c.c.  as  the  1-mm. 
quartz  plate  have  also  necessarily  varied;  over  20  different  values  have 
been  assigned  to  this  quantity,  the  amounts  ranging  from  16.000  gms. 
(Dubrunfaut)  to  16.471  gms.  (Clerget  and  Biot).  The  cause  of  these 
great  differences  is  due  partly  to  variations  in  the  quartz  standard  and 
partly  to  variations  in  the  purity  of  the  light  used  for  illumination. 

The  old  normal  weight  established  for  French  instruments  was 
16.35  gms.,  and  this  weight  is  still  largely  used  in  technical  work  with 
the  Soleil-Duboscq  saccharimeter.  In  1875  the  value  of  Girard  and 


THEORY  AND  DESCRIPTION  OF  SACCHARI METERS      113 


de  Luynes,  16.19  gms.,  was  adopted  as  the  official  weight  and  remained 
such  for  more  than  20  years,  notwithstanding  the  severest  criticism. 
In  1896  the  International  Congress  of  Applied  Chemistry  at  Paris 
established  the  value  of  16.29  gms.  sucrose  dissolved  at  20°  C.  in  100 
metric  c.c.,  and  this  is  the  official  weight  used  at  present  by  the 
French  Ministry  of  Finance. 

Ventzke  or  German  Sugar  Scale.  —  The  sugar  scale  most  generally 
used  outside  of  France  and  the  one  employed  upon  all  German  sac- 
charimeters  is  that  of  Ventzke.  This  scale  as  originally  devised  by 
Ventzke  *  was  based  upon  the  rotation  of  a  solution  of  pure  sucrose  of 
1.1  sp.  gr.  Y^  .  It  was  soon  found,  however,  inconvenient,  as  well  as 
inaccurate,  to  make  the  specific  gravity  of  solution  a  basis  for  saccha- 
rimetric  work,  and  the  grams  of  sugar  in  100  c.c.  of  solution  1.1  sp.  gr. 
was  used  for  the  -normal  weight;  this  was  determined  to  be  26.048  gms. 
weighed  in  air  with  brass  weights  and  dissolved  at  17.5°  C.  to  100 
metric  c.c. 

Mohr  Cubic  Centimeter  Standard.  —  With  the  introduction  in  1855 
of  the  Mohr  f  cubic  centimeter  (the  volume  of  1  gm.  of  water  at  17.5°  C. 
weighed  in  the  air  with  brass  weights),  the  original  normal  weight 
of  26.048  gms.,  designed  for  metric  cubic  centimeters,  was  strangely 
enough  retained  and  used  for  determining  the  100-degree  point  of  the 
sugar  scale.  In  this  way  the  standard  was  established  which  up  to 
1900  was  the  only  one  recognized  for  the  Ventzke  scale,  and  which  at 
the  present  time  is  still  the  one  most  commonly  used  in  commercial 
work.  In  accordance  with  this  standard,  the  100-degree  point  of  the 
sugar  scale  is  obtained  by  dissolving  26.048  gms.  of  chemically  pure 
sucrose  (weighed  in  air  with  brass  weights)  in  100  Mohr  c.c.  at  17.5°  C. 
and  polarizing  the  same  in  a  200-mm.  tube  at  17.5°  C.  in  a  saccharim- 
eter  whose  quartz-wedge  compensation  has  also  a  temperature  of 
17.5°  C.  This  normal  weight  calculated  to  100  metric  c.c.  (volume  of 
100  gms.  water  at  4°  C.)  is  equal  to  26.048  gms.  -=-  1.00234  =  25.9872 
gms.  (1  Mohr  c.c.  =  1.00234  metric  c.c.). 

Metric  Cubic  Centimeter  Standard.  —  On  account  of  the  confusion 
and  mistakes  resulting  from  two  standards  of  volume,  the  International 
Sugar  Commission,  at  its  third  meeting  in  Paris,  1900,  advocated  the 
abandonment  of  the  Mohr  for  the  metric  cubic  centimeter,  and  in  so 
doing  also  recommended  that  the  temperature  of  polarization  be  made 
20°  C.  The  change  in  temperature  from  17.5°  C.  to  20°  C.  necessitated 
a  recalculation  of  the  normal  weight  owing  to  the  difference  in  specific 

*  J.  prakt.  Chem.,  26,  84  (1842)  ;  28,  111  (1843). 

f  "Chemisch-analytische  Titrirmethode "  (1886),  pp.  44-50. 


114  SUGAR  ANALYSIS 

rotation  of  cane  sugar  and  quartz  at  these  two  temperatures.  The 
calculation  is  made  by  the  following  equation,  in  which  0.000184  is  the 
coefficient  of  decrease  in  specific  rotation  of  sucrose  at  20°  C.,  0.000148 
the  coefficient  of  increase  in  rotation  due  to  the  effect  of  temperature 
upon  wedge  and  scale,  and  0.000008  the  coefficient  for  expansion  of  the 
glass  observation  tube: 

2fi  048 

1  1  +(0.000184+0.000148  -  0.000008)    (20°  -  17.5°)}  =  26.0082 


gms.  The  International  Commission  decided,  however,  to  make  the  new 
normal  weight  exactly  26  gms.,  and  in  accordance  with  its  recommenda- 
tion the  following  definition  for  the  100-degree  point  of  the  Ventzke 
sugar  scale  has  been  universally  adopted:  "The  100-degree  point  of 
the  saccharimeter  scale  is  obtained  by  polarizing  a  solution  containing 
26.000  gms.  of  pure  sucrose  (weighed  in  air  with  brass  weights)  in  100 
true  c.c.  at  20°  C.  in  a  200-mm.  tube  in  a  saccharimeter  whose  quartz- 
wedge  compensation  must  also  have  a  temperature  of  20°  C."  All  sac- 
charimeters  using  the  Ventzke  scale  are  standardized  at  present  in 
accordance  with  this  definition.  According  to  Bates  and  Jackson*  a 
solution  of  chemically  pure  sucrose  under  the  above  conditions  gives 
a  reading  of  only  99.89  upon  the  German  scale. 

United  States  Coast  Survey  Standard.  —  The  old  original  standard 
of  the  Ventzke  scale  was  the  one  adopted  by  the  Department  of  Weights 
and  Measures  of  the  United  States  Coast  and  Geodetic  Survey,  and 
was  employed  for  many  years  by  the  United  States  Treasury  Depart- 
ment in  the  Custom  House  laboratories.  The  100-degree  point  of  the 
scale  was  taken  as  the  polarization  of  26.048  gms.  (in  vacuo)  of  pure 
sucrose  dissolved  to  100  true  c.c.  of  solution  at  17.5°  C.  and  polarized 
at  this  temperature  in  a  200-mm.  tube.  To  avoid  the  labor  of  reducing 
this  weight  of  sugar  to  vacuo,  the  flasks  employed  for  the  Coast  Survey 
standard  were  graduated  to  contain  100.06  true  c.c.,  the  excess  of 
0.06  c.c.  being  taken  to  correct  the  error  of  weighing  the  sugar  in  air 
against  brass  weights.  These  flasks  contain  0.174  c.c.  less  than  the 
old  Mohr  cubic  centimeter  flasks  (100.234  true  c.c.),  which  difference, 
unless  compensated,  would  cause  the  normal  weight  of  26.048  of  pure 
sucrose  to  polarize  0.17°  V.  too  high.  To  save  the  operators  the  trouble 
of  making  this  correction,  the  correction  of  0.17  was  applied  to  the 
quartz  test  plates  used  for  controlling  the  instruments.  The  computed 
values  of  the  Coast  Survey  test  plates  were  thus  0.17°  V.  lower  than 
the  values  marked  by  the  instrument  makers  for  the  Mohr  cubic  centi- 
meter standard. 

*  Scientific  Paper,  U.  S.  Bureau  of  Standards,  No.  268  (1916). 


, 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      115 


The  policy  of  the  Department  of  Weights  and  Measures  of  the  United 
States  Coast  Survey,  in  adopting  a  standard  different  from  that  in 
current  use,  was  unfortunate.  It  gave  rise  to  much  confusion  and  mis- 
understanding, and  traces  of  this  confusion  still  exist,  notwithstanding 
the  fact  that  the  United  States  Bureau  of  Standards,  the  Custom  House, 
and  all  other  United  States  Government  laboratories  have  abandoned 
the  old  Coast  Survey  standard  and  now  employ  the  standard  of  the 
International  Commission  of  26  gms.  to  100  true  c.c.  at  20°  C. 

According  to  the  work  of  both  Sawyer*  and  Rolfe,f  who  have  made 
comparative  readings  of  standard  quartz  plates  upon  various  sac- 
charimeters,  there  are  many  instruments  in  the  United  States,  even  of 
recent  manufacture,  which  are  standardized  for  a  normal  weight  of 
26.048  gms.  in  100  true  c.c.  Whether  this  condition  of  affairs  is  due 
to  a  mistaken  idea  of  some  manufacturers  that  the  old  Coast  Survey 
standard  is  still  recognized  officially  in  the  United  States,  is  difficult  to 
say.  It  is  evident,  however,  that  chemists,  in  order  to  avoid  the  con- 
siderable errors  due  to  confusion  in  standards,  should  state  explicitly, 
in  ordering  saccharimeters  from  manufacturers,  that  their  instruments 
be  graduated  according  to  the  standard  of  the  International  Commis- 
sion. When  purchasing  second-hand  saccharimeters,  chemists  should 
be  particularly  careful  to  subject  the  same  to  a  thorough  examination 
and  verification  before  using. 

Value  of  the  Ventzke  in  Circular  Degrees.  —  The  rotation  value  of  the 
100-degree  point  of  the  modern  Ventzke  scale  has  been  very  carefully 
determined  by  Schonrock,t  who  found  it  to  equal  34.657  circular  degrees 
for  spectral  pure  sodium  light.  This  is  the  value  used  at  present  by 
Schmidt  and  Haensch  §  in  the  standardization  of  all  their  saccharimeters. 
According  to  Bates  and  Jackson  (page  114)  the  rotation  value  of  the 
normal  quartz  plate  for  pure  sodium  light  is  34.620  circular  degrees. 

Bichromate  Light  Filter. — Schonrock||  has  shown  that  in  estab- 
lishing the  100-degree  point  of  the  Ventzke  scale  by  means  of  sucrose 
the  white  light  must  be  filtered  through  a  1.5-cm.  layer  of  6  per  cent 
potassium-bichromate  solution  in  order  to  eliminate  the  errors  of  rota- 
tion dispersion  between  cane  sugar  and  quartz  produced  by  the  light 
of  shorter  wave  length  at  the  violet  end  of  the  spectrum.  This  light 
filter  has  been  adopted  by  the  Physikalisch-Technische  Reichsanstalt 
of  Germany  and  also  by  the  United  States  Bureau  of  Standards  If  in 

*  J.  Am.  Chem.  Soc.  26,  990.     §  According  to  statement  in  a  letter  to  the  author. 

t  Technology  Quarterly  18,  294.     (1905)     ||  Z.  Ver.  Deut.  Zuckerind.,  64,  521. 

t  Z.  Ver.  Deut.  Zuckerind.,  64,  521. 

If  Upon  its  certificates  for  standardization  of  quartz  plates  a  sugar  degree  is  thus  de- 
fined by  the  United  States  Bureau  of  Standards :  "  A  sugar  degree  is  the  one-hundredth 


116 


SUGAR  ANALYSIS 


defining  the  100-degree  point  of  the  saccharimeter  scale,  and  its  use  is 
imperative  for  all  accurate  work.  Many  saccharimeters  have  a  3-cm. 
cell,  and  for  this  length  of  liquid  a  3  per  cent  bichromate  solution  is 
sufficient  (centimeter  length  of  cell  X  per  cent  bichromate  =  9).  For 
carbohydrate  materials  of  greater  rotation  dispersion  than  cane  sugar, 
such  as  dextrin,  commercial  glucose,  etc.,  the  author  has  found  it 
necessary  to  use  a  solution  of  double  the  above  concentration  (centi- 
meter length  of  cell  X  per  cent  bichromate  =  18)  in  order  to  secure 
constancy  of  results  between  different  observers  for  different  sources  of 
white  light. 

In  this  connection  it  is  important  to  note  that  the  rotations  of  the 
normal  weight  of  sucrose  with  bichromate-filtered  white  light  and  with 
sodium  light,  while  very  closely  agreeing,  are  not  absolutely  identical 
owing  to  the  slight  differences  in  optical  center  of  gravity.  Measure- 
ments by  Schonrock*  show  that,  while  a  normal  sugar  solution  at 
20°  C.  for  bichromate  filtered  white  light  is  exactly  equal  to  the  rota- 
tion of  a  quartz  plate  of  100°  V.  (34.657  angular  degrees),  by  using 
sodium  light  a  quartz  plate  of  100.03°  V.  (34.667  angular  degrees)  would 
be  required.  The  relationship  between  Ventzke  degrees  for  bichro- 
mate filtered  white  light  and  monochromatic  light  of  different  wave 
lengths  is  seen  from  the  following  table  :f 

TABLE  XX 
Showing  Rotation  of  Quartz  and  Sucrose  for  Different  Kinds  of  Light 


Source  of  light. 

Mean  wave 
length  /zM. 

Angular  rotation,  20°  C. 

Degrees 
Ventzke. 

Quartz  plate 
(1.595  mm.). 

Sucrose  solu- 
tion (26  gms. 
in  100  true  cubic 
centimeters  in 
200-mm.  tube). 

White  light  filtered  through  1.5cm.  \ 
of  bichromate  solution,  about  .  .  j 
Spectral  pure  sodium  light.  . 

600 

589.3 
551 

546.1 
535 
460.7 
420.2 

34.65 
34.657 
39.82 

40.73 
42.49 

58.65 

71.78 

34.65 
34.667 
39.87 

40.81 
42.67 
59.18 

72.87 

100.00 
100.03 

100.12 

100.19 
100.42 
100.91 
101.52 

White  light,  Welsbach,  unfiltered,  ) 
about.                                              ) 

Yellow-green  mercury  
Green  tantalum  

Blue  strontium 

Violet  rubidium  . 

part  of  the  rotation  shown  by  26  gms.  of  sucrose  dissolved  in  water  and  the  volume 
made  up  to  100  metric  cubic  centimeters,  for  light  from  an  incandescent  gas  mantle 
passed  through  1.5  centimeters  of  a  6  per  cent  potassium-bichromate  solution,  the 
temperature  being  20°  C.  for  graduation,  preparation,  and  observation." 

*  Z.  Ver.  Deut.  Zuckerind.,  54,  521. 

t  Compiled  from  results  by  Landolt  and  by  Schonrock. 


TI 

It  is  g 


THEORY  AND  DESCRIPTION  OF  SACCHARI METERS      117 

It  is  seen  that  while  the  quartz  and  sugar  exactly  agree  for  bichro- 
mate filtered  light,  the  sugar  is  rotated  to  a  continually  greater  extent 
than  quartz  for  light  of  decreasing  wave  length.  The  normal  sugar 
solution,  reading  100°  V.  with  filtered  white  light,  was  found  to  read 
100.12  degrees  with  unfiltered  white  light.  The  eyes  of  some  observers 
are  more  sensitive  than  those  of  others  to  the  disturbances  of  rotation 
dispersion  when  unfiltered  light  is  used  (owing  perhaps  to  some  differ- 
ence in  the  pigment  of  the  eye),  so  that  for  accuracy  and  constancy  of 
results  in  all  saccharimetric  measurements  the  bichromate  filter  should 
never  be  omitted.* 

Graduation  of  Saccharimeter  Scales.  —  Manufacturers  of  sac- 
charimeters  in  establishing  the  100-degree  point  of  their  sugar  scales 
employ  a  carefully  standardized  quartz  plate  instead  of  the  normal 
weight  of  sucrose.  The  errors  and  inconveniences  incident  to  the 
preparation  of  chemically  pure  sucrose  and  to  making  the  solution  up 
to  exact  volume  are  thus  avoided;  the  plate,  moreover,  has  the  advan- 
tage of  being  a  standard  which  at  constant  temperature  is  always  un- 
changeable. Messrs.  Schmidt  and  Haenschf  thus  describe  the  method 
of  graduating  the  scales  of  their  saccharimeters: 

"  The  establishment  of  the  scale  divisions  of  our  saccharimeters  is 
made  at  a  temperature  of  20°  C.  After  fixing  the  zero  point  the  linear 
distance  of  the  100-degree  division  is  determined  by  means  of  a  normal 
quartz  plate  reading  exactly  100  degrees  and  standardized  at  the 
Physikalisch-Technische  Reichsanstalt.  This  linear  distance  is  then 
divided  into  100  exactly  equal  parts,  the  intermediary  divisions  being 
also  verified  by  means  of  corresponding  normal  standardized  quartz 
plates.  The  surfaces  of  the  quartz  wedges  are  made  perfectly  plane  so 
that  a  quartz  stratum  of  half  thickness  corresponds  to  a  half  value  in  the 
division.  Slight  errors  cannot  be  prevented,  as  it  is  impossible  to 
obtain  quartz  wedges  of  the  necessary  length  which  are  absolutely 
optically  homogeneous  throughout.  The  variableness  in  the  specific 
rotation  of  sucrose  with  concentration  of  solution  is  not  taken  into  con- 
sideration in  the  establishment  of  the  scale  division,  and  this  must  be 
corrected  for  by  calculation.  Aberrations  in  the  scale  division  caused  by 
impurities  in  the  quartz  can  be  detected  by  the  control  observation  tube." 

The  view  that  the  Ventzke  scale  of  modern  saccharimeters  is  cor- 
rected for  variations  in  specific  rotation  of  sucrose  with  concentration, 

*  At  its  New  York  Meeting  (Sept.  10, 1912)  the  International  Commission  adopted 
the  following  resolution:  "  Wherever  white  light  is  used  in  polarimetric  determina- 
tions, the  same  must  be  filtered  through  a  solution  of  potassium  bichromate  of  such 
a  concentration  that  the  percentage  content  of  the  solution  multiplied  by  the  length 
of  the  column  of  the  solution  in  centimeters  is  equal  to  nine." 

t  In  a  letter  to  the  author. 


118 


SUGAR  ANALYSIS 


either  by  curving  the  surface  of  the  quartz  wedges  or  by  unequal  spac- 
ing of  the  scale  divisions,  is  not  substantiated  by  the  above  statement. 
Effect  of  Concentration  upon  Scale  Reading.  —  A  table  has  been  cal- 
culated by  Schmitz*  to  correct  for  the  changes  in  specific  rotation  of 
sucrose  through  varying  concentration,  which  gives  the  actual  sucrose 
value  of  each  scale  division  of  the  saccharimeter.  These  corrections, 
which  were  calculated  by  Schmitz's  formula,  [a]D=  66.514  —  0.0084153  c, 
would  seem  in  light  of  more  recent  work  to  require  considerable  modi- 
fication. The  formula  of  Landolt, 

[afS  =  66.435  +  0.00870  c  -  0.000235  c2,  (c  =  0  to  65), 

calculated  from  the  combined  observations  of  Tollens,  and  of  Nasini 
and  Villavecchia,  is  regarded  as  the  most  accurate  at  present  (see  page 
176).  In  the  following  table  the  author  has  recalculated  the  sucrose 
values  of  the  Ventzke  scale  for  different  concentrations,  using  Landolt's 
formula.  The  values  of  Schmitz  are  also  given  for  comparison. 

TABLE  XXI 
Showing  Effect  of  Concentration  of  Sucrose  upon  Saccharimeter  Readings 


Scale  division. 

Concentration. 
Grams  sucrose, 
100  true  cubic  centi- 
meters, 20°  C. 

Specific  rotation 
sucrose,  20°  C. 

Actual  sucrose  value  of  scale  division. 

By  Landolt's 
formula. 

By  Schmitz's 
formula. 

100.00 

26.00 

66.502 

100.00 

100.00 

96.00 

24.96 

66.506 

96.00 

95.98 

95.00 

24.70 

66.507 

94.99 

94.98 

90.00 

23.40 

66.510 

89.99 

89.97 

85.00 

22.10 

66.513 

84.99 

84.96 

80.00 

20.80 

66.514 

79.99 

79.95 

75.00 

19.50 

66.515 

74.99 

74.94 

70.00 

18.20 

66.516 

69.99 

69.93 

65.00 

16.90 

66.515 

64.99 

64.92 

60.00 

15.60 

66.514 

59.99 

59.92 

55.00 

14.30 

66.511 

54.99 

54.92 

51.00 

13.26 

66.509 

50.99 

50.92 

50.00 

13.00 

66.508 

50.00 

49.92 

45.00 

11.70 

66.505 

45.00 

44.92 

40.00 

10.40 

66.500 

40.00 

39.92 

35.00 

9.10 

66.495 

35.00 

34.92 

33.00 

8.58 

66.492 

33.00 

32.93 

32.00 

8.32 

66.491 

32.01 

31.93 

30.00 

7.80 

66.489 

30.01 

29.93 

25.00 

6.50 

66.481 

25.01 

24.94 

20.00 

5.20 

66.474 

20.01 

19.95 

15.00 

3.90 

66.465 

15.01 

14.96 

10.00 

2.60 

66.456 

10.01 

9.97 

6.00 

1.56 

66.443 

6.01 

5.98 

5.00 

1.30 

66.442 

5.00 

4.98 

Ber.,  10,  1414;  Z.  Ver.  Deut.  Zuckerind.,  28,  63,  887. 


• 

It  wi 


I 

II 


THEORY  AND  DESCRIPTION  OF  SACCHARI METERS      119 

It  will  be  seen  from  the  preceding  table  that  the  greatest  deviation 
of  the  actual  sucrose  value  from  its  scale  division  according  to  Landolt's 
equation  is  only  0.01°  V.,  which  is  too  small  to  be  detected  by  the 
ordinary  saccharimeter.  The  maximum  error  according  to  Schmitz 
is  0.08°  V. 

As  regards  the  concentration  of  sucrose  employed  in  ordinary  saccha- 
riinetric  work,  the  variations  due  to  changes  in  specific  rotation  may 
therefore  be  safely  disregarded.  The  small  extent  of  these  variations, 
which  are  distributed  both  above  and  below  the  scale  division,  justifies 
the  policy  of  the  manufacturers  in  neglecting  this  factor  when  estab- 
lishing the  divisions  of  the  saccharimetric  scale. 

VERIFICATION  OF  SCALES  OF  SACCHARIMETERS 

On  account  of  the  optical  imperfections  which  quartz  wedges  occa- 
sionally possess,  it  is  important  that  every  user  of  a  saccharimeter  should 
verify  the  accuracy  of  his  instrument. 

Owing  to  the  fact  that  the  quartz  parts  of  the  saccharimeter  are 
mounted  close  to  the  objective  of  the  telescope,  the  very  local  imper- 
fections of  the  wedge  system  are  fortunately  unnoticed,  since,  when  the 
telescope  is  focused  upon  the  polarizer,  the  cone  of  light  rays  emanating 
from  the  different  parts  of  the  field  covers  an  area  of  the  compensator 
equal  to  the  aperture  of  the  analyzer  diaphragm  (about  6  mm.  diameter) 
and  thus  distributes  and  neutralizes  any  slight  local  errors  due  to  defects 
of  the  quartz.  Such  defects  in  the  fixed  part  of  the  system  (small  wedge 
and  compensation  plate)  are  of  no  account,  since  the  rotatory  power  of 
this  remains  constant;  the  predominant  optical  defects  of  the  large 
movable  wedge  are  the  only  ones  which  vitiate  the  results  of  observation. 

Since  local  optical  impurities  in  the  large  wedge  are  diffused  over  a 
considerable  area,  for  the  reason  given  above,  the  errors  in  the  sac- 
charimeter scale  never  consist  of  sudden  jumps,  but  only  of  gradual 
undulations.  It  is  unnecessary,  therefore,  as  Landolt  has  shown,  to 
standardize  every  division  of  the  scale.  The  errors  at  every  fifth 
degree,  if  plotted  upon  coordinate  paper,  are  sufficient  to  establish  a 
correction  curve  from  which  the  error  of  any  division  upon  the  scale 
can  be  accurately  found  (see  Fig.  83). 

Verification  by  Quartz  Plates.  —  The  simplest  and  easiest  method 
of  scale  verification,  as  well  as  the  most  accurate,  is  by  means  of  care- 
fully standardized  quartz  plates.  The  cost  of  a  sufficient  number  of 
plates  to  standardize  the  entire  scale  is,  however,  prohibitive,  so  that 
the  chemist  is  usually  content  with  a  few  standard  plates  for  that 
portion  of  the  scale  most  used,  as  80  to  100  for  cane  sugar.  The  pos- 


120  SUGAR  ANALYSIS 

session  of  a  few  carefully  standardized  quartz  plates  is  a  necessity  for 
accurate  saccharimetric  work,  not  so  much  for  standardization  (since 
the  constant  error  of  the  scale  need  be  determined  but  once),  but  for 
the  determination  of  zero  point,  which  is  necessary  with  each  set  of 
observations. 

The  standard  quartz  plates  furnished  by  instrument  makers  are 
mounted  in  metal  tubes  upon  which  is  stamped  the  reading  that  the 
plates  should  give  upon  the  particular  saccharimeter  scale.  It  is  im- 
portant that  this  reading  be  verified  by  some  testing  bureau,  as  slight 
errors  in  marking  or  faults  in  optical  homogeneity  of  the  plate  are  not 
uncommon.  The  surface  of  the  plate  when  placed  in  the  instrument 
must  be  perpendicular  to  the  beams  of  polarized  light  which  traverse 
it;  for  this  reason  the  plates  should  never  be  loose  in  their  mountings. 
On  the  other  hand,  the  mounting  must  not  press  too  tightly  upon  the 
plate,  as  optical  errors  might  be  produced  in  the  quartz.  Rotation  of 
the  plate  about  the  axis  of  its  tube  should  cause  no  change  in  the  field 
at  the  end  point.  The  plate  when  being  used  should  be  brought  as 
close  to  the  analyzer  diaphragm  as  possible  in  order  to  give  the  greatest 
spread  to  the  cone  of  light  rays  emanating  from  each  part  of  the  field. 
Care  must  be  taken  that  the  standard  plate  during  polarization  have 
exactly  the  same  temperature  as  that  of  the  quartz  wedges  of  the 
instrument.  If  the  plate  have  a  temperature  above  that  of  the  wedges, 
it  will  give  a  reading  higher  than  its,  true  value.  The  temperature 
polarization  coefficient  of  quartz  is  0.000136,  so  that  the  polarization 
of  a  plate  reading  100°  V.  at  20°  C.  would  be  for  30°  C., 

100  f  1  +  (0.000136)  (30°  -  20°)  j  =  100.14°  V. 

If  plate  and  instrument  are  of  different  temperature,  the  plate  should 
remain  several  hours  in  the  trough  of  the  saccharimeter  before  using, 
that  sufficient  time  may  be  given  for  it  to  acquire  the  same  temperature. 
While  it  is  necessary  that  quartz  plate  and  wedge  system  have  the 
same  temperature,  it  is  not  essential  that  this  be  the  standard  tem- 
perature for  the  instrument,  since  the  variations  due  to  temperature 
are  practically  the  same  for  plate  as  for  wedge.  The  slight  differences 
due  to  effect  of  temperature  upon  shape  of  quartz  wedge  and  upon 
expansion  of  nickeline  scale  are  expressed  by  the  formula  (Schonrock), 
Vw  =  Vt  +  Vt  0.000005  (t  -  20),  in  which  F20  and  Vt  are  the  readings 
of  the  plate  at  20°  C.  and  t°  C.  respectively.  A  standard  plate  polar- 
izing 100°  V.  at  20°  C.  would  accordingly  polarize  99.99°  V.  at  40°  C. 
(plates  and  wedges  in  each  case  at  same  temperature),  a  variation  of 
0.01°  V.  for  20°  C.  difference,  which  is  negligible  in  practical  work. 


THEORY  AND  DESCRIPTION  OF  S AC CHARI METERS      121 

Verification  by  Pure  Sucrose.  —  A  second  means  of  verifying  the 
saccharimeter  scale  is  with  chemically  pure  sucrose.  The  preparation 
of  sucrose  of  requisite  purity  is  a  matter  of  some  difficulty;  the  method 
of  the  International  Commission  for  Unifying  Methods  of  Sugar  Analy- 
sis *  is  as  follows : 

"The  purest  commercial  sugar  is  purified  in  the  following  manner: 
Prepare  a  hot  saturated  aqueous  solution,  precipitate  the  sugar  with 
absolute  ethyl  alcohol,  spin  the  sugar  carefully  in  a  small  centrifugal 
machine,  and  wash  in  the  latter  with  absolute  alcohol.  Redissolve 
the  sugar  obtained  in  water,  again  precipitate  the  saturated  solution 
with  alcohol,  and  wash  as  above.  Dry  the  second  crop  of  crystals 
between  blotting  paper,  and  preserve  in  glass  vessels  for  use.  Deter- 
mine the  moisture  still  contained  in  the  sugar  and  take  this  into  account 
when  weighing  the  sugar  which  is  to  be  used."  If  a  hand  centrifugal 
is  not  available,  the  fine  crystals  of  sugar  may  be  filtered  and  washed 
free  of  sirup  upon  a  Buchner  funnel.  In  saturating  the  sugar  solution 
before  precipitation  with  alcohol,  it  is  well  not  to  heat  above  80°  C. 
The  sugar  solution  thus  prepared  is  filtered  through  a  hot-water  funnel 
into  the  alcohol,  stirring  vigorously.  In  this  way  the  sugar  is  precipi- 
tated in  the  form  of  fine  crystals  which  are  easily  dried  in  the  air. 
Moisture  is  determined  by  drying  at  105°  C. 

In  the  selection  of  sugar  for  purification,  the  finest  grades  of  small 
domino  sugar  (polarizing  99.90  to  99.95)  have  been  found  in  the  author's 
experience  to  give  the  best  results.  Rock-candy  crystals,  which  are 
sometimes  recommended,  should  never  be  used;  they  frequently  con- 
tain perceptible  quantities  of  acid,  with  the  result  that  inversion  takes 
place  during  purification.  Complete  absence  of  acidity  in  sugar  and 
alcohol  is  necessary. 

To  verify  the  100-degree  point  of  the  saccharimeter  scale,  the 
normal  weight  of  sugar  is  weighed  into  a  100-c.c.  flask,  dissolved  in  dis- 
tilled water,  and  the  solution  made  up  to  volume,  care  being  taken  that 
the  liquid  is  well  mixed  before  making  up  the  last  few  cubic  centimeters. 
The  solution,  which  must  be  perfectly  clear,  is  then  polarized  in  a  200- 
mm.  tube.  The  conditions  of  weight,  volume,  and  temperature  required 
for  the  saccharimeter  must  be  rigidly  observed;  the  flasks  and  tubes  em- 
ployed should  have  been  previously  calibrated.  The  average  of  10  read- 
ings is  taken  and  this  result  corrected  for  the  moisture  in  the  sugar, 
the  amount  of  which  must  be  determined  in  a  separate  portion  with 
each  set  of  observations.  The  sugar  used  for  polarization  should  not 
be  dried  in  a  heated-air  or  water  bath  owing  to  the  danger  of  slight 
*  Proceedings  of  Paris  Meeting,  July  24,  1900. 


122  SUGAR  ANALYSIS 

changes  in  composition.  If  the  vernier  of  the  scale  is  set  at  0  when 
the  field  is  matched,  the  polarization  of  the  sugar  corrected  for  moisture 
should  be  exactly  100.  In  the  same  manner,  other  divisions  of  the 
saccharimeter  scale  can  be  verified  by  taking  fractions  of  the  normal 
weight  (e.g.,  normal  weight  X  0.85  =  85-degree  point  of  scale,  etc.;  see 
Table  XXI). 

Verification  by  Control  Tube.  —  The  most  convenient  means  of 
verifying  the  scale  divisions  of  a  saccharimeter  when  using  sucrose  is 
by  means  of  the  Schmidt  and  Haensch  control  tube.*  This  method 
presents  the  advantage  that  perfectly  pure  sucrose  does  not  need  to  be 
used;  in  addition  to  this,  but  very  few  solutions  are  necessary  for 
verifying  the  entire  scale. 

The  control  observation  tube  according  to  Landolt's  latest  form  is 
shown  in  Fig.  82.  It  is  telescopic  in  construction  and  can  be  adjusted 


Fig.  82.     Control  tube  for  verifying  scales  of  saccharimeters. 

so  as  to  give  a  column  of  solution  for  any  length  between  220  mm.  and 
420  mm.  The  length  of  solution,  which  is  regulated  by  the  screw  T, 
is  read  off  upon  the  scale  S  by  means  of  the  vernier  J  to  0.1  mm.  The 
tube  is  surmounted  by  a  funnel  E,  which  does  not  serve  for  filling,  but 
simply  receives  the  overflow  of  solution  as  the  tube  is  shortened. 
For  filling  the  tube,  the  funnel  is  removed  and  the  opening  closed  by 
means  of  a  plug  (P) ;  the  tube  is  then  drawn  out  its  full  length  and 
filled  from  the  end  by  unscrewing  one  of  the  caps.  After  rescrewing 
the  cap,  the  tube  is  set  in  an  upright  position  and  the  funnel  replaced 
as  before.  After  shortening  the  tube  slightly,  a  few  cubic  centimeters  of 
solution  are  poured  in  the  funnel,  which  is  then  closed  with  a  small  cap 
to  prevent  evaporation. 

In  using  the  control  tube,  it  is  best  to  begin  at  the  100-degree  point 
(which  is  supposed  to  have  been  previously  verified)  of  the  saccharim- 

*  Z.  Instrument.,  4,  169. 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      123 


eter  scale  and  work  downwards.  A  sugar  solution  is  first  made  up  of 
such  concentration  as  to  give  a  reading  of  100  degrees  at  about  400  mm. 
length  of  tube.  This  will  be  sufficient  to  test  the  scale  the  few  divisions 
above  100  and  all  divisions  below  100  to  55.  If  the  reading,  for  example, 
is  100  at  400  mm.  upon  the  tube  scale,  it  should  read  105  at  420  mm., 
95  at  380  mm.,  etc.  If  a  deviation  be  found  at  any  division  from  the 
calculated  value,  other  readings  should  be  made  at  neighboring  points 
of  the  scale  to  determine  the  position  of  maximum  error.  After  test- 
ing the  scale  to  the  55th  division  (220  mm.),  another  solution  must  be 
prepared  which  will  give  a  reading  of  55  at  about  400  mm.  and  the 
scale  tested  down  to  30.  By  proceeding  in  this  way,  always  making 
the  final  point  of  one  series  the  starting  point  of  the  next,  the  scale  can 
be  tested  its  entire  length  with  5  solutions.  Landolt*  has  given  the 
following  table  of  concentration  for  solutions  to  be  used  with  the 
control  tube  in  testing  the  Ventzke  scale: 


Number. 

Grams  of  su- 
crose in  100  c.c. 
of  solution. 

Starting  point 
for  verifica- 
tion, °V. 

Range  of  scale  divisions  for 
verification. 

1 

12.53 

100 

95,  90,  85,   .  .    60,  55 

2 

6.89 

55 

50,  45,  40,  35,  30 

3 

3.76 

30 

25,  20,  16 

4 

2.00 

16 

15,  10,  9 

5 

1.13 

9 

5 

In  making  the  readings,  the  scale  of  the  saccharimeter  should  first 
be  set  at  the  division  which  it  is  desired  to  verify  and  then  the  screw 
of  the  observation  tube  turned  until  the  length  of  sugar  solution  gives 
a  matched  field.  The  reading  upon  the  scale  of  the  observation  tube 
is  then  taken  by  means  of  a  magnifying  glass.  The  observed  length  of 
tube  at  any  division  in  percentage  of  the  observed  length  for  the  100°  V. 
point  gives  the  actual  value  of  the  scale  division.  To  distribute  and 
equalize  the  errors  due  to  changes  in  room  temperature,  warmth  im- 
parted to  the  tube  by  the  hand  in  making  the  adjustment,  eye  fatigue, 
and  other  causes,  it  is  well  to  proceed  forward  and  backward  along  the 
tube  and  not  make  all  the  observations  for  one  point  at  one  time.  It 
is  desirable  to  make  several  sets  of  readings  upon  different  days  and  by 
different  observers,  and  to  take  the  average  of  the  several  series.  The 
following  results,  obtained  by  the  author  upon  one  of  the  saccharim- 
eters  belonging  to  the  New  York  Sugar  Trade  Laboratory,  will  illus- 
trate the  method: 

*  "  Das  optische  Drehungsvermogen  "  (1898),  p.  341. 


124 


SUGAR  ANALYSIS 


TABLE  XXII 

Verification  of  S.  &  H.  Saccharimeter,  No.  7075 
Series  No.  I 


Scale  division 
of  saccha- 
rimeter. 

Reading  of  scale 
of  control  tube 
(average  of  10 
readings). 

Value  of  scale 
division  (in  terms 
of  100-degree 
point). 

100 

mm. 

396.365 

100.000 

95 

376.495 

94.987 

90 

356.740 

90.003 

85 

336.930 

85.005 

80 

316.975 

79.972 

75 

297.120 

74.962 

70 

277.290 

69.957 

65 

257.465 

64.957 

60 

237.710 

59.972 

Average  of  Series 


Scale  division  of  saccharimeter. 

Number 

of  series. 

100 

95 

90 

85 

80 

75 

70 

65 

60 

1 

94.987 

90.003 

85.005 

79.972 

74.962 

69.957 

64.957 

59.972 

2 

95.022 

90.028 

85.010 

80.033 

75.000 

69.990 

64.988 

59.960 

3 

95.008 

90.005 

85.005 

79.985 

74.998 

70.003 

65.012 

59.980 

4 

94.995 

90.023 

85.005 

79.990 

74.993 

69.980 

64.968 

5 

94.985 

90.015 

84.985 

79.985 

75.003 

69.995 

64.997 

59.990 

6 

95.037 

90.025 

85.038 

80.038 

75.028 

70.008 

64.990 

60.002 

Final 

100.000 

95.002 

90.017 

85.007 

80.001 

74.997 

69.989 

64.985 

59.981 

average 

A  similar  average  made  upon  another  S.  &  H.  saccharimeter  (No.  6920)  gave 


100.000 

95.004 

90.034 

85.041 

80.050 

75.028 

70.035 

65.031 

60.015 

The  results  show  great  exactness  of  graduation,  the  error  in  no  in- 
stance exceeding  0.05°  V. 

By  marking  the  degrees  of  the  saccharimeter  scale  upon  a  straight 
line  and  laying  off  the  observed  errors  above  or  below  this  line  for  their 
respective  scale  divisions,  the  curve  connecting  the  error  points  will 
give  the  correction  for  any  degree  of  the  scale. 

The  following  diagram  (Fig.  83)  for  the  observations  of  Table  XXII 
will  illustrate  the  method: 


THEORY  AND    DESCRIPTION  OF  SACCHARI METERS      125 


To  verify  the  scales  of  a  double-wedge  saccharimeter,  the  scales  of 
both  wedges  are  first  set  at  zero  with  their  verniers  for  the  matched 
field,  any  deviation  of  zero  point  being  corrected  by  the  regulating 
screw.  The  working-wedge  scale  is  then  verified  and  its  curve  of  error 
determined  by  the  control  tube  in  the  manner  described.  The  control 
scale  is  then  compared  with  the  corrected  readings  of  the  working 
scale  and  its  own  error  curve  plotted.  A  still  better  direct  method  is 


100° 


95° 


90° 


85° 


80 


75° 


70° 


65 


—  ^" 

= 

1  —  - 

=^ 

.*•- 

•—  .  .. 

= 

= 

=S«-i 

•*= 

—  — 

— 

—     — 

60° 


Each  division  above  0  line  =0.01°  V  to  be  added  to  the  scale  reading 
n          »       below  0    »    =0.01°  V  "  "  subtracted  from  the  scale  reading 

Fig.  83.  —  Example  of  diagram  for  correcting  saccharimeter  readings. 

set  the  working  wedge  at  100  and  then  verify  the  control  scale  from 
the  0  division  upwards  by  means  of  the  control  tube,  using  the  same 
solutions  as  for  verifying  the  working  scale.  If  the  tube,  for  example, 
with  a  length  of  400  mm.,  gives  a  reading  of  100°  V.  on  the  working- 
wedge  scale  with  control-wedge  scale  at  0  degrees,  then  with  the  work- 
ing-wedge scale  at  100°  V.  the  control-wedge  scale  should  read  5  with  a 
tube  length  of  380  mm.,  10  with  a  length  of  360  mm.,  etc. 

The  millimeter  scale  of  the  control  tube  should  be  verified  before 
the  instrument  is  put  to  use.  The  control  tube  can  be  employed  only 
upon  the  large-sized  saccharimeters,  which  have  a  trough  length  of  420 


mm. 

v 


Verification  by  Scheibler's*  Method  of  "Hundred  Polariza- 
tion." —  Another  means  of  verifying  the  scale  readings  of  a  saccha- 
rimeter is  Scheibler's  so-called  method  of  "  hundred  polarization."  In 
this  process  of  verification  the  polarization  of  the  raw  sugar  or  other 
product  is  first  determined  and  then  the  calculated  amount  of  sub- 
stance weighed  out  which  should  give  a  polarization  of  exactly  100. 
Thus:  if  a  normal  weight  of  26  grams  of  a  sugar  dissolved  to  100  c.c. 


polarizes  82.5  then 


26  X  100 


=  31.515  grams,  the  weight  of  sugar  dis- 


solved  to  100  c.c.  necessary  to  polarize  exactly  100.     If  the  polariza- 


*  Z.  Zuckerfabr.  Deut.  Reiches,  21,  320. 


126  SUGAR  ANALYSIS 

tion  obtained  by  the  calculated  weight  of  sugar  is  found  to  be  100, 
then  the  original  scale  reading  of  the  saccharimeter  is  verified. 

EFFECT  OF  TEMPERATURE  UPON  THE  READING   OF  SACCHARIMETER 

SCALES 

In  the  polarization  of  sugars  and  other  materials  upon  quartz-wedge 
saccharimeters,  the  effect  of  temperature  upon  the  scale  reading  is  a 
most  important  factor.  The  saccharimeter  is  graduated  to  be  used 
at  a  fixed  temperature  (17.5°  C.  or  20°  C.),  and  in  the  most  carefully 
regulated  sugar  laboratories  this  temperature  is  maintained  through- 
out the  year.  But  very  few  laboratories,  however,  are  equipped  with 
the  necessary  appliances  for  maintaining  a  temperature  of  20°  C.  in 
summer,  and  the  influence  of  temperature  changes  upon  the  saccha- 
rimetric  readings  and  the  methods  for  correcting  the  errors  of  the  same 
should  therefore  be  considered. 

Temperature  Coefficient  of  Quartz.  —  The  changes  in  specific 
rotation  of  sugars  with  variation  in  temperature  are  considered  on 
page  178.  These  changes  apply  to  measurements  made  upon  any 
kind  of  polariscope.  But  with  the  saccharimeter,  as  distinguished  from 
the  rotating  polariscope,  there  must  be  considered  an  additional  error 
due  to  the  influence  of  temperature  upon  the  quartz  compensation  of 
the  instrument.  This  influence  has  been  shown  by  Schonrock*  to  be 
threefold.  There  is  (1)  the  change  in  shape  of  the  wedge  by  expan- 
sion or  contraction.  The  coefficient  of  expansion  per  1°  C.  of  quartz 
perpendicular  to  its  axis  (rj)  is  0.000013,  and  parallel  to  its  axis  (Y)  is 
0.000007.  The  polarization  value  of  the  100  point  of  the  scale  through 
change  in  shape  of  the  wedge  decreases  with  increasing  temperature 
by  ??'  -17,  or  by  the  coefficient -0.000006.  There  is  (2)  the  change 
per  millimeter  thickness  in  the  specific  rotation  of  quartz  itself,  which 
for  each  degree  increase  in  temperature  increases  by  the  coefficient 
0.000136.  The  combined  temperature  coefficient  of  the  wedge  system 
is  therefore  0.000130.  There  is  (3)  the  change  due  to  the  expansion 
and  contraction  of  the  material  constituting  the  scale.  The  error  due 
to  this  change,  together  with  that  resulting  from  atmospheric  humidity, 
was  so  great  with  the  old  ivory  scales  that  the  latter  have  been  replaced 
in  most  saccharimeters  with  the  alloy  nickeline  which  has  an  expansion 
coefficient  per  1°  C.  of  0.000018.  The  total  correction,  therefore,  for 
a  quartz-wedge  saccharimeter  with  nickeline  scale  is  0.000148.  The 
polarization  value  w  for  any  temperature  t  is  then  expressed  by  the 

*  Z.  Ver.  Deut.  Zuckerind.,  54,  521. 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      127 

equation  w*  =  w™\l+  0.000148  (t—  20) J.  With  saccharimeters  whose 
scale  is  etched  directly  upon  the  wedge  itself,  as  is  the  case  with  Schmidt 
and  Haensch  instruments  of  recent  construction,  the  coefficient  remains 
0.000130. 

The  above  increase  in  polarization  of  quartz  with  increase  in  tempera- 
ture necessarily  produces  a  lowering  in  the  readings  of  the  saccharimeter 
scale,  since  a  smaller  thickness  of  quartz  is  required  for  compensation. 
With  sugars  which  undergo  a  decrease  in  specific  rotation  with  increase 
in  temperature,  the  combined  influences  are  in  one  direction  and  the 
error  thus  introduced  may  be  considerable.  With  sucrose,  for  example, 
the  temperature  coefficient  of  polarization  becomes  at  10°  C.  0.000390 
(0.000148  +  0.000242),  at  20°  C.  0.000332  (0.000148  +  0.000184),  and 
at  30°  C.  0.000269  (0.000148  +  0.000121). 

Temperature  Coefficient  of  Sucrose.  —  The  variation  in  the 
Ventzke  reading  of  the  normal  weight  of  pure  sucrose  for  1°  C.  change 
in  temperature  has  been  found  by  different  authorities  to  be  as  follows: 

Andrews* 0.0300 

The  United  States  Coast  and  Geodetic  Survey 0.0293 

Wiley  t 0.0314 

Prinsen  Geerligs{. 0.0300 

Watts  &  Tempany§ 0.0310 

T 


Average  =  0.0303 


The  average  temperature  coefficient  of  the  above  is  therefore 
0.000303,  which  agrees  with  the  figure  of  Schonrock  for  25°  C.  (0.000148 
-f-  0.000152)  =  0.000300.  For  temperatures  between  20°  and  30°  C.  the 
general  equation  F20=F'Jl-f  0.0003  («-20){  may  be  used  for  chang- 
ing the  Ventzke  reading  (V1)  of  pure  sucrose  at  any  temperature  t  to 
the  reading-  (F20)  at  20°  C. 

Temperature  Coefficients  of  Other  Sugars.  —  The  temperature 
coefficients  of  other  common  sugars  for  readings  upon  the  Ventzke  scale 
are  given  in  the  following  table.  The  temperature  coefficient  for  fructose 
and  invert  sugar  are  for  readings  made  upon  the  negative  scale  of  the 
saccharimeter;  while  the  coefficients  of  these  sugars  decrease  the  same 
as  those  of  the  dextrorotatory  sugars,  the  direction  of  the  decrease  in 
both  cases  is  towards  the  0  point  and  therefore  opposite  to  each  other 
(as  indicated  by  the  arrow  points). 

*  Technology  Quarterly,  Mass.  Inst.  Technology,  May  (1889),  367. 

t  J.  Am.  Chem.  Soc.,  21,  568. 

t  Archief  Java  Suikerind,  July  (1903). 

§  West  Indian  Bull.,  Vol.  Ill,  p.  140. 


128 


SUGAR  ANALYSIS 


TABLE  XXIII 
Giving  Temperature  Coefficients  of  Different  Sugars  for  Ventzke  Scale 


Sugar. 

A 

[<• 

B 

Change  in 
Mffer 

1  °  C.  increase. 

C 

Temperature 
coefficient 
B 
A' 

Temperature  coefficient  of 
reading  upon  Ventzke  scale  for 
1°  C.  increase. 
C  +  coefficient  for  quartz 
(-0.000148). 

Fructose 

-92.50 
-20.00 
+52.53 
+  138.04 
+53.23 

+0.625 
+0.312 
-0.070 
-0.095 
No  change 

-0.006757 
-0.015600 
-0.001332 
-0.000688 
No  change 

-0.006905 
-0.015748 
-0.001480 
-0.000836 
-0.000148 

I  I 

O  O  0  O,O 

TTT 

Invert  sugar  .  .  . 
Lactose  

Maltose  ...  
Glucose  

In  case  a  mixture  of  sugar  is  polarized  upon  a  saccharimeter,  the 
combined  influence  of  the  temperature  coefficients  of  each  sugar  must 
be  considered.  To  arrive  at  a  better  understanding  of  the  use  of  such 
coefficients  the  following  special  problem  is  considered: 

It  is  desired  to  find  the  amount  of  fructose  and  of  invert  sugar  which, 
mixed  with  26  gms.  of  pure  sucrose,  will  give  a  constant  saccharimeter  reading 
at  all  temperatures. 

It  has  been  shown  that  26  gms.  of  pure  sucrose,  reading  100°  V.  at  20°  C., 
undergo  a  decrease  of  0.03°  V.  with  1°  C.  increase  in  temperature.  Since  a 
fructose  solution  reading  —  1°  V.  undergoes  a  decrease  in  polarization  of 


0.0069°  V.  (Table  XXIII),  then 


0.03 


=  -4.35°  V.,  the  scale  reading  of  the 


0.0069 

required  amount  of  fructose.  Since  0.1869  gm.  of  fructose  in  100  metric  c.c. 
reads  -1°  V.  at  20°  C.  in  a  200-mm.  tube,  then  4.35  X  0.1869  =  0.813  gm.,  the 
required  amount  of  fructose.  26  gms.  sucrose  and  0.813  gm.  fructose  (3.13 
per  cent  of  the  weight  of  sucrose)  will  give,  therefore,  a  constant  saccharimeter 
reading  at  all  temperatures. 


In  the  same  way  for  invert  sugar, 


0.03 


=  -1.90°V.,  the  scale  reading 


0.01575 

of  the  required  amount  of  invert  sugar.  Since  0.8645  gm.  invert  sugar  in 
100  metric  c.c.  reads  -1°  V.  at  20°  C.  in  a  200-mm.  tube,  then  1.90  X  0.8645 
=  1.642  gms.,  the  required  amount  of  invert  sugar.  26  gms.  sucrose  and 
1.642  gms.  invert  sugar  (6.32  per  cent  of  the  weight  of  sucrose)  will  give,  there- 
fore, a  constant  saccharimeter  reading  at  all  temperatures. 

The  effect  of  1°  C.  increase  in  temperature  upon  the  reading  of 
1  per  cent  each  of  sucrose,  fructose,  and  invert  sugar  for  a  normal  weight 
of  26  gms.  in  100  metric  c.c.  is  given  in  the  following  table: 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      129 

TABLE  XXIV 

Showing  Influence  of  Temperature  upon  Ventzke  Reading  of  1  per  cent  Sucrose,  Fruc- 
tose, and  Invert  Sugar  for  a  Normal  Weight  of  26  gms.     Solutions  made  up  to 
Volume  at  Temperature  of  Polarization 

1  per  cent  sucrose  =  -^  =  -0.0003°  V.  for  1°  C.  increase. 

1  per  cent  fructose          =  —^  =  +0.0096°  V.  for  1°  C.  increase. 
1  per  cent  invert  sugar  =  ^^  =  +0.0048°  V.  for  1°  C.  increase. 
(—  denotes  change  toward  the  left.     +  denotes  change  toward  the  right.) 

Since  the  influence  of  temperature  upon  the  rotation  of  glucose  is 
so  small  as  to  be  negligible,  the  change  in  rotation  for  1  per  cent  invert 
sugar  should  be  the  same  as  that  for  0.5  per  cent  fructose,  or  +0.0048°  V. 
This  is  the  result  actually  obtained,  so  that  the  calculation  is  verified. 

SHALL  SACCHARIMETERS  BE  ADJUSTED  TO  VARIABLE  TEMPERATURES? 

The  International  Commission*  has  provided  that  "for  laboratories 
in  which  temperatures  are  usually  higher  than  20°  C.,  it  is  permissible 
to  graduate  saccharimeters  at  any  suitable  temperature,  providing  that 
the  volume  be  completed  and  the  polarization  made  at  the  same  tem- 
perature." The  Commission  has  neglected,  however,  to  say  how  this 
graduation  shall  be  made.  It  is  evident  that  in  order  to  have  a  normal 
weight  of  sucrose,  under  the  conditions  prescribed  for  a  saccharimeter 
at  20°  C.,  polarize  100  at  25°  C.  or  30°  C.,  the  compensating  thickness 
of  quartz  in  the  wedge  system  must  be  made  thinner  for  each  part  of 
the  scale  in  order  to  counterbalance  the  decrease  in  specific  rotation  of 
sucrose. 

Owing,  however,  to  the  confusion  and  mistakes  which  would  arise 
in  the  use  of  standard  plates  with  saccharimeters  of  different  compen- 
sating power,  a  better  plan  would  be  to  make  no  change  in  the  instru- 
ment itself,  but  to  alter  the  conditions  of  polarization,  such,  for  example, 
as  increasing  the  normal  weight  of  sugar,  or  increasing  the  length  of  the 
observation  tube,  or  decreasing  the  volume  of  the  flask,  any  one  of  which 
means  will  bring  the  polarization  of  pure  sucrose  to  100  for  any  desired 
temperature  above  the  standard.  Since  odd  lengths  of  tube  or  volume 
of  flask  are  undesirable  as  well  as  confusing,  a  change  in  the  normal 

*  Proceedings  of  Paris  Meeting,  July  24,  1900. 


130  SUGAR  ANALYSIS 

weight  of  sucrose  is  the  simplest  of  all  means  of  correction.     The  method 
of  calculation  can  be  understood  from  the  following  example.  * 

What  would  be  the  normal  weight  at  25°  C.  for  a  quartz-wedge  saccharim- 
eter  standardized  at  20°  C.  for  26  gms.  sucrose  dissolved  to  100  true  c.c.  and 
polarized  in  a  200-mm.  tube? 

The  temperature  coefficient  of  the  specific  rotation  of  sucrose  at  22.5°  C. 
is  —  0.000168  (Schonrock).  The  temperature  coefficient  of  the  nickeline  scale 
and  quartz  wedge  is  0.000148;  the  expansion  coefficient  for  the  glass  observa- 
tion tube  is  0.000008.  The  new  normal  weight  would  then  be 

26,000  J 1  +(0.000148  +  0.000168  -  0.000008)  (25  -  20)  j  =  26.040  gms. 
dissolved  to  100  true  c.c.  in  a  flask  standardized  at  25°  C. 

When  saccharimeters  are  employed  constantly  in  the  investigation 
of  pure  sucrose  solutions,  it  might  be  advisable  to  make  a  change  such  as 
the  above  in  the  normal  weight.  But  for  varied  work  with  different 
classes  and  mixtures  of  sugars  whose  specific  rotations  are  affected  in 
opposite  ways  by  changes  in  temperature,  it  is  inaccurate  to  make  al- 
terations based  upon  the  change  in  properties  of  one  single  sugar. 
The  results  obtained  upon  saccharimeters  differently  standardized  are 
then  no  longer  comparable.  The  sucrose  normal  weight  is  frequently 
employed  upon  mixtures  of  sucrose  with  other  sugars;  in  such  cases 
changes  in  normal  weight  to  correct  for  rotatory  changes  in  the  sucrose 
alone  are  wholly  unwarranted.  In  view  of  the  fact  that  the  work  of 
saccharimeters  is  usually  of  a  varied  character,  it  seems  best  to  leave 
the  scale  and  standard  conditions  of  the  instrument  unchanged.  The 
chemist  should  work  wherever  possible  under  the  conditions  of  tem- 
perature prescribed  for  his  saccharimeter,  and  when  this  cannot  be  done 
he  should  correct  his  readings  as  well  as  possible  by  a  factor  established 
for  the  particular  product  which  is  being  examined. 

It  must  always  be  borne  in  mind  that  while  the  saccharimeter  scale 
is  established  for  the  rotation  of  sucrose,  its  divisions  indicate  percent- 
ages only  when  pure  sucrose  is  being  polarized;  in  all  other  cases  the 
scale  division  becomes  a  mere  conventional  number  (degrees  Ventzke, 
degrees  polarization,  degrees  sugar  scale,  etc.)  which  the  analyst  must 
interpret  according  to  his  particular  needs. 

*  This  example  is  from  a  calculation  supplied  by  the  Physikalisch-Technischc 
Reichsanstalt,  in  reply  to  a  suggestion  by  the  author  to  use  the  old  Mohr  c.c.  normal 
weight  26.048  gms.  (17.5°  C.)  for  true  c.c.  at  25°  C.  The  old  normal  weight  would 
give  a  reading  of  100.031°  V.  when  dissolved  in  100  true  c.c.  in  a  flask  standardized 
at  25°  C.  If  the  true  c.c.  flask  standardized  at  20°  C.  be  used  at  25°  C.,  this  error 
would  be  reduced  to  100.019°  V.,  which  is  within  the  limits  of  error  for  observation. 


THEORY  AND  DESCRIPTION  OF  SAC  CHARI  METERS      131 

DESCRIPTION  OF  SACCHARIMETEBS 
Tint  Saccharimeters 

The  saccharimeter  of  Soleil  as  modified  by  Ventzke  and  Scheibler 
in  Germany  and  by  Duboscq  in  France  consists  of  an  adaptation  of  the 
quartz- wedge  compensation  to  the  polariscope  of  Robiquet  (p.  86). 

The  Soleil- Ventzke-Scheibler  Saccharimeter.  —  The  construction 
and  arrangement  of  the  optical  parts  in  the  Soleil  saccharimeter  as 
modified  by  Ventzke  and  Scheibler  are  shown  in  Fig.  84.  A  is  a  Nicol 
prism  and  B  a  plate  of  left  or  right  rotating  quartz  cut  perpendicular 
to  its  optical  axis;  these  constitute  the  tint  producer  and  are  mounted 


D          C     B       A 

_,  LJ 

F 
Fig.  84.  —  Soleil- Ventzke-Scheibler  tint  saccharimeter. 

in  a  movable  sleeve  which  can  be  rotated  by  a  rod  and  pinion  from  J. 
C  is  a  condensing  lens,  D  the  polarizer,  and  E  a  Soleil  double  quartz 
plate  (p.  86).  The  quartz  compensation  is  at  F,  the  analyzer  at  G, 
and  telescope  at  H.  In  using  the  instrument  the  telescope  is  focused 
upon  the  bi-quartz  plate,  so  that  the  dividing  line  is  sharply  defined. 
The  zero  point  of  the  scale  is  then  determined  by  turning  K  until  both 
sides  of  the  field  have  the  same  tint  (in  the  manner  described  on  p.  88). 
By  rotating  the  regulator  or  tint  producer  from  /,  the  tint  which  is 
most  sensitive  to  the  eye  of  the  observer  is  obtained.  This  tint,  which 
is  different  for  different  eyes,  is  usually  of  a  very  delicate  violet  or 
pearl  color;  it  will  of  course  vary  according  to  the  angle  with  which 
the  Nicol  A  is  set  with  reference  to  the  Nicol  D  of  the  polarizer.  In 
order  to  remove  the  disturbances  in  transition  tint  due  to  colored 
solutions  (which  cannot  be  remedied  in  the  Robiquet  polariscope), 
the  adjustment  of  the  regulator  is  changed  until  the  tint  is  again  of 
greatest  sensitiveness.  With  very  dark  solutions  the  transition  tint  is 
almost  a  shadow  owing  to  the  absorption  of  color. 


132 


SUGAR  ANALYSIS 


The  Soleil-Duboscq  Saccharimeter.  —  The  Soleil  saccharimeter 
as  modified  by  Duboscq,  the  type  of  tint  instrument  used  in  France, 
differs  from  the  form  previously  described  in  that  the  Nicol  producing 
the  sensitive  tint  is  situated  in  the  eyepiece  of  the  telescope,  as  shown 
by  N  in  Fig.  85.  The  latter  is  rotated  by  a  milled  ring  B  until  the 
sensitive  tint  is  produced  with  the  quartz  plate  C,  which  in  the  Duboscq 
instrument  is  situated  between  the  analyzer  and  the  objective  of  the 
telescope.  The  telescope  is  focused  upon  the  Soleil  double  plate  at  R 


Fig.  85.  —  Soleil-Duboscq  tint  saccharimeter. 

by  moving  the  eyepiece  D  in  or  out;  longitudinal  guides  prevent  any 
lateral  rotation  which  might  disturb  the  tint.  In  the  Duboscq  instru- 
ment the  two  wedges  of  the  compensator  are  of  equal  size,  and,  being 
driven  past  each  other  by  the  pinion  in  opposite  directions,  give  a 
stratum  of  quartz  of  variable  thickness.  A  scale  and  vernier,  which 
follow  the  wedges  in  their  movement,  indicate  the  reading. 

According  to  Landolt,*  the  average  error  of  adjustment  with  the 
Soleil  saccharimeter  is  ±  0.2  degree  of  the  scale.  The  instrument  has 
the  same  objection  as  the  Robiquet  polarimeter,  in  being  unsuited  to 
the  color-blind.  The  adjustment  of  end  point  to  color  is  also  much 
more  fatiguing  to  the  eye  than  adjustment  to  uniformity  of  shade. 
Owing  to  these  objections  the  color  saccharimeter,  although  20  years 
ago  the  standard  instrument,  is  but  little  used  at  the  present  time.  Its 
use  is  in  fact  condemned  by  the  Imperial  Testing  Bureau  of  Germany. 

Half-shadow  Saccharimeters 

The  various  types  of  half-shadow  saccharimeter  used  at  the  present 
time  consist  simply  of  an  adjustment  of  the  quartz-wedge  compensation 
to  some  one  of  the  half-shade  polarizers  previously  described.  The 
principal  forms  are  the  double-field  saccharimeter  with  Jellet-Cornu 

*  "  Das  optische  Drehungsvermogen"  (1898),  p.  348. 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS       133 

polarizer;  the  double-,  triple-,  and  concentric-field  saccharimeters  with 
Laurent  plate;  and  the  double-  and  triple-field  instruments  with 
Lippich  polarizer. 

Saccharimeter  with  Jellet-Cornu  Prism.  —  A  single-wedge  half- 
shadow  saccharimeter  with  Jellet-Cornu  prism  as  polarizer  is  shown  in 
Fig.  86. 


Fig.  86.  —  Single-wedge  saccharimeter  with  Jellet-Cornu  prism. 

N.  Sliding  sleeve  containing  condensing  lens. 

0.   Modified  Jellet-Cornu  prism  (Schmidt  and  Haensch  prism). 

E,  F.   Parts  of  quartz- wedge  compensation. 

H.   Analyzer. 

J.   Telescope,  which  is  focused  upon  the  dividing  line  of  the  split  prism  at  0. 

K.  Microscope  for  reading  scale. 

The  above  saccharimeter,  which  15  years  ago  was  the  standard  form 
of  instrument  employing  the  Ventzke  scale,  is  at  present  almost  en- 
tirely replaced  with  saccharimeters  using  the  Lippich  polarizer. 

Laurent's  Saccharimeter.  —  As  a  type  of  the  saccharimeters  con- 
structed by  French  instrument  makers,  the  Laurent  instrument  shown 
in  Fig.  87  is  described.  The  arrangement  of  polarizer,  half-wave  plate, 
and  device  for  regulating  the  half-shadow  angle  is  identical  with  that  of 
the  Laurent  polarimeter  (Fig.  72).  The  divided  circle  and  rotating 
analyzer  of  the  latter,  however,  are  replaced  in  the  saccharimeter  by 
the  quartz-wedge  compensation. 

The  saccharimeter  is  adjusted  to  its  zero  point  by  first  turning  G 
until  the  two  halves  of  the  field  agree  in  shade.  If  it  should  be  found 
that  one  side  of  the  field  has  more  of  a  reddish  tinge  than  the  other  at 
the  end  point,  the  screw  F,  which  controls  the  analyzer,  is  turned  so  as 
to  darken  slightly  the  side  of  the  field  most  colored.  The  screw  G  is 


134 


SUGAR  ANALYSIS 


then  turned  again  to  equality  of  shade;  if  there  is  still  a  difference  in 
color,  F  is  moved  slightly  as  before,  and  G  again  turned  to  equality  of 
shade.  By  proceeding  cautiously  in  this  way  the  observer  will  at  length 
reach  the  point  where  both  sides  of  the  field  correspond  in  shade  and 
color.  When  this  point  is  reached  the  screw  T  is  turned  until  the  0  of 


M 


Fig.  87.  —  Laurent's  single-wedge  sacchari meter. 

A.  Lamp  for  producing  white  light  (oil,  gas,  electricity,  etc.),  placed  200  mm.  from  B. 

B,  E,  R,  K,  J,  X,  U,  D,  L,  the  same  as  under  Laurent  polarimeter  (Fig.  72). 

R.   Saccharimeter  scale,  which  with  vernier  V  is  illuminated  by  light  reflected  from 

A  by  the  mirror  M . 

N.   Magnifying  glass  for  reading  scale  and  vernier. 
G.   Screw  for  moving  quartz  wedges  of  the  Soleil  compensator. 

the  scale  coincides  with  the  0  of  the  vernier.     This  adjustment  should 
be  verified  by  taking  a  number  of  check  readings. 

The  100-degree  point  of  the  Laurent  saccharimeter  scale  corre- 
sponds to  a  rotation  of  21°  40',  the  value  given  by  French  physicists  to 
the  rotation  of  the  1-mm.  plate  of  quartz.  The  normal  weight  for  this 
angular  displacement,  as  previously  noted,  is  16.29  gms.  sucrose  for 
100  true  c.c.  polarized  in  the  200-mm.  tube.  The  Laurent  saccharim- 
eter is  also  manufactured  with  a  scale  adapted  to  the  so-called  Inter- 
national normal  weight  of  20  gms.  The  instrument  is  provided  with 
double  or  triple  field,  as  desired.  The  scale  divisions  extend  from  0  to 
110  to  the  right. 


THEORY  AND  DESCRIPTION  OF  SACCHARI METERS      135 

"Plaque  Type."  —  The  100-degree  point  of  the  Laurent  saccha- 
rimeter  is  verified  by  a  standard  plate  of  quartz  1  mm.  thick.  This 
standard  plate  "  plaque  type"  also  serves  for  the  polarization  of  levo- 
rotatory  solutions.  With  the  plate  in  the  trough  of  the  instrument, 
the  zero  point  of  the  scale  is  transferred  to  100;  levorotatory  solutions 
are  then  simply  read  backwards  upon  the  scale,  the  reading  being  the 
difference  between  readings  of  plate  and  solution.  A  solution,  for 
example,  reading  67.4  with  the  100-degree  plate  in  position  has  a 
polarization  of  —32.6.  This  method  of  polarizing  levorotatory  solu- 
tions is  of  course  applicable  to  all  single-wedge  saccharimeters. 

A  100-degree  Laurent  "plaque  type  "  was  remounted  by  the  author 
and  sent  to  the  United  States  Bureau  of  Standards  for  a  certification 
as  to  its  angular  rotation  and  its  value  in  sugar  degrees  upon  a  sac- 
charimeter  employing  the  Ventzke  scale.  The  rotation  of  the  plate 
for  sodium  light  of  589.23  ^  wave  length  was  given  as  +21.713 
+  0.003  (T  -  20)  =b  0.004,  and  the  rotation  in  sugar  degrees  as 
+62.65.  The  same  plate  read  by  the  author  upon  a  late-model 
Schmidt  and  Haensch  saccharimeter  gave  a  reading  of  +62.64,  and 
upon  a  late-model  Fric  saccharimeter  (Bates  modification)  a  reading 
of  +62.65.  These  readings  of  the  " plaque  type"  not  only  prove 
the  perfect  identity  of  the  Ventzke  sugar  scales  employed  by  two 
different  manufacturers,  but  also  permit  the  establishment  of  the 
exact  ratio  between  the  French  and  German  normal  weights;  for  all 
other  conditions  as  to  the  temperature  and  volume  are  the  same  in 
both  these  countries.  The  ratio  100  :  26  gms.  ::  62.65  :  X  shows  that 
the  ratio  of  the  German  normal  weight  to  the  French  normal  weight 
is  as  26  gms.  to  16.289  gms.,  or,  in  even  hundredths,  16.29  gms.,  which 
is  identical  with  the  official  normal  weight  prescribed  in  France. 

Duboscq-Pellin  Saccharimeter.  —  The  Duboscq-Pellin  saccharim- 
eter for  white  light,  as  regards  position  of  polarizer,  half-wave  plate, 
quartz-wedge  compensation,  etc.,  is  the  same  as  that  of  the  Laurent. 
The  concentric  field  of  the  Pellin  saccharimeter  requires  a  somewhat 
different  cutting  of  the  half-wave  plate,  but  in  other  respects  the  two 
saccharimeters  are  very  much  alike. 

The  saccharimeter  with  Lippich  polarizer  is  the  form  most  generally 
preferred  at  present.  The  half-shadow  angle  between  the  prisms  of 
the  polarizer  is  usually  between  5  and  8  degrees;  it  can  be  measured 
approximately  by  noting  the  interval  between  the  points  of  maximum 
light  extinction  each  side  of  the  zero  point.  The  degrees  Ventzke 
between  the  two  points  of  maximum  darkness  multiplied  by  0.34657 
gives  the  angle  of  the  half  shadow. 


136 


SUGAR  ANALYSIS 


Schmidt  and  Haensch  Saccharimeters.  —  A  single- wedge  Schmidt 
and  Haensch  saccharimeter  upon  tripod  support  with  electric  attach- 
ment for  illumination  is  shown  in  Fig.  88. 


Fig.  88.  —  Single-wedge  Schmidt  and  Haensch  saccharimeter  with  electric  attach- 
ment for  illumination. 

V.  Detachable  end  containing  lamp  and  for  inserting  cell  of  bichromate  solution. 
P.    Position  of  Lippich  polarizer  for  double  or  triple  field. 
G.   Casing  of  sheet  brass  for  protecting  wedges  from  dust. 

The  method  of  scale  illumination  in  Schmidt  and  Haensch  saccharim- 
eters  is  shown  in  Fig.  89  which  gives  the  arrangements  of  parts  for  a 
double- wedge  instrument.  The  light  from  the  lamp  is  focused  upon  the 
small  window  a  in  the  wedge  housing,  and  is  reflected  from  the  mirror 
b  through  the  ground-glass  plate  c  upon  the  scale  from  which  it  is  re- 
flected through  the  prism  p  into  the  microscope  whose  objective  is  at  d 
and  eyepiece  at  /  —  g.  The  working  wedge  is  operated  by  the  screw  A 
and  the  control  wedge  by  the  screw  K.  The  appearance  of  the  scale  of 
this  instrument  as  viewed  through  the  microscope  is  shown  in  Fig.  80. 

The  latest  and  most  improved  type  of  Schmidt  and  Haensch  sac- 
charimeter is  the  double-wedge  apparatus  shown  in  Fig.  90.  The 
instrument  is  mounted  upon  a  bock  or  trestle  support,  and  for  saccharim- 
eters  which  are  in  constant  use  this  method  of  mounting  is  most  satis- 
factory as  it  insures  perfect  rigidity  and  accurate  alignment.  The 
wedges  are  moved  by  milled  screw  heads  at  A  and  K  which  are  so 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      137 

H 

m :| 


Fig.  89.  —  Device  for  illuminating  scale  of  Schmidt  and  Haensch  saccharimeter. 


Fig.  90.  —  Double-wedge  Schmidt  and  Haensch  saccharimeter  upon  bock  support. 


138 


SUGAR  ANALYSIS 


placed  that  the  hand  can  rest  upon  the  table  during  adjustment.  The 
screw  K  moving  the  control  wedge  can  be  fastened  with  a  clamp,  and 
is  placed  at  a  slightly  higher  elevation  to  prevent  liability  of  confusion. 
Peters's  Saccharimeter.  —  Very  similar  in  construction  to  the 
above  apparatus  is  the  saccharimeter  of  Peters  shown  in  Fig.  91.  The 
long  tube  R  prevents  placing  the  light  too  close  to  the  polarizer. 
The  bichromate  cell  is  placed  within  S;  the  cover  C  of  the  trough  is  not 
hinged  but  simply  slides  over  or  under  the  tube.  The  scale  in  the 


Fig.  91.  —  Double-wedge  Peters  saccharimeter. 

sheet-metal  housing  is  illuminated  by  light  reflected  from  the  mirror 
L;  a  black  paper  disc  P  protects  the  eye  against  the  glare  of  the  obser- 
vation lamp. 

Fric's  Saccharimeter.  —  The  half-shadow  saccharimeters  of  J.  and 
J.  Fric  are  very  similar  in  construction  to  the  instruments  previously 
described  except  in  the  method  of  scale  illumination.  In  the  latest 
types  of  Fric  saccharimeter  a  part  of  the  light,  as  it  passes  from  the 
source  of  illumination  through  the  diaphragm  at  the  end  of  the  instru- 
ment, is  reflected  through  a  system  of  mirrors  and  lenses  upon  the 
scales.  This  illuminating  attachment  is  shown  in  the  Bates  sac- 
charimeter (L  in  Fig.  94),  but  the  distinctive  feature  of  the  Fric  illumi- 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS       139 


nating  device  is  at  the  scale  end  of  the  instrument  as  shown  in  Fig.  92. 
The  light  from  L  is  reflected  from  the  mirror  A  (which  in  the  instru- 
ments with  enclosed  wedges  is  stationary)  through  the  milk-glass  plate 
B  upon  the  scale  C,  the  latter  in 
the  latest  Fric  saccharimeters  being 
made  of  glass.  The  light  from  L" 
C  is  reflected  from  the  mirror  D 
through  the  focusing  lens  E  to  the 
eye  of  the  observer.  The  divisions 
of  the  scale  illuminated  in  this 
manner  appear  with  great  distinct- 
ness. The  Fric  double-wedge  in- 
struments are  provided  with  sepa- 
rate focusing  lenses  for  reading  the 
working  and  control  scales.  The 
lens  mountings  and  the  milk-glass 
plates  for  the  two  wedge  systems 
are  usually  of  different  colors  in 
order  to  prevent  confusion. 


SACCHARIMETERS  WITH  VARIABLE  SENSIBILITY 

Of  the  instruments  previously  described,  the  French  saccharimeters, 
using  a  Laurent  half-wave  plate  and  employing  monochromatic  or 
bichromate-filtered  white  light,  are  the  only  forms  of  apparatus  which 
permit  a  variation  of  the  half-shadow  angle  to  suit  the  requirements  of 
greatest  sensibility. 

In  all  the  Schmidt  and  Haensch  saccharimeters  the  half-shadow  angle 
is  fixed.  An  attachment  for  shifting  the  large  prism  of  the  Lippich 
polarizer  and  regulating  the  half-shadow  angle  has  been  supplied  by 
some  manufacturers.  While  this  regulating  device  presents  certain 
advantages,  it  has  been  condemned  by  Landolt*  on  the  ground  that 
every  change  in  the  half  shadow  introduces  a  change  in  the  zero  point 
which  has  to  be  corrected  by  rotating  the  analyzer  until  the  field  is 
again  evenly  illuminated  at  the  zero  point  —  an  impossible  remedy  in 
a  saccharimeter  with  fixed  analyzer. 

Bates's  Saccharimeter.  —  To  obviate  the  objection  last  named, 
Bates  f  has  devised  an  attachment  which  rotates  the  analyzer  automati- 
cally and  makes  it  possible  to  correct  the  zero-point  error  for  any  change 


"  Das  optische  Drehungsvermogen,"  351. 
t  U.  S.  Bur.  Stand.  Bull.,  Vol.  4,  p.  461;  Z.  Ver.  Deut.  Zuckerind.,  68,  105. 


140 


SUGAR  ANALYSIS 


in  the  half-shadow  angle  without  resetting  the  scale.     The  principle  of 
the  Bates  saccharimeter  can  be  understood  from  Fig.  93. 

Let  OP  be  the  direction  of  the  plane  of  the  large  Nicol  and  ON  that 
of  the  small  Nicol  .in  a  Lippich  polarizer,  let  AZ  be  the  plane  of  the 
analyzer  at  right  angles  to  OB  the  bisection  of  the  half-shadow  angle 
PON  or  a.  We  will  suppose  for  a  moment  that  the  intensities  of  light 
in  OP  and  ON  are  equal  and  that  the  plane  of  the  large  Nicol  be  moved 
from  OP  to  OP'  forming  with  the  plane  of  the  small  Nicol  the  new 


Fig.  93.  —  Illustrating  principle  of  Bates's  saccharimeter. 

angle  P'ON  or  a'  .     To  obtain  uniformity  of  field  at  the  zero  point  for 
the  new  angle  a'  the  bisection  OB  must  be  moved  to  OB'.    It  will  be 


seen  from  the  diagram  that  the  angle  BOB'  =      -  £  =       ~ 

Zi       2i  2i  i  ' 

To  correct,  therefore,  for  the  displacement  of  zero  point,  assuming  the 
intensities  of  light  to  be  always  the  same  for  both  Nicols,  the  plane  of 
the  analyzer  must  be  moved  through  one  half  the  angular  displace- 
ment of  the  large  Nicol  of  the  polarizer. 

In  the  Lippich  system,  however,  the  intensities  of  light  are  not  equal 
for  the  large  and  small  prisms  of  the  polarizer.     A  part  of  the  light  is 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS       141 

extinguished  in  the  small  Nicol  and  there  is  also  a  loss  from  reflection 
and  absorption.  We  will  consider  first  the  light  lost  by  absorption. 

Let  OK  =  amplitude  of  light  from  large  Nicol.  Draw  KL  _L  ON; 
then  OL  =  amplitude  of  light  from  small  Nicol;  the  plane  of  the 
analyzer  AZ  must  then  be  moved  to  A'Z'  that  the  amplitudes  OC  and 
OF  be  equal  in  each  half  of  the  field.  The  angles  AOAr  and  BOD, 
through  which  the  plane  of  the  analyzer  and  its  perpendicular  have 
moved,  is  5  or  the  change  from  the  true  zero  point  when  the  intensities 
of  light  in  OP  and  ON  are  equal,  in  which  case  a  =  0. 

We  will  suppose  in  order  to  increase  the  intensity  of  light  for  the 
half  shadow  that  the  plane  OP  of  the  large  Nicol  be  moved  to  OP'  in- 
creasing a  to  a.  The  amplitude  OK'  remains  the  same  as  OK.  Draw 
K'U  J_  ON;  then  the  amplitude  in  ON  =  OU.  The  plane  of  the 
analyzer  must  now  be  moved  to  A"Z"  in  order  that  the  -Is  K'C'  and 
L'Ff  cut  off  the  equal  amplitudes  OC'  and  OF'  in  the  two  halves  of  the 
field.  OD'  which  is  _L  A"Z"  will  then  form  with  OB',  the  bisection  of 
a',  the  new  angle  d'.  The  angle  0  =  DOD'  through  which  the  analyzer 
has  moved  from  its  previous  position  is  expressed  by  the  equation 


In  the  polariscope  of  Bates  (Fig.  94)  the  analyzing  Nicol  and  the 
large  Nicol  of  the  polarizing  system  are  mounted  in  bearings  and  are 
joined  by  gears  with  a  connecting  rod.  The  milled  head,  which  oper- 
ates the  driving  mechanism,  is  shown  at  H.  When  the  milled  head  is 
turned  the  two  Nicols  are  rotated  and  the  design  of  the  gears  is  such 
that  the  analyzing  Nicol  always  receives  one  half  the  angular  dis- 
placement of  the  large  Nicol  of  the  polarizing  system.  Above  the 
milled  head  is  a  circular  scale  which  shows  the  polarizing  angle  for  any 
position  of  the  Nicols.  In  moving  the  plane  of  the  large  polarizing 
Nicol  through  the  angle  POP'  (Fig.  93)  the  rotating  device  of  Bates's 
polariscope  moves  the  plane  of  the  analyzer  through  the  angle  BOB'. 
In  this  way  the  zero-point  error  of  the  instrument  will  always  be  equal 
to  the  value  of  d  for  any  angle  of  the  half  shadow,  assuming  that  the 
zero  had  been  previously  adjusted  for  a  =  0.  If  the  zero  point  of  the 
instrument  be  set  for  any  value  of  the  half  shadow  a,  and  a  be  then 

changed  to  a',  the  zero  will  have  an  error  of  5'  —  d  (  the  analyzer  hav- 
ing rotated  —  •=  —  ,  this  value  disappears  from  the  equation 


142 


SUGAR  ANALYSIS 


The  calculated  values  of  5  in  Ventzke  degrees  for  different  values  of 
the  half-shadow  angle  a  according  to  the  two  equations, 

,  a  1  —  COS  a  V0.92          a 

tan  5  =  tan3  s     and    tan  5  =  -  , tan  „ 

2  1  +  cos  a  V0.92         2 

(see  p.  96),  are  given  in  the  following  table. 

TABLE  XXV 

Giving  Calculated  Values  of  Error  in  Zero  Point  for  Bates 's  Saccharimeter 
VALUES  OF  a  IN  VENTZKE  DEGREES. 


I 

II 

Values  of 
a 
circular  degrees. 

By  formula 
tan  «  =  tans  |. 

By  formula 
_  l-cosaV/OL92^_  a 

ufln  o                           tfin   f. 
l+cosaV0.92          2 

1° 

0.003 

0.033 

2 

0.004 

0.064 

3 

0.005 

0.09G 

4 

0.008 

0.129 

5 

0.014 

0  .  164 

6 

0.024 

0.205 

7 

0.038 

0.249 

8 

0.057 

0.299 

9 

0.080 

0.352 

10 

0.110 

0.412 

11 

0.150 

0.482 

12 

0.192 

0.554 

The  values  of  6  in  the  second  column  are  greater  than  those  in  the 
first  column  by  0.03  a.  The  true  values  of  5  according  to  Bates  lie 
between  those  calculated  by  the  two  equations  and  will  vary  according 
to  the  construction  of  the  instrument.  This  true  value  of  8  will  be  the 
value  by  the  first  formula  ±  c  a  in  which  c  is  a  constant  for  each  in- 
dividual Lippich  system.  If  a  Bates  saccharimeter  be  set,  therefore, 
for  a  =  0,  the  calculated  change  in  zero  point  for  variations  in  a  can 
be  easily  applied  to  the  scale  reading.  If  the  instrument  be  set  for  any 
particular  value  of  a,  as  8  degrees,  the  half-shadow  angle  may  be  in- 
creased or  diminished  several  degrees  from  this  point  without  intro- 
ducing a  change  in  zero  greater  than  0.1°  V. 

The  Bates  saccharimeter,  constructed  by  Josef  and  Jan  Fric  of 
Prague,  is  at  present  the  standard  instrument  of  the  United  States 
Customs  Service.  While  the  apparatus  presents  several  advantages 
over  the  ordinary  saccharimeter,  the  mechanical  difficulties  of  con- 
struction make  it  expensive.  In  its  present  commercial  form  the 
instrument  is  not  provided  with  a  bichromate  light  filter.  While  this 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      143 

omission  may  occasion  no  serious  error  in  the  polarization  of  colored 
solutions  (as  of  low-grade  sugar-house  products),  a  bichromate  light 
filter  is  required  in  the  examination  of  high-grade  cane  sugars,  starch- 
conversion  products,  and  many  other  substances.  An  absorption  cell 
for  this  purpose  should  be  placed  just  in  front  of  the  aperture  between 
the  saccharimeter  and  the  source  of  light.  A  very  commendable  feature 
of  the  Bates  instrument  is  the  thermometer  (T  Fig.  94)  which  indicates 
the  temperature  of  the  quartz  wedges. 


Fig.  94.  —  Bates  saccharimeter  with  variable  sensibility. 

TF,  milled  head  for  operating  working  wedge. 

C,  milled  head  for  operating  control  wedge. 
w,  microscope  for  reading  working  wedge  scale. 

c,  microscope  for  reading  control  wedge  scale. 

S,_  scale  indicating  "  degrees  of  brightness  "  or  half-shadow  angle. 

SACCHARIMETERS  WITH  MAGNIFIED  SCALE. 

For  special  kinds  of  work  involving  the  investigation  of  products 
with  a  narrow  range  in  composition,  saccharimeters  have  been  con- 
structed with  a  limited  magnified  scale.     The  saccharimeter  devised 
by  Stammer,*  shown  in  Fig.  95,  for  polarization  of  sugar  beets  is  an 
*  Z.  Ver.  Deut.  Zuckerind.,  37,  474. 


144  SUGAR  ANALYSIS 

example  of  such  an  instrument.  In  this  apparatus  a  magnified  scale, 
reading  from  0  to  35,  is  attached  to  the  side  of  the  instrument  at  the 
observer's  left  and  permits  the  reading  of  polarizations  with  the  unaided 
eye.  The  pointer  of  the  scale  P  is  moved  by  the  tension  roller  R, 
which  is  connected  by  a  small  steel  chain  with  the  movable  quartz 
wedge. 

To  adjust  the  saccharimeter  the  field  is  brought  to  a  uniform  shade 
by  turning  K  when  the  0  of  the  wedge  scale  and  vernier  at  Q  should 
coincide.  If  the  latter  is  not  the  case,  coincidence  is  affected  by  turn- 


Fig.  95.  —  Stammer's  saccharimeter  with  magnified  scale  for  polarizing  sugar  beets. 

ing  the  regulating  key  V.  In  this  position  the  pointer  P  should  mark 
exactly  the  zero  division  of  the  large  scale  S.  Should  there  be  any 
deviation  the  error  is  corrected  by  turning  the  adjusting  lever  L  until 
the  pointer  is  exactly  at  0.  Turning  the  screw  K  to  any  division  upon 
the  wedge  scale  Q  should  then  give  the  same  reading  upon  the  scale 
S.  If  this  is  not  the  case  the  error  is  corrected  by  turning  a  small 
control  screw  upon  R  which  increases  or  diminishes  the  diameter  of  the 
roller.  The  adjustment  is  one  which  requires  considerable  care  and 
should  be  checked  repeatedly. 

Saccharimeters  of  the  above  type  are  especially  adapted  for  the 
polarization  of  mother  beets  for  seed  production;  they  are  constructed 
for  tubes  of  200  mm.,  400  mm.,  and  600  mm.  length. 

Similar  to  the  above  instruments  for  sugar-beet  analysis,  saccharim- 


THEORY  AND  DESCRIPTION  OF  SACCHARIMETERS      145 

eters  have  been  constructed  with  a  magnified  scale  reading  between 
80  and  100  for  polarization  of  sugars.  These  are  manufactured  usually 
only  for  use  with  tubes  400  mm.  long,  and  employ  a  normal  weight  of 
26  gms.  to  100  c.c.  solution.  Doubling  the  length  of  observation  tube 
necessitates  of  course  doubling  the  interval  between  the  scale  divisions 
and  thus  facilitates  the  reading. 

Instruments  with  a  magnified  limited  scale  will  be  found  to  relieve 
eye  fatigue,  where  large  numbers  of  analyses  of  a  single  product  have 
to  be  performed.  With  one  person  to  prepare  the  tubes  of  sugar 
solutions,  a  second  to  manipulate  the  saccharimeter,  and  a  third  to  note 
the  readings,  a  large  number  of  polarizations  can  be  made  in  a  very 
short  period  of  time. 

CONVERSION  FACTORS  FOR  POLARISCOPE  AND  SACCHARIMETER  SCALES 

In  the  following  table  factors  are  given  for  converting  1  degree  of 
the  various  polariscope  scales  into  its  equivalent  in  circular  degrees, 
or  in  degrees  of  the  different  saccharimetric  scales.  The  conversions 
are  based  so  far  as  possible  upon  recent  information  supplied  by  the 
manufacturers  of  the  several  instruments. 

Scale.  Equivalent. 

1°  Ventzke  sugar  scale  =  0.34657°  angular  rotation  D. 
1°  angular  rotation  D     =  2.88542°  Ventzke  sugar  scale. 
1°  French  sugar  scale    =  0.21666°  angular  rotation  D. 
1°  angular  rotation  D    =  4.61553°  French  sugar  scale. 
1°  French  sugar  scale    =  0.62516°  Ventzke  sugar  scale. 
1°  Ventzke  sugar  scale  =  1.59960°  French  sugar  scale. 
1°  Wild  sugar  scale       =  0. 13284°  angular  rotation  D, 
1°  angular  rotation  D    =  7.52814°  Wild  sugar  scale. 
1°  Wild  sugar  scale        =  0.38329°  Ventzke  sugar  scale. 
1°  Ventzke  sugar  scale  =  2.60903°  Wild  sugar  scale. 
1°  Wild  sugar  scale        =  0.61313°  French  sugar  scale. 
1  °  French  sugar  scale    =  1 . 63098°  Wild  sugar  scale. 

(Normal  weight  =  26. 00  gms.  Ventzke  scale;  16. 29  gms.  French  scale;  10. 00  gms. 
Wild  scale.) 

The  Ventzke  sugar  scale  is  employed  upon  the  Schmidt  and  Haensch, 
Peters,  and  Fric  saccharimeters.  The  French  sugar  scale  is  employed 
upon  the  Laurent-Jobin  and  Duboscq-Pellin  saccharimeters. 

The  slight  differences  in  ratio  between  normal  weights  and  scale 
equivalents  have  already  been  discussed. 


CHAPTER  VII 

POLARISCOPE  ACCESSORIES 

ILLUMINATION  OF  POLARISCOPES 

FOR  the  illumination  of  polariscopes  and  saccharimeters  numerous 
lamps  have  been  devised  and  the  chemist  must  be  guided  in  his  selec- 
tion by  type  of  instrument,  nature  of  substance  to  be  polarized,  and 
the  kind  of  light  supply  available.  Before  describing  the  various 
types  of  lamps,  a  word  should  be  said  regarding  the  general  subject 
of  illumination. 

A  much  neglected  point  in  the  illumination  of  polariscopes  and 
saQcharimeters  is  the  placing  of  the  light  at  the  proper  distance  from 
the  condensing  lens.  The  light  should  never  be  placed  so  near  as  to 
over-heat  the  metal  at  the  end  of  the  instrument;  neglect  of  this  pre- 
caution may  cause  a  softening  of  the  balsam  and  wax  mountings  of 
the  polarizer  and  lead  to  serious  derangement  of  the  optical  parts. 

The  proper  rule  in  setting  up  the  polariscope  is  to  place  the  light  in 
such  a  position  that  its  image  is  clearly  defined  upon  the  analyzer 
diaphragm;  this  is  best  accomplished  by  fastening  a  needle  or  other 
sharp-pointed  object  just  before  the  light  and  moving  the  instrument 
or  light  until  a  clear  inverted  image  of  the  point  is  obtained  upon  a 
piece  of  white  paper  placed  before  the  analyzer  diaphragm.  When 
the  light  is  thus  focused  the  polariscope  is  least  susceptible  to  changes 
in  zero  point.  The  proper  position  of  polariscope  with  reference  to 
light  can  be  seen  from  Fig.  96,  which  shows  the  arrangement  of  the 
optical  parts  in  a  double-wedge  saccharimeter.  When  correctly  placed 
an  inverted  magnified  image  of  the  light  7  is  obtained  at  A.  The 
reciprocal  of  the  focal  distance  of  the  condensing  lens  will  then  equal 
the  sum  of  the  reciprocals  of  the  distances  of  lens  from  light  and  of 
lens  from  image. 

Example.  —  In  the  case  of  a  Schmidt  and  Haensch  saccharimeter  the  focal 
distance  of  the  condensing  lens  was  found  to  be  5  inches;  the  distance  from 
lens  to  analyzer  diaphragm  was  20  inches;  the  distance  for  placing  the  light 

would  then  be--h^:  =  -or6f  inches  from  the  condensing  lens. 

X         ZO         O 

146 


POLARISCOPE  ACCESSORIES  147 

The  telescope  T  (Fig.  96)  is  focused  by  the  observer  upon  the 
dividing  line  of  the  field  at  C  and  the  analyzer  or  compensator  turned 
to  the  point  of  even  illumination.  The  dividing  line  at  C  will  then 
disappear  and  the  entire  field  appear  of  equal  intensity.  This  will  be 
the  case  even  with  slight  variations  in  intensity  in  different  parts  of 
the  illumination,  since  at  the  point  C,  upon  which  the  eye  of  the  ob- 
server is  focused,  the  light  from  any  part  p  of  the  illumination  will  be 
dispersed  through  different  parts  of  the  field  (as  shown  in  the  figure  by 
the  dotted  lines);  any  slight  uneveness  in  the  source  of  illumination 
will  thus  be  distributed  and  not  noticed  by  the  eye.  Great  irregular- 
ities in  illumination,  however,  must  be  avoided,  and  for  this  reason  it 


JP 
Fig.  96.  —  Showing  method  of  illuminating  polariscopes. 

is  important  that  the  instrument  be  kept  in  perfect  alignment  with 
its  longitudinal  axis  at  right  angle  to  the  source  of  light.  It  is  best  to 
have  instrument  and  light  rigidly  fixed.  Polariscopes  mounted  upon 
trestle  supports  are  preferable  to  those  upon  tripods  since  a  slight 
knock  may  swing  the  latter  out  of  alignment  and  cause  a  change  in 
the  zero  point. 

Variations  in  the  brightness  of  illumination  are  also  undesirable 
and  for  accurate  work  the  emission  of  light  should  be  constant.  The 
optical  center  of  gravity  of  purified  sodium  light,  for  example,  is 
589.22  HJJL  for  a  certain  average  brightness  of  flame;  variations  in  this 
brightness,  however,  may  change  the  wave  length  by  0.11  ///*  with 
corresponding  differences  in  the  rotation  of  polarized  light  (25"  for  a 
rotation  angle  of  20  degrees).  With  salts  of  the  alkalies  and  alkaline 
earths,  increasing  the  brightness  of  flame  (increase  of  vaporized  salt 
per  unit  volume  of  flame)  produces  an  irregular  broadening  of  the 
spectral  lines  with  a  shifting  of  the  mean  wave  length  toward  the  red 
«nd  of  the  spectrum. 

Lamps  for  Sodium  Light.  —  Of  the  various  polariscope  lamps  for 
sodium  light  only  a  few  of  the  more  common  forms  will  be  described. 
The  lamp  shown  in  Fig.  97  illustrates  the  essential  principles  of  most 
sodium  lamps.  This  consists  of  a  Bunsen  burner  with  side  entrance 
for  gas  at  s  to  prevent  stoppage  of  inlet  through  dropping  of  fused 
salt;  the  burner  is  surmounted  by  a  chimney  which  can  be  adjusted 


148 


SUGAR  ANALYSIS 


to  the  desired  height  by  the  screw  h.  The  holder  for  the  fused  salt 
consists  of  a  spoon-shaped  bundle  of  fine  platinum  wires  attached  to 
an  upright  support  and  can  be  moved  in  and  out  the  flame  through  a 
slot  in  the  chimney  by  means  of  the  screw  p; 
the  door  k,  which  closes  the  front  of  the  chimney, 
allows  only  the  brightest  section  of  the  flame  to 
shine  through  and  excludes 
the  greater  part  of  the  heat. 
The  flame  is  adjusted  so  as  to 
be  colorless,  with  as  strong  an 
air  blast  as  possible,  that  the 
light  may  be  free  from  incan- 
descent carbon  particles. 

In  place  of 
wire  holders  for 
the   salt  many 
sodium  lamps  use  spoons 
or  V-shaped  boats  of  sheet 
platinum  or  nickel,  which 
are  in  some   cases  perfo- 
rated with  fine  openings. 

The  hot  part  of  the 

flame    impinges 

upon  the  spoon  and 

produces  a  sheet  of 

sodium   light  upon 

each     side.        The 


Fig.  97.  —  Simple  form  of 
sodium  lamp. 


Fig.  98.  —  Pribram's 
sodium  lamp. 


fused  salt  must  be  renewed  as  fast  as  vaporized;  a  convenient  means 
of  effecting  this  renewal  is  shown  in  Pribram's  *  sodium  lamp,  Fig.  98, 
which  contains  two  boats;  the  empty  one  is  drawn  out  for  refilling  and 
the  one  in  reserve  inserted  in  its  place. 

The  sodium  lamp  of  Landolt  f,  Fig.  76,  gives  a  more  intense  flame 
than  either  of  the  lamps  just  described.  It  consists  of  a  powerful 
Muencke  gas  burner  with  cylindrical  chimney  L.  Upon  the  latter  are 
placed  two  heavy  nickel  wires  supporting  rolls  of  fine  nickel  wire  net- 
ting which  contains  fused  salt.  The  burner  is  surmounted  by  a  second 
rectangular  chimney  of  sheet  iron  with  a  movable  brass  door  containing 
apertures  of  20,  15,  and  10  mm.  diameter. 

The  simplest  and  cleanest  of  sodium  lamps  and  the  one  giving  the 
most  continuous  flame  is  that  of  Zeiss,  Fig.  99.  This  is  composed  of 
*  Z.  analyt.  Chem.,  34,  166.  f  Z.  Instrument.,  4,  390. 


POLARISCOPE  ACCESSORIES 


149 


an  upper  part  A,  capping  an  ordinary  Bunsen  burner  and  secured  to 
it  by  means  of  a  screw.  The  casting  A  carries  the 
diaphragm-screen  K,  out  of  which  the  rectangular 
opening  L  is  cut,  also  the  flat  burner  C  producing  a 
square  flame,  and  a  small  support  for  the  salt  carrier 
E,  which  consists  of  a  piece  of  pumice  stone,  measur- 
ing about  4  X 1  X  J  cm.,  saturated  with  salt.  It  is  held 
upon  the  support  by  the  spring  clip  F  and  can  be 
regulated  to  the  flame  by  means  of  the  screw  / 
operating  on  the  spring  GH.  It  is  best  to  adjust 
the  pumice  stone  so  that  it  merely  touches  and 
tinges  the  flame.  If  E  be  too  deeply  inserted  in  the 
flame,  the  latter  is  over-cooled  and  a  dark,  rather 
sharply  defined  zone  is  produced.  The  flickering 
margins  of  the  flame  are  cut  off  by  the  diaphragm  K. 
A  few  minutes  are  needed  for  heating  the  pumice 
before  the  flame  attains  its  maximum  brilliancy, 
after  which  it  will  remain  constant  for  hours  together. 
The  tablets  of  pumice  stone  saturated  with  salt  are 
supplied  by  the  trade  at  small  cost. 

In  place  of  common  salt,  sodium  bromide  is 
sometimes  used  for  illumination.  This  gives  a  much 
stronger  flame,  but  the  vaporization  is  much  more 
rapid  than  with  salt  and  there  is  the  additional  Fig.  99.  — The  Zeiss 
disadvantage  of  giving  off  bromine  vapors  which 
may  attack  the  instrument  unless  the  lamp  is  placed  under  a  hood. 

Sodium  carbonate,  sodium  phosphate,  sodium  nitrite,  and  mixtures 
of  these  with  salt  in  various  proportions  are  also  used  for  sodium 
lamps.  Sticks  of  fused  sodium  carbonate  heated  hi  an  oxygen  blast 
lamp  give  a  flame  of  great  brilliancy,  and  this  is  the  form  of  light 
recommended  by  Landolt  *  when  intense  illumination  is  desired. 

Purification  of  Sodium  Light.  —  For  accurate  polariscope  measure- 
ments it  is  necessary  to  purify  the  sodium  light  from  other  rays.  This 
can  be  done  either  by  use  of  light  filters  or  by  spectral  separation  of 
the  extraneous  rays. 

Sodium  light  can  be  freed  from  most  of  the  foreign  rays  at  the 
violet  end  of  the  spectrum  by  means  of  bichromate  solution,  which 
has  a  strong  absorption  band  in  the  green  and  blue.  The  rays  at  the 
other  end  of  the  spectrum  can  be  removed  by  uranous  sulphate  solu- 
tion, which  has  a  strong  absorption  band  in  the  red.  A  combination  of 
*  "Das  optische  Drehungsvermogen "  (1898),  p.  359. 


150 


SUGAR  ANALYSIS 


these  two  solutions,  as  in  the  Lippich  light  filter,  constitutes  the  most 
effective  absorbent  means  of  sodium-light  purification  known. 

Lippich  Light  Filter.  —  The  Lippich  light  filter  consists  of  a  tubular 
cell  closed  at  the  ends  by  tightly  fitting  cover  glasses  and  divided  by  a 
glass  plate  into  two  smaller  cells  of  unequal  size.  The  larger  cell,  10  cm. 
long,  is  filled  with  a  6  per  cent  filtered  solution  of  potassium  bichromate, 
the  smaller  cell  is  filled  with  a  solution  of  uranous  sulphate,  11(804)2, 
prepared  as  follows:  5  gms.  of  purest  uranyl  sulphate,  UO2S04  +  3  H20, 
are  dissolved  in  100  c.c.  of  water,  and  2  gms.  of  powdered  chemically 
pure  zinc  added;  3  c.c.  of  concentrated  sulphuric  acid  are  then  added 
in  1  c.c.  portions,  waiting  each  time  until  the  evolution  of  hydrogen  has 
nearly  ceased;  the  flask  is  corked  during  the  reaction,  and  is  allowed  to 
stand  about  six  hours,  when  the  solution  is  filtered  and  the  cell  imme- 
diately filled  in  such  a  way  as  to  leave  only  the  smallest  possible  bubble 
of  air  behind.  After  standing  for  a  day  the  cell  is  ready  for  use;  the 
uranous  solution  retains  its  stability  for  one  to  two  months,  or  until 
its  deep  green  color  is  changed  by  oxidation  into  the  yellow  of  the 
uranyl  compound,  when  the  cell  must  be  refilled  with  fresh  solution. 
The  weights  and  volumes  prescribed  for  making  up  the  absorbent  solu- 
tions must  be  rigidly  adhered  to. 

The  spectrum  purification  of  sodium  light  by  means  of  glass  prisms 
is  the  most  thorough  of  all  methods  of  purification.  The  process, 
which  is  a  somewhat  complicated  one,  is  required,  however,  for  only  the 
finest  physical  measurements.  Landolt  gives  the  following  average 
wave  lengths  for  sodium  light  from  different  sources  in  which  the  wave 
length  of  the  Dl  line  is  placed  at  589.62  w  and  the  A  line  at  589.02  ^. 

TABLE  XXVI 
Wave  Length  of  Different  Kinds  of  Sodium  Light 


Number. 


Source  of  light. 


Purification. 


Wave  length 
in  /x/x. 


Bunsen  flame  with  NaBr .  .  . 
Bunsen  flame  with  NaCl.. . .  I 
Burner  with  NaCl  or  NaBr.  j 

Sodium  light < 

Landolt  lamp  with  NaCl  . . .  j 

Bunsen  flame  with  NaCl . . . .  •< 
Landolt  lamp  with  NaCl 


10  cm.  layer  of  9  per  cent  ) 

K2Cr2O7  in  water. 
10  cm.  layer  of  9  per  cent 

K2Cr2O7  in  water. 
Lippich  filter  K2Cr2O7  and 

U(S04)2. 
Perfectly    spectral    pure; 

light  of  only  the  two  D 

lines. 
1.5  cm.  layer  of  6  per  cent 

K2Cr2O7  in  water. 
10  cm.  layer  of  9  per  cent] 

K2Cr2O7  in  water  and  1  ( 

cm.  layer  of  13.6  per  cent  j 

CuCl2  in  water.  J 

Unpurified 


592.04 
589.48 
589.32 

589.25 
588.94 

588.91 
588.06 


POLARISCOPE  ACCESSORIES 


151 


The  Lippich  light  filter  gives  a  wave  length  exactly  between  the 
two  D  lines  of  sodium  and  agreeing  very  closely  with  that  obtained  by 
spectral  purification.  In  all  cases  where  light  filters  are  used  the  solu- 
tions must  be  placed  between  lamp  and  condensing  lens  (see  Fig.  96). 

Lamps  for  White  Light.  —  For  illuminating  polariscopes  and  sac- 
charimeters  with  white  light,  a  large  number  of  lamps  have  been  devised 
for  use  with  oil,  alcohol,  gas,  acetylene,  and  electricity. 


100.  —  Hinks's  oil  lamp 
with  duplex  burner. 


Fig.  101.  —  Hinks's  gas  lamp 
with  triplex  burner. 


A  convenient  form  of  oil  lamp  with  duplex  burner  and  adjustable 
support  is  that  of  Hinks,  Fig.  100.  The  Hinks  gas  lamp  with  triplex 
burner  is  shown  in  Fig.  101.  The  metal  chimneys  of  these  lamps  are 
usually  fitted  on  the  inside  with  a  porcelain  reflector;  the  focusing  lens 
which  is  sometimes  placed  in  the  aperture  of  the  chimney  should  be 
removed  as  it  may  cause  an  incorrect  passage  of  the  beams  of  light 
through  the  polariscope. 


152 


SUGAR  ANALYSIS 


The  best  forms  of  gas  lamp  for  illuminating  are  those  provided  with 
an  Auer  or  Welsbach  mantle  (Fig.  102).  The  outer  cylinder  of  these 
lamps,  composed  of  sheet  metal  or  asbestos,  contains  an  opening  whose 
lower  half  is  covered  with  a  plate  of  ground  glass  for  diffusing  the 
light;  the  upper  uncovered  part  of  the  opening  serves  for  illuminating 
the  polariscope  scale.  A  form  of  lamp  for  burning  alcohol  somewhat 
similar  in  design  to  the  above  is  shown  in  Fig.  103.  Gas  burners  for 
producing  lime  or  zircon  light  are  also  used  for  illuminating  polari- 
scopes.  Acetylene  lamps  of  25  to  50  candle  power  give  a  light  of  great 


Fig.  102.  — Gas  lamp 
with  Welsbach  mantle. 


Fig.  103.  —  Alcohol  lamp 
with  Welsbach  mantle. 


Fig.  104.  —  Stereopticon 
electric  lamp. 


brilliancy  and  are  especially  valuable  upon  sugar  plantations  where  gas 
or  electricity  is  not  available.  The  acetylene  lamps  should  be  fitted 
with  cylinders  similar  to  those  in  Figs.  100  or  102. 

For  electrical  illumination  a  stereopticon  32-candle-power  incan- 
descent lamp  is  very  suitable  (Fig.  104);  the  closely  wound  filament 
concentrates  the  light  within  narrow  compass,  giving  great  intensity  of 
illumination.  These  lamps  are  best  mounted  in  cylinders  similar  to 
that  in  Fig.  102;  a  plate  of  ground,  glass  is  necessary  for  diffusing  the 


POLARISCOPE   ACCESSORIES 


153 


light,  otherwise  the  irregularities  in  source  of  emission  will  not  be  suffi- 
ciently equalized  for  obtaining  a  uniform  field. 

A  small  electric  attachment  devised  by  Schmidt  and  Haensch  for 
illuminating  their  saccharimeters  is  shown  in  Figs.  88  and  105.     The 


Fig.  105.  —  Schmidt  and  Haensch  six-volt  saccharimeter  lamp. 

small  lamps  are  adapted  for  a  six-volt  current  which  is  supplied  by  a 
storage  battery  or  from  the  main  line  after  reducing  the  voltage.  The 
apparatus  which  is  controlled  by  the  switch  S  (Fig.  88)  is  screwed  on 
the  polarizing  end  of  the  saccharimeter.  The  electric  lamp  is  held  in 
position  by  two  spring  clips  which  are  in  connection  with  the  two 
terminals.  The  lenses  K2  and  KI  (Fig.  105)  project  the  light  upon  the 
diaphragm  of  the  analyzer.  As  the  horizontal  filament  is  not  always 
quite  concentric  to  the  frame,  a  vertical  adjustment  is  necessary.  To 
work  the  adjustment,  the  ring  Z),  which  carries  the  lens  K2,  is  rotated 
by  the  screw  and  projecting  arm  6.  If  the  lamp  is  also  to  be  used  for 
illuminating  the  scale  of  the  instrument,  the  mirror  S'  (Fig.  88)  is  set 
at  an  angle  of  45  degrees,  in  which  position  the  reflected  light  is  con- 
centrated by  the  lens  H  upon  the  opening  a  (Fig.  89). 


POLARISCOPE  TUBES 

For  retaining  sugar  solutions  during  polarization  there  are  a  variety 
of  tubes  of  different  construction,  form,  and  length.  In  the  selection 
of  these  the  chemist  must  be  guided  more  or  less  by  the  nature  of  his 
work.  All  tubes,  however,  when  accuracy  of  observation  is  desired, 
must  conform  to  three  general  requirements:  (1)  the  length  of  the 
tube  must  be  accurately  fixed;  (2)  the  ends  of  the  tube  and  the  sur- 
faces of  its  cover  glasses  must  be  plane  parallel;  (3)  the  tube  must  be 
centered  evenly  in  its  mountings  and,  when  fitted  with  its  caps,  should 
be  free  from  eccentricity.  There  are  other  minor  requirements  of 


154 


SUGAR  ANALYSIS 


tube  construction  which  will  be  given  under  the  description  of  the 
different  forms. 

Fig.  106  shows  the  most  common  and  simplest  forms  of  glass  polar- 
ization tubes.  These  and  other  forms  of  tube  are  usually  supplied  in 
lengths  of  25  mm.,  50  mm.,  100  mm.,  110  mm.,  200  mm.,  220  mm., 
400  mm.,  500  mm.,  and  GOO  mm.;  for  special  kinds  of  work  tubes  of 
several  meters'  length  have  been  constructed. 

A  tube  of  200  mm.  length  is  used  for  the  normal  weight  of  all  sac- 
charimeters.  If,  on  account  of  depth  of  color,  a  100-mm.  or  50-mm. 
tube  is  employed  and  the  resultant  reading  is  recalculated  by  mul- 
tiplying by  2  or  4,  there  is,  of  course,  a  corresponding  doubling  or  quad- 
rupling of  the  errors  of  observation;  short  observation  tubes  are  to  be 
used  therefore  only  in  extreme  cases.  With  very  dilute  sugar  solutions 


25  mm.  tube. 


100  mm.  tube. 


200  mm.  tube. 
Fig.  106.  —  Forms  of  plain  glass  polariscope  tubes. 

and  with  sugars  or  sugar  mixtures  of  low  specific  rotation  the  400-mm. 
or  600-mm.  tube  will  increase  the  accuracy  of  the  observation,  provided 
the  color  be  not  too  great  to  disturb  the  reading.  Tubes  of  odd  lengths, 
such  as  55  mm.,  110  mm.,  220  mm.,  etc.,  should  be  distinctly  marked  lest 
they  be  confused  with  the  50-mm.,  100-mm.,  and  200-mm.  sizes. 

Mounting  of  Polariscope  Tubes.  — The  ends  of  the  glass  observa- 
tion tubes  are  cemented  into  metal  mounts  which  are  threaded  for  the 
purpose  of  receiving  the  screw  cap.  Litharge  and  glycerine  make  a 
much  better  cement  than  the  waxy  material  employed  by  most  manu- 
facturers. The  latter  substance,  especially  on  warm  days,  softens 
readily  and  when  in  this  condition  there  is  danger  in  screwing  on  the 
cap  of  drawing  the  mount  from  its  setting  so  that  it  projects  slightly 
beyond  the  ends  of  the  tube;  the  length  of  the  column  of  liquid  to  be 
polarized  may  thus  be  increased  and  a  considerable  plus  error  intro- 
duced in  the  observation.  The  ends  of  the  glass  tubes  should  project 
only  slightly  beyond  the  threaded  heads;  if  too  much  of  the  end  is 
exposed  there  is  danger  of  chipping  or  breakage.  The  chemist  should 
not  attempt  to  reset  his  tubes  unless  he  has  a  small  lathe  in  which  they 


POLARISCOPE  ACCESSORIES  155 

can  be  centered  and  revolved  while  the  cement  is  hardening,  otherwise 
the  tubes  may  not  be  evenly  mounted. 

A  simple  means  of  testing  for  eccentricity  of  mounting 
is  to  place  the  tube,  with  caps  screwed  on,  in  the  trough 
of  a  polariscope  and  while  giving  it  a  rotatory  motion  to 
view  the  opening  through  the  tube  with  reference  to  the 
polariscope  field.  If  the  tube  has  been  properly  centered 
and  the  caps  are  free  from  eccentricity  the  tube  opening  will 
remain  in  the  center  of  the  field  and  show  no  wabbling 
movement  during  rotation.  To  test  for  plane  parallelism  of 
the  ends  of  the  tube  and  of  cover  glasses,  the  experiment 
just  described  is  repeated  with  the  cover  glasses  in  position 
and  the  tube  filled  with  water.  If  the  ends  of  the  tube  have 
not  been  ground  squarely  across  or  the  cover  glasses  are  not 
plane  parallel,  the  opening  of  the  tube  will  wabble  perceptibly 
during  rotation  owing  to  the  refraction  of  light  through  the 
water  from  the  inclined  surfaces  of  the  cover  glasses.  A 
difference  of  several  tenths  of  a  Ventzke  degree  may  be  noted 
between  the  readings  of  a  tube  in  different  positions  through 
lack  of  plane  parallelism  in  ends  or  cover  glasses.  According 
to  Landolt  the  angle  between  the  opposite  ground-end  sur- 
faces of  a  polariscope  tube  should  always  be  less  than  10 
minutes  and  the  angle  between  the  two  planes  of  a  cover 
glass  less  than  5  minutes.  The  small  angles  of  inclination 
between  planes  of  cover  glasses  and  between  ends  of  tubes  not 
exceeding  200  mm.  in  length  is  measured  by  a  spectrometer. 

Calibration  of  Polariscope  Tubes.  —  A  most  convenient 
means  of  calibrating  the  length  of  polariscope  tubes  is  the 
measuring  gauge  of  Landolt,  shown  in  Fig.  107.    This  gauge, 
which  has  an  adjustable  handle  c,  consists  of  a  measuring 
rod  A  of  steel  graduated  for  a  distance  of  400  mm.  and 
provided  with  a  sliding  vernier  b  which  gives  readings  to 
0.1  mm.     The  lower  end  of  the  rod  and  the  bottom  of  the 
vernier  are  provided  with  knife  edges.    When  the  knife  edge 
of  the  rod  is  placed  upon  a  smooth  hard  surface,  such  as  glass, 
and  the  vernier  brought  down  until  its  knife  edges  are  in  Fig.  107.— 
close  contact  with  the  same  surface,  the  zero  point  of  scale     gauge  for 
and  vernier  should  agree.     If  there  is  lack  of  agreement,  the   calibrating 
zero  point  of  the  vernier  may  be  either  adjusted  or  the  differ-   polariscope 
ence  noted  and  applied  to  all  readings.     To  calibrate  an       tubes, 
observation  tube,  one  end  of  the  tube  is  closed  with  its  cover  glass  and 


156  SUGAR  ANALYSIS 

cap,  and  after  placing  in  an  upright  position  with  the  closed  end  down 
the  measuring  rod  is  inserted  until  its  knife  edgejtouches  the  cover 
glass;  holding  the  rod  perfectly  upright  the  vernier  is  slipped  down 
until  its  knife  edges  coincide  with  the  upper  end  of  the  tube;  the  read- 
ing of  the  scale  and  vernier  will  then  give  the  length  of  tube.  Other 
readings  are  made,  rotating  the  rod  a  little  each  time  from  its  original 
position,  and  the  average  taken.  Calibration  of  tubes  should  be  made 
at  the  standard  temperature  20°  C.;  if  measurements  are  made  at  tem- 
peratures very  different  from  this  the  changes  in  length  of  tube  and 
gauge  due  to  expansion  or  contraction  must  be  taken  into  account  (co- 
efficient of  expansion  in  length  1°  C.  for  steel  =  0.000013  and  for  glass 
=  0.000008).  Measuring  gauges  can  be  verified  as  to  accuracy  at  the 
Government  Bureau  of  Standards. 

The  measuring  gauge  of  Landolt  will  detect  an  error  of  0.1  mm., 
which  is  equivalent  to  an  error  of  0.05°  V.  for  a  sugar  solution  polarizing 
100°  V.  in  a  200-mm.  tube.  This  is  sufficiently  close  for  ordinary 
saccharimetric  measurements;  if  a  finer  determination  of  tube  length 
is  desired  the  measurement  must  be  made  upon  a  comparator;  by  means 
of  this  instrument  measurements  can  be  made  to  0.01  mm. 

Cover  Glasses.  —  The  cover  glasses  used  upon  polariscope  tubes 
must  be  of  strong,  colorless,  and  optically  inactive  glass;  their  surfaces 
must  be  plane  parallel  and  free  from  cracks  or  scratches.  In  screwing 
the  caps  upon  observation  tubes,  care  must  be  taken  that  no  severe 
pressure  is  brought  to  bear  upon  the  cover  glasses;  otherwise  the  strain 
will  render  the  glass  optically  active  and  produce  serious  errors  in  the 
observation.  If  a  cover  glass  is  optically  active  turning  the  tube  in  the 
trough  of  the  polariscope  will  usually  show  variations  in  the  intensity 
of  the  field  with  considerable  difference  in  the  reading  for  various  posi- 
tions of  the  tube.  The  practice  of  rotating  the  observation  tube  be- 
tween readings  is  always  a  good  one;  in  this  way  errors  due  to  defective 
cover  glasses,  bad  washers,  pressure  of  caps,  eccentricity,  etc.,  may  be 
detected  which  would  otherwise  escape  notice.  Cover  glasses  which 
have  been  rendered  optically  active  through  pressure  should  not  be 
used  for  a  day,  in  order  that  sufficient  time  may  elapse  for  readjustment 
to  neutrality. 

Washers.  —  Another  common  source  of  error  in  polariscopic  work 
are  badly  fitting  rubber  washers  in  the  screw  caps  of  the  tubes.  The 
washers  should  be  of  soft  rubber  and  lie  evenly  against  the  back  of 
the  cap  without  the  slightest  marginal  elevation,  otherwise  the  washer 
in  tightening  the  cap  may  give  the  cover  glass  an  inclined  position  and 
cause  a  considerable  increase  in  the  reading. 


POLARISCOPE   ACCESSORIES 


157 


Special  Forms  of  Polariscope  Tubes 

Schmidt  and  Haensch  Tube  with  Enlarged  End.  —  Another  form  of 
glass  polarization  tube  which  presents  several  advantages  is  the  Schmidt 
and  Haensch  tube  with  one  end  enlarged  (Fig.  108).  The  enlargement 
serves  as  a  receptacle  for  any  air  bubbles  which  may  be  enclosed  with 
the  liquid;  the  retention  of  a  small  air  bubble  in  the  tube  is  in  fact  de- 
sirable since,  by  moving  the  bubble  through  the  liquid  from  end  to  end 


Fig.  108.  —  Schmidt  and  Haensch  polariscope  tube  with  enlarged  end. 
(Air  bubbles  are  collected  at  the  point  a,  outside  of  the  field  of  vision.) 

before  reading  slight  differences  in  temperature  are  equalized,  and  no 
troublesome  striations,  due  to  currents  of  solution  of  different  tem- 
perature, are  present  to  distort  the  field.  Tubes  without  enlargement 
must  not  retain  air  bubbles  with  the  liquid;  if  striations  are  present 
the  tube  must  remain  at  rest  until  the  solution  has  reached  equilibrium. 
The  most  frequent  cause  of  a  striated  field  is  the  warming  of  the  solution 
in  the  tube  by  the  hand;  for  this  reason  tubes  should  be  handled  only 
by  the  metal  caps  when  placing  in  the  instrument. 


Fig.  109.  —  (a)  200  mm.  Landolt  polariscope  tube  with  sliding  cap  and  enlarged  end; 
(6)  200  mm.  metal  polariscope  tube. 

Landolt' s  Tube.  —  To  prevent  the  liability  of  excessive  pressure 
upon  cover  glasses,  Landolt  has  devised  a  tube  with  sliding  cap, 
which  is  shoved  into  position  over  the  metal  mount  (Fig.  109a).  The 
French  manufacturers  also  provide  a  cap  that  is  shoved  on  and 
fastened  with  a  bayonet  catch.  Tubes  with  screw  caps,  however,  are 
the  ones  most  preferred  and,  if  care  be  taken  not  to  draw  them  up 
too  tightly,  will  be  found  to  answer  all  requirements.  When  observa- 
tion tubes  are  used  in  large  numbers  it  is  a  great  advantage  to  have 
all  caps  interchangeable. 

Metal  Polarization  Tubes.  —  Polarization  tubes  of  brass  or  nickel  or 
other  metal  are  preferred  by  many  chemists.  Such  tubes,  a  form  of 
which  is  shown  in  Fig.  109b,  have  the  advantage  of  greater  durability, 


158. 


SUGAR  ANALYSIS 


but  the  disadvantage  of  being  susceptible  to  the  attack  of  acids  (as 
in  the  method  of  inversion)  or  other  corrosive  liquids.  Brass  tubes 
have  also  more  than  twice  the  coefficient  of  expansion  of  glass  tubes, 


Fig.  110.  —  Pellet's  tube  for  continuous  polarization. 

the  coefficient  (/?)  for  1°  C.  being  0.000008  for  glass  and  0.000019  for 
brass.  For  glass  and  brass  tubes  measuring  exactly  200  mm.  at  20°  C., 
the  length  at  35°  C.  (Le  =  L20°[l  +0  (*°-20)])  =  200.024  mm.  for  glass 


i 


Fig.  111.  —  Glass  polarization  tube  with  metal  jacket. 

and  200.057  mm.  for  brass,  errors  in  length  of  no  great  significance.  A 
more  serious  objection  against  metal  tubes  is  the  danger  of  their  being 
bent  out  of  alignment  through  hard  or  long  usage.  A  knock  or  fall 
may  cause  a  metal  tube  no  apparent  injury  yet  may  bend  it  sufficiently 
to  produce  a  considerable  error  in  the  polariscope  reading.  A  number 
of  brass  polariscope  tubes,  recently  submitted  to  the  author  for  examina- 


POLARISCOPE  ACCESSORIES 


159 


tion,  were  so  badly  out  of  alignment  that  rotating  the  tubes  in  the  trough 
of  the  polariscope  caused  a  difference  of  over  0.2°  V.  in  the  reading. 

Pellet's  Tube  for  Continuous  Polarization.  —  In  the  polarization  of  a 
large  number  of  solutions  in  succes- 
sion, as  in  the  analysis  of  sugar  beets, 
juices,  etc.,  the  Pellet  tube  for  con- 
tinuous polarizations  is  often  of  great 
use.  Sections  of  this  tube,  which  is 
made  of  metal,  are  shown  in  Fig. 
110.  The  ends  of  the  tube  are  closed 
and  after  placing  in  the  instrument 
the  solution  to  be  polarized  is  poured 
through  a  small  funnel  into  one  of 
the  nipples,  a  or  6,  the  excess  escap- 
ing through  an  exit  tube  connected 
by  rubber  tubing  to  the  nipple  at 
the  opposite  end.  As  soon  as  the 
solution  is  polarized,  the  succeeding 
solution  is  poured  into  the  tube;  the 
disappearance  of  striations  and  the 
clearing  of  the  field  indicate  when 
the  previous  solution  has  been  com- 
pletely displaced.  The  Pellet  tube 
will  accomplish  a  valuable  saving  of 
time  in  certain  kinds  of  work,  but  it 
is  usually  advisable  to  limit  its  use 
to  sugar  solutions  of  approximately 
the  same  density;  to  displace  a  con- 
centrated sugar  solution  with  one 
that  is  exceedingly  dilute,  or  vice 
versa,  is  attended  with  more  or  less 
risk  of  error. 

Polarization  Tube  with  Metal 
Jacket.  —  For  polarizing  sugar  solu- 
tions, where  the  temperature  must 
be  measured  or  controlled,  a  jacketed 
observation  tube  such  as  shown  in  Fig.  Ill  is  recommended.  This  con- 
sists of  an  inner  tube  of  glass  or  metal  with  a  central  opening,  c,  which 
can  be  used  for  filling  and  for  inserting  a  thermometer;  an  outer  mantle 
of  brass  or  nickel  surrounds  the  inner  tube  and  is  provided  with  nipples 
for  inlet  and  exit  of  hot  or  cold  water  as  may  be  desired. 


Fig.  112.  —  Reservoir  for  supplying 
water  of  constant  temperature. 


160 


SUGAR  ANALYSIS 


For  supplying  water  of  constant  temperature  for  observation  tubes, 
the  Zeiss  apparatus  described  on  page  59  may  be  used.  A  form  of 
water  supply  reservoir  with  stirrer,  recommended  by  Landolt,*  is  shown 
in  Fig.  112.  The  reservoir,  which  is  insulated,  is  filled  through  the 
opening  A  with  water  to  the  desired  level,  indicated  by  the  tube  D. 
The  water  is  heated  by  means  of  a  burner  to  the  desired  temperature, 
shown  by  the  thermometers  at  C,  the  heat  being  equalized  by  raising 
and  lowering  the  stirrer  B. 

A  form  of  constant  temperature  bath  designed  by  Hudson  f  is 
shown  in  Fig.  113.  The  mechanical  stirrer  not  only  secures  an  even 
temperature  through  the  bath,  but  also  acts  as  a  rotary  pump  which 


Mercury 
Sealed  Joint 


From.Polarimeter 


To  Polarimeter 


\ 


Fig.  113.  —  Hudson's  constant  temperature  water-bath. 

creates  a  constant  circulation  of  water  as  shown  by  the  direction  of 
the  arrows. 

Wiley's  Desiccating  Caps.  —  When  solutions  are  polarized  at  tem- 
peratures below  the  dew  point  of  the  atmosphere,  the  cover  glasses  of 
the  observation  tube  must  be  protected  against  condensation  of  moisture 
by  means  of  desiccating  caps  such  as  designed  by  Wiley  J  (Fig.  114). 
These  are  generally  made  of  some  non-conducting  material  such  as 
hard  rubber:  they  are  closed  at  the  end  with  a  tightly  fitting  cover 
glass  and  contain  a  tube  for  holding  calcium  chloride  or  other  desiccat- 
ing substance. 

"Das  optische  Drehungsvermogen "  (1898),  pp.  397. 
t  Hudson,  J.  Am.  Chem.  Soc.  30,  1572.  J  J.  Am.  Chem.  Soc.  18,  81. 


POLARISCOPE  ACCESSORIES 


161 


When  solutions  are  polarized  at  very  high  temperatures  as  at 
87°  C.  (the  point  of  inactivity  for  invert  sugar)  the  use  of  glass,  unless 
carefully  annealed,  for  the  inner  tube  of  the  water  jacket  is  precluded. 
Polariscopic  work  at  high  temperature  is  generally  performed  in 


(I) 

Fig.  114. —  (I)  Threaded  cap  of  polariscope  tube.  (II)  Dessicating  cap  which  screws 
on  over  threads  of  (I) ;  t,  removable  glass  tube  containing  dessicating  substance  s; 
w,  inner  perforated  metal  tube;  g,  cover  glass  held  in  position  by  threaded  disk  r; 
the  disk  is  unscrewed  by  inserting  a  spanner  in  the  two  holes  marked  in  black. 

jacketed  tubes  constructed  entirely  of  brass  or  nickel,  the  inner  surface 
of  which  has  been  gold  plated.  The  length  of  a  200-mm.  tube  (20°  C.) 
at  87°  C  would  be  200.107  mm.  for  glass  and  200.255  mm.  for  brass, 
equivalent  to  a  plus  error  of  0.054°  V.  and  0.128°  V.  respectively  for 
solutions  polarizing  100°  V.  in  a  200-mm.  tube. 


Fig.  115  —  Yoder's  volumetric  polariscope  tube. 

Yoder's  Volumetric  Polariscope  Tube.  —  A  volumetric  polariscope 
tube  is  convenient  for  certain  kinds  of  saccharimetric  work.  A  tube  of 
this  description,  designed  by  Yoder,  is  shown  in  Fig.  115. 

The  capacity  of  the  tube  to  the  graduation  mark  upon  the  neck  is 
10  c.c.  By  varying  the  length  and  diameter  the  tubes  can  be  adjusted 
to  any  convenient  volume. 


162 


SUGAR  ANALYSIS 


BALANCES  FOR  POLARISCOPIC  WORK 

For  the  operations  of  weighing  in  saccharimetric  work  three  types 
of  balances  are  required,  an  analytical  balance,  a  so-called  sugar  balance, 
and  a  balance  for  coarse  weighing. 

The  analytical  balance  should  have  a  capacity  of  200  gms.  and  with 
this  load  be  sensitive  to  0.1  mg.  Such  a  balance  is  required  for  all 
analytical  processes,  for  determination  of  specific  rotations,  for  cali- 
bration of  flasks,  weighing  of  pycnometers,  and  all  other  operations 
where  accuracy  is  essential.  A  balance  of  the  type  shown  in  Fig.  17 
will  answer  for  this  purpose.  With  this  balance  a  set  of  accurate 
analytical  weights  (including  one  100  gms.  weight)  will  be  needed. 


Fig.  116.  —  Sugar  balance. 


In  addition  to  the  above  a  less  delicate  balance,  sensitive  to  2.5  mgs. 
with  a  load  of  250  gms.,  will  be  required  for  the  rapid  weighing  of  definite 
amounts  of  sugar,  molasses,  and  other  products  for  ordinary  sacchari- 
metric work.  For  saccharimeters  employing  a  normal  weight  of 
26  gms.,  0.01  degree  Ventzke  corresponds  to  0.0026  gm.  sucrose  in 
100  true  cubic  centimeters.  Since  the  majority  of  saccharimeters  can 
be  read  only  to  0.05°  V  it  is  evident  that  weighing  within  5  mgs.  is 
sufficiently  accurate  for  ordinary  purposes  of  saccharimetry.  The 
weighing  out  of  normal  weights  of  sugar,  etc.,  for  saccharimeters  should 
not  be  done  upon  an  analytical  balance;  the  errors  due  to  evaporation 
from  moist  substances  during  the  slower  adjustment  of  the  analytical 
balance  will  usually  exceed  any  advantage  in  greater  accuracy  of 
weight.  A  so-called  "  sugar  balance  "  of  the  type  shown  in  Fig.  116 


POLARISCOPE  ACCESSORIES 


163 


answers  very  well  for  this  kind  of  work.  This  balance  may  also  be 
used  for  the  weighing  out  of  chemicals  for  making  up  solutions  of 
reagents.  A  set  of  second  quality  weights  should  be  provided  for  ap- 
proximate weighing,  and  also  the  normal  weights  belonging  to  the 
saccharimeter. 

The  Mohr  cubic  centimeter  normal  and  half-normal  weights  (26.048 
gms.  and  13.024  gms.)  are  usually  furnished  in  a  cylindrical  form  and 
the  true  cubic  centimeter  weights  (26.000  gms.  and  13.000  gms.)  in  a 
cubical  form  (Fig.  123),  the  shape  of  the  weight  thus  guarding  against 


Fig.  117.  —  Metric  solution  scale. 

confusion.  Normal  weights,  which  are  in  constant  use,  should  be  tested 
frequently  upon  the  analytical  balance  against  losses  in  weight  through 
wear.  If  a  deficiency  exceeding  1  mg.  is  noted,  the  stem  of  the  weight 
should  be  unscrewed  and  a  small  piece  of  tin  or  aluminum  foil  be  placed 
in  the  cavity  sufficient  to  bring  the  weight  up  to  its  proper  value. 

In  addition  to  the  two  balances  just  described  a  heavy  balance  or 
scale  for  weighing  out  material  in  bulk,  preparing  large  quantities  of 
reagents,  etc.,  will  be  required.  A  metric  solution  scale  with  sliding 
counterpoise  such  as  is  shown  in  Fig.  117  is  very  good  for  this  purpose. 
A  set  of  third  quality  weights  up  to  5  kgs.  should  also  be  provided  for 
coarse  weighings. 

FLASKS  FOR  POLARISCOPIC  WORK 

For  the  preparation  of  sugar  solutions  in  polarimetric  and  sac- 
charimetric  work  various  flasks  have  been  devised  of  different  shape 
and  construction. 


164  SUGAR  ANALYSIS 

Flasks  for  Solution  by  Weight.  —  When  sugar  solutions  are  made 
up  according  to  percentage  a  glass-stoppered  flask  of  the  form  shown 
as  No.  VI  in  Fig.  118  is  recommended.  The  flask,  which  is  supplied  in 
many  sizes,  need  not  be  graduated.  Before  using,  it  is  thoroughly 
cleansed  and  dried,  and  then  weighed.  The  approximate  quantity  of 
substance  to  be  examined  is  then  transferred  to  the  flask  and  after 
stoppering  the  latter  is  reweighed.  The  approximate  amount  of  dis- 
tilled water  or  other  solvent  is  then  added  and  the  flask  and  contents 
reweighed  as  before.  The  percentage  of  substance  in  solution  is 
then  readily  calculated  from  the  weight  of  substance  taken  and  the 
combined  weights  of  substance  and  solvent.  The  flask  should  not  be 
filled  too  full;  sufficient  space  should  be  left  for  gentle  rotation  of  the 
liquid  while  effecting  solution.  The  flask  should  always  be  kept 
stoppered  to  prevent  evaporation. 

Reduction  of  Solution  Weights  to  Vacua.  —  For  very  accurate  physical 
measurements  the  weights  taken  in  air  must  be  reduced  to  vacuo, 
since  a  substance  weighed  in  any  medium  loses  in  weight  an  amount 
equal  to  that  of  the  medium  displaced.  If  W  is  the  true  weight  of  a 

W 

substance  of  density  D,  in  vacuo,  then  the  volume  of  substance  is  -~> 

and  if  s  is  the  density  of  the  air  at  the  time  of  weighing,  the  loss  in 

sW 
weight  of  the  substance  in  air  will  be  -jr-  -     Similarly  if  P  is  the  value 

of  the  weights  in  vacuo  and  d  is  the  density  of  their  material  then  the 

sP 

loss  of  the  weights  in  air  will  be  -7-  •     The  equilibrium  upon  the  pans  of 

the  balance  between  substance  and  weights  in  air  will  then  be  repre- 
sented by  the  equation 


i-- 

whence  W  =  P  -  - 


The  mean  value  0.0012  gm.  may  be  taken  as  the  weight  of  1  c.c.  of 
air  without  sensible  error.  When  brass  weights  are  used  (d  =  8.4), 
the  weights  in  vacuo  of  glass,  water  and  sugar  are  found  as  follows: 
for  glass  (D  =  2.5)  W  =  1.000337  P,  for  water  20°  C.  (D  =  0.998234) 
W  =  1.001061  P,  for  cane  sugar  (D  =  1.59),  W  =  1.000612  P.  The 
following  example  will  illustrate  the  method  of  application. 


POLARISCOPE  ACCESSORIES 


165 


Weight  of  flask  +  sugar  in  air 35.2326  gms. 

Weight  of  flask  alone  in  air 25.1240  gms. 

Weight  of  sugar  in  air 10.1086  gms. 

Weight  of  sugar  in  vacuo  =  10.1086  X  1.000612  = 10.1148  gms. 

Weight  of  flask  +  sugar  +  water  in  air 95.3055  gms. 

Weight  of  flask  +  sugar  in  air 35.2326  gms. 

Weight  of  water  in  air  20°  C 60.0729  gms. 

Weight  of  water  in  vacuo  =  60.0729  X  1.001061  = 60.1366  gms. 

Weight  of  sugar  +  water  in  vacuo  = 70.2514  gms. 

Per  cent  sugar  in  solution  from  weights  in  air  =  14.403  per  cent. 
Per  cent  sugar  in  solution  from  weights  in  vacuo  =  14.398  per  cent. 

It  will  be  noted  that  the  difference  is  exceedingly  slight,  so  that 
weighing  in  air  is  sufficiently  exact  for  all  operations  except  those  de- 
manding extreme  accuracy. 

Volumetric  Sugar  Flasks.  —  When  solutions  of  dissolved  sugars 
are  made  up  to  a  definite  volume  before  polarization,  a  carefully  cali- 
brated volumetric  flask  must  be  used;  such  flasks  are  supplied  in  a 
variety  of  forms  and  sizes.  If  solutions  are  polarized  immediately 
after  making  up  to  volume,  as  is  usually  the  case,  it  is  not  essential 
that  the  flask  be  fitted  with  a  glass  stopper. 


'1 


III  JV  V 

Fig.  118.  —  Types  of  flasks  for  polariscopic  analysis. 

Volumetric  flasks  for  sugar  work  are  made  in  10-c.c.,  20-c.c.,  25-c.c., 
50-c.c.,  100-c.c.,  200-c.c.,  and  250-c.c.  sizes;  500-c.c.  and  1000-c.c.  flasks 
are  also  occasionally  used.  For  certain  kinds  of  work,  where  volume 
of  insoluble  matter  is  allowed  for,  flasks  of  irregular  capacity  are  used, 
as  100.6-c.c.,  201.2-c.c.,  etc.,  for  polarization  of  sugar-beet  pulp. 

A  few  of  the  more  ordinary  forms  of  sugar  flask  are  shown  in  Fig. 
118.  These  may  be  obtained  of  any  desired  capacity.  Small  sized 
stoppered  flasks  similar  to  No.  I  are  convenient  for  preparing  solutions 
when  small  amounts  of  substance  are  available.  Kohlrausch's  sugar 


166  SUGAR  ANALYSIS 

flask  (No.  IV)  with  enlarged  top  is  convenient  for  transferring  sub- 
stances and  is  in  many  ways  a  most  desirable  flask;  it  can  be  obtained 
in  the  small  sizes  and,  if  desired,  with  ground-glass  stopper.  Sugar 
flasks  with  double  graduation  (No.  Ill)  for  one-tenth  dilution  are  useful 
for  the  methods  of  inversion;  they  are  supplied  in  25-27.5-c.c.,  50- 
55-c.c.,  100-110-c.c.,  and  200-220-c.c.  sizes. 

Specifications  for  Sugar  Flasks.  —  In  the  selection  of  sugar  flasks 
the  following  requirements  of  the  United  States  Bureau  of  Standards 
for  volumetric  flasks  will  be  found  useful. 

"  The  cross  section  of  all  flasks  must  be  circular  throughout  and 
the  neck  must  merge  into  the  body  of  the  flask  so  gradually  that  there 
will  be  no  hindrance  to  uniform  drainage.  Flasks  that  are  manifestly 
fragile  or  otherwise  defective  in  construction  will  be  rejected.  The 
part  on  which  the  graduation  mark  is  placed  must  be  transparent,  of 
uniform  thickness,  and  free  from  striae.  The  graduation  mark  must  be 
placed  not  less  than  6  cm.  from  the  upper  end  and  not  less  than  2  cm. 
from  the  lower  end  of  the  neck  of  a  flask  larger  than  100  c.c.,  and  not 
less  than  3  cm.  from  the  upper  end  or  1  cm.  from  the  lower  end  of  the 
neck  of  a  flask  not  larger  than  100  c.c.  The  graduation  mark  must 
extend  entirely  around  the  neck.  The  bottom  of  the  flask  must  be 
slightly  reentrant,  and  the  flask  must  be  of  such  form  that  drainage 
can  take  place  from  the  whole  interior  surface  at  the  same  time.  The 
neck  of  a  flask  must  be  perpendicular  to  a  plane  tangent  to  the  bottom. 
The  flask  must  stand  solidly  when  placed  on  a  horizontal  plane." 

A  very  desirable  100-c.c.  flask  for  saccharimetric  work  is  that  shown 
in  No.  II,  Fig.  118,  and  in  Fig.  123  designed  for  use  in  the  Custom-House 
Laboratories  of  the  United  States  Treasury  Department.  The  pear- 
shaped  body  with  its  low  center  of  gravity  gives  the  flask  greater  stability 
than  a  spherical  form.  According  to  the  regulations  of  the  Treasury 
Department  "the  flasks  shall  have  a  height  of  130  mm.;  the  neck  shall 
be  70  mm.  in  length  and  have  an  internal  diameter  of  not  less  than 
11.5  mm.  and  not  more  than  12.5  mm.  The  upper  end  of  the  neck 
shall  be  flared,  and  the  graduation  marks  shall  be  not  less  than  30  mm. 
from  the  upper  end  and  15  mm.  from  the  lower  end  of  the  neck." 
With  this  size  of  flask  the  base  of  the  thumb  can  cover  the  mouth  and 
the  fingers  of  the  same  hand  easily  enclose  the  bottom  —  a  feature 
of  great  convenience  when  mixing  the  contents  after  making  up  to 
volume. 

Calibration  of  Sugar  Flasks.  —  Sugar  flasks  are  graduated  to 
contain  100  true  cubic  centimeters  at  20°  C.  or  100  Mohr  cubic  centi- 
meters at  17.5°  C.  and  should  be  calibrated  before  using  in  the  follow- 


POLARISCOPE  ACCESSORIES 


167 


ing  manner.     The  flask  to  be  tested  is  first  thoroughly  cleaned  and 

dried,  then  weighed  empty  at  the  temperature  of  standardization,  and 

then  again  when  filled  to  the  mark  with  distilled  water  at  the  standard 

temperature.     The  distilled  water  should  be  boiled  just  before  using, 

in  order  to  expel  dissolved  air,  and  then  cooled.    Special 

care  is  necessary  in  adjusting  the  meniscus   to  the 

graduation  mark;  the  lowest  point  of  the  curve  when 

viewed  against  a  white  surface  should  just  touch  the 

level  of  the  graduation  mark,  the  latter  appearing  to 

the  eye  in  proper  position  as  a  straight  line  and  not 

as  an  ellipse.     Fig.  119  indicates  the  proper  method  of 

adjustment.    The  inside  of  the  neck  above  the  meniscus 

should  be  wiped  perfectly  dry  with  filter  paper  before 

reweighing;  air  bubbles  should  not  be  allowed  to  adhere 

to  the  walls  of  the  flask  during  calibration.  Fig<  119.— Showing 

Volumetric  100-c.c.  sugar  flasks  graduated  according  proper  adjustment 
to  the  Mohr  system  should  contain  100  gms.  of  distilled  of  meniscus, 
water  at  17.5°  C.,  when  weighed  in  air  against  brass  weights;  100-c.c. 
flasks  graduated  according  to  true  cubic  centimeters  should  contain 
100  gms.  of  distilled  water  at  4°  C.  when  weighed  in  vacuo  or  99.7174 
gms.  at  20°  C.  when  weighed  in  air  with  brass  weights.  (Weight  in 
vacuo  of  100  c.c.  water  at  20°  C.  is  99.8234  gms.  and  weight  in  air 
(p.  164)  is  99.8234-^  1.001061  =  99.7174  gms.)  The  grams  of  water 
contained  by  the  flask  at  20°  C.  plus  the  correction  0.282  will  give  the 
volume  in  true  cubic  centimeters. 

The  limits  of  error  allowed  by  the  United  States  Bureau  of  Stand- 
ards for  volumetric  flasks  are  the  following: 


Capacity. 

Limit  of  error. 

c.c. 

c.c. 

2000 

0.5 

1000 

.3 

500 

.15 

250 

.1 

200 

.1 

100 

.08 

50 

.05 

25 

.03 

10 

.01 

The  limit  of  error  allowed  above  for  100-c.c.  flasks  is,  however,  too 
high;  the  error  of  graduation  should  not  exceed  0.05  c.c.  and  careful 
manufacturers  can  conform  to  this  requirement  without  trouble.  A 


168 


SUGAR  ANALYSIS 


lot  of  200  sugar  flasks  purchased  by  the  New  York  Sugar  Trade  Labora- 
tory showed  the  following  errors  upon  calibration. 


Error  in  volume. 

Number  of 
flasks. 

Percentage. 

Between  0.00  c.c.  and  0.01  c.c.  .  . 

65 

32.50 

Between  0.01  c.c.  and  0.02  c.c.  .  . 

56 

28.00 

Between  0.02  c.c.  and  0.03  c.c.  .  . 

43 

21.50 

Between  0.03  c.c.  and  0.04  c.c.  .  . 

27 

13.50 

Between  0.04  c.c.  and  0.05  c.c.  .  . 

7 

3.50 

Between  0.05  c.c.  and  0.06  c.c.  .  . 

2 

1.00 

200 

It  is  seen  that  99  per  cent  of  the  flasks  were  correct  within  0.05  c.c. 
and  that  over  95  per  cent  were  correct  within  0.04  c.c. 

FUNNELS  AND  CYLINDERS 

In  filtering  sugar  solutions  for  polarization  short-stemmed  funnels 
and  cylinders  of  any  of  the  forms  shown  in  Fig.  120  will  be  found  con- 


I  II  III  IV 

Fig.  120.  —  Types  of  cylinders  for  polariscopic  analysis. 

venient.  The  funnels  and  filters  should  be  of  sufficient  size  to  retain 
100  c.c.  of  solution;  they  should  be  covered  with  large  watch  glasses 
during  filtration  to  prevent  evaporation.  Tall  narrow  filtering  cylinders 
(Nos.  I  and  II,  Fig.  120)  are  preferred  by  some  chemists  for  the  reason 
that  the  least  surface  of  filtered  liquid  is  exposed  to  evaporation.  The 
small-lipped  filtering  jars  (No.  IV,  Fig.  120)  are  more  convenient,  how- 
ever, for  filling  tubes,  and  if  covered  by  funnels  and  watch  glasses  will 


POLARISCOPE  ACCESSORIES 


169 


not  allow  sufficient  evaporation,  during  the  necessary  time  of  filtra- 
tion, to  cause  any  appreciable  error  in  the  polariscope  reading. 

MOUNTING  OF  POLARISCOPES  AND  CARE  OF  APPARATUS 
If  the  circumstances  permit,  polariscopes  should  always  be  mounted 
in  a  separate  room  or  compartment,  where  there  is  no  danger  of  cor- 
rosion from  the  action  of  fumes  or  vapors.  The  polarizing  compart- 
ment should  be  well  ventilated  and  easily  darkened;  lamps  and  burners 
for  illumination  should  be  placed  upon  the  opposite  side  of  a  wall  or 
partition. 


Fig.  121.— Cabinet  for  constant  temperature  polarization  (New  York  Sugar 
Trade  Laboratory). 

In  the  New  York  Sugar  Trade  Laboratory  the  polariscope  cabinet 
(Fig.  121)  constitutes  a  section  of  the  constant-temperature  room. 
The  roof  of  the  cabinet  is  composed  of  shutters,  for  regulating  the 
downward  passage  of  cool  air,  and  the  sides  of  the  cabinet  are  enclosed 
by  dark  curtains,  which,  when  drawn,  leave  a  space  of  one  foot  at  the 
bottom.  This  arrangement  allows  free  circulation  of  air,  and  the 
presence  of  several  observers  in  the  cabinet  does  not  affect  the  tem- 
perature. 


170 


SUGAR  ANALYSIS 


Where  room  is  not  available  for  a  separate  compartment,  the 
polariscopes  may  be  mounted  in  a  large  box  in  a  dark  corner  of  the 
laboratory  as  shown  in  Fig.  122. 

The  table  supporting  polariscopes  should  be  of  solid  construction. 
By  placing  the  table  upon  rubber  cushions  and  setting  the  polariscopes 
upon  rubber  mats,  vibration  of  the  instruments  and  consequent  dis- 
turbance of  the  zero  point  will  be  largely  obviated. 


Fig.  122.  —  Portable  polariscope  cabinet  with  section  of  side  removed. 

It  is  essential  in  saccharimetric  work  that  all  apparatus  be  kept 
scrupulously  clean.  The  more  delicate  optical  parts  of  polariscopes, 
such  as  polarizer,  analyzer,  and  quartz  compensation,  are  enclosed,  in 
the  most  modern  apparatus,  in  dust-proof  housings,  and  very  rarely 
require  to  be  disturbed.  The  diaphragm  glasses  (A  and  P,  Fig.  96)  at 
each  end  of  the  polariscope  trough  are  the  parts  which  require  most 
attention.  Drops  of  solution,  accidentally  adhering  to  the  polariscope 
tubes,  are  occasionally  splashed  against  the  diaphragm  glasses.  The 


POLARISCOPE  ACCESSORIES  171 

diaphragms,  which  either  screw  or  slide  into  position,  should  be  ex- 
amined frequently  and  the  glasses  wiped  free  of  dirt  and  dust  particles. 
A  paper  napkin  will  be  found  very  suitable  for  cleaning  diaphragm 
glasses,  eye  pieces,  and  other  exposed  optical  parts. 

The  troughs  of  polariscopes  in  the  hasty  round  of  routine  fre- 
quently become  soiled  from  contact  with  wet  tubes  or  spilled  liquid. 
They  should  be  wiped  frequently  with  a  damp  cloth  and  the  metal 
surface  should  be  kept  smooth  and  clean. 

The  bichromate  cell  should  be  examined  frequently,  and  the  solu- 
tion replenished  as  soon  as  bubbles  begin  to  form,  otherwise  their 
appearance  may  obscure  the  field. 

When  the  polariscope  is  not  in  use,  the  trough  should  be  closed  and 
the  instrument  kept  covered. 

Strict  cleanliness  must  also  be  observed  in  the  use  of  polariscope 
tubes,  flasks,  and  other  accessories.  In  handling  and  carrying  obser- 
vation tubes  a  portable  rack  of  the  form  shown  in  Fig.  122  will  be 
found  convenient. 

Where  sugar  solutions  are  clarified  with  lead  subacetate,  the  walls 
of  flasks,  cylinders,  funnels,  and  tubes  become  coated  in  time  with  a 
thin  white  film  of  lead  carbonate.  A  good  solvent  for  this  coating  is  a 
warm  solution  of  sodium  hydroxide  and  Rochelle  salts,  such  as  is  used 
in  preparing  Fehling's  solution.  Hydrochloric  or  nitric  acid  may  also 
be  used  for  removing  the  deposit.  After  thorough  rinsing  in  clean 
water,  tubes,  flasks,  funnels,  and  cylinders  should  be  allowed  to  drain 
and  dry  upon  racks. 


CHAPTER  VIII 

SPECIFIC  ROTATION   OF  SUGARS 

IN  the  previous  chapters  the  principles  which  underlie  the  con- 
struction and  operation  of  polariscopes  were  described;  it  is  now  de- 
sired to  study  the  application  of  these  principles  to  some  of  the  problems 
of  sugar  analysis. 

The  polarizing  power  of  a  sugar  is  expressed  as  specific  rotation,  or 
specific  rotatory  power,  by  which  is  meant  the  angular  rotation  which 
a  calculated  100-per  cent  solution,  1-dcm.  long,  gives  to  the  plane  of 
polarized  light.  The  specific  rotation,  indicated  by  the  expression  [a] 
can  easily  be  calculated  from  the  angular  rotation  a  of  the  solution  of 

substance  by  means  of  the  equation  [a]  = =•  >  in  which  c  is  the  con- 

c  X  l 

centration  of  substance  (grams  per  100-c.c.  solution)  and  I  the  length 
of  the  observation  tube  in  decimeters.  Instead  of  the  foregoing  we 

may  use  the  equation  [u]  = ^ 7>  in  which  p  is  the  percentage  of 

J)  X  CL  X  L 

substance  in  solution  (parts  by  weight  hi  100  parts  by  weight  of  solu- 
tion) and  d  is  the  specific  gravity  of  solution,  (p  X  d  =  c  in  previous 
equation.) 

The  angular  rotation,  as  shown  below,  depends  upon  the  wave 
length  of  the  light  employed.  Sodium  light  is  the  illumination  most 
used  for  polariscopic  measurements  and  as  the  bright  yellow  line  of 
sodium  is  designated  the  D  line  of  the  solar  spectrum,  the  expression  [a] 
for  sodium  light  is  written  [a]b.  Specific  rotation  for  the  mean  yellow 
ray  j  (now  no  longer  used)  is  written  [a]j.  The  temperature  at  which 
the  specific  rotation  is  taken  is  also  usually  affixed.  Thus:  the  symbol 
for  specific  rotation  using  sodium  light  at  20°  C.  is  written  [a]™. 

The  method  of  calculating  specific  rotation  may  best  be  understood  by 
an  example;  20  gms:  of  cane  sugar  dissolved  to  100  c.c.  gives  an  angular 
rotation  for  sodium  light  of  +53.2  degrees  in  a  400-mm.  tube  at  20°  C. 

Substituting    these    values    in    the    equation    [a]  = =->   we  obtain 

c  x  l 

100  X  53  2 
MD  =  — on  x  4      =  ~^~  ^'**  *^e  specific  rotation  of  sucrose  for  the  given 

concentration. 

172 


SPECIFIC  ROTATION  OF  SUGARS 


173 


To  calculate  specific  rotation  from  the  reading  of  a  saccharimeter, 
the  scale  divisions  of  the  latter  must  first  be  converted  to  angular 
degrees  by  means  of  the  appropriate  factor.  Thus:  15  gms.  of  sucrose 
dissolved  to  100  metric  cubic  centimeters  gave  a  reading  of  +57.7  in 
a  200-mm.  tube  using  a  Ventzke  scale  quartz-wedge  saccharimeter. 
Since  1°  V  =  0.34657  angular  degrees  (page  145)  then 


r  ,                     100  (0.34657  X  57.7) 
[a]D  sucrose  = 15  x  2 


+  66.6. 


EFFECT  OF  KIND  OF  LIGHT  UPON  SPECIFIC  ROTATION  OF  SUGARS. 

Mention  has  been  made  of  the  influence  of  wave  length  of  light  upon 
specific  rotation.  In  Table  XX  a  comparison  was  given  of  the  rotations 
of  quartz  and  sucrose  for  light  of  different  wave  lengths  and  it  was 
shown  that  as  the  wave  length  decreases  the  polarizing  power  of  sucrose 
increases.  In  the  following  table  the  specific  rotations  of  nine  different 
sugars  are  given  for  light  of  different  wave  lengths  in  the  red,  yellow, 
green,  blue,  indigo,  and  violet  parts  of  the  spectrum,  according  to 
recent  measurements  by  Grossmann  and  Bloch.*  The  specific  rota- 
tions for  yellow  sodium  light,  [O\D,  the  standard  values  of  comparison, 
are  printed  in  heavier  type. 


Sugar. 

Concen- 
tration, 
gms. 
100  c.c. 

Red 
(r) 
656  MM- 

Yellow 
(f) 
589  'pp. 

Green 

to) 

535  MM- 

Blue 
(W 

508  MM- 

Indigo 
(•) 

479  MM- 

Violet 
(») 
447  MM- 

Disper- 
sion co- 
efficient 

V 

r 

Xylose  
Rhamnose  .  . 
Galactose  . 
Glucose  
Fructose.  .  . 
Sucrose  .... 
Lactose.  .  .  . 
Maltose.  .  . 
Raffinose.  . 

0.866 

6.948 
5.603 
4.500 
4.500 
4.275 
2.000 
6.021 
3.713 

+  13.28 
+     7.08 
+  60.80 
+  41.89 
-  76.39 
+  53.18 
+  39.82 
+  111.00 
+  79.63 

+  18.19 
+     8.37 
+  80.72 
+  52.76 
-  90.46 
+  66.50 
+  52.42 
+137.04 
+105.20 

+   21.08 

+  10.27 
+  99.63 
+  65.35 
-107.21 
+  82.25 
+  62.09 
+166.11 
+131.71 

+  24.50 
+  11.11 
+116.76 
+  73.61 
-136.85 
+  91.53 
+  72.25 
+176.26 
+150.75 

+  27.70 
+  12.84 
+131.84 
+  83.88 
-151.11 
+104.24 
+  83.25 
+227.12 
+163.77 

+  31.94 
+  14.38 
+  152.90 
+  96.62 
-166.55 
+  121.63 
+  98.17 
+233.36 
+  188.55 

2.41 
2.03 
2.51 
2.30 
2.18 
2.29 
2.47 
2.10 
2.37 

Average    2.296 

It  is  seen  that  of  the  nine  sugars  galactose  shows  the  greatest  and 
rhamnose  the  smallest  dispersion .  coefficient,  the  average  value  2.296 
being  the  same  as  that  of  sucrose  and  of  glucose. 

Various  formulae  have  been  proposed  for  expressing  the  relationship 
between  specific  rotation  and  wave  length  of  light.  Stefan  f  gives  for 

cy  COQ 

sucrose  the  formula  [a]  =  ^f-    -  5.58,  in  which  the  wave  length  X  is 

A 

*  Z.  Ver.  Deut.  Zuckerind.,  62,  19.  t  Ber.  Wiener  Akad.,  62,  486. 


174 


SUGAR  ANALYSIS 


expressed  in  ten-thousandths  of  a  millimeter 


The  results  as 


thus  calculated  have  only  an  approximate  value,  as  other  factors,  such 
as  temperature,  concentration,  etc.,  are  not  considered. 

The  specific  rotations  of  the  different  sugars  also  vary  according 
to  the  concentration  of  solution,  the  temperature  of  observation  and 
the  nature  of  the  solvent.  The  following  table  gives  the  approximate 
values  for  the  specific  rotation  of  a  number  of  sugars.  The  effect  of 
concentration  and  temperature  in  increasing  or  lowering  the  specific 
rotation  is  indicated  by  the  direction  of  the  arrow  in  the  respective 
columns. 

TABLE  XXVII 

Showing  Effect  of  Increase  in  Concentration  and  Temperature  upon  Specific  Rotation 

of  Sugars 


Sugar. 

wr- 

Increase  in 
concentration 

-o+ 

Increase  in 
temperature 

-0+ 

Arabinose  

+104.5 
+19.0 
+8.5 
+80.5 
+52.5 
-92.5 
-20.0 
+66.5 
+52.5 
+138.5 
+  104.5 

£ 

? 

? 

—  » 

? 

V 

5 

? 

«  — 
? 

Xylose 

Rhamnose 

Galactose 

Glucose  

Fructose  

Invert  sugar  

Sucrose  

Lactose  -.  

Maltose  .... 

Raffinose.  .  .  . 

EFFECT  OF  CONCENTRATION  UPON  SPECIFIC  ROTATION  OF  SUGARS 

The  effect  of  varying  concentration  upon  the  specific  rotation  of 
sugars  has  been  studied  by  many  observers  and  the  results  of  their  ob- 
servations have  been  expressed  in  the  form  of  equations.  The  method 
of  deriving  these  equations,  which  is  due  to  Biot,*  is  of  considerable 
importance  to  the  sugar  chemist  and  deserves  to  be  briefly  considered. 
Concentration  Equations.  —  If  the  specific  rotations  of  a  substance 
for  different  concentrations  be  laid  off  upon  a  diagram,  in  which  the 
specific  rotations  represent  the  ordinates  and  the  percentages  of  sub- 
stance in  solution  the  abscissae,  the  line  which  connects  the  several 
points,  will  be  either  a  straight  line,  a  section  of  a  parabola,  hyperbola, 
or  other  curve,  or  a  combination  of  any  two  or  more  of  these.  Calling 
the  percentage  of  sugar  in  solution  p,  the  specific  rotation  can  be  rep- 
resented as  follows:  according  to  the  well-known  algebraic  equations. 
*  Ann.  chim.  phys.  [3],  10,  385;  11,  96;  28,  215;  36,  257;  69,  219. 


SPECIFIC  ROTATION  OF  SUGARS  -  .       175 

I.   For  the  straight  line  [a]  =  a  +  bp. 
II.   For  the  parabola        [a]  =  a  +  bp  +  cp2. 

III.   For  the  hyperbola     [a]  =  a  +  -^— 

C  +  p 

Having  plotted  and  determined  the  nature  of  the  curve  it  remains 
to  calculate  the  values  of  the  constants  a,  b,  and  c  in  the  above  equa- 
tions. The  method  of  doing  this  (the  method  of  least  squares)  is  simple, 
although  the  work  of  calculation  is  somewhat  laborious.  The  following 
example  is  given  as  an  illustration : 

From  the  average  results  of  observations  by  Tollens,  Thomson,  Schmitz, 
Nasini,  and  Villavecchia,  the  following  specific  rotations  of  sucrose  were  found 
for  different  concentrations;  10  per  cent  +  66.56,  20  per  cent  +  66.52,  30  per 
cent  +  66.41,  40  per  cent  +  66.27,  50  per  cent  +  66.06.  An  equation  is  desired 
for  the  specific  rotation  of  sucrose  for  any  concentration  within  these  limits. 

By  plotting  the  above  observations  a  curved  line  is  obtained  presumably 
a  parabola.  (In  calculating  the  concentration  curves  for  the  specific  rotation  of 
sugars  the  hyperbola  is  but  little  used.)  Substituting  the  results  in  the  previous 
equation  II  for  the  parabola  we  obtain  the  following : 

1.  a  +  10  b  +    100  c  =  66.56. 

2.  a  +  20  b  +    400  c  =  66.52. 

3.  a  +  30  b  +    900  c  =  66.41. 

4.  a  +  40  b  +  1600  c  =  66.27. 

5.  a  +  50  b  +  2500  c  =  66.06. 
Average:  I.  a  +  30  6  +  1100  c  =  66.364. 

From  the  above  equations  we  obtain  by  subtraction  the  following: 

6.  (5-1)     40  b  +  2400  c  =  -  0.50. 

7.  (5-2)     30  b  +  2100  c  =  -  0.46. 

8.  (5-3)     20  6  +  1600  c  =  -  0.35. 

9.  (5-4)     106+    900  c  =-0.21. 

10.  (4-1)  30  b  +  1500  c  =  -  0.29. 

11.  (4-2)  20  6  +  1200  c  =  -  0.25. 

12.  (4-3)  10  b  +    700  c  =  -  0.14. 

13.  (3  -  1)  206+    800  c  =-  0.15. 

14.  (3-2)  106+    500  c  =-  0.11. 

15.  (2  -  1)  10  6  +    300  c  =  -  0.04. 
Average:  II.  20  6  +  1200  c  =  -  0.25. 

By  combining  equations  6  to  15  into  two  series  and  subtracting  we  obtain 
the  following: 

III.     (7  +  8  +  10  +  12  +  14)         100  6  +  6400  c  =  -  1.35 
IV.     (6  +  9  +  11  +  13  +  15)        100  6  +  5600  c  =-  1.15 

800  c  =  -  0.20 
c  =  -  0.00025. 


176  SUGAR  ANALYSIS 

Substituting  the  value  for  c  in  equation  II  we  obtain  b  =  0.0025,  and 
substituting  these  values  for  b  and  c  in  equation  I  we  obtain  a  =  66.564.  Sub- 
stituting these  values  in  the  original  equation  for  the  parabola  we  obtain: 

[a]g  =  66.564  +  0.0025  p  -  0.00025  p\ 

The  calculated  specific  rotation  of  sucrose  for  various  concentrations  according 
to  the  above  equation  is  as  follows:  10  per  cent  66.56,  20  per  cent  66.51, 30  per 
cent  66.41,  40  per  cent  66.26,  50  per  cent  66.06,  results  which  agree  perfectly 
with  the  average  observations  taken. 

The  above  equation  for  the  specific  rotation  of  sucrose  does  not  hold, 
however,  for  concentrations  below  10  per  cent  or  above  50  per  cent. 
Tollens  *  from  observations  upon  19  solutions  ranging  from  3.8202  per 
cent  to  69.2144  per  cent  sucrose  calculated  the  following  equations: 
For  p  =  4  to  18  per  cent  sucrose, 

[«]»  =  66.810  -  0.015553  p  -  0.000052462  p2. 
For  p  =  18  to  69  per  cent  sucrose, 

H2D°=  66.386  +  0.015035  p  -  0.0003986  p\ 

According  to  the  above  equations  the  maximum  specific  rotation 
of  sucrose  (66.53)  is  found  at  p  =  18.86  per  cent;  for  concentrations 
lower  than  this  the  specific  rotation  again  decreases. 

Schmitz  |  from  observations  upon  eight  solutions  for  p  =  5  to  65 
per  cent  gives  the  equation: 

[a]™  =  66.510  +  0.004508  p  -  0.00028052  p\ 

Nasini  and  Villavecchia  |  for  p  =  3  to  65  give  the  equation 
[a]™  =  66.438  +  0.010312  p  -  0.00035449  p2.  The  last  named  au- 
thorities found,  however,  for  very  dilute  solutions  (c  =  0.335  gm.  to 
1.2588  gms.  sucrose  per  100  c.c.)  that  the  specific  rotation  of  sucrose 
again  increases,  and  for  such  dilute  solutions  give  the  equation 
[«]g  =  69.962  -  4.86958  p  +  1.86415  p2.  The  variations  noted  in  the 
above  equations  for  the  specific  rotation  of  sucrose  are  no  doubt  partly 
due  to  the  effect  of  rotation  dispersion,  as  the  result  of  using  light  of 
slightly  different  wave  length  for  illumination. 

The  equations  of  Tollens  and  of  Nasini  and  Villavecchia  are  con- 
sidered to  be  the  most  accurate.     The  average  of  the  two  equations  gives 
probably  the  most  reliable  expression  for  the  specific  rotation  of  sucrose. 
I-   [a]2D  =  +  66.386  +  0.015035  p  -  0.0003986  p2.     (Tollens.) 
II.    [a]™  =  +66.438  +  0.010312  p  -  0.0003545  p2. 

(Nasini  and  Villavecchia.) 
Average:  III.   [«]»  =  +66.412  +  0.012673  p- 0.0003766  p2. 

*  Ber.,  10,  1403.  f  Ber.,  10,  1414. 

t  Public,  de  lab.  chim.  delle  gabelle.     Rome,  1891,  p.  47. 


SPECIFIC  ROTATION  OF  SUGARS 


177 


Landolt  *  by  recalculating  this  combined  equation  into  terms  of 
concentration  (grams  of  sugar  per  100  c.c.)  gives  the  expression: 

IV.   [«]»  =  +  66.435  +  0.00870  c  -  0.000235  c2  (c  =  0  to  65). 

The  following  table,  which  with  the  exception  of  column  /  is  taken 
from  Landolt,*  gives  a  comparison  of  the  specific  rotation  of  sucrose 
for  solutions  of  different  percentage  and  concentration,  according  to 
each  of  the  four  preceding  equations. 

TABLE  XXVIII 
Giving  Specific  Rotation  of  Sucrose  for  Different  Concentrations 


a 

6 

c 

d 

e 

/ 

g 

20° 

Concentra- 

Specific rotation  [af%. 

Percentage. 

Sp.gr.^. 

tion 
(c—n  j) 

(Tollens.) 

{C  —  p.ttj. 

(Tollens.) 

By  formula  I 
calculated  to 

By  formula  II 
calculated  to 

By  formula  III 
calculated  to 

By  formula  IV 
calculated  to 

P 

d 

c 

P 

P 

P 

c 

5 

.01786 

5.0893 

+66.451 

+66.480 

+66.466 

+66.473 

10 

.03819 

10.3819 

66.496 

66.506 

66.501 

66.500 

15 

.05926 

15.8889 

66.522 

66.513 

66.517 

66.514 

20 

.08109 

21.6218 

66.527 

66.502 

66.515 

66.513 

25 

.10375 

27.5938 

66.513 

66.474 

66.493 

66.496 

30 

.  12721 

33.8163 

66.479 

66.428 

66.453 

66.460 

35 

.15153 

40.3036 

66.424 

66.365 

66.394 

66.404 

40 

.17676 

47.0704 

66.350 

66.283 

66.316 

66.324 

45 

.20288 

54.1296 

66.256 

66.184 

66.220 

66.217 

50 

.22995 

61.4975 

66.142 

66.067 

66.104 

66.081 

Concentration  equations  for  the  specific  rotation  of  other  sugars  are 
given  below : 


(c=3  to  34  gms.  per  100  c.c.)  [«]»  =+18.095+0.06986  p. 

(c  =  34  to  61  gms.  per  100  c.c.)  [a]»  =+23.089-0.1827  p+0.00312  p2. 


(P 


to  35  per  cent) 
to  100  per  cent) 

I  to  30  per  cent) 
)  to  68  per  cent) 


Xylose  t 

Galactose  I 
Glucose  § 

Fructose  || 
Invert  sugar 

Maltose  ** 

Browne  (J.  Ind.  Eng.  Chem.,  2,  526)  has  calculated  the  observations  of  Tollens 
to  concentration  and  gives  the  equation  for  glucose  [a]g  =  +  52.50  +  0.0227c  + 
0.00022  c2. 

*  "  Das  optische  Drehungsvermogen"  (1898),  p.  420.  t  Schulze  and  Tollens, 
Ann.,  271,  40.  t  Meissl,  J.  prakt.  Chem.  [2],  22,  97.  §  Tollens,  Ber.,  17,  2238. 
II  Ost.  Ber.,  24,  1636.  1[  Gubbe.  Ber.,  18,  2207.  **  Meissl,  J.  prakt.  Chem.  [2], 
26,  114. 


(p  =  5  to  35  per  cent) 


[aj2o  =  +79.703+0.0785  p. 
[a]2o  _  +52.50+0.018796  p 

+0. 00051683  p2. 
[«]»  =  -(91. 90+0. Ill  p). 
[«]»  ==-19.447-0. 06068  p 

+0.000221  p2. 
[«]«>  =+138.475-0.01837  p. 


178  SUGAR  ANALYSIS 

EFFECT  OF  TEMPERATURE  UPON  SPECIFIC  ROTATION  OF  SUGARS 

The  effect  of  temperature  upon  the  specific  rotation  of  sugars  is 
no  less  pronounced  than  that  of  concentration  and,  with  a  number  of 
sugars  such  as  fructose  and  galactose,  the  influence  of  temperature  is 
the  factor  which  has  most  to  be  considered  in  polarimetric  measure- 
ments. The  change  in  rotation  of  a  sugar  solution  due  to  expansion 
or  concentration  in  volume  through  temperature  changes  must  not  be 
confused  with  changes  in  specific  rotation.  In  studying  the  latter 
phenomenon  the  sugar  solutions  must  either  be  made  up  to  volume  at 
the  same  temperature  at  which  they  are  to  be  examined  or  else  a  cor- 
rection be  made  for  the  changes  in  volume  due  to  expansion  or  con- 
traction. 

The  influence  of  temperature  upon  specific  rotation  is  studied  in 
the  same  way  as  that  of  concentration,  by  laying  off  the  specific  rota- 
tion for  each  temperature  upon  a  diagram.  The  connecting  points  for 
the  ordinary  ranges  of  atmospheric  temperature  lie  more  nearly  in  a 
straight  line  than  is  the  case  with  the  concentration  curves.  For 
wider  ranges  of  temperature,  however,  the  increase  or  decrease  in 
specific  rotation  is  found  to  proceed  unequally  and  the  change  must 
then  be  expressed  by  some  curve  equation. 

Effect  of  Temperature  upon  the  Specific  Rotation  of  Sucrose.  — 
The  earlier  investigators  Mitscherlich,  Hesse,  and  Tuchschmid  re- 
garded the  effect  of  temperature  upon  the  specific  rotation  of  sucrose 
as  insignificant.  Dubrunfaut*  was  the  first  to  recognize  the  fact 
that  increase  of  temperature  caused  a  decrease  in  the  value  of  this 
constant,  the  temperature  coefficient  of  the  specific  rotation  of  su- 
crose having  been  found  by  him  to  be  0.000232  per  1°C.  increase. 
Andrews,!  who  reinvestigated  the  question  in  1889,  found  a  decrease 
of  0.0114  in  the  specific  rotation  of  sucrose  for  1°  C.  increase.  The 
specific  rotation  of  sucrose  for  any  temperature  t  is  then  represented 
by  the  equation: 

MA  =  MS -0.01140 -20). 

SchonrockJ  in  1896,  as  a  result  of  observation  upon  10  sugar  solu- 
tions, showed  that  the  decrease  in  specific  rotation  for  1°  C.  increase 
lay  between  0.0132  and  0.0151 ;  for  temperatures  between  12°  C.  and 
25°  C.  the  change  is  expressed  by  the  equation: 

MA  =  MS  ~  °-0144  (*  -  20). 

*  Ann.  chim.  phys.  [3],  18,  201. 

t  Mass.  Inst.  Tech.  Quarterly,  May,  1889,  p.  367. 

t  Ber.  phys.-techn.  Reichsanstalt,  1896. 


SPECIFIC  ROTATION  OF  SUGARS  179 

This  equation  is  sometimes  written 

Mb  =  [<*}D  ~  MS  0.000217  (t  -  20), 
in  which  the  temperature  coefficient  of  the  specific  rotation, 

°-0144 
66.5 


0  000217  -- 


Later  experiments  were  made  by  Schonrock*  at  temperatures 
between  9°  C.  and  32°  C.  using  light  of  three  different  wave  lengths, 
the  yellow  sodium  line  589.3  w,  the  yellow-green  mercury  line  546.1  "/*/*, 
and  the  blue  mercury  line  435.9  /*/*.  These  experiments  showed  that  for 
the  German  normal  sugar  solution  (p  =  23.701  per  cent)  the  rotation 
angle  underwent  a  linear  deviation  with  changes  in  temperature,  this 
deviation  being  independent  of  the  wave  length  of  light  employed.  It 
was  found,  moreover,  that  the  temperature  coefficient  of  the  specific 
rotation  decreased  with  increase  in  temperature,  the  value  being  0.000242 
at  10°  C.,  0.000184  at  20°  C.,  and  0.000121  at  30°  C.  for  Sodium  light. 
This  decrease  proceeds  in  a  straight  line  and  the  values  of  the  tempera- 
ture coefficient  for  any  intermediate  temperature  can  be  estimated  by 
taking  the  proportionate  difference.  These  later  values  of  Schonrock 
are  used  by  the  Physikalisch-Technische  Reichsanstalt  of  Germany 
and  have  therefore  the  highest  sanction  of  authority. 

Effect  of  Temperature  upon  the  Specific  Rotation  of  Other  Sugars. 
-  The  effect  of  temperature  upon  the  specific  rotations  of  a  number 
of  other  sugars  is  given  in  Table  XXIX. 

TABLE  XXIX 

Rhamnosef  ................  H£  =  +     9.18-0.035  t  (1=  6°  to  20°  C.) 

GalactoseJ  (p  =  10)  ..........  [«]£  =  +  84.67-0.200  t  (<  =  10°  to  30°  C.) 

Fructose§  (p=9)  ............  H^  =  -  103.  92+0.  671  t  (/.  =  13°  to  40°  C.) 

Fructose§  (p=23.5)  .........  [a]^  =  -  107.  65+0.  692  t  (1=  9°  to  45°  C.) 

Invert  sugar||  (c  =  17.21)  .....  WD  =  -  27.9  +0.32    t  (t=  5°  to  35°  C.) 

Lactose^  ...................  [«!£  =  +  52.53-0.07    i-20  (*  =  15°  to  25°  C.) 

Maltose**  (p=10)  ...........  [«J^  =  +  140.  19  -0.095  t  (*  =  15°  to  35°  C.) 

*  Z.  Ver.  Deut.  Zuckerind.,  53,  650. 
t  Schnelle  and  Tollens,  Ann.,  271,  62. 
j  Meissl,  J.  prakt.  Chem.  [2],  22,  97. 

§  Honig  and  Jesser,  Z.  Ver.  Deut.  Zuckerind.,  38  (1888),  1028. 
||  Tuchschmid,  J.  prakt.  Chem.  [2],  2,  235. 
i  Schmoger,  Ber.,  13,  1922. 
**  Meissl.  J.  prakt.  Chem.  [2],  25,  114. 


180 


SUGAR  ANALYSIS 


While  a  linear  equation  is  sufficiently  exact  for  narrow  ranges  of  tem- 
perature, the  change  in  specific  rotation  for  wider  differences  of  temper- 
ature must  usually  be  expressed  by  an  equation  of  the  order: 


or  [<x}'D  =  [<*}%  +  a(t-20)+b(t-  20)2. 

Gernez,*  for  example,  gives  for  rhamnose  the  equation 

\aYD  =  9.22  -  0.03642  t  +  0.0000123  t2 
and  Gubbef  gives  for  invert  sugar  the  following  equations: 
For  *  =  0°  to  30°  C.,  [a]^  =  [ag+ 0.3041  (t  -  20)+0.00165  (*-20)2. 
For  *  =  20°  to  100°  C.,  [*]»  =  [«]%+ 0.3246  0-20) -0.00021  0-20)2. 

Sucrose  and  the  different  sugars  mentioned  in  Table  XXIX  all  show 
a  decrease  in  specific  rotation  with  increase  in  temperature.  Of  other 
sugars,  which  exhibit  this  property  in  marked  degree,  arabinose  should 
be  mentioned.  TanretJ  found  for  1-arabinose  [a]^  =  +105.54  and 
[a]g=  +88.61,  or  an  average  decrease  of  0.394  for  1°  C.  increase  in 
temperature,  which  is  greater  than  that  for  any  other  sugar  except 
fructose. 

Xylose  presents  an  exception  to  the  rule  just  noted,  Schulze  and 
Tollens  §  having  observed  for  temperatures  above  20°  C.  an  increase  in 
specific  rotation,  as  in  the  following  example  (p  =  10.0829). 


t 

[a]D  ]-xylose. 

15° 

+  18.898 

20 

18.909 

25 

19.248 

30 

19.628 

Glucose  also  seems  to  present  an  exception  to  the  rule  of  dimin- 
ished rotation  with  increase  in  temperature.  Observations  by  Dub- 
runfaut,  Mategczek,  and  others  show  that  the  specific  rotation  of 
d-glucose  undergoes  no  perceptible  change  between  0°  and  100°  C. 

Equations  giving  the  combined  influence  of  concentration  and  tem- 
perature upon  specific  rotation  have  been  worked  out  for  many  sugars. 
The  following  examples  are  given: 

*  Compt.  rend.,  121,  1150. 
t  Ber.,  18,  2207. 
j  Bull.  soc.  chim.  [3],  15,  195. 
§  Ann.,  271,  40. 


SPECIFIC  ROTATION  OF  SUGARS  181 

Galactose  *  [«]£  =  +  83.883  +  0.0785  p  -  0.209 1.     (Meissl.)t 

Fructose       [alp  =  —  [101.38  —  0.56 1  +  0. 108  (c  —  10)].       (Jungfleisch  and 

Grimbert.)t 
Fructose        [«]£  =  -  88.13  -  0.2583  p  +  0.6714  (t  -  20°).        (Honig    and 

Jesser.)§ 
Sorbose         [«]g  =  -  [42.65  +  0.047 p  +  0.00007 p2-  (t- 20) 0.02].    (Tollens 

and  Smith.) II 
Maltose        [«]g  =  +  140.375  -  0.01837p  -  0.095 1.     (Meissl.)  1F 

EFFECT  OF  SOLVENT  UPON  THE  SPECIFIC  ROTATION  OF  SUGARS 

The  constants  of  specific  rotation  for  sugars  are  all  expressed  for 
aqueous  solutions.  It  sometimes  happens,  however,  that  solutions  of 
sugar  in  other  solvents,  such  as  alcohol,  have  to  be  examined;  in  such 
cases  the  changes  in  specific  rotation  due  to  the  character  of  solvent 
must  be  taken  into  account. 

In  the  case  of  sucrose,  Tollens**  found  the  following  values  for  [a]^ 
with  different  solvents  for  a  10  per  cent  solution: 

In  water  +  66.667. 

In  1  part  water  +  3  parts  ethyl  alcohol  +  66.827. 
In  1  part  water  +  3  parts  methyl  alcohol  +  68.628. 
In  1  part  water  +  3  parts  acetone  +  67.396. 

Methyl  alcohol  and  acetone  are  thus  seen  to  raise  the  specific  rotation 
of  sucrose  perceptibly,  but  ethyl  alcohol  only  slightly.  Claassenft  also 
found  for  80  per  cent  alcohol  a  slight  increase  in  the  specific  rotation 
of  sucrose;  the  differences  (0.1  to  0.15),  however,  are  not  sufficient  to 
affect  seriously  the  analytical  results  in  such  operations  as  the  alcoholic 
extraction  of  sugar  beet  or  cane  pulp. 

In  the  case  of  fructose  and  invert  sugar,  ethyl  alcohol  produces  a 
marked  lowering  of  the  specific  rotation,  and  when  these  sugars  are 
present  the  influence  of  ethyl  alcohol  as  a  solvent  must  be  taken  into 

*  Tanret  (Bull,  societe"  chimique  [3],  16,  195)  gives  the  change  in  specific 
rotation  of  galactose  for  1°  C.  increase  between  13°  and  20°  -0.39,  between  20° 
and  25°  -0.226,  and  between  25°  and  30°  -0.180,  a  falling  off  in  the  temperature 
coefficient  with  increase  in  temperature  similar  to  the  one  noted  by  Schonrock  with 
sucrose. 

t  J.  prakt.  Chem.  [2],  22,  97. 
t  Compt.  rend.,  107,  390. 
§  Z.  Ver.  Deut.  Zuckerind.,  38  (1888),  1028. 
II  Ber.,  33,  1289. 
1f  J.  prakt.  Chem.  [2],  25,  114. 
**  Ber.,  13,  2287. 
ft  Z.  Ver,  Deut.  Zuckerind.,  40,  392. 


182  SUGAR  ANALYSIS 

account.  Fructose  according  to  Landolt*  has  a  specific  rotation  in 
alcohol  which  is  only  two-thirds  that  in  water.  Borntrsegert  found  for 
37.6  gms.  invert  sugar  in  100  c.c.  aqueous  solution  a  rotation  of  —49.2 
at  20°  C.;  when  the  solution  was  made  up  with  10.45  c.c.  alcohol 
the  rotation  decreased  to  —43.9  and  with  20.60  c.c.  alcohol  to  —38.3. 
According  to  Horsin-Deon  t  (whose  conclusion,  however,  requires  veri- 
fication) invert  sugar  in  absolute  alcohol  is  perfectly  inactive  and  only 
becomes  levorotatory  upon  the  addition  of  water.  It  should  also  be 
noted  that  the  rotation  of  alcoholic  invert-sugar  solutions  is  much 
more  sensitive  to  changes  in  temperature  than  water  solutions. 

With  a  number  of  sugars  the  specific  rotations  in  aqueous  and 
alcoholic  solutions  are  almost  the  reverse  of  one  another.  The  [O\D 
of  rhamnose§  for  example  in  water  is  +9-43  and  in  alcohol  —9.0. 
The  [O\D  of  sorbosej  in  water  is  —42.5  and  in  85  per  cent  alcohol 
+41.8.  The  effect  of  pyridine  and  formic  acid  upon  the  specific  rota- 
tions of  several  sugars  is  shown  on  page  190. 

Without  giving  detailed  results  of  experiments  upon  all  the  various 
sugars  it  may  be  said  that  the  effect  of  solvent  upon  specific  rotation 
is  too  great  to  be  disregarded;  wherever  possible  the  polarimetric  ex- 
amination of  sugars  for  purpose  of  analysis  should  be  made  in  aqueous 
solution. 

EFFECT  OF  ACCOMPANYING  SUBSTANCES  UPON  SPECIFIC  ROTATION 

OF  SUGARS 

Another  factor  of  importance,  especially  in  the  polarimetric  exami- 
nation of  impure  sugar  solutions,  is  the  effect  which  bases,  acids,  salts, 
and  other  substances  exert  upon  the  specific  rotation  of  the  sugars 
present.  A  very  large  amount  of  investigation  has  been  done  upon 
this  subject  and  for  complete  details  reference  must  be  made  to  the 
original  articles.  Only  brief  mention  will  be  made  of  the  effects  of  a 
few  substances  upon  the  rotation  of  the  more  important  sugars. 

The  changes  which  foreign  optically  inactive  substances  may  exert 
upon  the  rotation  of  sugars  may  be  either  chemical  or  physical.  The 
hydroxides  of  the  alkalies  and  alkaline  earths,  and  all  salts  of  alkaline 
reaction  in  general,  cause  a  decrease  in  the  specific  rotation  of  most 
reducing  sugars.  Such  changes  in  rotation  are  purely  chemical,  being 

*  Ber.,  13,  2335. 

t  Z.  ang.  Chem.  (1889),  507. 

J  J.  fabr.  sucre,  20,  37. 

§  Rayman  and  Kruis,  Bull.  soc.  chim.  [2],  48,  632. 

II  Adrian!,  Rec.  trav.  chim.  des  Pays  Bas.,  19,  184. 


SPECIFIC  ROTATION  OF  SUGARS 


183 


due  either  to  a  rearrangement  of  the  sugar  molecule  or  to  the  forma- 
tion of  alkali-sugar  compounds  of  lower  specific  rotation.  The  effect  of 
acids  and  acid  salts  upon  the  rotation  of  sucrose  by  inversion  is  another 
example  of  purely  chemical  change.  The  avoidance  of  such  chemical 
changes  is  imperative  in  accurate  polarimetric  work  and  to  prevent 
these  the  solutions  of  sugar  under  examination  should  be,  so  far  as 
possible,  neutral  in  reaction. 

The  influence  of  neutral  salts  upon  the  specific  rotation  of  sugars,  on 
the  other  hand,  is  largely  physical,  since  the  chemical  properties  of  the 
dissolved  sugars  are  not  appreciably  affected;  the  same  is  also  true  of 
the  influence  of  acids  upon  the  specific  rotation  of  sugars  which  do  not 
undergo  inversion. 

Influence  of  Mineral  Impurities  upon  the  Rotation  of  Sucrose.  — 
The  chlorides,  nitrates,  sulphates,  phosphates,  acetates,  and  citrates, 
of  the  alkalies,  the  chlorides  of  the  alkaline  earths,  magnesium  sulphate, 
and  many  other  salts  all  produce  a  decrease  in  the  specific  rotation  of 
sucrose,  this  decrease  being  generally  greater  with  increased  amount 
and  smaller  molecular  weight  of  salt. 

The  hydroxides  of  the  alkalies  and  alkaline  earths  and  the  carbon- 
ates of  the  alkalies  also  lower  the  specific  rotation  of  sucrose.  The  in- 
fluence of  these  substances,  which  is  of  especial  importance  technically, 
in  view  of  the  alkalinity  of  various  sugar-house  products,  has  been 
widely  studied,  the  results  being  often  expressed  in  parts  of  sugar  whose 
rotation  is  obscured  by  one  part  of  alkali.  Pellet  for  example  gives 
the  following  results: 


Substance. 

Concentration  of  sucrose  solution. 

5.4  gms. 
100  c.c. 

17.3  gms. 
100  c.c. 

1  gm.  caustic  potash  obscures  rotation  of  

Grams  sucrose. 

0.170 
0.140 
0.044 
0.040 
0.7 
0.190 

Grams  sucrose. 

0.500 
0.450 
0.065 
0.132 
1.0 
0.430 

1  gm.  caustic  soda  obscures  rotation  of. 

1  gm.  potassium  carbonate  obscures  rotation  of.  . 
1  gm.  sodium  carbonate  obscures  rotation  of  
1  gm.  calcium  oxide  obscures  rotation  of  

1  gm.  barium  oxide  obscures  rotation  of  

Strontium  oxide  also  diminishes  the  specific  rotation  of  sucrose. 
This  lowering  effect  of  alkalies  upon  the  specific  rotation  of  sucrose  is 
largely  due  to  the  formation  of  soluble  saccharates  of  lower  specific 
rotation;  the  influence  can  be  largely  eliminated  by  neutralization  with 
acetic  acid.  The  original  specific  rotation  is  not  entirely  restored, 


184 


SUGAR  ANALYSIS 


however,  since  the  soluble  acetates  themselves  lower  the  specific  rota- 
tion of  sucrose  to  a  slight  extent. 

The  probable  effect  of  a  mixture  of  salts  upon  the  polarization  of 
sucrose,  —  such  for  example  as  occurs  in  beet  molasses,  which  contains 
about  50  per  cent  of  sucrose  and  10  per  cent  of  soluble  salts  (mostly  of 
potassium),  —  may  be  judged  from  the  following  examples  taken  from 
experiments  by  Bodenbender  and  Steffens.* 

TABLE  XXX 


Salt. 

Sucrose, 
parts. 

Salt,  parts. 

Water, 
parts. 

Polarization, 
sugar  degrees. 

Difference. 

Potassium  chloride  .  .  .  .  < 
Sodium  chloride  < 
Barium  chloride  \ 

5 
10 
20 
5 
10 
20 
5 
10 

1 

2 
4 

1 
2 
4 
1 
2 

94 
88 
76 
94 
88 
76 
94 
88 

4.987 
9.856 
19.869 
4.969 
9.853 
19.586 
4.952 
9.944 

0.013 
0.144 
0.131 
0,031 
0.147 
0.414 
0.048 
0.056 

Magnesium  sulphate..  .  < 
Sodium  phosphate  .         < 

20 
5 
10 
20 
5 
10 

4 

1 
2 
4 
1 
2 

76 
94 

88 
76 
94 
88 

19.402 
4.995 
9.890 
19.880 
4.958 
9  933 

0.598 
0.005 
0.110 
0.120 
0.042 
0.067 

Potassium  carbonate.  .  .  < 
Sodium  carbonate  < 

20 
5 
10 
20 
5 
10 
20 

4 
1 
2 
4 
1 
2 
4 

76 

94 
88 
76 
94 
88 
76 

19.689 
4.927 
9.730 
19.300 
4.910 
9.711 
19.173 

0.311 
0.073 
0.270 
0.700 
0.090 
0.289 
0.827 

The  effect  of  four-fold  concentration  is  seen  to  depress  the  difference 
in  rotation  about  ten  times,  so  that  an  apparent  loss  of  sucrose  may 
seem  to  take  place  in  the  evaporation  of  sugar  solutions  rich  in  mineral 
salts,  when  such  solutions  are  examined  by  the  polariscope  before  and 
after  evaporation. 

The  effect  which  the  various  salts,  used  for  clarifying  impure  sugar 
solutions  for  optical  analysis,  exercise  upon  the  specific  rotation  of 
sucrose  and  other  sugars  is  also  of  great  importance.  Lead  subacetate 
is  the  salt  most  used  for  this  purpose;  its  effect  upon  the  rotation  of 
sucrose  is  considered  elsewhere  (page  216). 

Influence  of  Mineral  Impurities  upon  the  Rotation  of  Reducing 
Sugars.  —  The  action  of  salts  of  alkaline  reaction  in  depressing  the 
rotation  of  reducing  sugars  has  already  been  mentioned.  In  sacchari- 

*  Z.  Ver.  Deut.  Zuckerind.,  31,  808. 


SPECIFIC  ROTATION  OF  SUGARS 


185 


metric  analysis  the  influence  of  lead  subacetate,  as  a  clarifying  agent, 
upon  the  rotations  of  fructose  and  invert  sugar,  is  ©f  great  importance. 
As  was  first  observed  by  Gill*  in  1871  when  solutions  containing  invert 
sugar  are  treated  with  lead-subacetate  solution  in  excess,  the  formation 
of  soluble  lead  fructosate  of  low  specific  rotation  is  so  pronounced  that 
the  rotatory  power  of  fructose  sinks  below  that  of  glucose  and  the 
invert  sugar  becomes  dextrorotatory.  Similar  observations  have  been 
made  by  Pellet,  Bittmann,  Koydl,  Borntraeger,  and  many  others.  In 
the  following  experiments  by  Bittmann  f  50  c.c.  of  invert-sugar  solution 
were  treated  with  50  c.c.  of  a  mixture  of  water  and  lead  subacetate  in 
different  proportions. 


Water. 

Lead-subacetate 
solution. 

Polarization. 

c.c. 

c.c. 

50 

0 

-2.3 

40 

10 

-1.0 

30 

20 

+3.7 

10 

40 

+7.5 

The  influence  of  neutral  salts  upon  the  specific  rotation  of  reducing 
sugars  is  variable.  Some  salts  produce  an  increase,  others  a  decrease 
and  some  no  change  whatever  in  rotation;  no  general  rule  can  be  given. 

Of  particular  importance  in  this  connection  is  the  influence  of  differ- 
ent neutral  salts  upon  the  rotation  of  invert  sugar;  the  occurrence  of 
such  salts  in  molasses  and  other  low-grade  sugar-house  products  may 
increase  the  levorotation  of  the  invert  sugar  several  degrees,  with  the 
result  that  erroneous  conclusions  are  sometimes  drawn  from  the  polari- 
scopic  examination  of  such  products. 

Influence  of  Acids  upon  the  Specific  Rotation  of  Sugars.  —  The 
presence  of  free  mineral  acids  exerts  a  very  pronounced  influence  upon 
the  specific  rotation  of  certain  sugars.  This  influence  is  very  slight  in 
case  of  glucose,  but  is  most  pronounced  with  fructose  and  hence  also 
with  invert  sugar.  O 'Sullivan,  for  example,  found  for  invert  sugar, 
prepared  by  inverting  sucrose  with  invertase,  [a]J$  =  —  24.5,  and  for 
invert  sugar,  prepared  by  inverting  sucrose  with  sulphuric  acid  in  the 
cold,  [«]£  =  —  27.7,  an  increase  of  3.2,  which  if  referred  entirely  to 
fructose  would  mean  an  increase  of  6.4  in  the  specific  rotation  of  that 
sugar.  The  increase  in  rotation  increases  with  the  amount  of  acid,  as 
is  seen  from  the  following  results  by  Hammerschmidt  t  which  the  author 

*  Z.  Ver.  Deut.  Zuckerind.,  21,  257. 

t  Ibid.,  30,  875. 

}  Ibid.,  40,  465;  41,  157. 


186 


SUGAR  ANALYSIS 


has  calculated  to  the  [a]g  of  invert  sugar  and  fructose.  The  results 
Were  obtained  by  inverting  a  half-normal  weight  of  sucrose  with  vary- 
ing amounts  of  concentrated  hydrochloric  acid  and  then  completing 

the  volume  to  100  c.c. 

TABLE  XXXI 

Showing  Influence  of  Varying  Quantities  of  Hydrochloric  Acid  upon  the  Rotation 
of  Invert  Sugar  and  Fructose. 


Volume  of 
HC1  added. 

Observed  saccha- 
rimeter  reading, 
20°  C. 
(13.6842  gms.  invert 
sugar  to  100  c.c.) 

Calculated  [«]g 

Invert  sugar. 

Fructose. 

c.c. 
0 
5 
10 
15 
20 

°V. 

"-IG'SO" 

-17.06 
-17.58 
-18.02 

-20.00 
-20.89 
-21.60 
-22.26 

-22.82 

-92.50 
-94.28 
-95.70 
-97.02 
-98.14 

The  influence  of  the  change  in  specific  rotation  of  fructose  upon  the 
determination  of  sucrose  by  the  methods  of  acid  inversion  is  discussed 
on  page  270.  The  action  of  organic  acids  upon  the  rotation  of  fructose 
and  invert  sugar  is  much  less  pronounced  than  that  of  mineral  acids, 
and  can  usually  be  disregarded  in  polariscopic  analysis. 

Influence  of  Foreign  Optically  Active  Substances  upon  the  Specific 
Rotation  of  Sugars.  —  The  effect  of  other  optically  active  ingredients 
upon  the  rotation  of  a  sugar  is  of  importance  especially  in  determining 
the  polarizing  power  of  several  sugars  in  solution  or  of  mixtures  of 
sugars  with  organic  non-sugars  which  are  optically  active.  The  difficul- 
ties in  conducting  studies  of  this  kind  seem  to  have  deterred  investigation 
somewhat;  the  results  upon  the  polarizing  power  of  sugar  mixtures, 
so  far  as  they  have  been  carried,  show,  however,  no  change  in  the 
rotation  of  the  individual  sugars. 

The  polarizing  power,  for  example,  of  solutions  of  sucrose  and  glucose 
in  different  proportions  was  found  by  Hammerschmidt  *  to  agree  with 
the  sum  of  the  values  calculated  by  the  concentration  formulae  of 
Tollens  (page  177)  within  experimental  limits  of  error.  Similar  results 
were  also  obtained  by  Creydtf  in  case  of  cane  sugar  and  raffinose. 
Results  by  Brownet  upon  the  polarization  of  mixtures  of  glucose  and 
fructose,  glucose  and  galactose,  fructose  and  galactose,  fructose  and 

"  Das  specifishe  Drehungsvermogen  von  Gemengen  optisch  activer  Substan- 
zen,"  Dissertation,  Rostock  University,  1889. 
t  Z.  Ver.  Deut.  Zuckerind.  (1887),  37,  153. 
J  J.  Am.  Chem.  Soc.,  28  (1906),  339. 


SPECIFIC  ROTATION  OF  SUGARS 


187 


arabinose,  arabinose  and  xylose  also  show  that  it  is  safe  to  assume  in 
analytical  work  that  the  specific  rotation  of  these  sugars  is  not  per- 
ceptibly affected  by  other  sugars  in  solution. 

MUTAROTATION 

A  phenomenon  observed  in  the  polarization  of  all  optically  active 
reducing  sugars  is  that  of  mutarotation  (also  called  birotation  or  multi- 
rotation).  The  polarizing  power  of  such  sugars  undergoes  after  solu- 
tion at  first  a  rapid  change  which  slowly  becomes  more  gradual  until 
after  a  few  hours  the  polariscope  reading  remains  constant.  This  phe- 
nomenon was  first  observed  upon  glucose  in  1846,  by  Dubrunfaut  *  and 
the  fact  that  the  initial  rotation  of  this  sugar  was  about  twice  the  con- 
stant value  caused  the  introduction  of  the  name  birotation.  The  re- 
lation 2  :  1  was  found,  however,  to  be  different  in  the  case  of  other 
sugars;  Wheeler  and  Tollens,f  for  example,  found  the  ratio  in  case  of 
xylose  to  be  about  4.5:1  and  accordingly  suggested  the  name  multiro- 
tation.  This  term,  however,  in  recent  years  has  given  place  to  the 
more  expressive  word  mutarotation  (Latin  mutare  =  to  change)  intro- 
duced by  Lowry  1  in  1899. 

The  effect  of  mutarotation  upon  the  rotatory  power  of  sugars  is 
shown  in  the  following  table,  in  which  results  are  quoted  from  the  work 
of  Tollens  and  his  coworkers,  giving  the  specific  rotation  of  a  number 
of  sugars  directly  after  solution  and  after  standing  until  no  further 
change  was  noted.  The  time  after  solution  is  given  after  each  value 
for  [«]». 

TABLE  XXXII 
Showing  Mutarotation  of  Different  Sugars 


Sugar. 

Grams 
per 
100  c.c. 

[a]5>  initial. 

[a]JJ  constant. 

Difference. 

Velocity 
constant 
(Osaka). 

min. 

hours 

1-  Arabinose  

9.73 

+  156.7 

6.5 

+  104.6 

1.5 

-52.1 

0.031 

1-Xylose  

10.235 

+  85.9 

5. 

+  18.6 

2.0 

-67.3 

0.022 

d-Glucose  

9.097 

+  105.2 

5.5 

+  52.5 

4.5 

-52.7 

0.0104 

d-Galactose..  .  . 

10.000 

+117.4 

7. 

+  80.3 

4.5 

-37.1 

0.0102 

d-Fructose  

10.000 

-104.0 

6. 

-  92.3 

0.5 

-11.7 

0.096 

Rhamnose  

10.000 

-     5.0 

5.5 

+     9.4 

1.0 

+14.4 

0.039 

Fucose  

6.916 

-111.8 

11. 

-  77.0 

2.0 

-34.8 

0.022 

Lactose  

4.841 

+  87.3 

8. 

+  55.3 

10.0 

-32.0 

0.0046 

Maltose  

9.2 

+  118.8 

6. 

+136.8 

6.5 

+17.0 

0.0072 

*  Compt.  rend.,  23,  38. 

t  Ann.,  254,  312. 

t  J.  Chem.,  Soc.,  75,  212. 


188  SUGAR  ANALYSIS 

It  is  noted  that  in  case  of  rhamnose  there  is  a  decrease  in  rotation 
from  —  5.0  to  0  and  then  an  increase  from  0  to  +  9.4.  Maltose  also 
differs  from  the  other  sugars  in  showing  a  less  rotation  at  time  of  solu- 
tion than  after  standing. 

Effect  of  Temperature  on  Mutarotation.  —  The  speed  of  muta- 
rotation  is  influenced  by  a  large  number  of  factors.  It  is  accelerated 
by  increase  in  temperature,  the  change  proceeding  very  slowly  at 
0°  C.,  and  almost  instantly  at  100°  C.  Dilute  sugar  solutions  show  the 
same  velocity  of  change  for  all  concentrations.  Highly  concentrated 
solutions,  however,  do  not  always  give  the  true  end  rotation;  such 
solutions  must  first  be  diluted  and  then  allowed  to  stand  for  the  change 
in  rotation  to  be  completed.  This  fact  must  be  borne  in  mind  in  the 
polariscopic  examination  of  concentrated  sugar  solutions,  such,  for  ex- 
ample, as  liquid  honey,  otherwise  a  considerable  error  may  be  intro- 
duced in  the  work  of  analysis. 

Velocity  of  Mutarotation.  —  The  velocity  of  the  change  from 
initial  to  constant  rotation  is  different  for  different  sugars,  and  also 
varies  according  to  temperature,  solvent,  and  other  conditions.  Urech  * 
was  the  first  to  show  that  the  speed  of  mutarotation  followed  the  same 
law  as  that  noted  by  Wilhelmy  in  the  inversion  of  sucrose  (page  660), 
and  which  is  expressed  by  the  following  general  formula  for  a  reaction 
of  the  first  order, 

-£  =  k  (a  -  x), 

in  which  k  is  the  coefficient  of  velocity,  a  the  total  change  between  the 
beginning  and  end  point,  and  x  the  change  at  the  end  of  any  time  t. 
The  above  equation  by  integration  gives 

1,          a 

k  =  -  log  — —  • 
t     &  a  —  x 

Owing  to  the  impossibility  of  measuring  the  specific  rotation  of  a 
sugar  at  the  exact  moment  of  solution,  the  velocity  of  mutarotation  is 
generally  determined  by  the  modified  formula 


in  which  ft  and  ft  are  the  rotations  at  the  end  of  the  corresponding 
times  h  and  ^,  and  <f>  the  constant  end  rotation. 

The  method  of  calculation  is  shown  by  the  following  example, 
which  is  taken  from  the  work  of  Levy,f 

*  Ber.,  16,  2270;  17,  1547;  18,  3059. 
t  Z.  physik.  Chem.,  17,  301. 


SPECIFIC  ROTATION  OF  SUGARS 


189 


TABLE  XXXIII 
Showing  Velocity  of  Mutarotation  for  a  Glucose  Solution 

Per  cent,  C6H12O6  =  3.502.    d        =  1.0114.    Temperature.=  20.5°  to  20.9°  C. 


Time  after  solution. 

Angular  rotation 
(8  dm.  tube). 

<I-«1 

Temperature. 

*=rVlog>'(!H) 

Tj—  fj              \P»—  <£/ 

£i  =  25  min. 

0!  =  27.865° 

0 

20.9°  C. 

J2  =  30  min. 

02=27.060 

5 

20.9 

0.00649 

<2  =  35  min. 

02  =  26.159 

10 

20.9 

0.00719 

Z2  =  40  min. 

02  =  25.637 

15 

20.8 

0.00644 

£2  =  45  min. 

02=24.927 

20 

20.7 

0.00662 

*2  =  50  min. 

02=24.369 

25 

20.6 

0.00652 

£2  =  55  min. 

02  =  23.895 

30 

20.5 

0.00636 

<2  =  60min. 

02  =  23.166 

35 

20.5 

0.00677 

<2  =  65  min. 

02  =  22.797 

40 

20.5 

0.00656 

*2  =  70  min. 

02=22.171 

45 

20.5 

0.00687 

£2  =  75  min. 

02  =  21.837 

50 

20.5 

0.00674 

<2  =  80  min. 

02  =  21.470 

55 

20.5 

0.00671 

<2  =  85  min. 

02=21.088 

60 

20.5 

0.00675 

24  hours 

0  =  16.692 

Average 

0.00662 

The  velocity  constants  by  Osaka  *  given  in  Table  XXXII  were  cal- 
culated by  this  method.  It  is  seen  that  the  change  to  constant  rota- 
tion is  most  rapid  for  fructose  and  slowest  for  lactose. 

Effect  of  Acids,  Bases,  and  Salts  on  Mutarotation.  —  The  action  of 
acids,  bases,  and  salts  upon  the  velocity  of  mutarotation  has  been  a 
subject  of  considerable  study.  Acids  accelerate  the  change  according 
to  their  degree  of  dissociation,  or  electric  conductivity,  preserving  ap- 
proximately the  same  order  as  that  noted  in  the  inversion  of  sucrose. 
Levy,t  for  example,  gives  the  following  constants  for  the  speed  of 
mutarotation  of  glucose  in  presence  of  different  acids  dV  normal)  and 
the  relative  acceleration  of  each  acid  in  terms  of  hydrochloric  acid  =  100. 

TABLE  XXXIV 

Showing  Acceleration  of  Different  Adds  upon  Mutarotation 


In  presence  of. 

Velocity  con- 
stant of  muta- 
rotation. 

Temperature. 

Relative 
acceleration. 

Water.. 

0.00610 

20.1°C. 

Water  

0.00637 

20.25 

Hydrochloric  acid 

0.02300 

20.25 

100.00 

Nitric  acid.  ...       .    ... 

0.02283 

20.1 

98.99 

Trichloracetic  acid.  .... 
Sulphuric  acid  

0.02325 
0.01886 

20.25 
20.0 

96.67 
71.95 

Dichloracetic  acid  
Monochloracetic  acid  .  . 
Acetic  acid.  .       .       ... 

0.01670 
0.01004 
0.00716 

20.2 
20.25 
20.2 

62.41 
17.25 
4.70 

Propionic  acid  

0.00636 

19.8 

1.63 

Z.  physik.  Chem.,  35,  661. 


t  Z.  physik.  Chem.,  17,  301. 


190 


SUGAR  ANALYSIS 


The  values  for  relative  acceleration  of  the  different  acids  preserve 
the  same  order  as  those  noted  for  the  inversion  constants  in  Table  XCV 
(page  663). 

It  is  scarcely  necessary  to  state  that  the  speed  of  mutarotation 
increases  with  the  strength  of  acid  employed.  Thus  Levy  found  for 
ft/10  hydrochloric  acid,  k  =  0.02300  and  for  n/50  hydrochloric  acid, 
k  =  0.00971;  for  n/10  acetic  acid,  k  =  0.00716  and  for  n/50  acetic 
acid,  k  =  0.00654. 

Alkalies  also  accelerate  the  speed  of  mutarotation,  the  change  to 
constant  rotation  being  almost  instantaneous.  Schulze  and  Tollens* 
using  0.1  per  cent  ammonia  obtained  the  normal  constant  rotation 
with  arabinose,  xylose,  rhamnose,  galactose,  glucose,  fructose,  and  lac- 
tose within  9  minutes;  n/200  alkali  (KOH)  gives  the  end  rotation  of 
glucose  almost  instantly.  The  use  of  much  stronger  alkali,  however, 
induces  chemical  change  with  a  decrease  of  the  rotation  below  the  normal 
value.  Treyf  for  example  using  0.2  gm.  sodium  hydroxide  per  100  c.c. 
obtained  as  the  [O\D  for  glucose  after  15  minutes  +  52.7  (normal),  after 
24  hours  +  36.7,  after  48  hours  +  26.0,  after  34  days  +  15.1,  and  after 
65  days  -  0.4. 

The  different  salts  nearly  all  accelerate  the  speed  of  mutarotation, 
those  of  alkaline  reaction  standing  first  in  this  respect.  Sodium  chlor- 
ide, however,  presents  an  exception  to  this  rule,  having  been  found 
by  Levy  I  and  also  by  Trey  §  to  cause  the  mutarotation  of  glucose  to 
proceed  slower  than  in  pure  aqueous  solution. 

Mutarotation  of  sugars  takes  place  not  only  in  water  but  also  in 
o^her  solvents  such  as  absolute  methyl  alcohol,  ethyl  alcohol,  acetone, 
etc.  The  change  in  rotation  proceeds  much  more  slowly,  however,  in 
organic  solvents  than  in  aqueous  solution.  This  is  shown  in  the  follow- 
ing results  by  Grossmann  and  Bloch  ||  which  give  the  mutarotation  of 
several  sugars  in  pyridine  and  formic  acid. 


Sugar. 

fa]jT)  in  pyridine. 

[O\D  in  formic  acid. 

After  solution. 

Constant. 

After  solution. 

Constant. 

Xylose  

+  117.39 

Min. 

8 

+    40.63 

Days. 

4 

+  40.34 

Min. 
4 

+  66.60 

Days. 

Rhamnose  .... 
Galactose.  .  .  . 
Glucose  
Fructose. 

-  41.39 

+  154.28 
+  149.60 
-174.13 
+  103.48 

5 
23 
10 
10 
15 

-  32.77 
+  59.83 
+  74.79 
-  34.83 
+  123.80 

4 
3 
4 
1 
11 

+  10.20 
+  89.11 
+  72.16 
-  94.32 
+  129.11 

5 
5 
5 
5 

10 

-  35.76 
+  127.35 
+  122.51 
-47.83 
+  172.15 

6 
5 
4 
8 
3 

Maltose  

'  Ann.,  271,  49.  f  Z.  physik.  Chem.,  22,  439.  J  Ibid.,  17,  320. 

§  Z.  physik.  Chem.,  22,  424.  ||  Z.  Ver.  Deut.  Zuckerind.,  62,  19. 


SPECIFIC  ROTATION  OF  SUGARS  191 

A  peculiarity  of  xylose  and  rhamnose  in  pyridine  is  an  increase  in 
the  rotation  after  solution.  Grossmann  and  Bloch  observed  a  maximum 
of  +  122.07  in  case  of  xylose  15  minutes  after  solution  and  a  maximum 
of  —  45.92  in  case  of  rhamnose  30  minutes  after  solution.  It  is  seen 
that  mutarotation  in  the  two  solvents  proceeds  in  many  cases  in  opposite 
directions  and  that  there  is  no  relation  between  the  constant  rotations 
and  those  observed  in  aqueous  solution.  The  addition  of  water  to 
solutions  of  sugar  in  organic  solvents  accelerates,  and  conversely  the 
addition  of  alcohol,  acetone,  etc.,  to  aqueous  solutions  retards,  the  speed 
of  mutarotation.  As  a  general  rule  the  presence  of  any  soluble  non- 
electrolyte,  such,  for  example,  as  sucrose,  will  increase  the  time  necessary 
for  a  mutarotating  sugar  to  reach  constant  polarization. 

Mutarotation  takes  place  not  only  after  dissolving  reducing  sugars, 
but  also  occurs  upon  the  liberation  of  these  sugars  from  higher  saccharides 
by  the  action  of  enzymes.  The  phenomenon  is  one  which  the  sugar 
chemist  has  always  to  bear  in  mind.  Polariscopic  measurements  are 
always  referred  to  the  normal  constant  rotation.  The  latter  condition 
may  be  produced  almost  instantly  by  heating  the  solution  or  by  adding 
a  little  free  alkali,  but  when  such  means  are  employed  care  must  be 
taken  to  prevent  the  liability  of  chemical  change.  The  safest  course 
is  to  allow  the  solution  to  stand  until  the  rotation  has  come  to  equili- 
brium in  the  natural  way. 

Theories  of  Mutarotation.  —  Many  theories  have  been  proposed 
to  explain  mutarotation.  According  to  the  views  of  Landolt*  and  other 
authorities  it  was  thought  that  the  phenomenon  might  be  due  to  the 
formation  of  molecular  aggregates  immediately  after  solution,  which 
afterwards  decompose  into  simple  molecules  of  lower  rotation.  These 
earlier  theories  were  largely  disproved,  however,  by  the  experiments  of 
Arrhenius,t  and  of  Brown  and  Morris,!  who  showed  that  no  change 
occurred  in  the  molecular  weight  of  a  sugar  during  mutarotation. 
Tollens§  and  others  of  his  school  have  supposed  that  mutarotation 
might  be  caused  by  the  formation  of  unstable  hydrates  which,  by  the 
splitting  off  of  water,  cause  a  change  in  rotation. 

Much  additional  light  was  thrown  upon  the  subject  in  1895  by 
Tanret,  ||  who  discovered  that  sugars  could  exist  in  both  a  high-  and  a 
low-mutarotating  form.  The  relationship  of  these  several  modifica- 
tions, according  to  Tanret's  classification,  is  shown  for  four  different 
sugars  in  the  following  table. 

*  "Das  optische  Drehungsvermogen "  (1879),  58. 

t  Z.  physik.  Chem.,  2,  500.  t  Chem.  News,  67,  196. 

§  Ber.,  26,  1799.  0  Compt.  rend.,  120,  1060. 


192 


SUGAR  ANALYSIS 


Sugar. 

a 
Metastable. 

0 

Stable. 

y 
Metastable. 

d-Glucose  

+105° 

+52.5° 

+22.5° 

d-Galactose 

+135 

+81 

+52 

Lactose 

+  88 

+55 

+36 

Rhamnose 

-     6 

+  9 

+23 

Tanret's  a.  modification  represents  the  ordinary  sugar  as  obtained 
by  crystallization  from  aqueous  solution.  The  /3  modification,  or  form 
of  constant  rotation,  was  usually  obtained  by  precipitating  a  saturated 
aqueous  solution  of  the  a  sugar  with  several  volumes  of  absolute  alcohol. 
The  7  modification  was  usually  prepared  by  evaporating  a  concentrated 
solution  of  the  a  sugar  to  dryness  and  then  heating  for  several  hours  to 
about  100°  C.  Repeating  the  process  several  times  increases  the  purity 
of  the  various  modifications.  In  the  case  of  rhamnose  the  a  modifica- 
tion is  the  lower,  and  the  y  modification  the  higher  rotating  form. 

Previous  to  Tanret's  work,  Lippmann*  had  expressed  the  view  that 
mutarotation  might  be  due  to  a  stereochemical  change  between  two 
forms  of  the  same  sugar,  and  showed,  how  by  adopting  a  form  of  struc- 
ture first  proposed  by  Tollens,  that  one  of  the  terminal  carbon  atoms 
of  the  sugar  molecule  became  asymmetric  (i.e.  connected  to  four  dis- 
similar atoms  or  groups),  thus  permitting  the  existence  of  two  con- 
figurations for  the  same  sugar.  The  theory  of  mutarotation  most 
generally  accepted  at  the  present  time  assigns  one  of  these  configura- 
tions to  the  high-rotating,  and  the  other  configuration  to  the  low-rotat- 
ing form.  The  mutarotation  reaction  according  to  Lowryf  is  thus 
regarded  as  a  balanced  reaction  between  two  molecular  forms  of  the 
same  sugar,  as  for  example: 


CH2OH 
HOCH 

HCOH 
HOCH 


CH2OH 
HOCH 

C^H 

CH  > 

HCOH        < 

HOCH 

f^C— OH 

a  glucose 
MD  =  + 105 

Which  of  the  above  configurations  belongs  to  the  a  or  0  sugar  has 
not  been  determined. 

*    Ber.,  29,  203.  f  J.  Chem.  Soc.,  76,  212. 


glucose 
=+22.5. 


SPECIFIC  ROTATION  OF  SUGARS  193 

Lowry's  view  was  supported  by  Hudson,*  who  showed  by  quan- 
titative experiments  that  the  change  between  the  high-  and  low-rotating 
forms  of  lactose  was  a  balanced  reaction.  According  to  this  view, 
Tanret's  solid  (3  sugars  of  constant  rotation  are  simply  equilibrated 
mixtures  of  the  high-  and  low-rotating  forms.  The  designation  /3  is 
applied  at  present  to  Tanret's  y  modification. 

While  mutarotation  is  most  generally  regarded  at  present  as  a 
balanced  reaction  between  high-  and  low-rotating  forms,  the  intermediate 
steps  of  the  process  have  not  been  definitely  established.  The  change 
in  polarization  of  a  sugar  solution  to  constant  rotation  is  regarded  by 
some  chemists  as  simply  a  conversion  of  the  a  or  /3  oxygen  ring  com- 
pound into  the  ordinary  aldehyde  or  ketone  form.  Other  chemists 
regard  the  solution  at  constant  rotation  as  containing  simply  a  mixture 
of  the  a  and  /3  sugars  in  equilibrium,  while  still  others  believe  it  to 
contain  the  a  and  #  sugars  with  variable  amounts  of  the  aldehyde  or 
ketone  form.  For  a  review  of  the  different  hypotheses,  which  have 
been  proposed  in  this  connection,  the  chemist  is  referred  to  the  various 
special  works,  f 

*  Z.  physik.  Chem.,  44,  487.     See  also  page  711. 

f  Lippmann,  "Chemie  der  Zuckerarten"  (1904),  293. 

Hudson  (J.  Am.  Chem.  Soc.,  32,  889)  in  a  paper  entitled  "A  Review  of  Discov- 
eries on  the  Mutarotation  of  Sugars,"  gives  a  very  complete  review  and  bibliography 
of  the  subject. 


CHAPTER  IX 


METHODS   OF   SIMPLE  POLARIZATION 

DETERMINATION  OF  SUGARS  FROM  ANGULAR  ROTATION 

THE  amount  of  a  single  optically  active  sugar,  in  presence  of  opti- 
cally inactive  substances  or  in  presence  of  substances  without  effect 
upon  its  specific  rotation,  may  be  calculated  by  means  of  either  formula 
for  specific  rotation  (page  172). 

100  a      ,  100  a 


, 

whence 


100  a 


100  a 


lXdX[a]D 


As  to  which  of  the  above  methods  of  calculation  is  to  be  used,  the 
first  or  concentration  formula  is  the  better  where  a  definite  weight  of 
substance  is  made  up  to  volume  before  polarization,  the  usual  method 
of  procedure;  in  case,  however,  a  sugar  solution  of  known  specific 
gravity  is  polarized  directly,  then  the  second  or  percentage  formula 
is  to  be  employed. 

The  following  formulae  are  given  for  calculating  the  concentration 
(grams  per  100  c.c.)  of  different  sugars  from  the  angular  rotation  (a) 
in  a  2-dm.  tube. 


Arabinose  c  = 


x 


=  °-4785  a- 


3.   Glucose     c  = 


4.   Fructose    c  = 


5.   Galactose  c  = 


10° 


X 


&  X  -f-  ol.U 

6.  Sucrose      c  =        ~      =  0.7519  a. 


=  0.9470  a. 

=  0.5405  a  (left  degrees). 

=  0.6173  a. 


194 


METHODS  OF  SIMPLE  POLARIZATION  195 

8.   Lactose      c  =  =0.9524  a. 


9.   Raffinose  (+  5  H20)  c  =  2  x  5  =  0.4785  a. 

10.   Raffinose  (anhydride)     c  =  J*         =  0.4060  a. 

z  x  T~  iZo.io 

The  percentage  p  of  a  sugar  in  solution  is  equal  to  the  value  of  c, 
as  expressed  above,  divided  by  the  specific  gravity  of  the  solution. 

Such  formulae,  as  the  above,  are  sufficiently  accurate  for  most  pur- 
poses of  analysis.  In  cases,  however,  where  the  specific  rotation  of  the 
sugar  is  affected  by  changes  in  concentration  or  temperature,  the  results 
as  obtained  above  can  be  considered  only  approximate;  to  obtain  the 
correct  concentration  or  percentage,  it  is  necessary  to  calculate  the 
specific  rotation  corresponding  to  the  approximate  value  of  c  or  p  at 
the  temperature  of  polarization  and  substitute  this  corrected  specific 
rotation  in  formulae  (1)  or  (2)  for  the  final  calculation  of  c  or  p. 

Example.  —  50  gms.  of  a  dextrose  sirup  were  dissolved  to  100  cc.;  the 
constant  rotation  of  the  solution  thus  obtained  was  -f  34.55  circular  degrees 
in  the  200-mm.  tube.  Required  the  percentage  of  dextrose  in  the  sirup. 

From  formula  3  we  obtain  by  substitution  c  =  0.9470  X  34.55  =  32.72  gms. 
dextrose  in  the  100  cc.  of  solution  or  for  the  50  gms.  of  sirup,  65.44  per  cent 
approximately.  The  specific  rotation  of  dextrose  for  c  =  32.72  is  found  from 
the  formula  [«]g°  =  +  52.50  +  0.0227  c  +  0.00022  c2  (p.  177)  to  be  +53.48; 
substituting  this  in  the  general  formula  for  c  we  obtain 

<  =         5  =32.30  gm, 


in  the  100  cc.  of  solution  or  for  the  50  gms.  of  sirup  the  true  percentage  64.60,  — 
0.84  per  cent  less  than  the  value  by  the  uncorrected  formula. 

By  modifying  the  formula  for  c,  so  as  to  correct  for  the  variations 
in  specific  rotation,  the  labor  of  the  second  calculation  in  the  above  ex- 
ample may  be  eliminated.  In  the  case  of  glucose,  by  calculating  the 
angular  rotation,  (a)  for  the  2-dm.  tube,  corresponding  to  concentra- 
tions ranging  from  10  to  60,  we  obtain,  using  the  method  of  least 
squares  (p.  165),  the  formula  c*  =  0.958  a  -  0.00067  a2. 

Example.  —  Applying  the  last  formula  to  the  previous  example,  we  obtain 
for  c,  32.299  gms.  dextrose  in  the  100  cc.  of  solution  or  for  the  50  gms.  sirup 
64.60  per  cent. 

*  For  p  Landolt  gives  the  formula  p  =  0.948  a  -  0.0032  a2.  ("  Optisches  Dre- 
hungsvermogen,"  p.  447.) 


196  SUGAR  ANALYSIS 

DETERMINATION  OF  SUGARS  FROM  SACCHARIMETER  READINGS 

Conversion  of  Saccharimeter  Readings  into  Angular  Rotation. — 

The  general  methods  of  optical  analysis  just  described  are  more  es- 
pecially applicable  to  polarimeters,  where  readings  are  taken  in  angular 
degrees;  the  formulae  given  are  equally  applicable,  however,  to  saccharim- 
eters  in  which  case  the  scale  reading  of  the  latter  must  be  converted 
into  angular  degrees  by  means  of  the  proper  conversion  factor.  For 
general  purposes  the  factor  established  for  sucrose  may  be  applied  to 
other  sugars.  In  the  case  of  the  Ventzke  scale,  sugar  degrees 
X  0.34657  =  angular  rotation.  Since,  however,  the  rotation  disper- 
sion of  the  various  sugars,  with  reference  to  the  quartz  compensation  of 
the  saccharimeter,  may  differ  somewhat  from  that  of  sucrose,  it  is 
always  better,  where  exact  data  are  available  (which  is  unfortunately 
not  always  the  case),  to  use  the  conversion  factor  established  for  the 
particular  sugar.  In  the  case  of  a  few  sugars  Landolt  *  has  established 
the  following  factors  for  converting  divisions  of  the  Ventzke  scale  into 
circular  degrees. 

Sucrose 0.3465 

Lactose 0 . 3452 

Glucose 0.3448 

Invert  sugar 0 . 3432 

Raffinose 0.3450 

Brown,  Morris,  and  Millar f  give  the  following: 

Sucrose,  10  per  cent  solution 0.3469 

Maltose,  10  per  cent  solution 0 . 3449 

Maltose,  5  per  cent  solution 0 . 3457 

Glucose,  10  per  cent  solution ' 0.3442 

Glucose,  5  per  cent  solution 0 . 3454 

Starch  products,  10  per  cent  solution 0.3458 

Starch  products,  5  per  cent  solution 0.3454 

Herzfeld,J  with  a  solution  containing  11.29  per  cent  anhydrous 
maltose,  obtained  upon  a  Peters  saccharimeter,  using  a  Welsbach  light 
with  chromate  filter,  a  reading  of  93.88  Ventzke  degrees  at  20°  C.,  and 
with  the  same  solution  upon  a  Lippich  polarimeter  a  reading  of  32.60 
circular  degrees  at  20°  C.  The  value  of  a  Ventzke-scale  division  for 

maltose  under  these  conditions  is  therefore  H^  =  0.3471    circular 

9o.oo 

degree,  a  figure  perceptibly  greater  than  the  values  of  Brown,  Morris, 
and  Millar.  Differences  in  concentration  of  the  sugar  solutions  ex- 
amined but  more  especially  differences  in  the  optical  center  of  gravity 
of  the  light  employed  for  illuminating  the  saccharimeter  are  the  chief 
*  Ber.,  21,  194.  f  J-  Chem.  Soc.  Trans.,  71,  92.  J  Ber.,  28,  441. 


METHODS  OF  SIMPLE  POLARIZATION 


197 


causes  of  such  discrepancies.  The  chemist  should,  therefore,  employ 
any  prescribed  conversion  factor  with  caution  and  use  it  only  under  the 
same  conditions  for  which  it  was  established.  It  is  also  well  to  verify 
a  conversion  factor  wherever  possible,  by  comparative  readings  of  the 
same  sugar  solution  upon  a  polarimeter.  The  latter  instrument  does 
away  with  the  errors  of  rotation  dispersion  and,  aside  from  the  objection 
of  using  monochromatic  light,  is  always  to  be  preferred  in  methods 
where  the  concentration  or  percentage  of  sugar  is  calculated  from  the 
angular  rotation.  If  a  quartz-wedge  saccharimeter  is  the  only  instru- 
ment available,  the  average  factor  0.346  may  be  used  for  most  pur- 
poses without  serious  error. 

Normal  Weights  of  Sugars.  —  If  a  normal  weight  of  each  particular 
sugar  be  taken  for  polarization,  (i.e.  the  weight  of  pure  sugar  which 
dissolved  to  100  c.c.  will  give  a  scale  reading  of  100),  the  percentage 
(uncorrected)  of  sugar  may  be  read  directly  upon  the  saccharimeter. 

There  are  a  number  of  methods  of  calculating  the  normal  weight 
for  different  sugars.  If  we  assume  in  case  of  the  Ventzke  scale  that 
the  angular  rotation  of  each  division  is  0.34657  circular  degree  for  all 
sugars,  then  the  normal  weight  (20°  C.,  100  true  c.c.)  of  any  sugar,  for 
the  2-dm.  observation  tube,  as  compared  with  26.00  gms.,  will  be  in- 
versely proportional  to  the  specific  rotations  of  this  sugar  and  of  sucrose, 

that  is: 

1729 
[a]g:  66.5  :  :  26  gms.  :  X,  whence  X  (the  normal  weight)  =  f-W' 

\.a\D 

The  normal  weights  of  several  sugars  calculated  by  this  method  are  given 

in  the  following  table: 

TABLE  XXXV 
Giving  Normal  Weights  of  Different  Sugars  for  Ventzke  Scale 


Sugar. 

Specific  rotation  [a]%- 

Normal  weight. 

Glucose   >  -  

+53.46    c=32.5gms. 
-93.00    c=18.5gms. 
-20.00    c=  10.0  gms. 
+52.53 
+138.25    c=  12.  5  gms. 
+104.5 
+123.17 

^6  =32.342  gms. 
^  =  18.  592  gms. 
l™  -86.  450  gins. 

Fructose                 .       

I,aptr>9f»  (4-TToO^ 

1729  -32.  914  cms. 

IVIaltose 

52.53 
I™-  12.  506  gms. 

TJnflRnrxsA  (4-^  TT«O^ 

138.25 

179Q 

1/zy  -IQ  545  gms 

104.5 
1729    _j.  »„_ 

123.17                 B 

198  SUGAR  ANALYSIS 

While  the  normal  weights  calculated  in  this  manner  are  sufficiently 
exact  for  most  purposes  of  analysis  they  must  not  be  regarded  as 
absolute.  Owing  to  the  differences,  previously  mentioned,  in  rota- 
tion dispersion  for  the  different  sugars  the  angular  rotation  of  each 
Ventzke-scale  division  will  vary  slightly  from  0.34657  circular  degree 
with  a  corresponding  change  in  the  value  of  the  normal  weight. 

If  the  value  of  the  100-degree  saccharimetric  reading  of  each  sugar 
has  been  established  in  circular  degrees,  for  the  same  conditions  under 
which  analyses  are  made,  it  is  always  better  to  base  the  calculation  of 
the  normal  weight  upon  this.  The  method  of  calculation  for  the 
Ventzke  scale,  using  as  illustrations  four  of  the  sugars  previously  taken, 
is  as  follows: 

From  the  general  formula  c  =  ,  —  f-r—  we  obtain  for 

IX  [a\D 

Glucose 

(1°  V.  =  0.3448  circular  degree,  Landolt),  c  =  l™***'4*  =  32.248  gms. 

Z  X  oo.4o 

Lactose 

(1°  V.  =  0.3452  circular  degree,  Landolt)  ,  c  =  1™*J?*2  =  32.857  gms. 

Z  X 

Maltose 


l-  V.  .  0.3449  eircular  degrees,  c  -  ,  12,74  gms. 


Raffinose  +  5  H2O 

(1°  V.  =  0.3450  circular  degree,  Landolt)  ,  c  =  1'      =  16.507  gms. 

&  x\  104.0 

The  conversion  factors  to  be  employed,  and  hence  the  values  of  the 
normal  weights,  will  necessarily  depend  upon  the  quality  of  the  light 
used  for  illuminating  the  saccharimeter.  The  value  of  a  saccharimeter 
division  in  circular  degrees  for  a  solution  of  the  sugar  of  the  approximate 
concentration,  should,  therefore,  be  established  by  the  chemist  himself 
wherever  possible. 

Correction  for  Concentration  and  Temperature.  —  When  normal 
weights  of  the  different  sugars  are  used,  the  observed  saccharimeter 
readings  require  correction  for  changes  in  concentration  and  tempera- 
ture as  described  on  page  195.  Where  much  work  is  done  with  a  single 
sugar  a  table  of  corrections  should  be  prepared,  giving  the  actual  sugar 
value  corresponding  to  each  scale  division  of  the  saccharimeter.  The 
correction  table  for  sucrose  (page  118)  or  the  following  results  calcu- 
lated by  Browne*  for  glucose  upon  the  basis  of  the  normal  weight  of 
32.25  gms.  will  illustrate  the  method. 

*  J.  Ind.  Eng.  Chem.,  2,  526. 


METHODS  OF  SIMPLE  POLARIZATION 


199 


Scale  division. 

Concentration. 
Grams  glucose 
100  true  c.c. 
20°  C. 

Specific  rota- 
tion, glucose 

[«]£. 

Actual  glucose 
value  of  scale 
division. 

Correction 
to  be  added. 

100°  V. 

32.250 

53.46 

100.00 

0.00 

90 

29.025 

53.34 

90.20 

0.20 

80 

25.800 

53.23 

80.35 

0.35 

70 

22.575 

53.12 

70.45 

0.45 

60 

19.350 

53.02 

60.50 

0.50 

50 

16.125 

52.92 

50.51 

0.51 

40 

12.900 

52.83 

40.48 

0.48 

30 

9.675 

52.74 

30.41 

0.41 

20 

6.450 

52.66 

20.30 

0.30 

10 

3.225 

52.58 

10.17 

0.17 

1 

0.323 

52.51 

1.02 

0.02 

The  correction  necessary  to  be  added  to  any  reading  (s)  of  the 
saccharimeter  scale,  as  formulated  from  the  above  table,  is  equal  very 
closely  to  +  0.02  s  -  0.0002  s2.  The  percentage  of  glucose  (G)  corre- 
sponding to  any  scale  reading  (s)  of  the  saccharimeter  is,  therefore, 
expressed  by  the  formula 

G  =  s  +  0.02  s  -  0.0002  s2. 

Some  authorities  have  established  the  normal  weights  of  sugars  for 
5,  10,  15,  20,  and  25  per  cent  solutions.  Landolt*  gives  as  the  normal 
weight  of  glucose  for  a  5  per  cent  solution  32.91  gms.,  for  a  15  per  cent 
solution  32.75  gms.,  and  for  a  25  per  cent  solution  32.50  gms.,  in  which 
connection  he  states  that,  in  weighing  out  the  glucose-containing  ma- 
terial for  polarization,  the  chemist  must  select  his  normal  weight  ac- 
cording to  the  amount  of  glucose  present.  This,  of  course,  involves  a 
preliminary  assay  of  the  material  under  examination,  which  means  prac- 
tically doubling  the  work  of  analysis.  A  variable  normal  weight  is, 
moreover,  confusing,  and  a  source  of  error.  Wherever  possible  one 
fixed  value  should  be  given  to  the  normal  weight,  the  value  to  be  selected 
(as  in  the  case  of  sucrose)  being  that  weight  of  chemically  pure  sugar, 
which  dissolved  to  100  true  c.c.  and  polarized  at  20°  C.  in  a  200-mm. 
tube  will  give  a  constant  reading  of  exactly  100  upon  the  saccharimeter. 
If  in  the  use  of  such  a  normal  weight  with  impure  products,  readings  of 
less  than  100  are  obtained,  the  latter  are  corrected  by  a  table  or  formula 
similar  to  that  just  given  for  glucose. 

Conversion  of  Saccharimeter  Readings  into  Weight  of  Sugars.  — 
It  is  often  desirable  to  express  the  equivalent  of  a  saccharimeter  read- 
ing, for  a  200-mm.  tube,  in  grams  of  a  particular  sugar  in  100  c.c.     This 
equivalent  can  be  found  by  multiplying  the  values  of  the   formulae 

'  *  Landolt,  "Das  optische  Drehungsvermogen "  (1898),  p.  448. 


200  SUGAR  ANALYSIS 

on  page  194  by  the  angular  rotation  of  1  degree  of  the  saccharimeter 
scale  (page  145),  thus: 

1°  angular  rotation  D  =  0.4785  gm.  arabinose. 

1°  Ventzke  sugar  scale  =  0.4785  X  0.34657  =  0.1658  gm.  arabinose. 
1°  French  sugar  scale  =  0.4785  X  0.21666  =  0. 1037  gm.  arabinose. 
1  °  Wild  sugar  scale  =  0 . 4785  X  0 . 13284  =  0 . 0635  gm.  arabinose. 

Owing  to  the  lack  of  absolute  agreement  in  the  value  of  each  sac- 
charimeter scale  in  circular  degrees,  due  to  rotation  dispersion,  varia- 
tion in  quality  of  light,  etc.,  the  equivalent  of  1  degree  of  a  saccharimeter 
scale  is  best  expressed  as  T^  of  the  weight  of  sugar,  which  will  give  a 
reading  of  100  degrees  under  the  prescribed  conditions  of  analysis  (i.e.  T^ 
of  its  normal  weight).  The  correction  for  concentration  is  afterwards 
applied  as  indicated  above. 

The  approximate  value  of  1°  V.  for  the  more  common  sugars  is 

given  below. 

Weight  of  Sugar  in  100  metric  ex. 

1°  V.  at  20°  C.  =  0.2600  gm.  sucrose. 

1°  V.  at  20°  C.  =  0.3225  gm.  glucose. 

1°  V.  at  20°  C.  =  0.1859  gm.  fructose. 

1°  V.  at  20°  C.  =  0.3286  gm.  lactose  hydrate. 

1°  V.  at  20°  C.  =  0.1247  gm.  maltose. 

1°  V.  at  20°  C.  =  0.1655  gm.  arabinose. 

1°  V.  at  20°  C.  =  0.9100  gm.  xylose. 

1°  V.  at  20°  C.  =  0.2135  gm.  galactose. 

1°  V.  at  20°  C.  =  0.8645  gm.  invert  sugar. 

1°  V.  at  20°  C.  =  0.1651  gm.  raffinose  hydrate. 

Use  of  One  Normal  Weight  for  All  Sugars.  —  For  many  laboratory 
purposes  it  is  convenient  to  employ  but  one  fixed  normal  weight  for  all 
saccharimetric  work.  In  such  cases  the  normal  weight  of  sucrose  is 
usually  taken,  the  percentage  of  each  particular  sugar  being  calculated 
from  the  scale  reading  by  means  of  an  appropriate  factor. 

The  constant  polarizations  in  degrees  Ventzke  of  a  normal  weight 
of  26.00  gms.  of  different  sugars,  when  dissolved  to  100  metric  c.c.  and 
polarized  in  a  200-mm.  tube,  are  given  in  table  XXXVI.  The  values 
are  calculated  only  to  the  nearest  0.5  degree,  which  is  sufficiently  exact 
when  the  variations  due  to  change  in  concentration  are  considered. 

If  no  other  optically  active  substances  are  present,  the  scale  reading 
(V.°)  of  26.00  gms.  of  the  sugar-containing  substance  multiplied  by 
100  and  divided  by  the  corresponding  polarizing  power  of  the  pure 
sugar  will  give  the  percentage. of  sugar  present.  Owing  to  the  changes 
in  specific  rotation  with  varying  concentration,  the  percentages  thus 
calculated  will  not  be  absolutely  exact. 


METHODS  OF  SIMPLE  POLARIZATION 


201 


TABLE  XXXVI 
Giving  Ventzke  Reading  of  26.00  gms.  of  Different  Sugars  in  100  c.c. 


Sugar. 

wf 

26.00  gms.  in  100 
metric  c.c. 

Calculated  read- 
ing v°. 

M*D    X  100. 
66.5 

Sucrose  
Arabinose 

+  66.5 
+104  5 

+  100 

+157 

Xylose 

+19  6 

+29  5 

Glucose. 

+53  2 

4-80 

Fructose 

—93  2 

—  140 

Invert  sugar 

-20  0 

—30 

Galactose 

+81  8 

+123 

Maltose  .  .  . 

+138  0 

+207  5 

Lactose  (H2O).  .'  
Raffinose  (5  H2O)  
Raffinose  (anhydride)  .  . 

+52.5 
+104.5 
+123.2 

+79 
+157 
+  185 

TECHNICAL  METHODS  OF  SACCHARIMETRY 

The  saccharimeter  is  most  generally  employed  in  the  analysis  of 
products  of  the  cane-  and  beet-sugar  industry.  It  must  be  borne  in 
mind,  however,  that  the  readings  of  the  saccharimeter  scale  indicate 
percentages  of  sucrose  only  in  cases  where  other  constituents  have  no 
effect  upon  the  scale  reading;  the  results  obtained  with  impure  products 
are,  therefore,  more  correctly  expressed  as  degrees  polarization  or  degrees 
sugar  scale.  For  a  more  accurate  determination  of  sucrose  by  the 
saccharimeter,  the  method  of  inversion  must  be  used  which  will  be 
described  in  the  following  chapter. 

Methods  for  Polarizing  Raw  Sugars 

Rules  of  the  International  Commission.  —  The  rules  of  the  Inter- 
national Commission  for  Unifying  Methods  of  Sugar  Analysis*  are  as 
follows : 

"In  general  all  polarizations  are  to  be  made  at  20°  C. 

"The  verification  of  the  saccharimeter  must  also  be  made  at  20°  C. 
For  instruments  using  the  Ventzke  scale  26  grams  of  pure  dry  sucrose, 
weighed  in  air  with  brass  weights,  dissolved  to  100  metric  c.c.  at  20°  C. 
and  polarized  in  a  room,  the  temperature  of  which  is  also  20°  C.,  must 
give  a  saccharimeter  reading  of  exactly  100.00.  The  temperature  of  the 
sugar  solution  during  polarization  must  be  kept  constant  at  20°  C. 

"For  countries  where  the  mean  temperature  is  higher  than  20°  C., 
saccharimeters  may  be  adjusted  at  30°  C.  or  any  other  suitable  tem- 
*  Proceedings  of  Paris  Meeting,  July  24,  1900. 


202  SUGAR  ANALYSIS 

perature,  under  the  conditions  specified  above,  provided  that  the  sugar 
solution  be  made  up  to  volume  and  polarized  at  this  same  temperature. 

"In  effecting  the  polarization  of  substances  containing  sugar  employ 
only  half-shade  instruments. 

"During  the  observation  keep  the  apparatus  in  a  fixed  position 
and  so  far  removed  from  the  source  of  light  that  the  polarizing  Nicol 
is  not  warmed. 

"As  sources  of  light  employ  lamps  which  give  a  strong  illumination 
such  as  triple  gas  burner  with  metallic  cylinder,  lens  and  reflector;  gas 
lamps  with  Auer  (Welsbach)  burner;  electric  lamp;  petroleum  duplex 
lamp;  sodium  light. 

"Before  and  after  each  set  of  observations  the  chemist  must  satisfy 
himself  of  the  correct  adjustment  of  his  saccharimeter  by  means  of 
standardized  quartz  plates.  He  must  also  previously  satisfy  himself  of 
the  accuracy  of  his  weights,  polarization  flasks,  observation  tubes  and 
cover-glasses.  (Scratched  cover-glasses  must  not  be  used.)  Make 
several  readings  and  take  the  mean  thereof ,  but  no  one  reading  may  be 
neglected. 

"In  making  a  polarization  use  the  whole  normal  weight  for  100  c.c., 
or  a  multiple  thereof,  for  any  corresponding  volume. 

"As  clarifying  and  decolorizing  agents  use  either  subacetate  of 
lead,  alumina  cream,  or  concentrated  solution  of  alum.  Boneblack  and 
decolorizing  powders  are  to  be  excluded. 

"After  bringing  the  solution  exactly  to  the  mark  at  the  proper 
temperature,  and  after  wiping  out  the  neck  of  the  flask  with  filter 
paper,  pour  all  of  the  well-shaken  clarified  sugar  solution  on  a  rapidly 
acting  filter.  Reject  the  first  portions  of  the  filtrate  and  use  the  rest, 
which  must  be  perfectly  clear  for  polarization." 

Methods  of  the  New  York  Sugar  Trade  Laboratory.,—  Details  of 
manipulation  for  the  above  rules  are  left  largely  to  individual  prefer- 
ence or  requirement.  The  course  of  operations  pursued  by  the  New 
York  Sugar  Trade  Laboratory,  where  rapidity  as  well  as  accuracy  is 
required,  is  as  follows: 

Weighing.  —  Twenty-six  grams  of  sugar  are  weighed  out  in  a  nickel 
sugar  dish  provided  with  a  counterpoise  (Figs.  116  and  123).  The 
sugar  is  stirred  with  a  horn  spoon  and,  approximately,  the  normal 
weight  transferred  to  the  dish.  The  final  adjustment  is  then  made  with 
the  dish  upon  the  scale  pan  of  the  balance,  a  little  sugar  being  added 
or  removed  until  the  exact  weight  is  secured.  The  danger  of  spilling 
sugar  upon  the  scale  pan  during  the  weighing  is  thus  largely  avoided. 
The  weighing  is  performed  as  rapidly  as  possible  to  avoid  loss  from 


METHODS  OF  SIMPLE  POLARIZATION  203 

evaporation  of  moisture  and  does  not  usually  consume  more  than  a 
minute  of  time. 

Transferring.  —  The  26  gms.  of  sugar  in  the  nickel  dish  are  poured 
into  a  large  funnel  placed  in  a  sugar  flask;  any  sugar  adhering  to  the 
dish  and  funnel  is  then  washed  into  the  flask  with  distilled  water,  the 
funnel  being  thoroughly  rinsed  inside  and  outside  around  the  bottom 
to  insure  the  complete  removal  of  all  sugar  to  the  flask.  From  50  to  60 
c.c.  of  water  are  sufficient  to  effect  the  transference. 

The  funnels  employed  in  transferring  the  sugar  are  of  German 
silver,  and  have  a  mouth  4  in.  (ll£  cm.)  in  width  and  3  in.  (9  cm.)  in 
depth,  and  a  stem  3  in.  (9  cm.)  in  length.  The  inner  diameter  of  the 


(a)  (b)  (c) 

Fig.  123.  —  (a)  Nickel  weighing  dish  and  counterpoise.     (6)  Funnel  for  transferring 
sugar,     (c)  Normal  and  half-normal  metric  c.c.  sugar  weights. 

stem  (8J  mm.)  is  sufficiently  large  to  allow  a  free  passage  of  the  sugar 
into  the  flask  and  the  outer  diameter  (10  mm.)  sufficiently  small  to 
allow  the  escape  of  air  from  the  flask  (see  Fig.  123). 

Dissolving.  —  The  solution  of  the  sugar  in  the  flasks  is  performed  by 
means  of  a  mechanical  shaker.  The  machine  employed  in  the  New 
York  Sugar  Trade  Laboratory  is  a  modification  by  the  author  of  the 
Camp  shaker  used  in  iron  and  steel  laboratories.  (Fig.  -124.) 

The  metal  disk  of  this  shaker  is  replaced  by  a  circular  piece  of  oak 
1  in.  thick,  of  the  same  diameter  and  of  about  the  same  weight,  and 
containing  12  holes  2J  in.  in  diameter,  each  large  enough  to  accommodate 
the  bottom  of  a  sugar  flask.  Six  extra  gripping  devices  are  inserted  in 
the  collar  of  the  shaker,  thus  giving  12  grips  in  all  to  hold  the  necks 
of  the  flasks.  The  collar  is  adjusted  so  as  to  bring  the  grips  at  the 
right  height  and  exactly  over  the  centers  of  the  circular  holes  in  the 
wooden  disk.  The  bottom  of  the  flasks  are  inserted  in  the  holes,  and, 


204 


SUGAR  ANALYSIS 


by  pressing  the  necks  against  the  springs  of  the  grips,  the  flasks  are 
snapped  quickly  and  securely  into  position.  The  shaker  is  connected 
with  a  small  J  horse-power  electric  motor,  provided  with  a  rheostat, 
and  the  speed  of  its  driving  wheel  gradually  brought  up  to  120  to  130 
revolutions  per  minute.  At  this  speed,  solution  of  sugar  in  the  flasks, 
using  50  to  60  c.c.  of  water,  is  effected  in  from  5  to  10  minutes,  according 
to  the  size  of  grain,  stickiness  of  sample,  etc.  If  too  much  water  is 
used  in  transferring  the  sugar,  less  motion  is  given  to  the  body  of  the 
liquid,  and  a  longer  time  is  required  to  effect  solution. 


Fig.  124.  —  Mechanical  shaker  for  dissolving  sugars. 

Clarifying.  —  The  solution  is  then  clarified  with  the  requisite 
amount  of  lead  subacetate  solution  (sp.  gr.  1.25),  but  no  more  than 
the  amount  necessary  to  secure  a  clear  polariscope  reading  is  ever 
employed.  As  a  rule  not  over  1  c.c.  of  the  lead  subacetate  solution 
is  used  for  Java,  Peruvian,  and  high-grade  centrifugal  sugars,  not  over 
1  to  2  c.c.  for  muscovado  sugars,  from  2  to  6  c.c.  for  molasses  sugars, 
and  3,  4,  and  5  c.c.  for  Philippine  mat  sugars  according  to  grade.  Ex- 
cess of  lead  solution  increases  the  polarization  very  markedly  and 
strict  observance  is  paid  to  the  rule  of  minimum  quantity  necessary 
for  clarification.  After  the  lead  solution  2  c.c.  of  alumina  cream  are 
added,  the  contents  of  the  flask  are  well  mixed  and  the  volume  of  liquid 
made  up  to  100  c.c.,  after  allowing  sufficient  time  for  any  air  bubbles 
to  arise  which  may  have  been  occluded  in  the  lead  precipitate.  Foam 
and  air  bubbles,  adhering  to  the  surface  of  the  liquid  in  the  neck  of 
the  flask,  are  broken  up  with  a  fine  spray  of  ether  before  adjusting  the 


METHODS  OF  SIMPLE  POLARIZATION 


205 


I 


volume  to  the  graduation  mark.     A  small  bulb  atomizer  (Fig.  125) 

is  convenient  for  removing  foam. 

The  distilled  water  used  in  all  the  work  is  supplied  through 

rubber  tubing  from  a  large  bottle  placed  at  an  elevation  above 

the  laboratory  table.  The 
outlets  of  the  rubber  tubes 
are  fitted  with  pinch  cocks 
and  glass  tips  of  large  and 
fine  opening,  the  former 
being  used  for  transferring 
the  sugar  and  the  latter  for 
setting  the  meniscus.  The 
adjustment  of  the  meniscus 
to  the  graduation  mark  is 
the  same  as  that  used  in 
calibration  (Fig.  119).  The  /\ 
distilled  water  used  for  solu- 
tion is  kept  as  nearly  as 
Fig.  125.-Ether  atomizer.  ^^  ^  2Qo  c>  ^  ^ 

completion  of  the  volume  of  sugar  solution  to  100  c.c.  is  always 
made  with  the  contents  of  the  flask  at  this  temperature. 

Filtering.  —  The  contents  of  the  flasks  after  thorough  mixing 
are  poured  upon  plaited  filters  in  stemless  funnels  resting  in 
J-pint  jars  or  cylinders  (Fig.  120).  All  glassware  is  thoroughly 
cleaned  and  dried  before  using.  The  plaited  filters,  which  are 
large  enough  to  hold  the  entire  contents  of  the  flask,  are  kept 
in  a  large  desiccator  until  ready  for  use.  The  funnels  are 
covered  with  watch  glasses  during  the  filtration  to  prevent 
concentration  of  liquid  through  evaporation.  The  first  run- 
nings (10  to  15  c.c.)  of  the  filtrate  are  rejected  and  the  re- 
mainder used  for  polarization. 

Methods  for  Polarizing  Juices,  Sirups,  Molasses, 

Massecuites,  etc. 

The  method  of  polarization  just  described  for  raw  sugars 
may  be  applied  with  minor  modifications  to  the  examination  ^8- 126.— 
of  sugar-cane,  sugar-beet,  sorghum,  and  other  plant  juices, 
sirups,  molasses,  massecuites,  and  all  other  products  which  are    pipette. 
mostly  soluble  in  water. 

Sucrose  Pipette.  —  In  the  analysis  of  sugar-containing  juices  the 
work  of  analysis  may  be  lightened  considerably  by  the  use  of  Spencer's 


\ 


206  SUGAR  ANALYSIS 

or  Crampton's  sucrose  pipette  shown  in  Fig.  126.  This  pipette  is  grad- 
uated upon  the  stem  with  divisions,  divided  into  tenths,  reading  from 
5  to  25.  The  pipette  is  so  calibrated  that  the  volume  of  juice  de- 
livered from  the  division  upon  the  stem,  which  corresponds  to  its 
degrees  Brix,  is  exactly  a  double  normal  weight.  The  pipette  is  con- 
structed either  for  Mohr  cubic-centimeter  or  true  cubic-centimeter 
flasks,  delivering  52.096  gms.  and  52.000  gms.  of  juice  respectively. 
The  method  of  employing  the  pipette  is  thus  described  by  Spencer.* 

"  Determine  the  density  of  the  juice  with  a  Brix  hydrometer, 
noting  the  degree  Brix  without  temperature  correction.  Fill  the 
pipette  with  juice  to  the  mark  corresponding  with  its  observed  degree 
Brix,  and  discharge  it  into  a  100-c.c.  flask.  Add  3  to  5  c.c.  of  diluted 
lead-subacetate  solution,  complete  the  volume  to  100  c.c.  with  water, 
mix  thoroughly  and  filter  the  contents  of  the  flask.  Polarize  the 
filtrate,  using  a  200-mm.  tube,  and  divide  the  polariscope  reading  by 
2  to  obtain  the  percentage  of  sucrose.  The  juice  should  not  be  .expelled 
from  the  pipette  by  blowing,  and  sufficient  time  should  be  allowed  for 
thorough  drainage.  Each  pipette  should  be  tested  when  received  from 
the  maker,  and  in  regular  work  should  be  used  under  the  conditions  of 
the  test.  The  pipette  may  be  conveniently  checked  against  a  balance 
by  delivering  a  measured  quantity  of  juice  into  a  tared  capsule  and 
weighing  it.  The  uncorrected  degree  Brix  and  juice  of  the  temperature 
of  the  Brix  observation  must  be  used.  If  the  hydrometer  and  pipette 
are  correct  at  the  parts  used,  the  juice  delivered  should  weigh  52.096 
gms.  (or  52.00  gms.  for  true  cubic  centimeters). 

"  It  is  not  advisable  to  use  these  pipettes  with  liquids  of  a  higher 
density  than  25  degrees  Brix  or  of  greater  viscosity  than  cane  juice. 
These  pipettes  are  usually  used  in  the  analysis  of  miscellaneous  samples 
of  juice  and  in  the  rapid  testing  of  diluted  massecuites  and  molasses  for 
guidance  in  the  vacuum-pan  work.  They  should  be  frequently  cleaned 
with  a  strong  solution  of  chromic  acid  in  sulphuric  acid." 

For  the  analysis  of  highly  concentrated  sugar  products,  such  as 
sirups,  molasses,  massecuites,  etc.,  the  normal  weight  of  substance  is 
weighed  out  as  with  raw  sugar.  In  case  of  very  dark-colored  molasses 
and  massecuites,  it  is  often  necessary  to  make  the  normal  weight  of 
substance  after  clarification  up  to  200  c.c.  instead  of  100  Q.C.  in  order 
to  reduce  the  depth  of  color  sufficiently  to  polarize  in  a  200-mm.  or, 
even  at  times,  in  a  100-mm.  tube.  The  reading  thus  obtained  is  mul- 
tiplied by  2  (or  if  polarization  is  made  in  a  100-mm.  tube  by  4)  to 
obtain  the  true  direct  polarization. 

*  Spencer's  "Handbook  for  Cane  Sugar  Manufacturers  "  (4th  Ed.),  p.  122. 


METHODS  OF  SIMPLE  POLARIZATION  207 

CLARIFYING  AGENTS  AND  ERRORS  ATTENDING  THEIR  USE 

In  the  clarification  of  dark-colored  molasses  and  other  sugar-house 
products  a  much  larger  amount  of  clarifying  agent  must  be  used  than 
is  necessary  with  raw  sugars,  juices,  and  other  substances  of  high 
purity.  The  employment  of  excessive  quantities  of  clarifying  agent 
introduces,  however,  serious  errors  in  the  work  of  polarization.  These 
errors  for  convenience  will  be  considered  under  the  following  heads: 
I.  Errors  due  to  the  volume  of  precipitated  impurities. 

II.   Errors  due  to  precipitation  of  sugars  from  solution. 
III.   Errors  due  to  change  in  specific  rotation  of  sugars. 

The  influence  of  these  errors  will  first  be  considered  in  connection 
with  the  different  acetates  of  lead  which  are  the  salts  most  generally 
used  for  clarification. 

Acetates  of  Lead.  —  Three  well  characterized  acetates  of  lead* 
have  been  isolated  in  the  crystalline  form.  These  are  (1)  the  normal 
or  neutral  acetate  of  lead  Pb(C2H302)2,3  H20;  (2)  the  basic  acetate 

3  Pb(C2H302)2,PbO,3  H20;    (3)  the  basic  acetate  Pb(C2H3O2)2,2  PbO, 

4  H20.     The  clarifying  power  of  solutions  of  these  acetates  is  in  general 
proportionate  to  the  content  of  basic  PbO.    The  normal  acetate,  although 
deficient  in  decolorizing  power  and  unsuited  for  the  clarification  of  dark- 
colored  products  for  polariscopic  readings,  has  certain  advantages  in 
that  it  does  not  precipitate  reducing  sugars  from  solution  and  does  not 
form  soluble  lead-sugar  compounds  of  different  specific  rotation.     For 
these  reasons  the  neutral  acetate  of  lead  should  be  employed  for  clarify- 
ing wherever  possible  in  preference  to  the  basic  salt. 

Neutral  Lead-acetate  Solution.  —  In  preparing  the  neutral  acetate 
of  lead  reagent,  a  concentrated  solution  of  commercial  lead  acetate 
(sugar  of  lead)  is  made,  any  free  alkali  or  acid  neutralized  with  acetic 
acid  or  sodium  hydroxide,  and  the  liquid  diluted  to  a  density  of  30 
degrees  Be\  (54.3  degrees  Brix  or  1.2536  sp.  gr.  ^°).  The  solution  is 
filtered  and  kept  in  a  stock  bottle  ready  for  use. 

Lead-subacetate  Solution.  —  Upon  digesting  litharge  with  normal 
acetate  of  lead  solution  varying  amounts  of  lead  oxide  are  dissolved  ac- 
cording to  the  time  and  temperature  of  digestion.  Numerous  methods 
are  employed  for  preparing  lead-subacetate  reagent.  The  following 
examples  are  given: 

I.  Concentrated  Solution.] — Heat,  nearly  to  boiling,  for  about  half 
an  hour,  860  gms.  of  neutral  lead  acetate,  260  gms.  of  litharge,  and 

*  R.  F.  Jackson:  Scientific  Paper,  U.  S.  Bureau  of  Standards,  No.  232  (1914). 
t  Spencer's  "  Handbook  for  Cane  Sugar  Manufacturers,"  p.  229. 


208 


SUGAR  ANALYSIS 


500  c.c.  of  water.  Add  water  to  compensate  for  the  loss  by  evaporation. 
Cool,  settle,  and  decant  the  clear  solution.  The  solution  may  be  pre- 
pared without  heat,  provided  the  mixture  is  set  aside  several  hours 
with  frequent  shaking. 

Dilute   Solution.  —  Proceed    as    described    above,   using,   however, 
1000  c.c.  of  water.     The  solution  should  be  diluted  with  cold,  re- 
cently boiled  distilled  water  to  54.3 
degrees   Brix    (30    degrees    Be.,  or 
1.2536  sp.gr.  ^°). 

II.*  Boil  430  gms.  of  normal  lead 
acetate,  130  gms.  of  litharge,  and 
1000  c.c.  of  water  for  half  an  hour. 
Allow  the  mixture  to  cool  and  settle 
and  dilute  the  supernatant  liquid 
to  1.25  sp.  gr.  with  recently  boiled 
distilled  water. 

Ill.t  Treat  600  gms.  of  neutral 
lead  acetate  and  200  gms.  of  litharge 
with  2000  c.c.  of  water.  After  stand- 
ing 12  hours  in  a  warm  place  with 
occasional  shaking,  the  solution  is 
filtered  and  the  nitrate  stored  in 
tightly  stoppered  bottles.  The  solu- 
tion thus  prepared  must  show  a 
strongly  alkaline  reaction  and  have 
a  specific  gravity  of  1.20  to  1.25  (at 
17.5°  C.)  with  a  content  of  about  20 
per  cent  PbO. 

IV.  Lead  -  subacetate  solution 
may  also  be  prepared  by  dissolving 
the  solid  basic  salt  (see  page  214). 
The  concentrated  solution  is  diluted 
with  distilled  water  to  a  specific 
gravity  of  1.25. 

Stock  solutions  of  lead  subace- 
tate, both  in  bottle  and  burette, 


Fig.  127.  — Stock  bottle  and  burette  for 
lead  subacetate  solution. 


should  be  protected  by  a  soda-lime  tube  from  the  carbon  dioxide  of  the 
air  to  prevent  deposition  of  lead  carbonate  (see  Fig.  127). 

*  "  Methods  of  Analysis  A.  O.  A.  C.,"  Bull.  107  (revised),  U.  S.  Bur.  of  Chem., 
p.  40. 

t  Fruhling's  "Anleitung,"  p.  457. 


METHODS  OF  SIMPLE  POLARIZATION  209 

I.  Errors  of  Clarification  Due  to  Volume  of  Precipitated  Impurities 

Since  all  sugar  solutions  after  clarification  with  lead  subacetate,  or 
other  means,  are  made  up  to  a  definite  volume,  the  space  occupied  by 
the  precipitated  impurities  will  cause  the  sugar  solution  to  occupy  a 
somewhat  smaller  volume  than  that  of  the  flask  in  which  the  solution 
was  made  up.  An  increase  in  concentration  and  also  in  polarization 
is  the  result. 

Scheibler's  Method  of  Double  Dilution.  —  Several  methods  have 
been  devised  for  estimating  the  extent  of  this  error.  The  first  to  be 
described  is  Scheibler's*  method  of  double  dilution.  In  this  method  a 
normal  weight  of  product  is  dissolved  in  water,  clarified  with  a  meas- 
ured volume  of  lead  subacetate,  the  volume  completed,  and  solution 
filtered  and  read  in  the  usual  way.  A  second  normal  weight  of  product 
is  then  weighed  out,  clarified  with  the  same  volume  of  reagent  as  be- 
fore and  the  solution  made  up  to  twice  the  volume  of  the  previous 
experiment.  The  second  solution  is  filtered  and  polarized  as  before. 
The  true  polarization  (P)  is  then  calculated  as  follows: 

Let  PI  be  the  polarization  of  the  first  solution  made  up  to  volume 
V,  and  P%  the  polarization  of  the  second  solution  made  up  to  volume 
2  V.  Let  v  be  the  volume  of  the  precipitated  impurities  which  is 
assumed  to  be  the  same  in  both  experiments.  The  normal  weight  in 
the  second  solution  may  be  considered  to  be  divided  as  follows:  one 
half  dissolved  in  volume  V  free  from  precipitate,  the  reading  of  which 

p 

would  be  —  j  and  one  half  dissolved  in  volume  V  containing  precipitate, 
A 

p 

the  reading  of  which  would  be  -^  •     The  sum  of  these  quantities  divided 

2 

by  2  is  the  value  of  P2,  or 


2 

whence  P  =  4  P2  —  PI.  In  other  words  the  true  polarization  is  equal 
to  four  times  the  polarization  of  the  diluted  solution  less  the  polariza- 
tion of  the  undiluted  solution,  f 

*  Z.  Ver.  Deut.  Zuckerind.,  25,  1054. 

f  The  true  polarization  is  also  expressed  in  other  ways  as:  multiply  reading 
of  dilute  solution  by  2,  subtract  the  product  from  reading  of  undiluted  solution; 
twice  the  remainder  subtracted  from  reading  of  undiluted  solution  will  give  the  true 
polarization:  or  the  difference  between  the  reading  of  the  undiluted  solution,  and 
twice  the  reading  of  diluted  solution  subtracted  from  twice  the  reading  of  the  diluted 
solution  will  give  the  true  polarization. 


210  SUGAR  ANALYSIS 

Example.  —  Polarization  of  26  gms.  raw  sugar,  dissolved  in  water,  clarified 
with  2  c.c.  lead  subacetate  and  made  to  100  c.c.  =  94.2  (Pi). 

Polarization  of  26  gms.  same  sugar,  dissolved  in  water,  clarified  with  2  c.c. 
lead  subacetate  and  made  to  200  c.c.  =  47.0  (P2). 

True  polarization  (P)  =  (47.0  X  4)  -  94.2  =  93.8. 

The  volume  v  occupied  by  the  precipitated  impurities  is  calculated 

V  X  P 
as  follows.     The  reading  PI  of  the  undiluted  solution  is  equal  to  y  _    > 

V  (Pi  -  P) 
whence  v  =  • —  —  • 

r\ 

Example.  —  Required  the  volume  of  the  lead  precipitate  hi  the  previous 
example. 

Substituting  the  values  for  V,  P  and  Pi,- we  obtain 

9  - 10°  (94'V293'8)  =  °-42  c-c- 

The  method  of  Scheibler  owing  to  its  rapidity  and  ease  of  execution 
has  been  very  widely  used  for  correcting  polarizations  for  the  error  due 
to  volume  of  the  lead  precipitate.  The  method  is  open  to  several 
objections.  It  is  not  probable  that  the  volume  of  the  precipitate  is 
exactly  the  same  in  the  dilute  as  in  the  undiluted  solution,  but  the  prin- 
cipal objection  against  the  method  is  the  very  large  multiplication  of 
any  error  made  in  reading  the  diluted  solution. 

Sachs's  Method  of  Correcting  Precipitate  Error.  —  The  method 
devised  by  Sachs*  in  1880  for  determining  the  error  due  to  volume  of 
precipitate  was  intended  to  obviate  the  errors  of  Scheibler's  method. 
In  the  Sachs  method  the  precipitate  of  impurities  obtained  in  the 
clarification  of  the  sugar  solution  is  washed  with  cold  and  hot  water 
until  all  sugar  is  removed.  The  precipitate  is  then  transferred  to  a 
100-c.c.  flas'k,  a  one-half  normal  weight  of  sucrose  added,  the  latter 
dissolved  and  the  volume  completed  to  100  c.c.  The  solution  is  mixed, 
filtered,  and  polarized  in  a  400-mm.  tube.  The  volume  of  precipitate 
is  then  calculated  as  follows:  Let  P  =  the  true  polarization  of  the 
sucrose  used  and  PI  =  the  polarization  of  the  sucrose  with  precipitate. 
The  volume  (v)  of  precipitate  is  then  found  by  the  equation 

100  (Pi  -  P) 


Pi 

Example.  —  A  normal  weight  of  granulated  sugar  dissolved  to  100  c.c. 
polarized  99.8  in  a  200-mm.  tube. 

A  one-half  normal  weight  of  the  same  sugar  -+-  lead  precipitate  dissolved 
to  100  c.c.  polarized  100.25  in  a  400-mm.  tube.  Volume  of  precipitate  (v)  = 


*  Z.  Ver.  Deut.  Zuckerind.,  30,  229. 


METHODS  OF  SIMPLE  POLARIZATION 


211 


Knowing  the  volume  (v)  of  lead  precipitate,  the  true  polarization  (P) 
of  a  product  may  be  determined  by  the  equation  P  =  — 1  ~  V   S  or 

when  V=  100,  P  =  -  )^1Q~*;Pl. 

Example.  —  The  polarization  of  a  raw  sugar  (26  gms.  to  100  c.c.)  was 
96.20  (Pi).  The  volume  of  the  lead  precipitate  bySachs's  method  was  0.22  c.c.  (v). 


The  true  polarization  (P)  of  the  sugar  = 


100  X  96.2  -  0.22  X  96.2 
100 


=  95.99. 


The  method  of  Sachs  has  been  modified  as  follows.  Instead  of 
making  a  polarization  with  the  washed  precipitate  the  latter  is  first 
dried.  From  the  weight  and  specific  gravity  of  the  dried  lead  precipi- 


tate the  volume  is  calculated  [v  = 


sp.  gr. 


and  from  the  volume  the 


true  polarization  is  determined  by  means  of  the  preceding  formula. 

The  specific  gravity  of  the  dried  lead  precipitates  of  raw  cane  sugars 
was  determined  by  Wiechmann*  by  weighing  in  a  pycnometer  with 
benzine.  The  results  of  Wiechmann  are  given  in  Table  XXXVII. 

TABLE  XXXVII 

Giving  Specific  Gravity  and  Volume  of  Lead  Precipitates  from  26   gms.  of  Different 

Raw  Cane  Sugars 


Sugar. 

(Weight 
of  precipitate 
in  grams. 

Specific  gravity 
H2O  =  1.00. 

Volume  in 
cu.  centimeters 

Jamaica  Muscovado 

0  4559 

1.88 

0.24 

Maceio  Muscovado  .   . 

0  8112 

1.65 

0.49 

San  Domingo  centrifugal   

0.2525 

2.91 

0.09 

Sandwich  Island  centrifugal. 

0.1378 

2.84 

0.05 

San  Domingo  concrete 

1  0139 

3  80 

0  27 

Porto  Rico  molasses  sugar  

0.8959 

4.35 

0.21 

Sandwich  Islands 

1  0195 

4.38 

0.23 

Cebu  mats 

1  5400 

2.17 

0.71 

Manila  mats 

1.3350 

2.22 

0.60 

Similar  results  by  Home  are  given  in  Table  XXXVIII.  The 
method  employed  by  Hornet  consists  in  weighing  the  freshly  washed 
precipitate  in  a  calibrated  pycnometer  filled  to  the  mark  with  distilled 
water;  the  precipitate  is  then  washed  upon  a  weighed  filter,  dried  and 
weighed. 

The  methods,  which  are  based  upon  the  separation  and  examina- 
tion of  the  washed  lead  precipitate,  throw  much  light  upon  the  errors 

*  Proc.  Fifth  Int.  Cong.  Applied  Chem.  (Berlin,  1904)  III,  118. 
t  J.  Am.  Chem.  Soc.,  26,  186. 


212 


SUGAR  ANALYSIS 


of  clarification;  they  are  not  adapted,  however,  to  practical  work 
owing  to  the  large  amount  of  time  and  labor  involved. 

Home's  Method  of  Dry  Defecation.  —  A  third  method  of  eliminat- 
ing the  volume  of  precipitate  error  is  Home's*  process  of  dry  defeca- 
tion. The  method  is  thus  described  by  its  author: 

"  The  normal  weight  of  sugar  is  dissolved  in  water  in  a  100-c.c. 
flask  and  made  up  to  the  mark  without  defecation.  The  concentra- 
tion is  thus  at  exactly  the  proper  degree.  It  now  remains  to  defecate 
the  solution  properly  by  precipitating  the  impurities  in  such  a  way  as  to 
produce  the  minimum  change  in  the  concentration  of  the  solution  of 
sucrose.  This  is  accomplished  by  adding  to  the  100  c.c.  of  liquid 
small  quantities  of  powdered  anhydrous  lead  subacetate  until  the  im- 
purities are  nearly  all  precipitated.  This  point  is  as  easily  determined 
as  in  the  defecation  by  a  solution  of  the  same  salt.  The  organic  and 
mineral-acid  radicals  in  the  solution  combine  with  and  precipitate  the 
lead  and  lead  oxide  of  the  dry  salt,  while  the  acetic-acid  radical  of  the 
lead  subacetate  passes  into  solution  to  combine  with  the  bases  originally 
united  to  the  other  acid  radicals." 

Results  obtained  by  Home  upon  12  raw  cane  sugars  are  given  in 
Table  XXXVIII,  and  show  a  very  close  agreement  between  the  cor- 
rected polarization  by  Sachs's  method  and  the  polarization  by  dry 
defecation. 

TABLE  XXXVIII 


Grade,  country. 

Ordinary 
polariza- 
tion. 

Specific 
gravity  of 
precipitate. 

Volume  of 
precipitate. 

Corrected 
polariza- 
tion. 

Dry  lead 
polariza- 
tion. 

1 

2 

3 
4 
5 

6 
7 
8 
9 
10 
11 
12 

Centrifugal  
Centrifugal  (mixed        ( 

95.0 
94.5 

96.95 
97.425 
85.8 
89.4 
89.225 
86.45 
90.675 
89.35 
89.4 
88.4 

2.98 

c.c. 

0.10 
0.0765 

0.0378 
0.0884 
0.4118 
0.39 
0.4204 
0.7108 
0.3204 
0.8500 
0.4554 
0.4924 

94.9 
94.43 

96.91 
97.33 
85.45 
89.05 
88.85 
85.84 
90.39 
88.59 
88.99 
87.97 

94.9 
94.4 

96.95 
97.375 

85.5 
89.0 
88.85 
85.95 
90.45 
88.775 
89.0 
88.0 

Centrifugal,  Trinidad  .  . 
Centrifugal,  Java  
Muscovado,  St.  Croix  .  . 
Molasses,  Cuba  
Molasses.  .  .  . 

2.91 
2.30 
1.91 
3.20 

2.85 
1.96 
3.20 

Molasses  

Molasses 

Molasses   . 

Molasses   .  . 

3.01 
2.64 

Molasses,  Cuba 

Home's  method  has  been  tested  by  a  number  of  chemists  upon 
raw  cane  sugars  with  results  very  similar  to  the  above.    Pellet,  f  how- 
*  J.  Am.  Chem.  Soc.,  26,  186. 
t  Bull,  assoc.  chim.  sucr.  dist.,  23,  285. 


METHODS  OF  SIMPLE  POLARIZATION  213 

ever,  has  criticized  the  method  principally  upon  the  ground  that  the 
increase  in  polarization  due  to  the  volume  of  precipitate  is  not  as 
great  as  calculated,  owing  to  the  decrease  in  polarization  caused  by  the 
retention  of  sucrose  in  the  precipitate,  this  retention  error  frequently 
more  than  counterbalancing  the  error  due  to  volume  of  precipitate. 
Subsequent  results  by  Home*  and  other  chemists  show,  however,  that 
there  is  no  appreciable  retention  of  sucrose  when  the  dry  lead  reagent 
is  used  in  minimum  amounts.  Another  objection  by  Pellet,  that  only 
part  of  the  lead  salt  acts  and  that  the  rest  passes  into  solution,  thus 
increasing  the  volume  and  diminishing  the  polarization,  deserves  con- 
sideration. 

With  the  higher  grade  of  sugar-house  products  there  is  no  difficulty 
in  securing  a  satisfactory  clarification  with  a  minimum  amount  of  the 
dry  lead  salt,  the  lead  dissolved  being  immediately  precipitated  and 
but  very  little  remaining  in  solution.  With  low-grade  sugars,  molasses, 
etc.,  the  case  is  otherwise.  If  dry  lead  subacetate,  or  subacetate  solu- 
tion, be  added  to  a  solution  of  such  products  to  the  point  of  satis- 
factory clarification  a  considerable  amount  of  lead  salt  will  usually 
remain  dissolved.  The  rule  of  adding  the  powdered  salt  until  no  more 
precipitate  forms  is  not  always  a  criterion  of  the  absence  of  lead  in  the 
filtrate.  When  subacetate  is  added  to  solutions  of  low  purity  the  first 
portions  of  lead  are  completely  precipitated;  then  comes  a  point  where 
with  the  formation  of  additional  precipitate  a  small  amount  of  lead 
remains  in  solution;  the  amount  of  the  latter  continues  to  increase 
until  at  the  point  where  no  more  precipitate  is  formed  nearly  all  of  the 
lead  added  remains  dissolved.  (See  Table  XXXIX.)  With  very  low 
grade  products  there  is  therefore  a  danger  of  the  dry  lead  salt  increasing 
the  volume  of  solution;  whether  this  increase  will  cause  a  lowering  of 
the  polarization  or  not  will  depend  upon  the  character  of  the  product. 
With  low-grade  sugar-cane  products  the  error  due  to  increase  in  volume 
of  solution  may  be  more  than  counterbalanced  by  the  precipitation 
of  levorotatory  fructose. 

In  the  following  experiments  by  Hall  f  in  the  New  York  Sugar  Trade 
Laboratory  the  effect  of  increasing  amounts  of  dry  lead  subacetate  upon 
the  polarization  of  a  Philippine  mat  sugar  was  studied.  The  quantity 
of  lead  in  the  clarified  filtrates  was  determined  and  the  dilution  calcu- 
lated by  allowing  an  increase  of  0.22  c.c.  in  volume  for  1  gm.  of  dry 
subacetate  dissolved  in  100  c.c.  of  solution. 

*  J.  Am.  Chem.  Soc.,  29,  926. 

t  Bull.  122,  U.  S.  Bur.  of  Chem.,  p.  225. 


214 


SUGAR  ANALYSIS 


TABLE  XXXIX 

Showing  Estimated  Dilution  of  a  Sugar  Solution  by  Dry  Lead  Subacetate 


Amount  of 

In  100  c.c 

-.  filtrate. 

Estimated 

Clarifying  agent. 

clarifying 
agent  used. 

PbO. 

Pb  sub- 
acetate. 

dilution. 

Polarization. 

Subacetate  solution.  . 

3  0  c.c. 

grams. 

0.2678 

grams. 

c.c. 

86  70 

Dry  subacetate    . 

0.5  gm. 

Trace 

Trace 

Too  dark  to  read. 

Dry  subacetate  
Dry  subacetate  
Dry  subacetate  

1.0  gm. 
2.0gms. 
4.0  gms. 

0.1530 
0.7203 
2.1078 

(0.20) 
(0.94) 
(2.73) 

0.05 
0.20 
0.60 

86.50 
86.60 
86.50 

It  is  noted  that  with  an  estimated  dilution  of  0.2  c.c.  instead  of  a 
decrease  in  polarization,  as  would  be  expected,  there  is  an  increase. 
With  an  estimated  dilution  of  0.6  c.c.  the  reading  is  the  same  as  that 
first  obtained,  so  that  the  combined  effect  of  the  dry  lead  upon  the 
precipitation  of  fructose  and  upon  the  lowering  of  the  rotation  of  the 
fructose  in  solution  is  seen  to  be  most  pronounced.  With  sugar-cane 
products  the  use  of  dry  lead  subacetate  to  the  point  of  satisfactory 
clarification  would  seem  to  involve  no  decrease  in  polarization.  With 
low-grade  sugar-beet  and  other  products,  which  are  comparatively 
free  from  fructose,  there  is  however  a  danger  of  too  low  polarization 
since  there  is  no  compensating  influence  for  the  dilution  caused  by  the 
excess  of  lead  subacetate  dissolved. 

In  using  dry  lead  subacetate  for  defecation  the  chemist  must  be 
certain  of  the  composition  of  his  preparation.  The  powdered  salt  must 
be  dry  and  should  contain  the  requisite  amount  of  basic  lead.  Some 
samples  of  dry  lead  subacetate  sold  by  the  trade  have  been  found  by 
the  author  to  consist  almost  entirely  of  the  normal  acetate.  A  very 
pure  anhydrous  lead  subacetate  is  manufactured  at  present  having 
closely  the  formula,  3  Pb(C2H302)2,  2  PbO.  A  sample  of  such  a  prepa- 
ration analyzed  at  the  New  York  Sugar  Trade  Laboratory  gave  the 
following  results: 


Total  Pb. 

Basic  Pb. 

Found  

Per  cent. 
7Q  00 

Per  cent. 
Qn  n^ 

Theory  for  3  Pb(C2H3O2j2,  2  PbO..  .  . 

72.84 

29.14 

The  above  formula   would   correspond   to  a  mixture  of  four  parts 


METHODS  OF  SIMPLE  POLARIZATION  215 

of  the  basic  acetate  3  Pb(C2H302)2,PbO  and  three  parts  of  the  basic 
acetate  Pb(C2H302)2,2  PbO.* 

A  solution  of  lead  subacetate  of  1.259  sp.  gr.,  as  employed  for  clari- 
fication in  the  wet  way,  was  found  to  contain  0.2426  gm.  total  Pb  per 
Ic.c.  One-third  gram  dry  salt  is  therefore  equivalent  to  1  c.c.  subace- 
tate solution  in  clarifying  power.  A  low-grade  sugar  requiring  6  c.c. 
of  subacetate  solution  of  the  above  strength  for  clarification  would 
accordingly  need  2  gms.  of  salt  for  dry  defecation. 

The  dry  subacetate  of  lead  employed  in  sugar  analysis  should  be 
finely  ground  in  order  that  it  may  be  acted  upon  quickly  and  com- 
pletely by  the  dissolved  impurities.  The  tendency  to  form  insoluble 
crusts  upon  the  powdered  grains  of  dry  salt  has  been  noted  by  Home, 
especially  in  refinery  products  subjected  to  the  influence  of  bone  black. 
In  such  cases  Home  recommends  the  addition  of  a  little  dry  sand  with 
the  powdered  lead  salt;  the  particles  of  sand  in  shaking  will  grind  off 
the  crusts  of  insoluble  matter  and  allow  the  lead  to  be  acted  upon. 

II.   Errors  of  Clarification  due  to  Precipitation  of  Sugars  from  Solution 

In  the  absence  of  free  alkalies  sucrose  is  not  precipitated  from  solu- 
tion by  lead  subacetate.  Reducing  sugars,  however,  are  precipitated 
by  solutions  of  basic  lead  salts.  This  precipitation  does  not  occur 
with  the  amounts  of  lead  used  in  ordinary  clarification  except  in  pres- 
ence of  those  salts  or  acids  which  form  insoluble  lead  compounds!  (as 
chlorides,  sulphates,  phosphates,  carbonates,  oxalates,  tartrates, 
malates,  etc.).  Whether  this  precipitation  of  reducing  sugars  is  due 
to  simple  occlusion  or  to  the  formation  of  insoluble  sugar-lead  com- 
plexes is  not  definitely  known. 

The  extent  to  which  the  common  reducing  sugars,  glucose  and 
fructose,  are  precipitated  by  different  lead  clarifying  agents,  has  been 
investigated  by  Bryan.  J  Separate  solutions  of  glucose  and  fructose 
were  prepared,  using  5  gms.  of  sugar  with  1  gm.  each  of  magnesium 
sulphate  and  ammonium  tartrate.  To  50  c.c.  of  this  solution  the 
clarifying  agent  was  added  and  the  volume  made  up  to  100  c.c.  After 
filtering,  the  excess  of  lead  was  removed  with  potassium  oxalate,  and 
the  sugar  in  solution  determined  by  Allihn's  method.  The  results  of 
Bryan's  experiments  are  given  in  the  following  table. 

*  Jackson  in  an  unpublished  experiment  communicated  to  the  author  shows  that 
Home's  dry  subacetate  is  in  fact  a  mixture  of  these  two  basic  acetates. 
t  Prinsen  Geerligs,  Deut.  Zuckerind.,  23,  1753. 
t  Bull.  116,  U.  S.  Bur.  of  Chem.,  p.  73. 


216 


SUGAR  ANALYSIS 


TABLE  XL 

Showing  Precipitation  of  Glucose  and  Fructose  by  Basic  Lead  Salts 


Clarifying  agent. 

Amount  per 
100  c.c.  of 
solution. 

Glucose  pre- 
cipitated. 

Fructose  pre- 
cipitated. 

Neutral  lead  acetate  solution  
Neutral  lead  acetate  solution  
Lead  subacetate  solution 

3.  5  c.c. 
7.0  c.c. 
3  5  c.c. 

Per  cent  of  total. 

0.93 
0.84 
3  35 

Per  cent  of  total. 

0.00 
0.00 
8  03 

Lead  subacetate  solution 

7.0  c.c. 

8.34 

19  91 

Dry  lead  subacetate 

1.0  gm. 

3.85 

14  93 

Dry  lead  subacetate   

2.5  gms. 

17.48 

35.33 

Basic  lead  nitrate  solution  
Basic  lead  nitrate  solution  

4.0  c.c. 
8.0  c.c. 

6.27 
5.61 

13.84 
25.12 

It  is  seen  that  neutral  lead  acetate  precipitates  but  very  little  reduc- 
ing sugar,  whereas  the  basic  lead  salts  remove  a  large  percentage  of 
both  glucose  and  fructose,  the  latter  sugar,  however,  in  more  than 
double  the  amount.  This  precipitation  of  reducing  sugars  during 
clarification  has  a  most  marked  effect  upon  the  polarization,  the  re- 
moval of  glucose  from  solution  diminishing  the  dextrorotation,  and  that 
of  fructose  the  levorotation.  The  greater  precipitation  of  fructose  in 
mixtures  with  sucrose  and  glucose,  as  in  the  clarification  of  sugar-cane 
products,  jellies,  jams,  etc.,  causes  an  increase  in  the  dextrorotation, 
frequently  exceeding  1°  Ventzke.  The  precipitation  of  reducing  sugars, 
while  of  no  consequence  as  regards  the  saccharimetric  or  gravimetric 
determination  of  sucrose,  is  of  the  greatest  importance  when  the  valua- 
tion of  a  product  is  based  upon  the  polarization  alone,  or  upon  a  deter- 
mination of  reducing  sugars. 

III.   Errors  of  Clarification  due  to  Change  in  Specific  Rotation  of  Sugars 

Action  of  Lead  Subacetate  on  Rotation  of  Sucrose.  —  The  results 
of  Miintz,*  Weisberg,|  Svoboda,t  Groger§  and  other  investigators  show 
no  perceptible  influence  of  basic  lead  acetate  upon  the  specific  rotation 
of  sucrose  in  aqueous  solution.  Recent  experiments  by  Bates  and 
Blake  ||  indicate,  however,  a  very  perceptible  influence  in  case  the  lead 
reagent  is  used  in  large  excess.  The  following  table,  showing  the  loss 
and  gain  in  polarization  for  a  normal  weight  of  pure  sucrose,  is  taken 
from  the  work  of  Bates  and  Blake. 

*  J.  fabr.  sucre.,  17,  25. 

t  Sucrerie  Beige,  16,  407. 

t  Z.  Ver.  Deut.  Zuckerind.,  46,  107. 

§  Oest.  Ung.  Z.  Zuckerind.,  30,  429. 

||  Bull.  U.  S.  Bur.  of  Standards,  3  (1),  p.  105. 


METHODS  OF  SIMPLE  POLARIZATION 


217 


TABLE  XLI 


Number  of  cubic 
centimeters  of 
basic  lead  solution 
(1.25  sp.  gr.)  added. 

Difference  in 
degrees  Ventzke 
between  similar 
solutions,  one  with 
the  other  without, 
basic  lead  acetate. 

0.5 

-0.09 

1.0 

-0.13 

2.0 

-0.13 

3.0 

-0.08 

4.0 

-0.06 

5.0 

-0.03 

6.0 

0.00 

7.0 

+0.05 

8.0 

+0.09 

10.0 

+0.19 

15.0 

+0.29 

20.0 

+0.45 

25.0 

+0.58 

30.0 

+0.62 

35.0 

+0.77 

40.0 

+0.77 

63.0 

+0.95 

The  +  sign  indicates  that  the  solution  containing  the  lead  sub- 
acetate  gives  the  higher  polarization,  and  conversely  for  the  —  sign. 

Action  of  Lead  Subacetate  on  Rotation  of  Fructose.  —  While  the 
specific  rotation  of  sucrose  under  the  ordinary  conditions  of  analysis 
is  not  modified  sufficiently  by  subacetate  of  lead  to  introduce  serious 
errors,  the  case  is  otherwise  with  fructose.  Gill*  first  showed,  in  1871, 
that  the  specific  rotation  of  fructose  was  greatly  diminished  by  the 
presence  of  lead  subacetate,  this  decrease  being  so  great  that  in  presence 
of  sufficient  basic  lead  the  rotation  of  invert  sugar  ([a]™=  —  20)  was 
changed  to  the  right.  This  change  in  rotation  is  due  to  the  formation 
of  soluble  dextrorotatory  lead  fructosate,  the  presence  of  which,  even 
in  small  amounts,  is  sufficient  to  reduce  the  figure  for  the  rotation  of 
fructose  (Wg=-92)  below  that  of  glucose  (Ms  =  +  52.5).  Gill  f 
showed  that  the  error  due  to  formation  of  soluble  lead  fructosate  could 
be  entirely  avoided  by  adding  acetic  acid  to  the  point  of  acidity,  thus 
decomposing  the  soluble  lead  fructosate  into  lead  acetate  and  free 
fructose  of  normal  specific  rotation.  In  case  the  soluble  lead  fructosate 
is  not  decomposed  by  some  precipitating  agent  of  lead,  acetic  acid 

*  Z.  Ver.  Deut.  Zuckerind.,  21  (1871),  257. 

t  LOG.  cit.  See  also  "Spencer's  Handbook  for  Cane  Sugar  Manufacturers" 
(4th  Ed.),  p.  88;  Edson,  Z.  Ver.  Deut.  Zuckerind.,  40,  1037;  Pellet,  Bull,  assoc. 
chim.  sucr.  dist.,  14,  28,  141. 


218  SUGAR  ANALYSIS 

should  be  added  to  weak  acidity  before  making  up  the  volume  of  the 
clarified  solution  to  100  c.c.  for  the  direct  polarization  of  low-grade 
fructose  containing  products. 

Miscellaneous  Methods  of  Clarification 

Numerous  modifications  of  the  lead  process  of  clarification  have 
been  proposed  as  a  means  of  reducing  or  eliminating  the  several  sources 
of  error  just  mentioned.  Freshly  precipitated  lead  carbonate,  lead 
chloride,  and  lead  nitrate  have  been  employed  as  clarifying  agents,  but 
with  only  indifferent  success.  Two  methods  of  lead  clarification, 
which  have  found  considerable  favor  in  France  and  Austria,  should, 
however,  be  mentioned  in  addition  to  the  processes  previously  de- 
scribed. These  are  Zamaron's  method  by  means  of  hypochlorite  of 
lime  and  neutral  lead  acetate,  and  Herles's  method  by  means  of  basic 
lead  nitrate. 

Zamaron's  *  Method  of  Clarification  with  Hypochlorite.  —  625 
grams  of  dry  commercial  bleaching  powder  are  thoroughly  ground  up 
in  a  large  mortar  with  1000  c.c.  of  water.  The  mass  is  squeezed  out 
in  a  sack  and  the  extract  filtered  through  paper.  The  solution  thus 
obtained  (700  c.c.  to  800  c.c.  of  about  18°  Be.),  is  preserved  in  a  stop- 
pered bottle  of  dark  glass  away  from  the  light. 

The  solution  to  be  clarified  is  treated  with  a  few  cubic  centimeters 
of  the  hypochlorite  solution,  sufficient  to  effect  decolorization,  and 
then  a  few  cubic  centimeters  of  neutral  lead  acetate  solution  are  added. 
There  is  usually  a  slight  rise  in  temperature  after  addition  of  the  clarify- 
ing agents  so  that  the  solution  must  be  recooled  before  making  to 
volume. 

The  Zamaron  process  secures  usually  a  good  clarification,  does  not 
precipitate  reducing  sugars,  and  forms  no  objectionable  lead  sugar 
compounds.  The  chief  fault  of  the  method  is  the  volume  of  precipitate 
error,  which  in  this  case  is  augmented  by  the  formation  of  considerable 
lead  chloride. 

Herles's  f  Method  of  Clarification  with  Basic  Lead  Nitrate. — Dis- 
solve 100  grams  of  solid  sodium  hydroxide  in  2000  c.c.  of  water;  a  second 
solution  is  prepared  by  dissolving  1000  gms.  of  neutral  lead  nitrate  in 
2000  c.c.  of  water.  Upon  mixing  equal  volumes  of  the  two  solutions 
basic  lead  nitrate  is  precipitated  according  to  the  equation 

2  Pb(N03)2  +  2  NaOH  =  Pb(NO3)2.Pb(OH)2  +  2  NaN03 

Lead  nitrate  Basic  lead  nitrate 

*  Fribourg's  "Analyse  chimique,"  p.  129. 

t  Z.  Zuckerind.,  Bohmen,  13,  559;  14,  343;  21,  189. 


METHODS  OF  SIMPLE  POLARIZATION  219 

The  precipitated  basic  lead  nitrate  is  washed  free  from  sodium  com- 
pounds and  then  mixed  with  water  to  a  cream,  in  which  form  it  may  be 
used  for  clarification. 

The  clarification  is  performed  more  commonly  by  forming  the  basic 
nitrate  within  the  solution  to  be  clarified.  This  is  done  by  first  adding 
a  measured  quantity  of  the  lead-nitrate  solution  (1  c.c.  to  15  c.c.  accord- 
ing to  depth  of  color)  and  then,  after  mixing,  an  equal  volume  of  the  so- 
dium hydroxide  solution.  After  shaking,  the  solution  is  made  to  volume, 
well  mixed,  and  filtered.  Care  must  be  taken  that  the  reaction  of  the 
solution  is  not  alkaline  after  mixing;  this  is  best  provided  for  by  testing 
the  two  solutions  against  one  another  before  using. 

Formation  of  the  basic  lead  nitrate  within  the  solution  gives  usually 
a  much  better  clarification  than  addition  of  the  washed  cream,  but  has 
the  disadvantage  of  introducing  considerable  sodium  nitrate,  which,  if 
present  in  large  quantity,  will  affect  the  rotation  of  the  sugars. 

The  basic  lead  nitrate  method  gives  an  exceedingly  brilliant  clari- 
fication. The  process  is  open,  however,  to  the  same  errors  as  basic 
lead  acetate.  There  is  first  the  volume  of  precipitate  error,  which  is 
further  augmented  by  the  copious  bulk  of  the  basic  lead  nitrate  itself; 
and  secondly  there  is  a  precipitation  of  reducing  sugars  as  shown  by 
the  results  of  Bryan  in  Table  XL. 

The  numerous  errors  incident  to  the  use  of  basic  lead  compounds 
in  clarification  have  led  chemists  to  seek  other  means  of  decolorizing 
solutions  for  polarization.  It  is  impossible,  as  well  as  unnecessary,  to 
take  up  all  the  processes  which  have  been  devised  to  accomplish  this 
end.  Two  of  these  methods,  however,  should  be  described:  (1)  De- 
colorization  by  means  of  bone  black  or  blood  charcoal;  (2)  Decoloriza- 
tion  by  means  of  hydrosulphites,  sulphoxylates,  etc. 

Decolorization  of  Sugar  Solutions  by  means  of  Bone  Black.  —  The 
use  of  bone  black  as  a  decolorizing  agent  in  sugar  refineries  is  well 
known.  The  same  substance  in  a  more  finely  divided  specially  pre- 
pared form  is  employed  at  times  as  a  decolorizer  in  sugar  analysis. 

Purification  of  Bone  Black.  —  If  purified  animal  charcoal  (preferably 
blood  charcoal)  has  not  been  obtained  from  the  dealer  the  chemist  may 
purify  the  commercial  product  as  follows:  The  char  is  finely  ground  in 
a  mortar  and  then  digested  several  hours  in  the  cold  with  dilute  hydro- 
chloric acid.  The  acid  is  then  decanted,  the  char  brought  upon  a 
filter  and  washed  with  distilled  water  until  all  traces  of  hydrochloric  acid 
are  removed.  After  drying  in  a  hot-air  oven,  the  char  is  heated  to  dull 
redness  in  a  covered  porcelain  crucible,  and  then,  after  cooling  suffi- 
ciently, placed  while  still  warm  in  a  dry  stoppered  bottle. 


220  SUGAR  ANALYSIS 

Several  methods  are  followed  in  the  employment  of  animal  charcoal 
for  decolorizing.  One  very  common  practice  is  to  make  up  the  solu- 
tion to  volume  and  shake  thoroughly  with  a  small  quantity  of  charcoal, 
using  from  0.5  to  3  gms.  according  to  depth  of  color.  The  contents  of 
the  flask  are  then  poured  upon  a  dry  filter  and  the  filtrate  taken  for 
polarization. 

Absorption  Error  of  Bone  Black. — In  the  above  method  of  decolor- 
izing, a  certain  error  is  introduced  owing  to  the  absorption  and  reten- 
tion of  sugar  by  the  char.  Sugars  differ  markedly  in  the  extent  to 
which  they  are  absorbed  by  animal  charcoal.  In  the  case  of  the  simple 
reducing  sugars,  glucose,  fructose,  etc.,  the  error  through  absorption  is 
so  small  as  to  be  almost  negligible,  but  in  the  case  of  sucrose  and  other 
higher  saccharides  the  absorption  is  so  great  that  an  error  of  several 
degrees  Ventzke  may  be  occasioned  in  the  polarization. 

One  method  of  eliminating  the  error  through  absorption  of  sucrose 
consists  in  adding  a  correction  previously  established  by  experiment 
upon  pure  sugar  solutions.  If,  for  example,  a  sucrose  solution  polariz- 
ing 95.0°  V.  gives,  after  shaking  50  c.c.  with  2  gms.  of  charcoal  for  5 
minutes,  a  polarization  of  only  94.7°  V.,  then  a  correction  of  0.3°  V.  must 
be  added  to  all  polarizations  of  about  95°  V.  for  sugars  decolorized  in 
this  same  way.  A  correction  table  is  thus  made  for  sugar  solutions  of 
different  concentrations,  but  in  applying  these  corrections  care  must  be 
taken  that  the  quality  and  quantity  of  the  char  are  alike  in  both  in- 
stances and  that  the  time  of  shaking  is  always  the  same.  With  impure 
products  of  variable  composition  the  employment  of  absorption  factors 
is  attended  with  considerable  uncertainty. 

Spencer*  has  recommended  a  different  method  of  employing  animal 
charcoal  for  the  purpose  of  reducing  the  absorption  error  to  a  minimum. 
The  process  is  thus  described: 

"  Place  a  small  quantity  of  bone  black,  about  3  gms.,  in  a  small 
plain  filter,  selecting  a  rather  slow  filtering  paper.  Add  a  volume  of 
the  solution  equal  to  that  of  the  char,  or  just  completely  moisten  the 
latter,  and  let  this  liquid  filter  off.  After  four  or  five  similar  nitrations, 
the  filtrates  from  which  are  rejected,  test  the  filtrates  by  a  polariscopic 
observation  and  note  whether  the  reading  varies.  Solutions  must  be  pro- 
tected from  evaporation  during  the  filtration.  As  soon  as  the  reading 
is  constant,  showing  no  further  absorption,  record  it  as  the  required 
number." 

The  method  just  described,  while  largely  eliminating,  does  not 
completely  remove,  the  errors  of  absorption,  for  while  the  retention  of 

*  Spencer's  "  Handbook  for  Cane  Sugar  Manufacturers"  (4th  Ed.),  p.  89. 


METHODS  OF  SIMPLE  POLARIZATION 


221 


sucrose  by  the  char  rapidly  diminishes  with  each  successive  portion  of 
solution,  it  soon  becomes  only  a  gradually  receding  quantity.  This  is 
shown  by  the  following  experiments  upon  a  sucrose  solution  polarizing 
49.9°  V. 


Fraction  of  filtrate. 

Polarization. 

Absorption 

error. 

First  running.  .  .  . 

48  9 

1  0 

Second  running.       .    . 

49  4 

0  5 

Third  running  
Fourth  running  
Fifth  running  

49.75 
49.80 
49.80 

0.15 
0.10 
0.10 

With  dark-colored  solutions  it  also  happens  that  with  each  suc- 
ceeding portion  of  the  nitrate,  the  charcoal  loses  its  absorptive  power 
for  coloring  matter  as  well  as  for  sucrose,  so  that  the  final  running  least 
free  from  the  error  of  absorption  is  too  dark  for  satisfactory  polariza- 
tion. 

The  general  consensus  of  opinion  regarding  the  use  of  animal  char- 
coal in  sugar  analysis  is  that  it  should  be  used  as  a  decolorizing  agent 
only  as  a  last  resort.  Its  employment  in  the  polarization  of  raw  cane 
sugars  has  been  condemned  by  the  International  Commission  upon 
Unification  of  Methods.*  In  the  polarization  of  low-grade  sugar 
products  its  use,  however,  seems  at  times  justified  by  necessity;  in 
all  such  cases  efforts  should  be  made  to  reduce  the  absorption  error  to 
a  minimum. 

Decolorization  of  Sugar  Solutions  by  Means  of  Hydrosulphites.  — 
Attempts  have  been  made  to  employ  various  decolorizing  agents  for 
the  purpose  of  avoiding  the  precipitate  errors  of  basic  lead  salts  and 
the  absorption  error  of  bone  black.  The  most  promising  of  the  numer- 
ous substances  which  have  been  tried  in  this  connection  are  the  salts 
and  derivatives  of  hydrosulphurous  acid.f 

The  employment  of  commercial  hydrosulphite  preparations,  such 
as  "  Blankit,"  "  Redo,"  etc.,  has  been  common  in  the  sugar  factory, 

*  See  page  202. 

t  The  dry  sodium  hydrosulphite  is  prepared  by  allowing  zinc,  sodium  bisulphite, 
and  sulphuric  acid  to  react  in  the  following  molecular  proportions: 

2  NaHSOa  +  Zn  +  H2SO4  =  ZnS2O4  +  Na2SO4  +  2  H2O. 
The  zinc  hydrosulphite  is  then  decomposed  with  sodium  carbonate, 

ZnS2O4  +  Na2CO3  =  Na2S204  +  ZnCO3. 

The  sodium  hydrosulphite  is  salted  out  from  solution  by  means  of  sodium  chloride 
and  dehydrated  by  warming  with  strong  alcohol.  The  compound  is  then  dried  in 
vacuo  at  50°  to  60°  C. 


222  SUGAR  ANALYSIS 

where  they  have  been  used  for  bleaching  dark-colored  massecuites  and 
also,  in  solution,  as  a  wash  for  whitening  sugars  in  the  centrifugal. 
They  have  also  been  employed  by  unscrupulous  manufacturers  for 
bleaching  low-grade  molasses  in  the  preparation  of  table  sirups. 

For  their  use  in  sugar  analysis  the  solution  to  be  decolorized  is 
treated  with  a  lew  cubic  centimeters  of  alumina  cream  and  a  few 
crystals  of  sodium  hydrosulphite  (0.1  gm.  to  1.0  gm.,  according  to  the 
depth  of  color) ;  after  mixing  and  dissolving,  the  volume  is  made  up  to 
the  mark,  and  the  solution  filtered.  The  filtrate  should  be  polarized 
immediately. 

In  many  cases  tjiere  is  a  rapid  redarkening  of  solutions  decolorized 
with  hydrosulphites.  Weisberg,*  from  his  study  of  the  action  of 
hydrosulphites,  concludes  that  the  bleaching  action  is  a  double  one, 
first,  by  means  of  the  free  sulphurous  acid  when  decolorization  is  per- 
manent, and  secondly  by  means  of  the  nascent  hydrogen  which  is 
evolved,  when  there  is  a  redarkening  of  the  solution  through  oxidation- 
Afterdarkening  may  be  prevented  by  the  use  of  another  hydrosulphite 
derivative,  sodium  sulphoxylate-formaldehyde,  sold  commercially  as 
"  Rongalite."  The  latter,  however,  is  much  slower  in  its  bleaching 
action  than  hydrosulphite  and  is  not  always  an  effective  decolorizing 
agent. 

A  serious  objection  against  hydrosulphite  is  its  action  upon  the 
polarizing  power  of  certain  reducing  sugars.  Bryan  f  has  found  that 
the  polarizing  power  of  glucose  was  decidedly  lowered  after  the  ad- 
dition of  hydrosulphite,  owing  to  the  formation  of  a  levorotatory  oxy- 
sulphonate.  Rongalite  did  not  produce  this  effect.  Neither  rongalite 
nor  hydrosulphite  caused  any  immediate  change  in  the  polarization  of 
fructose  or  sucrose.  Numerous  cases  of  inversion  of  sucrose  by  the 
prolonged  action  of  hydrosulphites  have  been  reported,  however,  in  the 
literature. 

The  experience  of  chemists,  in  the  use  of  hydrosulphites  as  a  de- 
colorizing agent  for  sugar  analysis,  has  been  upon  the  whole  unfavor- 
able. In  many  cases  the  decolorized  solution  becomes  turbid  through 
separation  of  sulphur,  thus  rendering  polarization  impossible.  The 
bleaching  action  of  hydrosulphite  is  also  limited,  and  has  but  little 
decolorizing  effect  upon  caramel  substances,  which  are  among  the 
chief  causes  of  discoloration  in  sugar-house  products. 

Aluminum  Hydroxide  as  a  Clarifying  Agent.  —  A  common  prepa- 
ration, used  in  connection  with  other  clarifying  agents,  yet  having  but 

*  Centrbl.  Zuckerind,  15,  975. 

t  Bull.  116,  U.  S.  Bur.  of  Chem.,  p.  76. 


METHODS  OF  SIMPLE  POLARIZATION  223 

little  decolorizing  power  in  itself,  is  aluminum  hydroxide,  or,  as  it  is 
more  generally  termed,  "alumina  cream."  The  method  of  preparing 
alumina  cream,  as  prescribed  by  the  Association  of  Official  Agricultural 
Chemists,  is  as  follows:* 

"Prepare  a  cold  saturated  solution  of  alum  in  water  and  divide 
into  two  unequal  portions.  Add  a  slight  excess  of  ammonium  hydrox- 
ide to  the  larger  portion  and  then  add  by  degrees  the  remaining  alum 
solution  until  a  faintly  acid  reaction  is  secured." 

The  reagent  as  above  prepared  consists  of  aluminum  hydroxide 
suspended  in  a  solution  of  ammonium  and  potassium  sulphates.  The 
salts  have  a  certain  advantage,  when  alumina  cream  is  used  as  an 
adjunct  with  lead  salts,  in  helping  to  precipitate  any  excess  of  lead 
from  solution.  In  certain  cases,  however,  the  presence  of  ammonium 
and  potassium  sulphates  is  detrimental,  so  that  for  many  purposes  it  is 
better  to  employ  a  salt-free  cream.  For  the  preparation  of  the  latter, 
concentrated  alum  solution  is  precipitated  with  a  slight  excess  of  am- 
monia and  then  washed  by  decantation  with  water  until  the  solution 
is  free  from  sulphates.  The  excess  of  water  is  then  poured  off  and 
the  residual  cream  stored  in  a  stoppered  bottle. 

The  clarifying  effect  of  alumina  cream  is  chiefly  mechanical;  its 
action  consists  largely  in  carrying  down  finely  suspended  or  colloidal 
impurities  which  would  otherwise  escape  filtration.  When  used  in 
connection  with  lead  subacetate  it  promotes  the  coagulation  of  the 
precipitated  impurities  and  renders  filtration  more  perfect  and  rapid. 

For  the  polarization  of  very  high  grade  sugars,  sirups,  honeys,  etc., 
alumina  cream  is  the  only  clarifying  agent  required.  In  all  such  cases 
only  the  salt-free  reagent  should  be  used.  About  2  c.c.  of  the  cream 
are  sufficient  for  clarification  and  the  volume  of  aluminum  hydroxide 
in  this  amount  is  too  insignificant  to  affect  the  polarization. 

Concentrated  alum  solution  is  sometimes  used  with  lead  subacetate 
for  clarifying.  The  precipitate,  formed  between  the  lead  salt  and  alum, 
helps  to  remove  coloring  matter,  but  the  increase  in  precipitate  and 
other  errors  tend  to  nullify  any  advantages  of  the  method. 

Comparisons  of  Different  Clarifying  Agents. 

A  few  examples,  taken  from  the  reports  of  Referees  upon  Sugar  for 
the  Association  of  Official  Agricultural  Chemists,  are  given  in  order  to 
show  the  probable  error  of  different  clarifying  agents  in  polarization. 

*  Methods  of  Analysis  A.  O.  A.  C.  Bull.  107  (revised),  U.  S.  Bur.  of  Chem., 
p.  40. 


224 


SUGAR  ANALYSIS 


TABLE  XLII 

Polarization  of  Mixtures  of  Sucrose,  Glucose,  and  Fructose  with 
0.5  gm.  Ammonium  Oxalate  and  0.5  gm.  Sodium  Sulphate, 
using  Different  Clarifying  Agents  (Bryan)  * 


Clarifying  agent. 

Amount  of  clari- 
fying agent  used. 

Direct  polari- 
zation. 

Alumina  cream  .  .  . 

5  c.c. 

89  00°  V. 

Lead  subacetate  solution  

3.5  c.c. 

89  50 

Lead  subacetate  solution  
Neutral  lead  acetate  solution.  .  . 
Neutral  lead  acetate  solution.  .  . 
Basic  lead  nitrate  solution  
Dry  lead  subacetate 

7  c.c. 
3  c.c. 
6  c.c. 
4  c.c. 
1  5  gms. 

89.55 
89.20 
89.20 
89.00 
89  05 

Sodium  hydrosulphite  . 

1  cm. 

88.60 

Taking  the  experiment  with  alumina  cream  as  the  true  polarization, 
it  is  seen  that  the  lead  subacetate  solution  gives  a  reading  0.5°  V.  too 
high  and  the  normal  lead  acetate  0.2°  V.  too  high.  The  excess  reading 
in  the  second  case  is  due  to  the  volume  of  precipitate  and  in  the  former 
to  both  volume  of  precipitate  and  precipitation  of  fructose.  The  dry 
lead  subacetate  and  basic  lead  nitrate  clarifications  give  readings 
practically  identical  with  the  true  polarization.  This  might  seem  to 
indicate  no  precipitation  of  optically  active  reducing  sugars;  such  a 
precipitation  does  take  place,  however,  and  the  experiment  only  shows 
that  in  this  particular  instance  the  various  errors  of  clarification  happen 
to  neutralize  one  another.  Treatment  with  hydrosulphite  gives  a 
polarization  below  the  true  value  owing  to  the  change  in  rotation  of  the 
glucose. 

TABLE  XLIII 

Polarizations  of  Raw  Cane  Sugar  and  Cane  Molasses,  using  Different  Clarifying 
Agents  (Average  Results  of  Several  Collaborators) 


Sugar. 

Molasses. 

Alumina  cream  and  hydrosulphite 

+92  75 

+41   09 

Neutral  lead  acetate  solution  

92  92 

42  46 

Basic  lead  acetate  solution.  . 

93  05 

42  82 

Basic  lead  nitrate  solution  

92  98 

43  23 

Dry  lead  subacetate  

92  90 

42  63 

Direct  polarization. 


The  experiments  show  a  lower  polarization  using  hydrosulphite,  a 
result  due  in  large  part  to  the  change  in  rotation  of  glucose.     Basic  lead 
*  Bull.  116,  U.  S.  Bur.  of  Chem.,  p.  71. 


METHODS  OF  SIMPLE  POLARIZATION  225 

acetate  and  nitrate  solutions  give  much  higher  polarizations  owing  to  both 
the  volume  of  precipitate  error  and  the  precipitation  of  fructose.  Neutral 
lead  acetate  solution  and  dry  lead  subacetate  give  polarizations  between 
these  two  extremes,  there  being,  however,  in  case  of  the  former,  a  volume 
of  precipitate  error  and  in  case  of  the  dry  lead  an  error  due  to  precipita- 
tion of  reducing  sugars.  The  true  polarization  would  be  somewhere  be- 
tween the  results  obtained  with  hydrosulphite  and  neutral  lead  acetate. 
The  selection  of  an  appropriate  clarifying  agent  is  one  of  the  most 
important  operations  of  saccharimetry,  and  in  making  his  selection  the 
chemist  must  be  governed  by  the  requirements  of  each  particular  case. 
Rapid  nitration  and  brightness  of  clarification  are  factors  which  must 
be  considered  as  well  as  minimum  degree  of  error.  Beginning  with 
products  of  highest  purity  alumina  cream  alone  should  be  used  wherever 
possible.  With  products  of  slight  discoloration,  when  alumina  cream 
is  insufficient,  neutral  lead  acetate  solution  should  be  tried.  When 
alumina  cream  and  neutral  lead  solution  fail,  lead  subacetate,  or  basic 
lead  nitrate,  or  neutral  lead  acetate  with  hypochlorite  may  be  employed; 
dry  lead  subacetate  will  usually  give  more  accurate  results  with  sugar- 
cane and  other  products  containing  fructose.  Animal  charcoal  or  hydro- 
sulphites  should  be  used  only  as  a  last  resort,  when  other  means  of 
clarification  have  failed.  The  smallest  possible  quantity  of  clarifying 
agent  should  be  used  in  all  cases. 

POLARIZATION  OF  SUGAR  PRODUCTS  CONTAINING  INSOLUBLE  MATTER 

In  the  analysis  of  juices,  sirups,  molasses,  massecuites,  and  sugars, 
the  chemist  has  to  deal  with  substances  which  are  entirely  soluble  in 
water.  The  work  of  polarization  becomes  more  complicated  when 
considerable  insoluble  matter  is  present,  as  happens  in  the  analysis  of 
fruits,  tubers,  stalks,  and  other  vegetable  substances  or  in  the  examina- 
tion of  filter-press  cake,  scums,  and  other  sugar-house  residues. 

The  methods  for  polarization  of  succulent  plant  materials  may  be 
divided  into  three  general  classes:  (1)  Methods  of  Expression;  (2) 
Methods  of  Extraction,  and  (3)  Methods  of  Digestion.  As  an  illus- 
tration of  these  several  methods  the  polarization  of  sugar  beets  offers 
a  good  and  classic  example. 

Sampling  Sugar  Beets,  Etc.  —  In  preparing  sugar-beets,  sugar 
cane,  fruits,  etc.,  for  analysis  the  material  must  first  be  reduced  to  a 
finely  divided  condition.  For  this  purpose  any  of  the  numerous 
mechanical  rasps,  shredders,  graters,  etc.,  may  be  employed,  provided 
that  the  cellular  tissue  be  thoroughly  disintegrated  and  that  no  losses 
occur  through  leakage  of  juice  or  evaporation. 


226 


SUGAR  ANALYSIS 


Keil's  Beet  Sampler.  —  The  Keil  boring  machine  (Fig.  128)  is  very 
frequently  used  for  taking  samples  of  individual  sugar  beets.  The 
essential  feature  of  the  apparatus  consists  of  a  hollow  detachable  bit, 
the  construction  of  which  is  shown  in  Fig.  129.  The  conical  rasp  at 


Fig.  128.  —  Keil's  boring  rasp  for  sampling  sugar  beets. 

the  end,  revolving  at  a  speed  of  about  3000  revolutions  per  minute,  re- 
duces the  substance  of  the  beet  to  an  extreme  degree  of  fineness  and  at 
the  same  time  forces  the  pulp  through  a  small  opening  into  the  cavity 


Fig.  129.  —  Detachable  bit  of  Keil's  boring  rasp. 

within.  Each  beet  is  bored  in  an  inclined  direction,  as  shown  in  Fig. 
130,  in  order  to  secure  the  best  representative  sample.  When  only 
single  beets  are  examined  (as  in  the  selection  of  "  mother  beets  "  for 
seed  production)  the  bit  is  detached  after  each  boring  and  a  new  one 
screwed  on.  The  bits  are  numbered,  and  to  obtain  the  sample  the 
conical  rasp  is  removed  and  the  pulp  (from  8  to  14  gms.,  according  to 
the  size  of  beet  and  length  of  boring)  forced  out  with  a  rod.  In  samp- 
ling large  numbers  of  beets  the  bit  is  kept  in  constant  use,  the  pulp 


METHODS  OF  SIMPLE  POLARIZATION 


227 


being  discharged  in  a  continuous  stream  into  a  covered  container  at 
the  end  of  the  apparatus. 

/.   Determination  of  Sugar  in  Sugar  Beets  by  Expression  of  Juice 

The  determination  of  the  sugar  in  sugar  beets  by  polarization  of  the 
expressed  juice  was  formerly  quite  common,  but  has  now 
given  place  to  more  accurate  methods  of  analysis. 

Assuming  (as  is  incorrect)  that  the  sugar,  amides, 
albuminoids,  salts,  gums,  and  other  water-soluble  solids 
of  the  beet  are  in  the  same  condition  of  solution  within 
the  beet  as  in  the  expressed  juice,  and  letting  M  =  the 
per  cent  of  water-insoluble  matter  or  "  marc  "  and  100 
-  M  =  the  per  cent  of  juice,  then  the  sugar  content  (S) 
of  the  beet  can  be  calculated  from  the  polarization  (P) 
of  the  expressed  juice  by  the  formula 

P(100  -  M) 
100 

Example.  —  The  expressed  juice  of  a  sugar  beet  gave  a 
polarization  of  16.2°  V.  for  the  normal  weight:  the  beet  con- 
tained 4.6  per  cent  of  marc.  Required  the  per  cent  of  sugar  in 
the  beet. 

o  =  16.2  (100  -  4.6) 
100 


15.45  per  cent. 


rection  of 
boring  in 
sampling 
sugar  beets. 


The  above  method  is,  of  course,  equally  applicable  to      «?'    1 
the  analysis  of  sugar  cane,  fruits,  and  other  succulent 
plant  substances. 

Method  of  Expressing  Juice.  —  For  expressing  the 
juice  from  the  pulp  of  sugar  beets,  sugar  cane,  etc.,  any 
suitable  form  of  hand  press  may  be  used.  The  small  hydraulic  press 
shown  in  Fig.  131  is  one  of  great  efficiency  and  is  a  piece  of  apparatus 
almost  indispensable  in  a  sugar  laboratory. 

The  pulp  to  be  pressed  is  placed  in  a  strong  sack  inside  the  per- 
forated container  C,  and  covered  evenly  with  a  heavy  metal  disk.  By 
turning  the  wheel  W  the  screw  A  is  driven  downward  as  far  as  possible 
upon  the  disk,  thus  squeezing  out  through  the  openings  of  C  a  con- 
siderable part  of  the  juice,  which  escapes  by  the  spout  D  into  a  can  or 
other  receptacle.  The  horizontal  hydraulic  screw  B  is  then  turned  in- 
wards. This  screw,  operating  by  means  of  glycerol  which  fills  the 
hollow  base  H,  forces  the  piston  E  upwards  and  removes  by  vertical 
pressure  a  second  fraction  of  juice.  The  final  pressure,  indicated  by 


228 


SUGAR  ANALYSIS 


the  manometer  M,  can  be  raised  to  300  atmospheres.  The  juice,  as  the 
pressure  increases,  is  of  gradually  diminishing  purity;  it  is  important 
therefore  that  all  the  runnings  should  be  well  mixed  before  taking  the 
sample  for  polarization. 


W 


Fig.  131.  —  Laboratory  hydraulic  press  for  expressing  juices. 

Determination  of  Marc.  —  A  determination  of  the  insoluble  cellular 
matter,  or  marc,  is  necessary  before  the  per  cent  of  sugar  in  plant  sub- 
stances can  be  calculated  from  the  polarization  of  the  expressed  juice. 
For  rough  purposes  of  estimation  a  constant  percentage  of  5  per  cent 
or  4.75  per  cent  marc  is  sometimes  assumed  for  the  sugar  beet  and  10 
per  cent  or  12  per  cent  for  the  sugar  cane.  Such  figures,  however, 
have  no  exact  value,  as  the  percentage  of  cellular  matter  varies  con- 
siderably according  to  the  age  of  the  plant,  dryness  of  the  season,  and 
many  other  conditions. 

For  the  determination  of  marc  20  to  50  gms.  of  the  finely  divided 
pulp  are  digested  with  200  to  500  c.c.  of  cold  water  for  30  minutes, 
and  then  filtered  as  dry  as  possible  upon  a  piece  of  finely  woven  linen, 
using  suction.  The  washing  is  repeated  with  successive  portions  of 
cold  water  until  the  filtrate,  from  color  and  taste,  is  judged  to  be  free 
of  extractive  matter.  The  residue  is  then  washed  several  times  with 
hot  distilled  water,  then,  after  pressing  together,  with  2  to  3  portions  of 


METHODS  OF  SIMPLE  POLARIZATION  229 

90  per  cent  alcohol,  and  finally  with  a  little  ether.  After  the  ether  has 
volatilized  the  marc  is  dried  in  an  oven,  gradually  raising  the  tem- 
perature after  a  few  hours  to  between  100°  and  110°  C.  After  cooling 
in  a  desiccator  the  residue,  which  is  very  hygroscopic,  is  rapidly  weighed 
(preferably  in  a  stoppered  weighing  bottle)  and  the  weight  taken  as 
the  amount  of  cellular  matter  or  marc.  For  a  determination  of  the 
organic  cellular  matter,  the  marc  is  incinerated  and  the  percentage  of 
ash  deducted. 

The  percentage  of  marc  subtracted  from  100  gives  the  percentage 
of  juice. 

Where  many  determinations  of  marc  have  to  be  performed,  a 
battery  of  small  continuously  operating  percolators  will  effect  a  con- 
siderable saving  of  time. 

Errors  of  Expression  Method.  —  Several  sources  of  error  are 
involved  in  the  determination  of  sugar  in  plant  substances  by  analysis 
of  the  expressed  juice.  In  the  first  place  a  considerable  amount  of 
juice,  varying  from  10  per  cent  to  30  per  cent,  according  to  the  effi- 
ciency of  the  press,  is  not  eliminated  and  this  residual  juice,  containing 
a  larger  amount  of  albuminoids,  pectin,  etc.,  is  of  much  lower  purity 
than  the  part  first  expressed.  This  excess  of  impurities  in  the  unex- 
pressed juice  is  washed  out,  however,  in  the  marc  determination. 
The  polarization  of  the  expressed  juice  is  thus  higher  than  that  of  the 
composite  juice  of  the  entire  plant.  (See  under  Distribution  of  Water, 
page  230.) 

A  second  source  of  error  is  the  extraction  during  the  marc  determi- 
nation —  by  the  excessive  amounts  of  cold  water,  but  more  especially 
by  the  hot  water,  alcohol,  and  ether  —  of  variable  amounts  of  hemi- 
celluloses,  wax,  oil,  and  other  substances  which  are,  strictly  speaking, 
not  juice  constituents  and  should  therefore  be  included  in  the  marc. 
The  percentage  of  juice  is  thus  estimated  too  high,  and  a  plus  error 
introduced  in  the  calculation.  Except  for  the  disadvantage  of  loss  of 
time  in  drying,  the  use  of  alcohol  and  ether  as  dehydrating  agents 
should  be  omitted  in  the  marc  determination,  and  cold  water  alone  be 
used  for  extracting. 

"  Colloidal  "  or  "  Imbibition  "  Water.  —  A  third  source  of  error  to 
be  mentioned  is  the  much-debated  question  of  "  colloidal  "  or  "  imbibi- 
tion" water,  by  which  is  meant  water,  in  a  more  or  less  hydrated 
form,  in  combination  with  hemicelluloses  and  other  plant  constituents. 
This  imbibed  water  contains  no  sugar  in  solution,  and,  being  expelled 
from  the  pulp  upon  drying,  the  percentage  of  sugar-containing  juice  is 
overestimated.  v  ^  , 


230  SUGAR  ANALYSIS 

Heintz*  showed,  in  1874,  when  the  air-dried  and  sugar-free  marc  of 
beets  was  placed  in  sugar  solutions,  that  water  was  imbibed,  thus  leav- 
ing the  sugar  more  concentrated  and  increasing  the  polarization.  In 
the  following  experiments  by  Heintz  air-dried  beet  marc,  which  had 
been  washed  completely  free  from  sucrose,  was  treated  16  hours  in  a 
cool  place  with  solutions  containing  a  normal  and  half-normal  weight 
of  sucrose,  in  the  proportion  of  1  gm.  marc  to  20  c.c.  of  solution. 


Half  normal 
weight. 

Normal  weight 

PolH.riza.tion  before  marc  treatment 

49  8 

99  6 

Polarization  after  marc  treatment 

53  9 

104  6 

The  observations  of  Heintz  were  verified  in  a  different  way  by 
Scheibler.f  The  latter  found  that  samples  of  sugar  beets,  whose  ex- 
pressed juice  polarized  14.5  had  a  marc  "content  of  4.71  per  cent.  The 
percentage  of  sugar  in  the  beets  according  to  the  formula 

pqoo  -  3Q 
~ 


would  be  13.82.  Scheibler  found,  however,  by  his  method  of  alcoholic 
extraction  a  percentage  of  only  13.1  or  a  difference  of  0.72  per  cent. 
The  percentage  of  sugar-containing  juice  in  the  beets,  assuming  that 
this  juice  is  of  the  same  polarization  as  the  part  expressed,  is  found  by 

the  formula,  per  cent  juice  =  100-^  =  100  -^-=  —  90.34  per  cent,  in 

Jr  14.  o 

which  p  is  the  polarization  of  the  beets  by  the  extraction  method  and 
P  the  polarization  of  the  expressed  juice.  The  percentages  of  juice  and 
marc  being  respectively  90.34  and  4.71,  there  is  left  a  remainder  of 
4.95  per  cent,  which  Scheibler  termed  "  colloidal  "  water.  This  method 
of  estimation  is  based,  however/  upon  the  assumption  that  the  juice 
expressed  is  of  the  same  composition  as  the  combined  juices  of  the 
beet,  which  is  not  exactly  true.J 

Distribution  of  Water  in  Plant  Tissues.  —  The  distribution  of  the 
water  in  plant  tissues  has  such  an  important  bearing  upon  certain 
problems  of  sugar  analysis  that  a  short  discussion  of  the  question  may 
be  introduced  with  profit  at  this  point. 

*  Z.  analyt.  Chem.  (1874),  262. 
t  Ibid.  (1879),  176,  256. 

|  For  a  very  full  discussion  with  bibliography  of  the  subject  of  "colloidal" 
water  see  Rumpler,  "  Die  Nichtzuckerstoffe  der  Ruben  "  (1898),  pp.  1-13. 


METHODS  OF  SIMPLE  POLARIZATION  231 

Fig.  132  shows  a  magnified  cross  section  of  a  part  of  a  sugar-cane 
stalk.  The  sugar-containing  juice  proper,  represented  by  S  (the 
vacuoles),  constitutes  the  principal  part  of  the  cell  contents  in  the 
thin-walled  parenchyma  or  fundamental  tissue,  and  includes  the  great- 
est part  of  the  water  in  the  cane.  Lining  the  walls  and  permeating 


Fig.  132.  —  Magnified  cross-section  of  sugar-cane  (protoplasmic 
lining  P  much  intensified) . 

through  these  cells  are  thin  layers  and  threads  of  protoplasmic  matter 
P  which  contains  a  considerable  amount  of  water,  but  is  deficient  in 
sugar.  Running  longitudinally  through  the  stalk  are  large  numbers  of 
fibro vascular  bundles  whose  ducts,  D,  are  filled  with  water  taken  up 
from  the  soil.  The  water  of  these  ducts  may  often  be  seen  spurting 
from  the  end  of  a  cane  stalk  as  it  passes  between  the  rollers  of  a  mill, 
and  is  found  upon  analysis  to  be  almost  free  of  sugar.  Running  parallel 
with  the  ducts  are  the  sieve  tubes  T  which  carry  in  solution  the  prod- 
ucts of  assimilation  from  the  leaf  to  the  stalk.  The  water  of  these 
tubes  contains  reducing  sugars  but  is  deficient  in  sucrose.  The  cellular 
walls  of  the  parenchyma  and  fibrovascular  tissues  contain  about  50 
per  cent  cellulose,  20  per  cent  xylan,  5  per  cent  araban  and  a  remainder 
of  lignin  substances,  all  of  which  may  hold  a  certain  amount  of  water 
in  the  imbibed  or  colloidal  form. 


232 


SUGAR  ANALYSIS 


Variation  in  Composition  of  Juice  from  Different  Mills.  —  The  press- 
ings from  the  first  rollers  or  crusher  of  a  cane  mill  consist  mostly  of 
the  sugar-containing  juice  S  (Fig.  132).  The  pressings  from  succeed- 
ing rollers,  where  the  pressure  is  greater,  contain  more  and  more  of 
the  protoplasmic  juice  P  and  the  juice  from  the  ducts  and  tubes.  The 
colloidal  water  of  the  cellular  substance  is  of  course  not  affected  by 
the  milling. 

The  composition  of  the  pressings  from  the  different  rollers  of  a 
cane  mill  is  given  in  Table  XLIV. 


TABLE  XLIV 


First  rollers. 

Second  rollers. 

Third  rollers. 

Water  

Per  cent. 

84.64 

Per  cent. 

85.40 

Per  cent. 

85.35 

Sucrose  

12.93 

11.41 

11.30 

Reducing  sugars 

1  54 

1  29 

1  23 

Ash     . 

0  37 

0.58 

0  77 

Albuminoids. 

0.18 

0.50 

0  58 

Gums,  acids,  etc  .      .    . 

0.34 

0.82 

0.77 

Total  

100.00 

100.00 

100.00 

Per  cent  extraction  of  cane  

64.50 

5.50 

2.13 

The  pressed  cane  (bagasse)  from  the  third  rollers  still  contained 
over  60  per  cent  of  water,  corresponding  to  about  20  per  cent  of  the 
total  juice  in  the  cane.  If  this  residual  juice  could  all  be  squeezed 
out  by  some  inconceivable  pressure,  its  sugar  content  would  be  much 
inferior  to  that  of  the  pressings  from  the  third  rollers.  It  would  of 
course  be  inaccurate  to  estimate  the  sugar  content  of  the  cane  from  the 
polarization  of  the  first  pressings;  the  same  is  also  true,  but  to  a  much 
less  degree,  of  the  composite  pressings  of  several  mills. 

The  impossibility  of  obtaining  by  pressure  a  true  composite  sample 
of  the  different  juices  of  a  plant,  the  difficulty  of  estimating  the  true 
content  of  marc,  and  the  uncertain  influence  of  the  colloidal  or  imbibed 
water  are  the  chief  objections  to  the  expression  methods  of  sugar  de- 
termination. 

II.   Determination  of  Sugar  in  Sugar  Beets  by  Extraction  with  Alcohol 

The  method  most  accurate  in  principle  for  determining  sugar  in 
beets  and  other  plant  substances,  is  that  of  extraction.  In  this  pro- 
cess the  sugar  is  washed  out  from  the  pulp  and  the  extract  made  up 
to  volume  and  polarized.  The  errors  due  to  uneven  composition  of 


METHODS  OF  SIMPLE  POLARIZATION  233 

juices,   faulty  marc   estimation,   and   colloidal   water  are  thus   com- 
pletely eliminated. 


Fig.  133.  —  Apparatus  for  Scheibler's  alcohol-extraction  method. 

Scheibler's  Alcohol-extraction  Method.  —  The  solvent  most  gener- 
ally used  for  the  extraction  of  sugar  from  beet  pulp  is  90  per  cent  ethyl 
alcohol.  The  original  method  of  Scheibler*  as  modified  by  Sickelf  is 
as  follows: 

*  Neue  Zeitschrift,  2,  1,  17,  287;  3,  242. 

t  Ibid.  2,  692. 


234  SUGAR  ANALYSIS 

A  normal  (or  double  normal)  weight  of  finely  prepared  pulp  is 
weighed  rapidly  in  a  weighing  dish,  3  c.c.  of  lead  subacetate  (6  c.c.  for 
the  double  normal  weight)  are  then  added  and  thoroughly  mixed  with 
the  pulp  by  means  of  a  glass  rod,  adding  at  the  same  time  5  to  10  c.c. 
of  90  per  cent  alcohol.  The  pulp  is  then  transferred  to  the  extraction 
cylinder  B  of  a  Soxhlet  extractor,  of  which  Fig.  133  shows  six  in  the 
form  of  a  battery.  The  bottom  of  the  extraction  cylinder  is  covered 
with  a  clean  wad  D  of  felt  or  cotton;  the  pulp  is  washed  in  with  90  per 
cent  alcohol,  and  pressed  down  so  that  its  upper  surface  is  below  the 
upper  bend  of  the  siphon  tube  S.  The  top  of  the  extraction  vessel  is 
then  connected  by  means  of  a  tight-fitting  cork  with  the  condensing 
tube  C,  and  the  bottom  with  the  100  c.c.  flask  F,  which  should  contain 
about  75  c.c.  of  90  per  cent  alcohol. 

The  water  in  the  bath  is  heated  until  the  alcohol  in  the  flask  begins 
to  boil  vigorously,  when  the  heat  is  regulated  to  this  constant  temper- 
ature. The  vapor  from  the  boiling  alcohol  passes  upward  through  the 
side  tube  A  and  condensing  in  C  drops  back  upon  the  pulp  in  B.  As 
soon  as  the  level  of  alcohol  in  B  rises  above  the  bend  of  the  tube  S, 
the  alcoholic  solution  of  sugar  siphons  mechanically  into  the  flask  F. 
The  distilling  and  siphoning  are  continued  until  all  the  sugar  is  ex- 
tracted, which,  according  to  the  fineness  of  the  pulp, 
usually  requires  from  1  to  2  hours.  Immediately  after 
the  last  siphoning  the  flask  F  is  disconnected,  cooled  to 
room  temperature,  the  volume  completed  to  100  c.c., 
and  the  solution  mixed,  filtered,  and  polarized. 

A  form  of  extraction  vessel  devised  by  Miiller  (Fig. 
134)  permits  the  withdrawal  of  a  small  sample  of  liquid 
from  the  siphon  tube  for  determining  the  completion  of 
extraction.  The  opening  at  a  is  closed  during  operation 
with  a  stopper.  To  obtain  the  sample  this  stopper  is 
removed,  a  few  cubic  centimeters  of  liquid  are  sucked 
up  with  a  pipette  and  subjected  to  the  a-naphthol  test 
(page  341 ).  If  the  test  is  positive,  the  stopper  is  replaced 
Fig.  134.  —  Miil-  and  the  extraction  continued  until  the  reagent  gives  no 

tlon  Tsfxh"  coloration- 

let's  extractor"  ^n  determining  sugar  by  the  Scheibler  process  of 
extraction  special  care  must  be  exercised  to  prevent 
evaporation  of  alcohol  during  filtration.  The  funnel  should  be  covered 
with  a  watch  glass  and  the  filtrate  received  in  a  cylinder  or  flask  with 
narrow  neck.  The  first  20  to  30  c.c.  of  the  runnings  should  be  dis- 
carded. The  greater  susceptibility  of  alcoholic  sugar  solutions  to 


METHODS  OF  SIMPLE  POLARIZATION 


235 


expansion  and  contraction  with  changes  in  heat  and  cold  necessitates 
the  maintenance  of  uniform  temperature  conditions  during  the  polar- 
ization. The  specific  rotation  of  sucrose  in  ethyl  alcohol  is  slightly 
higher  (0.1  degree  to  0.2  degree)  than  in  water;  but  the  difference  is  so 
small  that  it  falls  within  the  limits  of  experimental  error. 

The  method  of  alcoholic  extraction  gives  results  considerably  lower 
than  those  calculated  from  the  polarization  of  the  expressed  juice.  The 
results  of  Scheibler  previously  quoted  (page  230)  show  a  difference  of 
about  0.75  for  the  polarization  of  sugar  beets. 

Some  authorities  prefer  adding  the  lead  subacetate  to  the  alcoholic 
extract  rather  than  to  the  pulp  previous  to  extraction.  This  practice 
is  attended,  however,  with  some  danger.  One  main  object  of  adding 
the  basic  lead  to  the  pulp  is  to  neutralize  any  free  acid  which  would 
otherwise  invert  some  of  the  sucrose  in  the  hot  solution.  In  presence 
of  alcohol,  lead  subacetate  solution  must  be  used  in  lowest  possible 
amount  owing  to  the  danger  of  precipitating  sucrose  or  of  changing  its 
specific  rotation  through  formation  of  lead  saccbarate. 

The  alcoholic  extraction  method  can  be  applied  to  the  polarization 
of  fruits  and  all  other  sugar-containing  plant  substances.     With  very 
dry  materials  the  strength  of  the  alcohol  should 
be  correspondingly  reduced.     With  substances 
containing  reducing  sugars  in  large  amount,  it 
is  desirable  to  omit  the  addition  of  lead  sub- 
acetate,  but  when  this  is  done  the  substance 
should  be  well  mixed  with  powdered  calcium 
carbonate  to  neutralize  any  free  acid  that  might 
cause  inversion. 

II.   Determination  of  Sugar  in  Plant  Substances 
by  Extraction  with  Water 

Water  is  sometimes  used  instead  of  alcohol 
in  extracting  sugar  for  the  polarization  of  plant 
substances.      In  such  cases  a  process  of  per- 
colation must  be  used  in  place  of  distillation  Fig.  135. — Section  of  Zam- 
owing  to  the  danger  of  decomposition  through 
the  prolonged  boiling  of  aqueous  extracts.     As 
an  example  of  the  water  extraction  process  the  Zamaron*  method  for 
determining  sugar  in  sugar  cane  is  given. 

Zamaron's  Water-extraction  Apparatus. — The  Zamaron  extraction 
apparatus  (Figs.  135  and  136)  consists  of  a  cylindrical  copper  vessel 
*  Sidersky's  "  Manuel,"  p.  261. 


aron's  hot-water  extrac- 
tion apparatus. 


236 


SUGAR  ANALYSIS 


V  provided  at  the  bottom  with  a  small  cock  C.  A  basket  B  of  per- 
forated copper,  provided  with  a  tripod  support,  fits  loosely  within  this 
copper  vessel;  100  gms.  of  the  finely  divided  pulp  are  transferred  to 
the  basket,  and  200  c.c.  of  hot  water  poured  in,  the  pulp  being  pressed 


Fig.  136.  —  Battery  of  Zamaron's  hot-water  extractors. 


down  beneath  the  surface  of  the  liquid  by  means  of  the  plunger  P. 
The  contents  of  the  vessel  are  then  boiled  for  10  minutes,  after  which 
the  flame  is  turned  down,  the  cock  opened,  and  the  hot  solution  drawn 
off  into  the  1000-c.c.  graduated  flask  F,  as  much  as  possible  of  the 
liquid  being  pressed  out  by  means  of  the  plunger.  The  cock  is  then 
closed  and  the  process  repeated  with  a  second  portion  of  150  c.c.  water. 
The  process  is  continued  6  times,  making  altogether  about  950  to  975  c.c. 
of  extract.  After  cooling  and  adding  a  few  cubic  centimeters  of  lead 
subacetate,  the  contents  of  the  flask  are  made  to  1000  c.c.,  shaken, 
filtered,  and  polarized  in  a  400-mm.  tube.  The  reading  multiplied  by 
1.3  gives  the  polarization  (degrees  Ventzke)  of  the  sugar  cane. 

The  principal  objection,  which  has  been  brought  against  the  Zam- 
aron  process,  is  the  danger  of  incomplete  extraction.  Some  idea  of  the 
probable  magnitude  of  this  error  may  be  formed  from  the  following 
consideration : 


METHODS  OF  SIMPLE  POLARIZATION 


237 


Suppose  a  sugar  cane  to  contain  18  per  cent  of  sucrose;  suppose 
also  that  6  extractions  of  the  pulp  are  made  and  that  one- third  of  the 
liquid  is  retained  by  the  fiber  after  each  extraction.  If  the  sugar  is 
evenly  diffused  through  all  parts  of  the  liquid  at  the  end  of  each  10 
minutes  boiling,  as  is  no  doubt  very  nearly  true,  there  would  be  the  fol- 
lowing percentages  of  sugar  removed  at  each  extraction. 


Percentage 
removed  of 
total  sugar. 

Percentage  of 
sugar  removed 
per  100  of  cane. 

First  extraction 

66  66 

12  00 

Second  extraction 

22  22 

4  00 

Third  extraction 

7  41 

1  33 

Fourth  extraction 

2  47 

0  44 

Fifth  extraction.  .  . 

0  82 

0  15 

Sixth  extraction.  .  .  . 

0  27 

0  05 

Amount  extracted  
Amount  unextracted  

99.85 
0.15 

17.97 
0.03 

It  is  seen  that  the  residual  sugar  left  after  6  extractions  can  be 
only  very  slight.  In  order  to  reduce  the  possibility  of  error  through 
incomplete  extraction  Fribourg*  recommends  that  only  50  gms.  of 
pulp  be  taken  for  analysis.  This,  however,  while  halving  the  errors  of 
extraction,  necessitates  a  doubling  of  any  error  in  the  polariscope 
reading. 

Another  source  of  error,  in  the  method  of  hot  water  extraction  as 
described,  is  the  danger  of  inversion  of  sucrose  through  the  natural 
acidity  of  the  pulp.  One  method  of  preventing  this  is  to  mix  with 
the  pulp  previous  to  extraction  finely  powdered  calcium  carbonate. 
Another  method*  is  to  employ  very  dilute  milk  of  lime  water  for  the  ex- 
traction. The  presence  of  minute  quantities  of  free  alkali  does  not 
affect  the  determination  of  sucrose;  a  danger  exists,  however,  in  the 
action  of  hot  alkaline  solutions  (even  where  very  dilute)  in  modifying 
or  destroying  reducing  sugars.  Careful  neutralization  of  the  free  acid 
in  the  pulp  with  lime  water,  or  dilute  sodium  hydroxide,  would  eliminate 
the  risk  of  inversion  without  serious  danger  of  affecting  the  reducing 
sugars. 

Another  objection  to  the  method  of  hot-water  extraction  is  the 

solution  of  optically  active  dextrins,  gums,  and  hemicelluloses.     These 

substances  introduce  at  times  a  considerable  error  in  the  polarimetric 

determination  of  sugars  in  aqueous  plant  extracts.     The  error  does 

*  Fribourg's  "Analyse  chimique,"  p.  223. 


238  SUGAR  ANALYSIS 

not  exist  in  the  alcohol-extraction  method,  owing  to  the  insolubility  of 
dextrinoid  substances  in  ethyl  alcohol. 

///.   Determination  of  Sugar  in  Sugar  Beets  by  Methods  of  Digestion 

The  method  of  alcoholic  extraction,  although  the  most  accurate 
and  scientifically  perfect,  is  not  the  best  from  a  practical  standpoint 
on  account  of  the  long  period  of  time  necessary  for  extraction,  and  also 
because  of  the  rather  fragile  nature  of  the  extraction  apparatus.  For 
the  rapid  determination  of  sucrose  in  sugar  beets  some  one  of  the  num- 
erous digestion  processes  is  usually  followed. 

The  digestion  method  may  be  regarded  in  principle  as  a  combination 
of  the  extraction  and  juice-expression  methods.  A  weighed  amount  of 
pulp  is  digested  with  5  to  6  times  its  volume  of  alcohol  or  water.  After 
the  complete  diffusion  of  the  sugar  through  the  liquid,fthe  solution 
is  made  up  to  volume,  allowing  for  the  space  occupied  by  insoluble 
matter,  and  then  filtered  and  polarized. 

Rapp-Degener  Alcohol-digestion  Method.  —  The  first  process  of 
digestion  employed  alcohol,  and  is  known  as  the  Rapp-Degener  *  method. 
The  double  normal  weight  of  fine  beet  pulp  is  transferred  to  a  201.2-c.c. 
flask  (the  extra  1.2  c.c.  being  the  estimated  volume  of  the  insoluble 
cellular  matter  in  52.  gms.  of  pulp).  The  forms  of  flask  shown  in 
Fig.  137  are  convenient  for  the  purpose.  Three  to  four  c.c.  of  lead- 
subacetate  solution  are  mixed  with  the  pulp  and  then  about  150  c.c.  of 
90  per  cent  alcohol  added.  The  flask  is  closed 
with  a  stopper  containing  a  condensing  tube 
and  placed  in  a  hot- water  bath.  The  alcohol 
is  gently  boiled  for  20  minutes,  when  diffusion 
of  the  sugar  through  the  solution  may  be  con- 
sidered complete.  The  tube  and  stopper  are 
rinsed  into  the  flask  and  the  volume  completed 
nearly  to  the  mark  with  90  per  cent  alcohol. 
Fig.  137. -Flasks  for  alco-  The  flagk  ig  in  laced  in  the  hot-water  bath 
hohc  .digestion  of  beet  -  -  ,  0  .  .  £ 

pul  for  1  to  2  minutes,  to  secure  even  mixing  of 

the  contents  and  expulsion  of  air  bubbles,  and 

then  allowed  to  cool  slowly  in  the  air  for  J  hour.  The  liquid  is  then 
brought  to  room  temperature  and  the  volume  completed  to  201.2  c.c. 
with  90  per  cent  alcohol.  The  solution  is  then  mixed,  filtered  and 
polarized  in  a  200-mm.  tube,  using  the  necessary  precautions  to  prevent 
evaporation  and  changes  in  temperature. 

*  Z.  Ver.  Deut.  Zuckerind.,  32,  514,  786. 


METHODS  OF  SIMPLE  POLARIZATION 


239 


The  employment  of  alcohol  in  analytical  work  is  expensive;  it  was 
also  found  that  with  any  coarse  particles  of  pulp  the  diffusion  of  sugar 
through  the  alcohol  was  considerably  retarded.  Pellet*  was  accord- 
ingly induced  in  1887  to  devise  a  method  for  determining  sugar  in  beets 
in  which  water  was  used  for  digesting  instead  of  alcohol.  The  Pellet 
method  may  be  carried  out  with  either  hot  or  cold  water. 

Pellet's  Cold- water-digestion  Process. — Twenty  six  gms.  of  finely 
divided  pulp  are  transferred  by  means  of  a  jet  of  water  into  a  200.6-c.c. 
flask  (the  extra  0.6  c.c.  being  the  estimated  volume  of  the  insoluble 
marc  in  26  gms.  of  pulp);  5  to  6  c.c.  of  lead-subacetate  solution  are 
then  added  and  sufficient  water  to  fill  the  flask  about  two-thirds.  After 
mixing,  the  flask  is  allowed  to  stand  for  20  to  30  minutes  to  permit 


Fig.  138.  —  "  Sans-Pareille  "  press  for  preparing  finely  divided  pulp.  The  substance, 
which  is  placed  in  the  cell  C,  is  forced  in  a  semiliquid  condition  by  the  piston  P 
through  the  fine  openings  at  the  bottom  into  a  container  underneath;  the  latter 
also  receives  any  overflow  of  juice  which  escapes  by  the  outlet  T. 

diffusion  of  sugar  and  allow  enclosed  air  bubbles  to  escape.  Water  is 
then  added  nearly  to  the  mark,  any  foam  destroyed  with  a  drop  of 
ether,  and  the  volume  completed  to  200.6  c.c.  The  solution  is  well 
mixed,  filtered,  and  polarized  in  a  400-mm.  tube;  the  scale  reading 
gives  without  correction  the  polarization  of  the  beet. 

With  pulp  of  extreme  fineness,  such  as  is  obtained  with  the  "Sans- 
Pareille"  press  (Fig.  138),  the  diffusion  of  sugar  from  pulp  to  water 
becomes  almost  instantaneous,  and  the  solution  can  be  completed  to 
volume  as  soon  as  air  bubbles  have  arisen.  The  time  of  analysis  is 
thus  considerably  lessened. 

*  Deut.  Zuckerind.  (1888),  1229;  (1889),  531. 


240  SUGAR  ANALYSIS 

Pellet's  Hot- water-digestion  Process. — If  apparatus  is  not  avail- 
able for  obtaining  pulp  of  suitable  fineness,  hot  water  should  be  used  to 
promote  the  diffusion  of  sugar  from  the  coarser  particles  of  pulp. 
Twenty-six  grams  of  pulp,  mixed  with  6  c.c.  of  lead-subacetate  solution, 
are  washed  into  a  200.6  c.c.  flask,  water  is  added  with  shaking  until 
the  volume  is  almost  up  to  the  mark,  and  the  flask  heated  in  a  boiling 
water  bath  for  J  to  1  hour,  according  to  the  fineness  of  the  pulp.  The 
flask  is  then  immersed  in  cold  water;  as  soon  as  the  contents  are  of 
room  temperature,  the  volume  is  completed  to  the  mark.  The  remain- 
der of  the  process  follows  as  under  cold-water  digestion. 

Kriiger's  Cold- water-digestion  Process.  —  Kriiger,*  in  1896,  de- 
vised a  water-digestion  process,  an  interesting  feature  of  which  is  that 
the  use  of  normal  weights  and  of  volumetric  flasks  is  entirely  dis- 
pensed with.  The  principle  of  the  method  may  be  understood  from 
the  following: 

The  weight  of  juice  per  26  gms.  in  an  average  sugar  beet  of  5  per 
cent  marc  content  is  26  X  0.95  =  24.7  gms.  The  specific  gravity  of 
the  average  beet  juice  is  very  nearly  1.07,  so  that  the  volume  of  juice 
in  a  normal  weight  (26  gms.)  of  pulp  is  24.7  gms.  -r-  1.07  =  23.08  c.c. 
The  amount  of  water  necessary  to  complete  this  volume  of  juice  to 
100  c.c.  is  therefore  100  -  23.08  =  76.92  c.c.  The  ratio  of  normal 
weight  to  volume  of  added  water  is  then  26  gms.  :  76.92  c.c.  =  1  gm.  : 
2.958  c.c.,  or  in  round  numbers  1  gm.  :  3  c.c.  The  addition,  therefore, 
of  water  in  the  proportion  of  3  c.c.  to  every  1  gm.  of  pulp  yields  a 
solution  whose  polarization  in  a  200-mm.  tube  will  give  the  approximate 
sugar  content  of  the  beet. 

The  automatic  pipette  (Figs.  139,  140)  for  rapidly  measuring  water 
and  lead  solution  is  an  essential  feature  of  the  Kriiger  process.  The 
pipette  is  prepared  in  several  sizes  for  approximate  double-normal, 
normal,  half-normal,  and  quarter-normal  weights  of  pulp  (i.e.,  approxi- 
mately 50,  25,  12,  and  6  gms.),  the  smaller  sizes  being  used  in  polarizing 
mother  beets,  where  the  quantities  of  pulp  obtained  by  the  Keil  sam- 
pler (p.  226)  are  small  (8  to  14  gms.).  The  pipette,  which  is  fastened 
to  a  fixed  support  S  (Fig.  140),  is  provided  at  opposite  ends  with  the 
three-way  cocks  C  and  C',  the  movements  of  which  are  controlled  by 
the  double  lever  L.  The  lower  inlet  of  the  pipette  is  connected  by  the 
tube  A  to  the  vessel  V  which  contains  the  "lead  water"  (9  vols.  of 
water  to  1  vol.  of  lead-subacetate  solution).  The  upper  outlet  which 
permits  the  escape  of  air  is  connected  with  the  upright  tube  B.  By 
raising  L  to  the  stop  c  (Fig.  139)  the  pipette  is  filled  with  "lead  water," 
*  Deut.  Zuckerind.  (1896),  2434. 


METHODS  OF  SIMPLE  POLARIZATION 


241 


any  overflow  passing  into  the  tube  B.  Upon  dropping  L  to  the  stop  d, 
the  cocks  are  both. reversed,  air  entering  through/,  and  the  contents 
of  the  pipette  being  discharged  through  e  into  the  metal  weighing  dish 
D,  which  contains  the  weighed  sample  of  pulp. 


d 

Fig.  139  Fig.  140 

Kriiger's  automatic  pipette  for  sugar  beet  analysis. 

The  weight  of  pulp  corresponding  to  each  pipette  is  determined  by 
calibration  with  water,  as  in  the  following  example.  The  weight  of 
distilled  water  discharged  by  a  Kriiger  pipette  at  20°  C.  was  found  to 
be  78.38  gms.  The  volume  of  the  pipette  in  true  cubic  centimeters  is 
then  78.38  -v-  0.9972  =  78.6  c.c.  78.6  ^  3  =  26.2  gms.,  the  weight  of 
beet  pulp  corresponding  to  the  pipette. 

After  mixing  the  pulp  and  "  lead  water  "  the  weighing  dish  is 
covered  and  the  contents  allowed  to  remain  for  20  to  30  minutes. 
The  solution  is  then  well  stirred,  filtered,  and  polarized  in  a  200-mm. 
tube. 


242 


SUGAR  ANALYSIS 


The  Kriiger  method,  while  not  claiming  extreme  accuracy,  is  suffi- 
ciently exact  for  many  purposes  of  analysis.  On  account  of  its  sim- 
plicity and  rapidity  the  method  has  been  widely  used  in  such  places  as 
beet-seed  nurseries,  depots  for  purchase  of  beets,  etc.,  where  large  num- 
bers of  samples  have  to  be  polarized  with  the  least  possible  loss  of  time. 

Sachs-Le  Docte  Process  of  Water  Digestion.  —  The  occlusion  of 
air  bubbles  by  pulp  and  the  uncertainty  of  knowing  whether  such 
bubbles  are  completely  absent  before  making  up  to  volume  have  been 
the  principal  objections  against  the  original  Pellet  process  of  digestion. 
This  error  does  not  occur  in  the  Kriiger  method,  where  the  volume  of 
solution  is  established  independent  of  any  occluded  air.  The  necessity 
of  employing  irregular  weights  for  each  individual  pipette  and  the  use 
of  insufficient  water  for  the  complete  diffusion  of  the  sugar  during  the 
cold  digestion  have  been  raised  on  the  other  hand  as  objections  against 
the  Krtiger  method.  Sachs  *  and  Le  Docte  f  have  met  these  difficulties 
by  always  taking  the  regular  normal  weight  (26  gms.)  of  pulp  for 
analysis  and  adding  a  constant  volume  (177  c.c.)  of  water  and  lead 
subacetate  so  that  the  final  estimated  volume  of  solution,  regardless 
of  insoluble  marc  or  occluded  air,  is  always  200  c.c. 

The  constant-volume  figure  177  c.c.  in  the  Sachs-Le  Docte  process 
is  derived  from  the  following  consideration.  Sachs  assumes  as  the 
average  marc  and  juice  content  of  the  sugar  beet  4.75  per  cent  and 
95.25  per  cent  respectively.  For  the  normal  weight  (26  gms.)  of  pulp 
there  would  then  be  26  gms.  X  .9525  =  24.765  gms.  juice.  The  aver- 
age sugar  content  and  density  of  juices  from  beets  of  different  richness 
are  given  in  the  following  table  together  with  the  calculated  volume  of 
juice  (24.765  -f-  sp.  gr.),  the  volume  of  lead-water  solution  (200  c.c.  less 
the  volume  of  juice)  and  the  polarization  error  resulting  from  use  of  the 
constant  volume  177  c.c. 

TABLE  XLV 


Sugar  in  beet. 

Sugar  in 
juice. 

Brix  of 
juice. 

Specific 
gravity  of 
juice. 

Volume  of 
juice. 

Volume  of 
lead-water 
solution. 

Calculated 
polariza- 
tion.* 

Polariza- 
tion error. 

Per  cent. 
12 

13 
14 
15 
16 
17 

Per  cent. 
12.59 
13.65 

14.70 
15.75 
16.80 
17.85 

14.86 
15.82 
16.82 
17.86 
18.92 
20.00 

1.0609 
1.0651 
1.0694 
1.0740 
1.0787 
1.0835 

c.c. 

23.34 
23.25 
23.16 
23.06 
22.96 
22.86 

176.66 
176.75 
176.84 
176.94 
177.04 
177.14 

11.979 
12.984 
13.988 
14.995 
16.003 
17.012 

-0.021 
-0.016 
-0.012 
-0.005 
+0.003 
+0.012 

*  Calculated  polarization 


sugar  in  beet  X  200 
volume  of  juice  -f-  177 


*  Z.  Ver.  Deut.  Zuckerind.  (1906),  56,  918.         f  Ibid.  (1906),  66,  924. 


METHODS  OF  SIMPLE  POLARIZATION 


243 


It  is  seen  that  by  use  of  the  constant 
volume  177  c.c.  the  calculated  polariza- 
tion error  is  too  small  to  be  detected 
upon  the  saccharimeter. 

The  constant-volume  pipette  em- 
ployed in  the  Sachs-Le  Docte  process  is 
shown  in  Fig.  141.  A  three-way  cock 
K  at  the  bottom  serves  for  the  inlet  of 
lead  reagent  and  water  at  B  and  C  and 
for  the  delivery  of  the  177  c.c.  of  mixed 
solution  through  D.  The  cap  A  at  the 
top,  which  receives  the  overflow,  is  con- 
nected with  a  waste  bottle.  Instead  of 
drawing  in  the  lead  reagent  and  water 
separately,  a  single  "  lead- water  "  solu- 
tion of  proper  dilution  may  be  used. 
One  of  the  cock  connections  may  thus 
be  dispensed  with.  By  raising  or  lower- 
ing the  capillary  tube  h  upon  its  support 
at  H  the  capacity  of  the  pipette  is  easily 
adjusted  to  exactly  177  c.c. 

The  method  of  operation  is  similar 
to  that  in  the  Kriiger  process.  Weigh 
26  gms.  of  pulp  in  one  of  the  tared  metal 
beakers;  the  latter  are  of  about  250-c.c. 
capacity  and  are  provided  with  a  tight- 
ficting  cover  of  rubber;  add  177  c.c.  of 
water  containing  5  to  6  c.c.  of  lead  sub- 
acetate  solution  (of  about  30°  Be.)  and 
shake  thoroughly.  Filter,  add  a  drop 
of  glacial  acetic  acid  to  the  filtrate,  and 
polarize  in  a  400-mm.  tube.  The  scale 
reading  gives  the  polarization  of  the 
beet.  Where  many  analyses  have  to 
be  performed  a  large  number  of  metal 
beakers  are  used,  all  of  which  are 
counterpoised  against  the  same  weight. 

If  the  particles  of  pulp  are  coarse  Fig  141i_Sach8.Le  Docte 
the  Sachs-Le  Docte  process  should  be  matjc  pipette  for  sugar 
carried  out  by  hot  digestion.*  The  analysis. 

*  Sucrerie  Beige,  Oct.  15,  1908.  Bull,  assoc.  chim.  sucr.  dist.,  27,  180. 


auto- 
beet 


244  SUGAR  ANALYSIS 

method  of  operation  is  similar  to  that  just  described,  except  that  the 
metal  beakers,  after  addition  of  the  177  c.c.  of  lead- water  solution  to  the 
pulp,  are  each  covered  with  a  special  pneumatic  cap  of  rubber  which 
prevents  any  loss  by  evaporation.  Fig.  142  shows  a  water  bath  for 
the  Sachs-Le  Docte  hot-digestion  process.  The  metal  beakers  are 
placed  for  30  minutes  in  a  water  bath  heated  to  80°  C.  After  cooling 
the  beakers  are  well  shaken,  when  the  contents  are  filtered  and  polarized 
in  the  usual  way. 

Herzfeld*  has  slightly  modified  the  Sachs-Le  Docte  process  for  hot 
digestion.     The  pulp  is  weighed  into  small  copper  cans,  11  cm.  high, 


Fig.  142.  — Sachs-Le  Docte  bath  for  hot-water  digestion. 

6  cm.  body  diameter,  and  4  cm.  mouth  diameter.  The  cans  are  closed 
during  digestion  with  rubber  stoppers  or  with  good  corks  covered  with 
tinfoil.  The  blowing  out  of  stoppers  during  digestion  has  been  raised 
as  an  objection  against  the  Herzfeld  modification.  Stanek  and  Urban f 
recommend  the  use  of  cans  provided  with  a  spring  cap  and  rubber 
gasket.J 

A  comparison  of  sugar  determinations  in  beets  by  the  Sachs- 
Le  Docte  cold-  and  hot-digestion  methods  and  by  the  Kruger  method  is 
given  in  the  following  table.  The  results  are  the  average  of  many  de- 
terminations reported  by  Herzfeld.* 

*  Z.  Ver.  Deut.  Zuckerind.,  69,  627. 

t  Z.  Zuckerind.  Bohmen,  34,  625. 

t  A  very  full  description  of  methods  for  analyzing  sugar  beets  and  a  complete  bib- 
liography of  the  subject  from  1839  to  1907  has  been  compiled  by  Bryan  (Bull.  146, 
U.  S.  Bur.  of  Chem.) 


METHODS  OF  SIMPLE  POLARIZATION 


245 


Sachs-  Le  Docte  method. 

Kriiger  method, 
cold  digestion. 

Cold  digestion. 

Hot  digestion. 

Average  14  analyses  
Average  19  analyses.  .  .  . 

Per  cent. 
16.66 
15.91 

Per  cent. 
16.87 
16.28 

Per  cent. 
16.56 

16.12 

Errors  of  Digestion  Methods 

Solution  of  Dextrorotatory  Gums. — It  is  noted  in  the  preceding  table 
that  the  hot-digestion  gives  from  0.2  to  0.3  higher  than  the  cold-digestion 
methods.  This  excess  is  no  doubt  due  in  large  part  to  a  higher  extrac- 
tion of  sucrose  from  the  coarser  particles  of  pulp.  Some  chemists, 
however,  attribute  a  part  of  the  excess  to  a  solution  of  dextrorotatory 
hemicelluloses  (parapectin,  metapectin,  etc.)  which  are  dissolved  by  the 
hot  water  from  the  pulp.  According  to  Pellet  these  substances  are 
completely  precipitated  by  the  lead-subacetate  solution,  when  this 
reagent  is  of  proper  strength  (about  30  degrees  Be.)  and  used  in  proper 
amount  (5  to  6  c.c.  per  26  gms.  of  pulp).  To  insure  complete  precipi- 
tation of  all  dextrorotatory  gums  some  authorities  advise  using  7 
or  8  c.c.  of.  basic-lead  solution.  Herzfeld,*  however,  has  shown  that 
lead  subacetate  in  hot  solution  forms  a  levorotatory  combination 
with  certain  constituents  of  beet  pulp  and  is  opposed  to  the  use  of 
more  than  5  c.c.  of  the  reagent  per  26  gms.  pulp  for  hot-water 
digestion. 

The  extraction  of  high  polarizing  dextrorotatory  gums  is  very  liable 
to  occur,  even  with  cold-water  digestion,  in  the  case  of  sugar  beets 
which  are  unripe,  frost-bitten,  diseased,  or  otherwise  abnormal.  Under 
such  circumstances  the  method  of  extraction  with  alcohol,  in  which 
the  gums  are  insoluble,  should  be  employed. 

Solution  of  Asparagine.  —  Another  constituent  of  sugar  beets  which 
may  introduce  an  error  in  the  polarization  is  asparagine.  Degenerf 
has  shown  that  asparagine,  which  in  neutral  solutions  is  slightly  levo- 
rotatory ([a]D  =  —5.2),  becomes  strongly  dextrorotatory  ([O\D  =  +61.76 
to  +69.10)  in  presence  of  10  per  cent  lead-subacetate  solution,  every 
0.1  per  cent  asparagine  polarizing  about  the  same  as  every  0.1  per  cent 
sucrose.  To  obviate  this  error  the  French  chemists  add  a  drop  of 
glacial  acetic  acid  to  the  filtered  solution  from  the  aqueous  digestion 
before  polarizing.  Asparagine  is  dissolved  only  1  part  in  290  parts  of 

*  Z.  Ver.  Deut.  Zuckerind.,  59,  627. 
f  Deut.  Zuckertnd.  (1897),  65. 


246  SUGAR  ANALYSIS 

80  per  cent  alcohol  and  this  solubility  is  diminished  by  the  addition  of 
lead  subacetate.  The  asparagine  error  is  therefore  negligible  in  the 
methods  of  alcoholic  extraction  or  digestion. 

Variation  in  Marc  Content.  —  Among  other  sources  of  error  peculiar 
to  the  digestion  methods  may  be  mentioned  the  difference  in  quantity 
and  volume  of  insoluble  cellular  matter  in  the  normal  weight  of  pulp. 
This  volume  is  in  fact  variously  given  by  different  authorities  as  0.6  c.c.,* 
0.75  c.c.,f  1.35  c.c.,{  and  the  digestion  flasks  have  been  correspondingly 
graduated  at  200.6  c.c.,  200.75  c.c.,  and  201.35  c.c.  Pellet  has  devised 
a  special  digestion  flask  with  5  graduations  at  200.0  c.c.,  200.5  c.c., 
200.75  c.c.,  201.0  c.c.,  and  201.5  c.c.,  so  that  the  chemist  may  vary  the 
volume  according  to  the  weight  and  character  of  pulp.  While  the 
volume  most  generally  prescribed  is  200.6  c.c.  for  26  gms.  of  pulp,  it 
is  evident  that  this  figure  must  be  greater  for  wilted  beets  and  less  for 
unripe  beets.  In  the  same  way  the  volume  of  lead-water  solution  in 
the  Sachs-Le  Docte  process  would  be  greater  or  less  than  177  c.c.  The 
polarization  errors  due  to  normal  variations  from  the  average  of  4.75  per 
cent  marc  are  considerably  less  than  0.1,  but  in  extreme  cases  of  wilted 
or  watery  beets  the  alcoholic  extraction  method  should  be  used  as  a 
control. 

The  error  due  to  imbibition  or  colloidal  water  (p.  229)  has  also 
been  raised  against  the  digestion  methods.  The  average  difference 
between  the  expression  and  extraction  methods  was  found  by  Scheibler 
to  be  about  0.75  per  cent,  which  difference  represents  the  combined 
influence  of  unequal  composition  of  juice  and  of  the  colloidal  water. 
In  the  digestion  methods  the  23  c.c.  of  juice  is  diluted  to  200  c.c.  or 
nearly  ninefold,  so  that  the  combined  errors  of  the  juice  methods  are 
reduced  to  less  than  0.1.  In  the  digestion  methods  the  error  due 
to  unequal  composition  of  juice  is  largely  eliminated;  the  residual 
error  due  to  the  so-called  colloidal  water  must  therefore  be  very 
small. 

The  agreement  between  the  aqueous  digestion  and  alcoholic  extrac- 
tion methods  upon  normal  sugar  beets  is  usually  very  close.  As  to 
which  of  the  water-digestion  methods  is  preferable  it  may  be  said  that 
if  apparatus  is  available  for  securing  pulp  of  extreme  fineness  the  cold- 
water  digestion  is  upon  the  whole  less  open  to  error.  But  for  pulp  of 
coarse  or  uneven  character  hot-water  digestion  should  be  used  to  insure 
complete  extraction. 

*  Friihling's  "  Anleitung,"  209. 

t  Fribourg's  "  Analyse  chimique,"  253. 

t  Sidersky's  "Manuel,"  241. 


METHODS  OF  SIMPLE  POLARIZATION  247 

POLARIZATION  OF   PLANT   SUBSTANCES   CONTAINING  BUT   Low  PER- 
CENTAGES OF  SUGAR 

The  methods  previously  described  may  be  applied  with  minor 
modifications  to  the  polarization  of  plant  substances  containing  but 
low  percentages  of  sugar.  The  polarization  of  spent  sugar-beet  chips 
and  sugar-cane  bagasse  may  serve  as  illustrations  of  the  methods. 

Polarization  of  Spent  Beet  Chips  by  the  Expression  Method.  — 
While  the  water  circulating  through  the  diffusion  battery  removes 
most  of  the  sugar  from  the  beet  chips,  a  small  amount  of  sugar  always 
remains  unextracted;  this  residual  sugar  occurs  for  the  most  part 
within  the  uncrushed  cells  of  the  beet.  It  is  necessary,  therefore,  in 
squeezing  out  the  water  from  diffusion  chips  to  apply  extreme  pressure, 
in  order  to  secure  the  maximum  quantity  of  residual  sugar.  A  polari- 
zation of  the  expressed  diffusion  water  and  a  determination  of  its 
amount  are  sufficient  for  the  calculation. 

Example.  —  100  c.c.  of  the  diffusion  water  pressed  from  a  sample  of  spent 
beet  chips  were  clarified  with  2  c.c.  of  lead-subacetate  solution  and  the  volume 
completed  to  110  c.c.  The  filtered  solution  gave  a  polarization  of  2.0°  V.  in  a 
400-mm.  tube.  The  water  content  of  the  chips,  upon  drying  10  gms.  at  100°  to 
110°  C.  to  constant  weight,  was  90.5  per  cent. 

The  polarization  corrected  for  the  dilution  is  2.0  X  1.1  =  2.2°  V.  Calling 
the  sp.  gr.  of  the  waste  diffusion  water  1.000  (which  can  be  done  without  serious 
error)  the  polarization  of  a  normal  weight  would  be  (26.00  X  2.2)  -5-  100  = 
0.572°  V.,  or  for  a  200-mm.  tube  0.29°  V.  The  polarization  of  the  spent  chips 
would  then  be  (90.5  X  0.29)  ^  100  =  0.26. 

Polarization  of  Dried  Beet  Chips  by  the  Alcoholic  Digestion  and 
Extraction  Method.  —  Dried  sugar-beet  chips  have  frequently  under- 
gone a  change  in  composition  through  formation  of  water-soluble 
optically  active  gums  at  the  high  temperature  of  drying.  The  aqueous 
digestion  method  may  then  give  a  polarization  different  from  the  true 
sucrose  content.  In  such  cases  it  is  recommended  to  use  the  alcoholic 
digestion  and  extraction  method  of  Herzfeld.* 

A  half  normal  weight  of  the  finely  ground  dry  chips  is  digested  in 
a  hot-water  bath  with  50  to  60  c.c.  of  60  per  cent  alcohol,  adding 
3  to  5  c.c.  of  lead-subacetate  solution,  for  30  minutes.  The  contents 
of  the  digestion  flask  are  then  transferred  by  means  of  a  little  60  per 
cent  alcohol  to  a  Soxhlet  extractor  and  extracted  under  reduced  pres- 
sure for  5  to  6  hours  (see  Fig.  143).  The  alcoholic  extract  is  then  made 
up  to  100  c.c.,  filtered,  and  polarized  in  a  400-mm.  tube. 
*  Z.  Ver.  Deut.  Zuckerind.,  69,  627. 


248 


SUGAR  ANALYSIS 


Polarization  of  Sugar-cane  Bagasse  by  Hot-water  Extraction. — 

The  hot-water-extraction  method  of  Zamaron  may  be  employed  upon 
bagasse  in  the  same  manner  as  described  for  sugar  cane.  Owing,  how- 
ever, to  the  much  larger  amount  of  cellular  matter  in  bagasse  only 

50  gms.  are  taken  for  extraction.  The  ex- 
tract is  made  up  to  1000  c.c.  and  polarized 
in  a  400-mm.  tube.  The  reading  multiplied 
by  2.6  gives  the  polarization  of  the  bagasse. 
Extraction  waters  of  very  low  sugar  con- 
tent are  sometimes  concentrated  before 
polarization.  Five  hundred  cubic  centi- 
meters of  the  neutralized  solution  are  evapo- 
rated to  somewhat  less  than  the  desired 
volume,  and  then  made  up  to  100  c.c.  or 
250  c.c.  for  polarization.  The  saccharimeter 
reading  is  divided  by  5  or  2  to  obtain  the 
polarization  of  the  extract. 

Polarization  of  Sugar-cane  Bagasse  by 
Hot-water    Digestion.  —  Bagasse    is    also 
polarized  by  the  method  of  hot- water  diges- 
tion, in  which  case,  however,  it  is  necessary 
to  know  the  percentage  of  fiber.     The  de- 
termination may  be  made  by  the  methods 
Fig.    143.-HerZfeld's   appa-  of  the  Hawaiian  chemists.* 
ratus  for  alcoholic  extraction  .      t .  . 

under  reduced  pressure.  Determination  of  Fiber  in  Bagasse.  -  One 

hundred  grams  of  bagasse  are  placed  in  a 

strong  linen  bag,  and  the  juice  pressed  out  with  an  hydraulic  press. 
The  sample  is  then  treated  with  cold  running  water  for  two  minutes, 
and  again  pressed,  the  two  operations  being  repeated  alternately  five 
times.  The  bag  is  then  placed  in  an  air  bath  at  125°  C.  for  half  an  hour, 
after  which  the  fiber  is  removed  from  the  bag  and  dried  in  a  shallow 
dish  for  four  hours  at  the  same  temperature.  When  an  hydraulic  press 
is  not  available,  the  sample  may  be  treated  in  cold  running  water  for 
12  hours  and  dried  as  above  described. 

Digestion  of  Bagasse.  —  Fifty  grams  of  bagasse  are  weighed  in  a 
tared  flask;  500  c.c.  of  water  containing  2  c.c.  of  5  per  cent  sodium 
carbonate  are  added,  and  the  flask  connected  with  a  vertical  condenser. 
The  solution  is  boiled  gently  for  one  hour,  the  flask  being  shaken 
thoroughly  every  15  minutes.  After  cooling  the  flask  is  re  weighed,  and 
the  weight  of  contents  determined.  The  weight  of  contents  multi- 
*  Hawaiian  Planters'  Record,  3,  317. 


METHODS  OF  SIMPLE  POLARIZATION  249 

plied  by  2  gives  the  weight  (W)  of  fiber  and  solution  corresponding  to 
100  gms.  of  bagasse.  Letting  F  =  the  per  cent  fiber  in  the  bagasse, 
W  —  F  =  the  weight  of  solution  corresponding  to  100  gms.  of  bagasse. 
The  aqueous  extract  obtained  by  the  hot  digestion  is  squeezed  out; 
99  c.c.  of  the  solution  are  made  up  to  100  c.c.  with  lead-subacetate 
reagent,  filtered,  and  polarized  in  a  400-mm.  tube.  The  polarization 

100  jP 

(P)  corrected  for  dilution  is      .      ,  and  this  reduced  to  a  normal  weight 

26       100  P      26  P 
of  extract  is  -r—  X  -7^—  =  ~7^r  ,  which  value  for  a  200-mm.  tube  be- 

iuu       yy         yy 
13  P 

comes    QQ   •     The  polarization  of  the  bagasse  is  then  found  by  the 
yy 

13  P      (W-  F)      P(W  -  F) 
formula  -99-       -—     .  ^  - 


II 


POLARIZATION    OF    SUBSTANCES    CONTAINING    INSOLUBLE    MINERAL 

MATTER 

The  polarization  of  substances  containing  insoluble  mineral  matter 
can  in  general  be  carried  out  by  the  methods  of  extraction  or  digestion 
previously  described.  Certain  classes  of  products,  however,  such  as 
carbonatation  filter-press  cake  may  contain  sugar  in  the  form  of  in- 
soluble saccharates,  and  in  such  cases  special  methods  of  treatment  are 
required.  As  examples  of  methods  to  be  employed  several  processes 
for  the  polarization  of  filter-press  cake  will  be  described. 

Polarization  of  Filter-press  Cake  Free  from  Saccharate.  —  If 
saccharate-free  press  cake  be  triturated  with  a  known  quantity  of 
water  and  the  filtered  extract  polarized,  the  polarization  of  the  cake 
may  be  calculated  very  closely,  provided  its  moisture  content  has  been 
determined. 

Example.  —  50  gms.  of  press  cake  were  ground  in  a  mortar  with  200  c.c.  of 
water.  The  solution  (which  should  not  be  alkaline)  was  then  clarified  with  a 
little  dry  lead  subacetate  and  polarized  in  a  400-mm.  tube.  A  reading  of  5.2°  V. 
was  obtained.  The  moisture  content  of  the  cake,  determined  by  drying  10  gms. 
in  a  hot-water  bath  to  constant  weight,  was  45.6  per  cent.  It  is  desired  to 
know  the  polarization  of  the  cake. 

The  weight  of  water  in  the  50  gms.  of  cake  is  50  X  0.456  =  22.8  gms. 
The  total  volume  of  liquid  (disregarding  the  slight  increase  in  volume  through 
solution  of  sugar)  is  then  200  +  22.8  =  222.8  c.c.  The  polarization  of  the 
solution  reduced  to  a  normal  weight  of  26  gms.  to  100  c.c.  (calling  the  sp.  gr. 
1.000,  which  may  be  done  without  serious  error)  is  (5.2  X  26)  -s-  100  =  1.35°  V., 
which  for  a  200-mm.  tube  is  0.68°  V.,  or  0.68  gms.  of  sucrose  in  100  c.c.  of 


250  SUGAR  ANALYSIS 

solution.  This  corrected  to  222.8  c.c.  =  0.68  X  2.228  =  1.52,  the  grams  of 
sucrose  in  50  gms.  of  cake;  1.52  X  2  =  3.04,  the  polarization  or  percentage 
of  sucrose  in  the  cake,  if  no  other  optically  active  substances  are  present. 

The  above  method  of  calculation  is  sufficiently  exact  for  substances 
of  low  polarization.  When  the  polarization  is  high,  however,  neglect 
of  the  increase  in  volume  through  solution  of  sugar  and  of  the  change 
in  specific  gravity  introduces  a  considerable  error.  In  such  cases  the 
polarization  should  be  determined  by  some  method  of  extraction. 

In  sugar-house  practice  the  determination  of  moisture  in  the  press 
cake  is  usually  dispensed  with,  it  being  assumed  that  the  volume  of  in- 
soluble matter  in  26  gms.  of  cake  is  4  c.c.  The  normal  weight  of  cake 
is  then  made  up  to  104  c.c.;  or,  if  a  100-c.c.  flask  be  used,  25  gms.  of 
cake,  when  triturated,  clarified  with  lead  solution,  and  the  liquid  made 
up  to  volume,  will  give  the  polarization  (104  :  26  :  :  100  :  25).  In 
practice  50  gms.  of  cake  are  generally  weighed  out  and  the  volume 
made  up  to  200  c.c. 

In  the  previous  example  if  the  50  gms.  of  cake  had  been  made  up  with 
water  to  200  c.c.,  there  would  be  192.3  c.c.  of  solution  (allowing  4  c.c.  for  volume 
of  insoluble  matter  in  26  gms.).  The  polarization  for  222.8  c.c.  of  solution  was 
5.2°  V.,  therefore  192.3  :  5.2  :  :  222.8  :  6.02,  the  calculated  polarization  of  the 
cake  for  a  400-mm.  tube.  This  for  a  200-mm.  tube  would  be  3.01,  which  is 
only  0.03°  V.  lower  than  the  result  previously  found. 

Polarization  of  Filter-^press  Cake  Containing  Saccharate.  —  When 
filter-press  cake  contains  insoluble  saccharates,  the  sugar  must  be 
liberated  from  combination  before  the  solution  to  be  polarized  is  made 
up  to  volume.  Several  methods  have  been  followed  for  accomplishing 
this  result. 

Decomposition  of  Saccharate  by  Means  of  Acetic  Acid.  —  The  50  gms. 
of  press  cake,  after  transferring  with  water  to  a  200-c.c.  flask,  are  heated 
to  boiling,  and  acetic  acid  added  drop  by  drop  until  all  free  alkali  is 
neutralized.  The  solution  is  then  cooled,  clarified,  made  up  to  volume, 
filtered,  and  polarized  as  previously  described. 

Decomposition  of  Saccharate  by  Means  of  Carbon  Dioxide.  —  The 
method  is  practically  the  same  as  that  just  described,  except  that  a 
stream  of  carbon  dioxide  led  into  the  solution  is  used  for  decomposing 
the  saccharate,  instead  of  acetic  acid. 

The  frothing,  caused  by  evolution  of  carbon  dioxide,  is  the  principal 
objection  against  the  acetic-acid  method,  and  the  decomposition  by 
means^of  carbon  dioxide  usually  requires  considerable  time.  Methods 
have  been  devised,  therefore,  to  decompose  insoluble  saccharates  in  other 
ways.  One  of  the  most  common  of  such  methods  is  the  following: 


METHODS  OF  SIMPLE  POLARIZATION  251 

Decomposition  of  Saccharate  by  Means  of  Ammonium  Nitrate.  — 
The  saccharates  of  calcium  are  quickly  decomposed  by  ammonium 
nitrate  with  formation  of  free  sugar,  calcium  nitrate,  and  ammonia. 
The  reaction  for  monocalcium  saccharate  is 

Ci2H22OnCaO  +  2  NH4N03  +  H20  =  dsH^On  +  Ca(N03)2  +  2  NH4OH. 

Saccharate  Sucrose 

In  carrying  out  the  process  50  gms.  of  press  cake  are  ground  up 
with  15  gms.  of  ammonium  nitrate  and  100  c.c.  of  cold  distilled  water. 
The  mixture  is  then  washed  into  a  200-c.c.  flask,  clarified  with  a  little 
lead-acetate  solution,  made  up  to  volume,  and  polarized  in  the  usual 
way. 

An  objection  against  the  ammonium-nitrate  method  is  the  libera- 
tion of  free  ammonia,  which  in  presence  of  the  lead-clarifying  agent 
may  precipitate  a  part  of  the  sucrose  as  lead  saccharate.  The  free 
ammonia  in  some  cases  causes  a  darkening  of  the  solution;  contact 
with  the  brass  fittings  of  polariscope  tubes  may  also  color  the  ammo- 
niacal  solution  blue.  Care  should  be  exercised,  therefore,  to  prevent 
contact  of  the  solution  with  copper  or  brass  during  the  analysis. 

Decomposition  of  Saccharate  by  Means  of  Zinc  Nitrate.  —  In  order  to 
eliminate  the  formation  of  free  alkali  Stanek*  has  proposed  the  em- 
ployment of  zinc  nitrate  for  decomposing  the  saccharate.  The  reaction 
proceeds  as  follows: 

CisH^OnCaO  +  Zn(N03)2  +  H20  =  Ci2H22On  +  Ca(N03)2  +    Zn(OH)2 

Monosaccharate         Zinc  nitrate  Sucrose  Calcium  nitrate      Zinc  hydroxide. 

The  precipitated  zinc  hydroxide  is  removed  with  the  insoluble  mineral 
matter  of  the  cake  and  a  perfectly  neutral  filtrate  is  obtained. 

In  carrying  out  the  process  a  double  normal  weight  (52  gms.)  of 
press  cake  is  thoroughly  triturated  with  100  c.c.  of  water;  a  few  drops 
of  phenolphthalein  indicator  are  then  added,  and  a  neutral  solution  of 
zinc  nitrate  run  in  until  the  red  color  is  just  discharged.  The  volume 
is  then  completed  to  210  c.c.  (10  c.c.  being  allowed  for  the  volume  of 
insoluble  cake  and  zinc  hydroxide),  and  the  solution  filtered  and  polarized. 

The  methods,  which  have  been  described  for  polarizing  products  of 
the  cane-  and  beet-sugar  industry,  may  be  applied  equally  well  to  the 
polarization  of  other  sucrose-containing  substances,  such  as  maple  and 
sorghum  products,  jellies,  preserves,  confections,  etc.  The  same 
methods  may  also  be  applied  to  the  polarization  of  substances  which 
contain  other  sugars  than  sucrose,  the  only  change  necessary  to  make 

*  Z.  Zuckerind.  Bohmen,  34,  161. 


252 


SUGAR  ANALYSIS 


being  in  the  constant  for  the  normal  weight.  As  an  example  of  the 
application  of  saccharimetric  methods  to  other  sugars  besides  sucrose, 
the  determination  of  milk  sugar  in  milk  is  selected. 

SACCHARIMETRIC  DETERMINATION  OF  LACTOSE 

Polarization  of  Milk.*  —  The  normal  weight  of  lactose  for  a  saccha- 
rimeter  with  the  Ventzke  sugar  scale  may  be  taken  ^is  32.9  gms.  (see 
p.  197).  Owing  to  the  low  percentage  of  lactose  in  milk  (2  to  8  per 
cent)  it  is  best  to  employ  double  the  normal  weight,  and,  as  it  is  more 
convenient  to  measure  the  milk,  tables  have  been  prepared  which  give 
the  volumes  of  milk  corresponding  to  multiples  of  the  normal  weights 
for  different  saccharimeters.  The  following  table  gives  the  volumes 
of  milk  for  65.8  gms.  which  correspond  to  different  specific  gravities. 

TABLE  XLVI 
Giving  the  Volumes  of  Milk  Corresponding  to  a  Lactose  Double  Normal  Weight 


Specific  gravitv  of 
milk. 

Volume  of  milk  for  a 
Lactose  double  normal 
weight  (Ventzke  scale). 

.024 

c.c. 

64.25 

.025 

64.20 

.026 

64.15 

.027 

64.05 

.028 

64.00 

.029 

63.95 

.030 

63.90 

.031 

63.80 

.032 

63.75 

.033 

63.70 

.034 

63.65 

1.035 

63.55 

1.036 

63.50 

For  ordinary  purposes  a  pipette  graduated  to  deliver  64  metric  c.c. 
is  sufficiently  exact. 

Acid  Nitrate  of  Mercury  Solution.  —  In  clarifying  milk  for  polariza- 
tion acid  nitrate  of  mercury  is  generally  used.  The  reagent  is  prepared 
as  follows:  Dissolve  metallic  mercury  in  twice  its  weight  of  nitric  acid 
of  1.42  sp.  gr.,  and  dilute  with  an  equal  volume  of  water. 

Mercuric-iodide  Solution.  —  Mercuric-iodide  solution  may  also  be 
used  for  clarification.  The  reagent  is  prepared  by  adding  33.2  gms.  of 
potassium  iodide  to  a  solution  of  13.5  gms.  mercuric  chloride  in  20  c.c. 
of  glacial  acetic  acid  and  640  c.c.  of  water. 

*  Methods  of  Analysis  A.  O.  A.  C.  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  118. 


METHODS  OF  SIMPLE  POLARIZATION  253 

In  carrying  out  the  process,  the  volume  of  milk  corresponding  to 
the  lactose  double  normal  weight  is  measured  into  a  102.6-c.c.  flask. 
For  clarification  either  1  c.c.  of  the  acid  mercuric  nitrate,  or  30  c.c.  of 
the  mercuric-  iodide  solution  may  be  used  (an  excess  of  either  -reagent 
does  no  harm).  The  liquid  is  shaken  and  then  made  up  to  a  volume 
of  102.6  c.c.,  the  extra  2.6  c.c.  being  the  estimated  volume  of  the  pre- 
cipitated casein,  albumin,  and  fat.  After  mixing,  the  liquid  is  filtered 
and  polarized  in  a  400-mm.  tube;  the  scale  reading  divided  by  4  gives 
the  approximate  percentage  of  lactose  in  the  milk. 

Wiley  and  Swell's  *  Double-dilution  Method.  —  The  volume  of  precipi- 
tate in  the  preceding  method  varies  according  to  the  content  of  protein 
and  fat  so  that  the  fixed  estimate  of  2.6  c.c.  is  not  always  accurate. 
For  more  exact  purposes  of  analysis  the  double-dilution  method  of 
Wiley  and  Ewell  may  be  used.  The  general  principle  of  double  dilu- 
tion, due  to  Scheibler,  has  been  considered  on  page  209. 

Two  separate  double  lactose-normal-weight  portions  of  milk  are 
introduced  into  a  100-c.c.  and  200-c.c.  flask  respectively.  The  same 
volume  of  clarifying  agent  is  then  added  to  each  flask  and  the  volume 
completed  to  the  mark.  The  solutions  are  shaken,  filtered,  and  read 
in  a  400-mm.  tube.  The  reading  of  the  100-c.c.  solution  subtracted 
from  4  times  the  reading  of  the  200-c.c.  solution  gives  the  reading  cor- 
rected for  volume  of  precipitate,  and  this  reading  divided  by  4  gives  the 
percentage  of  lactose  in  the  milk. 

Example.  —  The  saccharimeter  readings  (400-mm.  tube)  of  a  milk  analyzed 
by  the  above  method  were  20.00  for  the  100-c.c.  flask  and  9.80  for  the  200-c.c. 
flask. 

The  reading  corrected  for  volume  of  precipitate  is  then  (4  X  9.80)  —  20.00 
=  19.20,  and  the  percentage  of  lactose  is  19.20-=-  4  =  4.80. 

The  volume  of  precipitate  according  to  the  above  observations  would  be 

100  (2o.o-  19.2),  4e-e  .  (seep.210). 

Leffman  and  Beam's  Method.  —  When  the  percentages  of  fat  and 
protein  are  known  in  a  milk,  the  volume  of  precipitate  formed  during 
clarification  can  be  calculated  according  to  Leffman  and  Beam  f  by  the 
following  method. 

Calling  the  specific  gravity  of  milk  fat  0.93  the  volume  of  precipi- 
tated fat  is  found  by  multiplying  the  grams  of  fat  in  the  weight  of 

sample  by  ^r-^  =  1.075.     In  the  same  way  the  volume  of  the  precipi- 


Analyst, 21,  182.  t  "  Analysis  of  Milk  and  Milk  Products  "  (1896),  p.  39. 


254 


SUGAR  ANALYSIS 


tated  protein-mercury  compound  is  found  by  multiplying  the  grams  of 
protein  in  the  weight  of  sample  by  -^=  =  °-8-     The  sum  of  the  volumes 

of  fat  and  protein  is  the  volume  in  cubic  centimeters  of  the  precipitate. 

For  the  polarization  of  evaporated  or  condensed  milks  the  single 
lactose-normal-weight  of  substance  is  taken.  The  method  of  analysis 
in  other  respects  is  the  same  as  described  for  ordinary  milk. 

The  determination  of  lactose  in  milk  by  the  saccharimeter  is  not 
considered  upon  the  whole  to  be  as  accurate  as  by  the  gravimetric 
method  of  copper  reduction.  A  considerable  variation  is  frequently 
found  in  the  determinations  by  the  two  methods.  In  ten  comparative 
determinations  of  lactose  in  condensed  milk  by  different  collaborators 
of  the  Association  of  Official  Agricultural  Chemists*  an  average  varia- 
tion of  ±  0.30  was  found  between  the  results  by  the  optical  and  by 
the  gravimetric  method,  the  differences  ranging  from  0.03  to  0.90.  In 
a  series  of  comparative  determinations  by  Patrick  and  Boylef  upon 
unsweetened  condensed  milks,  the  following  results  were  obtained: 


Lactose. 

Sample. 

By  polariscope, 
clarification  with 

By  copper  reduc- 
tion, 

acid  Hg(NO3)2. 

Soxhlet's  method. 

1 

10.07 

10.04 

2 

10.19 

10.51 

3 

10.57 

10.69 

4 

9.97 

10.15 

5 

8.71 

9.20 

6 

9.00 

9.37 

The  correction  for  volume  of  mercury  precipitate  in  the  above 
samples  was  made  by  the  method  of  Leffman  and  Beam.  It  is  seen 
that  there  is  an  average  difference  of  about  0.25  between  the  two 
methods. 

The  cause  of  the  occasional  wide  deviations  between  the  results  of 
the  optical  and  gravimetric  methods  for  determining  lactose  has  been 
variously  explained.  The  difference  has  been  attributed  by  some  to 
the  presence  of  foreign  optically  active  substances,  such  as  unpre- 
cipitated  proteids,  organic  acids,  "  animal  gum,"  etc.,  but  this  has  not 
been  conclusively  established.  Differences  due  to  variation  in  volume 

*  Proceedings  A.  O.  A.  C.,  1906,  1907,  Bulls.  105  and  116,  U.  S.  Bur.  of  Chem. 
t  Bull.  105,  U.  S.  Bur.  of  Chem.,  p.  109. 


METHODS  OF  SIMPLE  POLARIZATION  255 

of  precipitated  fat  and  proteids  are  of  course  greater  in  case  of  con- 
densed or  evaporated  milks. 

Polarization  of  Milk  Sugar.  —  The  optical  method  for  determining 
lactose  is  easily  applied  to  the  analysis  of  commercial  milk-sugar, 
when  other  optically  active  compounds  are  absent.  The  lactose- 
normal-weight  of  sugar  is  made  up  to  100  c.c.  with  the  addition  of 
a  little  alumina  cream;  with  dark-colored  products  containing  milk 
sugar  the  solution  of  substance  must  be  clarified,  following  the  same 
methods  and  precautions  as  in  the  polarization  of  :*aw  cane  sugars. 
In  polarizing  milk  sugar  the  saccharimeter  reading  must  not  be  taken 
until  mutarotation  has  disappeared;  the  solution  of  sugar  is  either  al- 
lowed to  remain  in  the  tube  until  a  constant  reading  is  obtained  or 
the  mutarotation  is  destroyed  by  adding  a  few  cubic  centimeters  of 
N/ 10  sodium  carbonate  solution  at  the  time  of  making  up  to  volume. 

The  methods  of  simple  polarization  described  in  the  present  chapter 
may  obviously  be  applied  to  the  polarization  of  products  containing 
glucose,  maltose,  and  other  sugars.  But  in  practical  work  it  is  found 
that  such  sugars  generally  occur  in  mixtures  with  other  carbohydrates, 
and  the  methods  for  their  determination  are  accordingly  given  elsewhere. 

INFLUENCE  OF  TEMPERATURE  UPON  SACCHARIMETRIC  OBSERVATIONS* 

Before  concluding  this  chapter  upon  methods  of  simple  polarization, 
the  influence  of  changes  in  temperature  upon  the  accuracy  of  sac- 
charimetric  observations  should  be  considered. 

It  has  been  shown  (p.  127)  that  with  an  increase  in  temperature 
the  specific  rotation  of  sucrose  undergoes  a  decrease  and  the  rotatory 
power  of  the  quartz  compensation  an  increase,  the  combined  effect  of 
all  influences  producing  a  decrease  in  the  saccharimeter  reading  of  a 
normal  weight  of  pure  sucrose  of  0.03°  V.  for  1°  C.  increase  in  temper- 
ature, and  that  for  temperatures  between  20°  and  30°  C.  the  general 
equation  F20°  =  V*\  1  +  0.0003  (t  -  20)  J  may  be  used  for  changing  the 
Ventzke  reading  (V)  of  pure  sucrose  at  any  temperature  t  to  the  read- 
ing at  20°. 

Saccharimeter  Temperature  Corrections.  —  The  employment  of 
a  temperature  correction,  similar  to  the  above,  was  made  by  the 

*  For  a  full  discussion  of  this  question  with  bibliographic  references  see  paper 
by  Browne,  "  The  Use  of  Temperature  Corrections  in  the  Polarization  of  Raw  Sugars 
and  Other  Products  upon  Quartz  Wedge  Saccharimeters,"  read  before  Section  V, 
Seventh  International  Congress  of  Applied  Chem.,  London,  1909,  also  in  J.  Ind. 
and  Eng.  Chem.  I,  567,  and  Z.  Ver.  Deut.  Zuckerind.,  69,  404. 


256  SUGAR  ANALYSIS 

United  States  Treasury  Department  in  1897,  in  its  polarization  of 
sugars  assessed  for  duty.  The  right  of  the  Treasury  Department  to 
make  such  corrections  in  the  observed  saccharimeter  readings  was  con- 
tested in  the  courts  by  several  importers  of  sugar,  who  founded  their 
case  largely  upon  the  claim  that  the  rotation  of  pure  sucrose  is  not  ap- 
preciably affected  by  changes  in  temperature.  The  chemists  repre- 
senting the  government  were  successful,  however,  in  showing  that  the 
specific  rotation  of  sucrose  is  thus  affected,  and  after  a  final  appeal  to 
the  United  States  Supreme  Court  the  case  of  the  importers  was  dis- 
missed for  want  of  jurisdiction.* 

The  decision  of  the  courts,  which  apparently  justified  the  use  of 
temperature  corrections  established  for  pure  sucrose  in  correcting  the 
polarization  of  all  grades  of  raw  sugars,  has  unfortunately  seemed  to 
many  chemists  sufficient  authorization  to  use  such  corrections  indis- 
criminately in  the  polarization  of  any  and  every  kind  of  sugar-contain- 
ing material.  Since  the  saccharimetric  reading  of  a  raw  sugar  or  other 
impure  product  is  simply  an  expression  of  the  sum  of  the  optical  ac- 
tivities of  the  various  constituents,  sucrose,  glucose,  fructose,  organic 
acids,  gums,  etc.,  it  is  evident  that  a  system  of  temperature  corrections 
which  shall  give  the  saccharimeter  reading  that  would  be  obtained  at 
20°  C.,  must  correct  for  the  variations  produced  by  temperature  in  the 
specific  rotation  of  all  the  optically  active  ingredients  and  not  of  the 
sucrose  alone. 

Wiley's  Temperature  Correction  Table.  —  Wiley  f  has  prepared  a 
temperature  table  for  correcting  the  readings  of  quartz  wedge  sac- 
charimeters  which  is  based  upon  the  variations  in  the  Ventzke  scale 
reading  of  normal  and  fractional  normal  weights  of  pure  sucrose. 
This  table  has  a  range  from  75°  V.  to  100°  V.  for  temperatures  be- 
tween 4°C.  and  40°  C.;  the  corrections  are  to  be  subtracted  from 
the  observed  readings,  when  the  temperature  of  polarization  is  be- 
low and  to  be  added  when  the  temperature  is  above  that  of  stand- 
ardization. 

United  States  Treasury  Department  Method  of  Temperature  Cor- 
rections. —  The  method  of  temperature  corrections  devised  by  the 
Office  of  Weights  and  Measures  of  the  United  States  Coast  and  Geodetic 
Survey  and  adopted  by  the  United  States  Treasury  Department  for 
use  in  the  Custom-House  laboratories,  consists  in  increasing  or  dimin- 
ishing the  saccharimeter  reading  of  each  sugar  solution  by  the  variation 

*  For  testimony  in  this  case  see  "Transcript  of  Record,"  U.  S.  Supreme  Court, 
the  American  Sugar  Refining  Company,  vs.  The  United  States, 
t  J.  Am.  Chem.  Soc.,  21,  568. 


METHODS  OF  SIMPLE  POLARIZATION 


257 


in  reading  which  a  standard  quartz  plate  shows  from  the  computed 
sugar  value  of  this  plate  for  the  temperature  of  observation. 

The  following  report  gives  the  temperature  corrections  in  sugar 
degrees  for  a  quartz  control  plate  tested  by  the  United  States  Bureau 
Standards. 

DEPARTMENT  OF  COMMERCE  AND  LABOR,  BUREAU  OF  STANDARDS, 

WASHINGTON 

ACCOMPANYING  REPORT  OF  TEMPERATURE  CORRECTIONS  IN  SUGAR  DEGREES  FOR 
QUARTZ  CONTROL  PLATE  233-B.S.  1910 


Degrees 
centigrade. 

Sugar 
value. 

Degrees 
centigrade. 

Sugar 
value. 

Degrees 
centigrade. 

Sugar 
value. 

Degrees 
centigrade. 

Sugar 
value. 

13.0° 

90.04° 

20.0° 

90.25° 

25.0° 

90.40° 

30.0° 

90.55° 

14.0 

90.07 

20.5 

90.27 

25.5 

90.42 

30.5 

90.57 

15.0 

90.10 

21.0 

90.28 

26.0 

90.43 

31.0 

90.58 

16.0 

90.13 

21.5 

90.30 

26.5 

90.45 

31.5 

90.60 

17.0 

90.16 

22.0 

90.31 

27.0 

90.46 

32.0 

90.61 

17.5 

90.18 

22.5 

90.33 

27.5 

90.48 

32.5 

90.63 

18.0 

90.19 

23.0 

90.34 

28.0 

90.49 

33.0 

90.64 

18.5 

90.21 

23.5 

90.36 

28.5 

90.51 

34.0 

90.67 

19.0 

90.22 

24.0 

90.37 

29.0 

90.52 

35.0 

90.70 

19.5 

90.24 

24.5 

90.39 

29.5 

90.54 

36.0 

90.73 

If  the  polarization  temperature  is  above  20°C.,  add  to  the  reading  the  difference 
between  the  reading  of  the  plate  and  the  sugar  value  of  the  plate  at  the  polariza- 
tion temperature  shown  by  the  above  table.  If  the  polarization  temperature  is 
below  20°C.,  subtract  the  correction. 

It  will  be  noted  from  this  table  that  the  variation  of  0.030°  V.  per 
1°  C.,  for  the  reading  of  a  normal  weight  of  pure  sucrose,  is  applied 
without  change  to  a  plate  testing  90.25°  V.  at  20°  C.  The  true  tem- 
perature correction  for  a  sucrose  solution  reading  90.25°  V.  upon  the 
saccharimeter  would  of  course  be  0.030  X  0.9025  =  0.027  per  1°  C. 
The  correction  table  is  strictly  true  therefore  only  for  sugar  solutions 
polarizing  100°  V.  at  20°  C.  It  would  be  wrong  in  principle  to  apply 
such  corrections  to  sucrose  solutions  testing  80°  V.  or  50°  V.  or  20°  V. 
since  in  the  latter  instances  the  corrections  are  only  80  per  cent,  50  per 
cent,  and  20  per  cent,  respectively,  of  the  correction  for  a  100°  V.  sucrose 
solution.  The  correction  formula  720°=  V1  \1  +0.0003  (t  -  20)\  or 
the  equivalent  corrections  of  Wiley's  table  are,  therefore,  to  be  pre- 
ferred to  the  method  used  by  the  United  States  Treasury  Department, 
when  it  is  desired  to  correct  the  polarizations  of  pure  sucrose  solutions 
for  change  in  temperature. 

Errors  Involved  in  Use  of  Saccharimeter  Temperature  Corrections.  — 
The  probable  errors  involved  in  the  use  of  the  above  methods  for  cor- 


258 


SUGAR  ANALYSIS 


recting  polarizations  may  be  seen  from  the  following  diagram  (Fig. 
144),  which  gives  the  correction  for  pure  sucrose  solutions,  and  the  ap- 
proximate corrections  for  solutions  of  sugar-beet  and  sugar-cane  prod- 
ucts (according  to  results  obtained  by  Browne*),  to  be  applied  to  the 
readings  of  the  Ventzke  scale  for  1°  C.  increase  in  temperature. 

It  will  be  seen  that  the  correction  for  beet  products  is  much  nearer 


+  U.U3U 

+  0.025 

-1-0.020 
|f0.015 
g+  0.010 
P.+  0.005 
S  n  noo 

s 

^S 

eo(.on 

\ 

i 

^ 

'      ^ 

-ii«u 

s^ 

QUO* 

07 

\ 

^ 

- 

^s^j 

. 

^ 

^^ 

a-  0.005 

9 

0        8t 

\ 

0        6 
Vent; 

0        5 
keRe 

ading^ 

0         J 

0        2 

0         1 

0          i 

g  -0.015 

- 

\ 

9 

% 

u 

00-0.025 

rH 

% 

^? 

./ 

g  O.OaO 
"£-0.035 

- 

\3* 

\ 

x 

,g    U.U4U 

|-  0.045 

-:'. 

^ 

^ 

o    U.UoU 
|-0.055 

\ 

» 

g-  0.065 

- 

\ 

'-g  -0.075 

- 

^ 

'? 

\ 

8-0.085 
—0  000 

\ 

-0.095 

\ 

Fig.  144.  —  Diagram  for  correcting  polarizations  of  sugar  products  for 
changes  in  temperature. 

the  correction  for  pure  sucrose  than  that  for  cane  products.  This  is 
due  to  the  fact  that  raw  cane  products  contain  a  larger  amount  of 
fructose,  the  change  in  specific  rotation  of  which  towards  the  right,  as 
the  temperature  increases,  compensates  to  a  greater  or  less  degree  the 
change  in  specific  rotation  of  sucrose  towards  the  left.  This  is  made 
more  evident  in  Table  XL VII,  which  gives  the  polarization  and  com- 
position of  various  grades  of  raw  cane  sugar. 

*  J.  Ind.  Eng.  Chem.,  1,  567. 


METHODS  OF  SIMPLE  POLARIZATION 


259 


TABLE  XLVII 

Showing  Effect  of  Increase  in  Temperature  upon  the  Polarization  of  Sugar-cane 

Products,  Browne  f 


No. 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 

Description  of  sugar. 

Polari- 
zation. 

Sucrose 

Invert 
sugar. 

Water. 

Ash. 

Organic 
non- 
sugar 
by  dif- 
ference. 

cent. 
0.22 
0.96 
0.50 
0.53 
0.48 
0.89 
1.40 
0.86 
2.57 
2.46 
7.32 

8.47 

Change  in  polarization 
for  1  °  C.  increase. 

Found. 

By  formula 
0.0003  P. 

Java 

98.55 
97.45 
97.15 
96.15 
94.50 
93.75 
89.20 
87.60 
82.40 
79.65 
67.70 

20.06 

Per 
cent. 

98.74 
97.61 
97.38 
96.61 
95.05 
94.44 
90.59 
89.00 
84.64 
81.69 
71.05 

29.58 

Per 
cent. 

0.64 
0.52 
0.78 
1.53 
1.83 
2.29 
4.63 
4.67 
7.45 
6.80 
11.18 

30.09 

Per 
cent. 

0.19 
0.45 
1.03 
0.85 
1.97 
1.83 
2.11 
2.30 
3.49 
4.84 
6.70 

23.62 

Per 
cent. 

0.21 
0.46 
0.31 
0.48 
0.67 
0.55 
1.27 
3.17 
1.85 
4.21 
3.75 

8.24 

-0.0311 
-0.0301 
-0.0276 
-0.0230 
-0.0212 
-0.0160 
-0.0110 
-0.0106 
0.0000 
+0.0068 
+0.0286 

+0.1120 

-0.0296 
-0.0292 
-0.0291 
-0.0288 
-0.0287 
-0.0281 
-0.0268 
-0.0263 
-0.0247 
-0.0239 
-0.0203 

-0.0060 

Peru 

Cuba 

San  Domingo.  . 
Cuba  

Cuba  
Philippine  
Louisiana  
Philippine  

Louisiana  

Cuba 

Louisiana         ) 
molasses*..  ) 

Calculated  mixtures  of  sucrose  and  cane  molasses. 


Sucrose, 
per  cent  . 

Molasses, 
per  cent. 

95 

5 

96.00 

96.50 

1.50 

1.10 

0.40 

0.50 

-0.0229 

-0.0288 

90 

10 

92.00 

93.00 

3.00 

2.20 

0.80 

1.00 

-0.0158 

-0.0276 

85 

15 

88.00 

89.50 

4.50 

3.30 

1.20 

1.50 

-0.0087 

-0.0264 

80 

20 

84.00 

86.00 

6.00 

4.40 

1.60 

2.00 

-0.0016 

-0.0252 

75 

25 

80.00 

82.50 

7.50 

5.50 

2.00 

2.50 

+0.0055 

-0.0240 

70 

30 

76.00 

79.00 

9.00 

6.60 

2.40 

3.00 

+0.0126 

-0.0228 

*  Average  of  4  samples. 

Raw  sugars  can  be  regarded  as  simple  mixtures  of  sucrose  crystals 
and  molasses,  and  the  results  in  the  second  part  of  the  table  calculated 
for  various  theoretical  mixtures  of  sucrose  and  exhausted  cane  molasses 
agree  closely  with  those  observed  for  the  different  raw  sugars. 

The  observations  by  Browne  in  Table  XL VII  have  also  been  con- 
firmed by  Wiley  and  Bryan  J  who  obtained  very  similar  figures  upon 
different  grades  of  raw  cane  sugar. 

The  effect  of  temperature  upon  the  polarization  of  American  beet 
sugar  and  molasses  is  shown  in  Table  XL VIII. 


t  J.  Ind.  Eng.  Chem.,  1,  567. 


Z.  Ver.  Deut.  Zuckerind.,  59,  916. 


260 


SUGAR  ANALYSIS 


TABLE  XLVIII 

Showing  Effect  of  Increase  in  Temperature  upon  the  Polarization  of   Sugar-beet 

Products,  Browne  f 


Change  in  polari- 

Organic 

zation  for  1°C. 

d 
K 

Product. 

Polari- 
zation. 

Su- 
crose. 

Raffi- 
nose. 

Invert 
sugar. 

Water. 

Ash. 

non- 
sugar 
by  dif- 

increase. 

ference. 

Formula 

0.0003  P. 

Per 
cent. 

Per 
cent. 

Per 

cent. 

Per 
cent. 

Per 

cent. 

Per 
cent. 

1 

Beet  sugar  .  . 

91.25 

-0.0276 

-0.0274 

2 

Beet  sugar.  . 

86.60 

-0.0263 

-0.0260 

3 

Beet  sugar 

85  50 

-0.0214 

-0.0257 

4 

Beet             \ 
molasses*  ) 

51.22 

48.13 

1.72 

0.94 

19.86 

7.62 

21.74 

-0.0053 

-0.0154 

Calculated  mixtures  of  sucrose  and  beet  molasses. 


Sucrose, 
per  cent 

Molasses, 
per  cent. 

90 
80 
70 
60 

10 
20 

30 
40 

95.00 
90.00 
85.00 
80.00 

94.80 
89.60 
84.40 
79.20 

0.15 
0.30 
0.45 
0.60 

0.10 
0.20 
0.30 
0.40 

2.0 
4.0 
6.0 
8.0 

0.75 
1.50 
2.25 
3.00 

2.20 
4.40 
6.60 
8.80 

-0.0275 
-0.0250 
-0.0225 
-0.0200 

-0.0285 
-0.0270 
-0.0255 
-0.0240 

*  Average  of  3  samples. 

It  will  be  seen  from  the  above  that  the  temperature  formula 
P20  =  Pi  [1  +  0.0003  (t  -  20)],  or  the  corresponding  corrections  of  the 
Wiley  table,  can  be  applied  without  serious  error  to  practically  all 
grades  of  beet  sugar  and  to  those  grades  of  cane  sugar  polarizing  over 
96.  As  the  polarization  of  raw  cane  sugars  falls  below  96,  and  the 
percentage  of  invert  sugar  (or  fructose)  increases,  the  effect  of  change 
in  temperature  upon  the  rotation  of  the  latter  begins  to  lower  appre- 
ciably the  temperature  coefficient  for  the  rotation  of  sucrose  until,  at  a 
point  about  80°  V.,  the  two  influences  —  that  of  the  temperature  upon 
the  fructose  and  other  impurities  and  that  of  the  temperature  upon 
the  sucrose  and  quartz  wedges  of  the  instrument  —  exactly  counter- 
balance one  another.t  Under  these  conditions  a  sugar  will  polarize  the 
same  at  all  temperatures.  Below  80°  V.  the  temperature  coefficient  for 
the  rotation  of  the  sucrose  in  raw  cane  sugars  is  usually  more  than 

t  J.  Ind.  Eng.  Chem.,  1,  567. 

I  The  calculation  upon  page  128  shows  that  the  proportion  of  fructose  to  sucrose 
for  equilibrium  between  their  temperature  coefficients  is  3.13  to  100.0. 


METHODS  OF  SIMPLE  POLARIZATION  261 

counterbalanced,  the  result  being  that  the  polarization  of  these  sugars 
increases  with  elevation  of  temperature.  This  increase  continues,  as 
the  polarization  diminishes  (the  percentage  of  fructose  and  other  im- 
purities being  greater),  until,  at  a  polarization  of  about  +  20  for  ex- 
hausted cane  molasses,  an  increase  of  1°  C.  in  temperature  causes  an 
increase  of  over  0.1°  V.  in  the  saccharimeter  reading. 

Correction  of  Polarizations  for  the  Combined  Influence  of  Temperature 
upon  the  Rotation  of  Sucrose  and  Invert  Sugar.  —  Since  the  ingredient  of 
sugar  products,  whose  polarization  is  most  susceptible  to  the  influence 
of  temperature,  is  invert  sugar,  a  more  accurate  method  of  correcting 
saccharimeter  readings  is  to  combine  the  temperature  coefficients  of 
sucrose  and  invert  sugar  as  by  the  formula:  P20  =  Pt  +  0.0003  S  (t  -  20) 
-  0.0045  I  (t  —  20)  in  which  Pt  is  the  polarization  at  t°  C.,  S  the  per- 
centage of  sucrose  and  /  the  percentage  of  invert  sugar. 

If  the  percentage  of  invert  sugar  is  unknown  the  temperature  correc- 
tion for  converting  polarizations  to  20°  C.  may  be  determined  approxi- 
mately by  the  following  empirical  equations: 

For  cane  products,  P20  =  Pl  +  0.0015  (P<  -  80)  (t  -  20), 

For  beet  products,  P20  =  Pt  +  0.0006  (Pt  -  50)  (t  -  20). 

Such  formulae  as  the  above  while  more  accurate  than  corrections 
which  are  based  upon  the  temperature  coefficients  of  pure  sucrose,  fail 
to  give  accurate  results  upon  many  individual  products  whose  com- 
position differs  from  that  of  the  average  type. 

Polarization  at  Constant  Temperature.  —  It  is  evident  from  the 
foregoing  that  the  method  of  applying  temperature  corrections  es- 
tablished for  pure  sucrose  to  the  polarization  of  sugar  products  in 
general  is  faulty.  Since  it  is  impossible  to  devise  a  simple  reliable 
method  of  temperature  corrections  that  can  be  applied  to  the  polari- 
zation of  all  kinds  of  substances,  the  one  means  of  securing  uniformity 
and  accuracy  in  saccharimetric  work  is  to  make  all  polarizations  at  the 
temperature  at  which  the  instruments  are  standardized.  Custom- 
house laboratories,  arbitration  laboratories,  and  all  other  laboratories, 
upon  the  results  of  which  great  interests  are  involved,  should  be 
equipped  with  cooling  and  warming  apparatus  for  maintaining  a  uni- 
form standard  temperature  throughout  the  year. 

The  New  York  Sugar  Trade  Laboratory  was  the  first  testing  labo- 
ratory in  the  United  States  to  follow  out  the  requirements  of  the  In- 
ternational Commission  for  Uniform  Methods  of  Sugar  Analysis  and 
make  all  polarizations  at  20°  C.  The  laboratory  room  and  polarizing 
cabinet  used  for  this  purpose  are  insulated.  In  warm  weather  the  air 


262 


SUGAR  ANALYSIS 


is  circulated  by  an  electric  fan  through  ducts  over  cooling  coils,  fresh 
air  being  introduced  from  outside  according  to  the  needs  of  ventilation. 
A  small  ammonia  compressor  driven  by  an  electric  motor  serves  for 
the  work  of  refrigeration.  The  temperature  can  be  controlled  either 


Fig.  145.  —  Refrigerating  machine  for  constant  temperature  polarization 
(New  York  Sugar  Trade  Laboratory) . 

automatically  by  means  of  a  thermostat  which  operates  dampers  regu- 
lating the  passage  of  air  to  and  from  the  cooling  box,  or  directly  by 
means  of  the  rheostats  controlling  the  speed  of  compressor  and  venti- 
lating fan.  The  general  arrangement  of  the  equipment  is  shown  in 
Figs.  145  and  121. 


CHAPTER  X 

METHODS  OF  INVERT   OR  DOUBLE  POLARIZATION 

THE  methods  of  direct  polarization,  as  previously  explained,  give 
percentage  of  sucrose  only  in  the  absence  of  other  optically  active  sub- 
stances. To  determine  the  percentage  of  sucrose  when  other  optically 
active  substances  are  present,  the  method  of  inversion  or  double  polari- 
zation is  used,  the  principle  of  which  may  be  understood  from  the 
following. 

Law  of  Inversion.  —  When  a  solution  of  sucrose  is  acted  upon  by 
some  inverting  agent,  such  as  an  acid  or  the  enzyme  invertase,  the 
sucrose  molecule  is  broken  up  or  inverted,  giving  rise,  by  the  addition 
of  one  molecule  of  water,  to  one  molecule  each  of  glucose  and  fructose, 
the  mixture  of  these  two  sugars  in  equal  amounts  being  termed  invert 
sugar.  This  reaction,  known  as  hydrolysis  or  inversion,  is  expressed  by 
the  following  equation: 

C12H22On      +       H20       =       C6H1206        +      C6H1206. 

Sucrose  (342)  Water  (18)  Glucose  (180)  __  Fructose  (180) 

Invert  Sugar  (360) 

It  is  seen  from  the  above  that  one  part  of  sucrose  is  converted  into 

360 

n  =  1.05263  parts  of  invert  sugar.      Calling  the  specific  rotation  at 


20°  C.  +66.5  for  sucrose,  and  -  20.00  for  invert  sugar  (p.  174),  the 
relation  of  the  optical  activity  of  one  part  sucrose  before  and  after  in- 
version will  be  +  66.5  :  1.05263  (-  20.00)  =  66.5  :  -  21.0526  or  a  de- 
crease of  87.5526  in  specific  rotation.  This  decrease  for  one  degree  of 

87  5526 

the  saccharimeter  scale  would  therefore  be  -         -  =  1.3166.    The  gen- 

bo.  o 

eral  law  of  inversion*  as  applied  to  the  determination  of  sucrose  may 
then  be  stated  as  follows: 

The  total  decrease  in  the  saccharimeter  reading  at  20°  C.  of  the 
normal  weight  of  product  after  inversion  divided  by  1.3166  gives  the 
percentage  of  sucrose  when  no  other  optically  active  ingredient  is 
hydrolyzed  and  when  the  inverting  agent  produces  no  change  in  the 
specific  rotation  of  the  other  optically  active  constituents  present. 

*  For  a  fuller  discussion  of  the  laws  of  inversion  see  page  659. 
263 


264  SUGAR  ANALYSIS 

The  enzyme  invertase  fulfills  most  perfectly  the  conditions  above 
named,  and  when  this  is  used  as  the  inverting  agent  the  percentage  of 
sucrose  in  mixtures  with  glucose,  fructose,  invert  sugar,  maltose,  milk 
sugar,  etc.,  may  be  determined  very  closely  by  use  of  the  factor  1.3166. 
The  inverting  agent  most  commonly  used  in  optical  analysis  is  not  in- 
vertase, however,  but  hydrochloric  acid,  the  presence  of  which,  as  shown 
on  page  185,  has  a  most  pronounced  influence  in  increasing  the  specific 
rotation  of  fructose.  When  hydrochloric  acid  is  used  for  inverting,  the 
factor  1.3166  must  be  modified  according  to  the  amount  of  acid  used  for 
inverting,  the  concentration  of  the  sugar  solution,  and  the  manner  of 
conducting  the  inversion.  The  extreme  susceptibility  of  fructose  to 
changes  in  specific  rotation  and  composition  makes  it  necessary  in 
employing  any  method  of  inversion  to  adhere  most  rigidly  to  the  rules 
of  procedure  prescribed. 

THE  CLERGET  METHOD  OF  INVERSION 

The  method  of  inversion  for  determining  sucrose  was  devised  in 
1849,  by  Clerget,*  who  found  that  a  solution  of  the  French  normal 
weight  of  pure  sucrose  in  100  c.c.,  reading  +  100  degrees  upon  the 
saccharimeter,  gave  after  inversion  with  hydrochloric  acid  a  reading  of 
-  44  degrees  at  0°  C.  or  -  34  degrees  at  20°  C.  The  total  difference 
between  the  readings  before  and  after  inversion,  correcting  for  the  in- 
fluence of  temperature,  is  expressed  by  the  quantity 

100-  (-44)-|  =  144-|, 

t  being  the  temperature  of  the  inverted  solution  at  polarization. 

If  D  represents  the  algebraic  difference  (P  —  Pf)  between  the  direct 
polarization  (P)  and  the  invert  polarization  (P'}  of  a  given  product, 
then  the  percentage  (S)  of  sucrose  by  Clerget's  formula  is  expressed  by 

the  equation  S  —  -  -  •     If  the  invert  polarization  is  made  at  20°  C. 


the  equation  becomes  S  =     Q  .    or  ^-~oT'  The  factor  1.34  is  considerably 


greater  than  the  factor  1.3166  for  pure  aqueous  solutions  of  invert  sugar. 
Tuchschmidf  who  subjected  the  Clerget  process  to  an  exhaustive 
analysis,  arrived  at  the  following  formula, 

100  D 


S 


144.16035-  0.50578 1 


*  Compt.  rend.,  16, 1000;  22, 1138;  23,  256;  26,  240;  Ann.  chim.  phys.  [3],  26,  175. 
t  Z.  Ver.  Deut.  Zuckerind.,  20,  649. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION      265 

The  original  Clerget  formula  does  not  differ  sufficiently  from  this 
to  warrant  the  greater  labor  of  calculation  involved  in  the  use  of  the 
long  decimals. 

If  the  direct  and  invert  readings  are  made  upon  a  polarimeter  with 
circular  degrees  the  Clerget  formula  would  be,  for  the  German  normal 
weight  (1°  sugar  scale  =  0.34657  circular  degrees), 

100  D  100  D 

.34657  (144  -.50""  49.906  -  0.173  V 

for  the    French    normal    weight    (1°   sugar   scale  =  0.21719    circular 
degrees), 

100  D  100  D 


.21719  (144  -  .5  0      31.275  -  0.109 1 

One  gram  of  sucrose  dissolved  to  100  metric  cubic  centimeters  gives 
a  direct  reading  of  — ^ —  =  1.333  circular  degrees  and  an  invert  read- 

15  249 

ing  of ^Q~  =  —0.5865  circular  degrees  at  0°C;  the  grams  of  su- 
crose (C)  in  100  c.c.  of  any  solution  may  be  found  from  the  polarimeter 
reading  before  and  after  inversion  by  the  equation 

P-P'  P-P' 

(49.906-  0.173  Q      1.9195  -  0.0067 1 
26 

The  Clerget  formulae,  given  above,  are  to  be  employed  only  when 
the  following  method  of  inversion  prescribed  by  Clerget  is  followed. 
After. taking  the  direct  polarization  (p.  202),  the  clarified  solution  re- 
maining is  filled  up  to  the  50-c.c.  graduation  mark  of  a  flask  graduated 
at  50  and  55  c.c.;  concentrated  hydrochloric  acid  is  then  added  to  the 
55-c.c.  mark,  a  thermometer  is  inserted,  and  the  flask  slowly  warmed 
until  the  temperature  reaches  68°  C.,  15  minutes  being  taken  in  the  heat- 
ing.* The  solution  is  then  quickly  cooled,  filtered  if  necessary,  and 
polarized  as  nearly  as  possible  at  the  original  temperature  of  making  up 
to  volume.  The  polariscope  reading  for  a  200-mm.  tube  of  solution  must 
be  increased  by  TV  to  correct  for  the  dilution  with  acid.  The  reading 
of  the  inverted  solution  is  sometimes  made  in  a  220-mm.  tube,  when 
no  correction  for  dilution  is  needed. 

*  The  addition  of  the  acid  causes  an  elevation  of  2°  to  3°  C.  in  temperature; 
there  is  also  a  slight  loss  from  evaporation  during  the  inversion.  It  is,  therefore, 
better  to  control  the  temperature  by  inserting  the  thermometer  in  a  50-55  c.c.  flask 
filled  with  water  and  placed  in  the  bath  with  the  solutions  undergoing  inversion. 
After  cooling  to  room  temperature,  the  volumes  are  readjusted  to  55  c.c. 


266  SUGAR  ANALYSIS 

In  carrying  out  the  inversion  special  attention  must  be  paid  to  all 
details.  If  the  temperature  of  68°  C.,  or  the  time  of  15  minutes,  is  ex- 
ceeded, a  partial  destruction  of  fructose  may  result;  if  the  temperature 
of  68°  C.  is  not  reached,  or  if  the  time  of  heating  is  less  than  15  min- 
utes, some  of  the  sucrose  may  escape  inversion.  Care  must  also  be 
taken  to  maintain  a  constant  temperature  in  the  polarization  tube 
during  the  reading.  Even  a  slight  warming  of  the  tube,  as  from  han- 
dling, will  affect  the  observation.  A  polarization  tube  provided  with  a 
jacket  for  circulation  of  water  at  the  desired  temperature  is  very  de- 
sirable for  polarizing  inverted  solutions.  (See  Fig.  111.) 

Herzf eld's  Modification  of  the  Clerget  Method.  —  The  original 
method  of  Clerget  has  been  variously  modified  from  time  to  time  in 
order  to  diminish  the  danger  of  destroying  fructose  and  to  secure  better 
uniformity  of  conditions.  The  inversion  method  of  Herzfeld,*  which  is 
the  one  most  generally  employed  at  present,  is  as  follows: 

The  half  normal  weight  (13.00  gms.)  of  product  is  transferred  with 
75  c.c.  of  water  into  a  100-c.c.  flask;  after  solution  of  soluble  matter, 
5  c.c.  of  hydrochloric  acid  of  sp.  gr.  1.188  are  added,  a  thermometer 
is  introduced  and  the  flask  placed  in  a  water  bath  heated  to  between 
72°  and  73°  C.  As  soon  as  the  thermometer  in  the  flask  indicates 
69°  C.  (2.5  to  5  minutes)  the  solution  is  kept  at  this  temperature  for 
exactly  5  minutes,  rotating  the  flask  gently  at  frequent  intervals  to  se- 
cure even  distribution  of  the  heat.  The  entire  time  of  heating,  accord- 
ing to  the  length  of  the  preliminary  period,  will  vary  thus  from  7 J  to 
10  minutes,  and  should  never  exceed  10  minutes.  When  the  5-minute 
heating  at  69°  C.  is  completed  the  flask  is  cooled  as  quickly  as  possible 
to  20°  C.,  the  thermometer  is  rinsed  from  adhering  sugar  solution  and 
the  volume  made  to  100  c.c.  After  mixing  and  filtering,  the  solution  is 
polarized  with  all  the  precautions  previously  mentioned.  The  polari- 
scope  reading  is  doubled  to  obtain  the  correct  invert  reading  for  a  nor- 
mal weight  of  substance. 

The  invert  reading  for  26  gms.  of  chemically  pure  sucrose  under  the 
above  conditions  is  -42.66°  V.  at  0°,  or  -32.66°  V.  at  20°  C.  The 
Clerget  formula,  according  to  Herzfeld's  modification,  is  then  expressed 
by  the  equation  ~  _  100  D 

~  142.66  -0.5*; 
or,  if  the  polarization  be  made  always  at  20°  C.,  by 

100  D         7_Qft 
=  132^6  ==07538Z>- 

*  Z.  Ver.  Deut.  Zuckerind.  (1888),  38,  699. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION       267 


Effect  of  Concentration  on  the  Clerget  Factor.  —  The  factor  132.66  in 
the  preceding  equation  is  correct  only  for  a  solution  containing  the 
half  normal  weight  of  sugar  to  100  c.c.  For  other  concentrations  than 
this  the  value  of  the  invert  reading  will  vary  according  to  the  general 
formula  P/20°  =  -  (31.78  +  0.0676  c),  or  P'°°  =  -  (41.78  +  0.0676  c),  in 
which  Pf  is  the  invert  reading  upon  the  Ventzke  scale  and  c  the  grams 
of  sucrose  in  100  c.c.  The  following  table  gives  the  value  of  the 

factor  142.66  in  the  equation  S  = 
trations  of  sucrose. 


142.66-0.5* 


for  different  concen- 


TABLE  XLIX 

Giving  Clerget  Factors  at  Different  Concentrations  of  Sucrose 
for  Herzfeld's  modified  Method 


Grams  sucrose 
in  100  c.c. 

Factor. 

Grams  sucrose 
in  100  c.c. 

Factor. 

1 

141.85 

14 

142.73 

2 

141.91 

15 

142.79 

3 

141.98 

16 

142.86 

4 

142.05 

17 

142.93 

5 

142.12 

18 

143.00 

6 

142.18 

19 

143.07 

7 

142.25 

20 

143.13 

8 

142.32 

21 

143.20 

9 

142.39 

22 

143.27 

10 

142.46 

23 

143.33 

11 

142.52 

24 

143.40 

12 

142.59 

25 

143.47 

13 

142.66 

26 

143.54 

Instead  of  the  above  correction  table  the  following  general  formula 
has  been  proposed  by  Herzfeld:* 

100  (P  -  P') 
141.84  +  0.05 N-  0.5*' 


S 


in  which  P  and  P'  are  the  direct  and  invert  polarizations  for  a  normal 
weight  of  substance  and  N  the  scale  reading  of  the  inverted  solution. 
This  formula  assumes  that  the  value  N  always  bears  a  constant  ratio 
to  the  concentration  of  sucrose,  which  is  of  course  only  true  when 
other  optically  active  substances  are  absent. 

Example.  —  The  application  of  the  above  Herzfeld  formula  is  best  illus- 
trated by  an  example:  26.00  gms.  of  a  sugar  sirup  dissolved  to  100  true  c.c.  at 
20°  C.  gave  a  direct  reading  in  a  200-mm.  tube  of  +  60.00  (P).  13.00  gms.  of 

*  Z.  Ver.  Deut.  Zuckerind.,  40,  194. 


268 


SUGAR  ANALYSIS 


this  same  sirup  inverted  according  to  Herzfeld's  method  gave  a  reading  of 
9.7  (N)  at  20°  (t)  upon  the  negative  scale,  -  9.7  X  2  =  -  19.4  (P').  Substi- 
tuting these  values  in  the  formula,  we  obtain 

S  -  100  [+60 -(-19.4)]  _ 

~  141.84 +(0.05X9.7)- (0.5  X  20)  ~ 
the  amount  of  sucrose  present  in  the  sirup. 

If  the  direct  and  invert  polarizations  be  made  at  20°  C.  the  Clerget 
and  Herzfeld  formulae  become  simplified  as  follows: 

100  (P  -  P') 


Clerget  formula  = 
Herzfeld  formula  = 


144-2 
30  (P - 


=  0.7463  (P-P'); 
=  0.7538  (P  -  P'). 


66  - 

The  values  of  the  Herzfeld  factor  in  the  simplified  formula  for  tempera- 
tures between  10°  and  409  C.  are  given  in  Table  L. 

TABLE  L 

Giving  the  Inversion  Factors  for  Herzfeld's  Modification  of  Clerget' s  Method 
at  Different  Temperatures 


Temper- 
ature. 

Factor. 

Temper- 
ature. 

Factor. 

Temper- 
ature. 

Factor. 

10°  C. 

0.7264 

20°  C. 

0.7538 

30°  C. 

0.7833 

11 

0.7290 

21 

0.7566 

31 

0.7864 

12 

0  7317 

22 

0.7595 

32 

0.7895 

13 

0.7344 

23 

0.7624 

33 

0.7926 

14 

0.7371 

24 

0.7653 

34 

0.7957 

15 

0.7398 

25 

0.7682 

35 

0.7989 

16 

0.7426 

26 

0.7712 

36 

0.8021 

17 

0.7454 

27 

0.7742 

37 

0.8053 

18 

0.7482 

28 

0.7772 

38 

0.8086 

19 

0.7510 

29 

0.7802 

39 

0.8119 

40 

0.8152 

The  inversion  method  of  Herzfeld  gives  correct  results  only  when 
the  prescribed  conditions  of  concentration,  amount  of  acid,  volume, 
temperature  and  time  of  inversion  are  carefully  followed.  The  tem- 
perature of  inversion  for  the  5-minute  period  should  be  maintained  at 
exactly  69°  C.  if  possible;  a  variation  of  1°  C.  from  this  temperature  is 
found  to  produce  a  difference  of  over  0.1  in  the  calculated  percentage 
of  sucrose.  The  extreme  sensibility  of  fructose  to  decomposition  during 
inversion  and  its  wide  fluctuation  in  optical  rotation  with  slight  changes 
of  temperature  necessitate  the  greatest  care  in  manipulation.  Neglect  of 
this  precaution  is  a  frequent  cause  of  variation  between  the  results  of 
different  analysts. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION       269 

Inversion  at  Ordinary  Temperature.  —  The  dangers  of  too  high  or 
too  prolonged  heating  in  the  Clerget  determination  may  be  avoided  by 
inverting  at  the  ordinary  laboratory  temperature.  The  time  neces- 
sary to  invert  a  half-normal  weight  (13  gms.)  of  sucrose  in  100  c.c.  of 
solution  employing  hydrochloric  acid  of  1.18  sp.  gr.  was  found  by  Ham- 
merschmidt  *  to  be  as  follows : 


Temperature. 

5  c.c.  HC1. 

10  c.c.  HC1. 

°C. 
10 

Hours. 

225 

Hours. 

94 

15 

101 

44 

20 

47 

20 

25 

23 

10 

30 

11.6 

5 

The  method  of  Tolmanf  for  cold  acid  inversion  is  to  place  50  c.c. 
of  a  solution  containing  the  half-normal,  or  normal,  weight  of  substance 
in  a  100-c.c.  graduated  flask,  add  5  c.c.  of  strong  hydrochloric  acid, 
allow  to  stand  at  room  temperature  (above  20°  C.)  for  20  to  24  hours, 
make  up  to  100  c.c.  and  polarize.  At  25°  C.  the  inversion  is  complete 
in  about  10  hours  and  at  20°  C.  in  about  20  hours.  The  Clerget  factor 
for  a  half-normal  weight  (13  gms.)  of  sucrose  inverted  in  the  cold  was 
found  by  Tolman  to  be  142.88. 

Effect  of  Amount  of  Acid  on  the  Clerget  Factor.  —  The  effect  of  vary- 
ing the  quantity  of  hydrochloric  acid  used  for  inversion  upon  the 
Clerget  factor  was  studied  by  Hammerschmidt,*  who  obtained  the  fol- 
lowing invert  readings  at  20°  C.  for  a  normal  weight  of  pure  sucrose, 
using  5  c.c.,  10  c.c.,  15  c.c.,  and  20  c.c.  of  hydrochloric  acid  per  100  c.o. 

5  c.c.        10  c.c.         15  c.c.       20  c.c. 

Reading  of     normal  weight,         (Degrees  Ventzke)  -34.00  -35.04  -35.95  -36.80 
Reading  of  \  normal  weight  X  2,  (Degrees  Ventzke)  -33.00  -34.12  -35.15  -36.03 

It  will  be  noted  that  there  is  a  pronounced  but  diminishing  increase 
in  the  invert  reading  with  the  addition  of  each  5  c.c.  of  acid. 

Results  similar  to  those  of  Hammerschmidt  were  obtained  by 
Tolman,  f  who  found  for  a  solution  of  invert  sugar  made  up  to  volume 
with  no  hydrochloric  acid  a  reading  of  —23.0°  V.,  for  the  same  amount 
of  invert  sugar  solution  made  up  with  5  c.c.  hydrochloric  acid  a  reading 
of  —24.2,  and  for  a  third  similar  portion  made  up  with  10  c.c.  hydro- 
chloric acid  a  reading  of  —25.0. 


*  Z.  Ver.  Deut.  Zuckerind,  40,  465.        t  Bull.  73,  U.  S.  Bur.  Chem.,  p. 


270 


SUGAR  ANALYSIS 


Effect  of  Fructose  on  the  Clerget  Factor.  —  Owing  to  the  influence  of 
hydrochloric  acid  upon  the  polarization  of  fructose  a  Clerget  formula 
based  upon  the  inversion  of  pure  sucrose  by  means  of  this  acid  is  not 
absolutely  correct  when  applied  to  the  analysis  of  impure  products 
containing  invert  sugar,  since  the  specific  rotation  of  fructose  is  differ- 
ent in  the  neutral  and  acid  solutions  before  and  after  inversion.  A 
considerable  error  is  introduced,  in  fact,  if  the  Clerget  formula  estab- 
lished for  pure  sucrose  be  employed  in  the  examination  of  molasses, 
honey,  jam,  jelly,  and  other  materials  containing  considerable  fructose. 

Effect  of  Amino  Compounds  on  the  Clerget  Factor.  —  The  hydrochloric 
acid  used  for  inversion  may  also  affect  the  polarization  of  other  ingredi- 
ents than  fructose.  Low-grade  molasses,  plant  extracts,  and  other 
sugar-containing  materials  frequently  contain  considerable  quantities  of 
optically  active  ammo  compounds  such  as  asparagine,  aspartic  acid, 
glutaminic  acid,  leucine,  isoleucine,  etc.,  the  optical  activity  of  which 
varies  with  the  alkalinity  and  acidity  of  the  solution.  This  may  be 
seen  from  the  following  table  which  gives  the  approximate  specific  rota- 
tions of  several  amino  derivatives  in  alkaline  solution,  in  water,  and  in 
hydrochloric  acid. 

TABLE  LI. 
Approximate  Value  for  [a\D. 


In  presence  of 
NaOH. 

In  water. 

In  presence  of 
HC1. 

Asparagine 

-  8 

-    6 

+34 

Aspartic  acid  

-  9 

+  4 

+34 

Glutaminic  acid  

-68 

+10 

+20 

Leucine  

+  7 

+17 

Isoleucine  

+  11 

+10 

+37 

The  influence  of  such  variations  upon  the  Clerget  calculation  is 
illustrated  in  the  work  of  Andrlik  and  Stanek  *  who  showed  that  a  1  per 
cent  solution  of  glutaminic  acid  gave  a  reading  of  —  1 .45°  V.  in  presence 
of  lead  subacetate,  —0.35°  V.  in  water  alone,  and  +-1.77°  V.  in  dilute 
hydrochloric  acid.  In  the  case  of  an  osmose  water  from  a  beet-sugar 
factory  the  direct  polarization  was  14.75°  V.  in  alkaline,  14.85°  V.  in 
neutral,  and  15.80°  V.  in  acid  solution.  Ehrlichf  had  previously  also 
called  attention  to  the  large  errors  in  the  Clerget  method  due  to  the 
presence  of  amino  compounds. 


*  Z.  Zuckerind.  Bohmen,  31,  417. 
t  Z.  Ver.  Deut.  Zuckerind.,  63,  809. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION      271 

Clerget  Modifications  for  Impure  Sugar  Products.  —  It  is  evident 
that  to  overcome  the  variations  in  specific  rotation  of  fructose,  amino 
compounds,  etc.,  which  occur  in  the  presence  and  absence  of  hydro- 
chloric acid,  the  original  method  of  Clerget  must  be  considerably  modi- 
fied in  the  case  of  impure  products.  Several  such  modifications  of  the 
method  have  in  fact  been  devised  and  these  for  convenience  may  be 
grouped  into  two  general  classes.  I.  Clerget  modifications  which  at- 
tempt to  equalize  the  conditions  before  and  after  inversion  with  hydro- 
chloric acid.  II.  Clerget  modifications  which  employ  an  inverting  agent 
free  from  the  objections  of  hydrochloric  acid. 

Among  the  modifications  of  Class  I  may  be  mentioned  the  following. 

(1)  Neutralizing  the  Free  Acid  after  Inversion  before  Making  the  In- 
vert Polarization.  —  This  modification  is  best  carried  out  in  the  Herzfeld 
process  of  inversion.     After  cooling  the  solution  the  free  hydrochloric 
acid  is  carefully  neutralized  by  means  of  sodium  hydroxide,  using  phe- 
nolphthalein  as  indicator,  and  avoiding  any  excess  of  alkali.     After 
neutralizing,  the  volume  is  completed  to  100  c.c.  at  20°  C.  and  the  in- 
vert polarization  made  in  the  usual  way.     In  order  that  the  direct 
polarization  may  be  made  under  similar  conditions  Saillard*  recom- 
mends that  sodium  chloride,  equivalent  to  the  amount  present  after 
neutralizing  the  hydrochloric  acid,  be  added  to  a  separate  solution  before 
making  up  to  the  100  c.c.  for  the  direct  polarization.     The  fructose, 
amino  compounds,  etc.,  are  thus  polarized   under  similar  conditions 
before  and  after  inversion.     The  Clerget  constant  for  this  method  is 
determined  by  making  a  parallel  analysis  upon  pure  sucrose. 

(2)  Making  the  Direct  Polarization  in  Presence  of  Hydrochloric  Acid 
and  Urea. — This  modification,  due  to  Andrlik  and  Stanek,f  is  based 
upon  the  retarding  influence  which  urea  (or  betaine)  exercises  upon  the 
inversion  of  sucrose  with  hydrochloric  acid  in  the  cold.     Fifty  cubic 
centimeters  of  the  solution  for  the  direct  polarization  are  made  up  to 
100  c.c.  with  a  solution  containing  5  gms.  urea  and  5  c.c.  strong  hydro- 
chloric acid  per  50  c.c.  of  reagent.     After  mixing,  the  solution  is  filtered 
and  polarized  as  quickly  as  possible.     It  is  claimed  by  the  authors  of  the 
method  that  a  sufficient  interval  (7  to  10  minutes)  elapses  before  inver- 
sion is  noticeable  to  make  the  direct  polarization.     While  this  claim 
may  be  true  for  certain  classes  of  products,  it  is  certainly  not  the  case 
with  substances  rich  in  sucrose.     The  following  experiment  shows  a 
comparison  of  the  rate  of  inversion  of  13  gms.  of  sucrose  at  20°  C.  in 
presence  of  5  c.c.  strong  hydrochloric  acid  and  in  presence  of  5  c.c.  strong 
hydrochloric  acid  plus  5  gms.  urea  in  100  c.c.  of  solution. 

*  Eighth  Int.  Cong.  Applied  Chem.,  Communications  Vol.  XXV,  p.  541. 
t  Z.  Zuckerind.  Bohmen,  31,  417. 


272 


SUGAR  ANALYSIS 


TABLE  LII 
Showing  Influence  of  Urea  upon  the  Rate  of  Inversion  of  Sucrose 


Inversion  with  5  c.c.  HC1. 

Inversion  with  5  c.c.  HC1  +  5  gins, 
urea. 

rftt 

Reading  V. 

Velocity  constant. 

Reading  V°. 

Velocity  constant. 

0  min 

+49  9 

+49.9 

2  min. 

49.4 

0.0016 

49.6 

0.0009 

5  min. 

48.9 

0.0013 

49.4 

0.0007 

7  min. 

48.6 

0.0012 

49.3 

0.0005 

10  min. 

48.0 

0.0012 

49.1 

0.0005 

30  min. 

44.3 

0.0013 

47.2 

0.0006 

60  min. 

39.7 

0.0012 

44.8 

0.0006 

120  min. 

31.4 

0.0012 

40.1 

0.0006 

180  min. 

24.7 

0.0012 

35.8 

0.0006 

2  days 

—  16  5 

—  17.2 

4  days 

—  16  5 

-21.3 

Average 

0.00128 

0.00063 

Taking  the  reading  before  inversion  as  +  49.9  and  the  reading  at 
completion  of  inversion  as  —  16.5  it  is  seen  that  the  velocity  of  inver- 
sion (k  =  -  log—  — >  see  p.  660),  is  diminished  one-half  by  the  addition 

of  5  gms.  urea.  There  is  no  suspension  of  the  inversion  at  the  beginning, 
there  being  a  decrease  of  0.3  in  the  reading  at  the  end  of  2  minutes, 
and  of  0.5  after  5  minutes.  Under  such  circumstances  it  is  impossible 
to  take  the  true  direct  polarization. 

A  second  objection  to  the  Andrlik-Stanek  modification  is  that  the 
method  cannot  be  used  when  reducing  sugars  are  present  owing  to  the 
change  which  the  urea  causes  in  their  specific  rotation.  The  extent  of 
this  change  can  be  seen  from  the  following  experiments  upon  solutions 
of  fructose,  glucose,  and  invert  sugar.  The  same  volume  of  sugar  solu- 
tion was  taken  in  each  case  and,  after  addition  of  substance,  was 
completed  to  100  c.c.  The  readings  were  taken  immediately  except  as 
otherwise  stated. 


Fructose. 

Glucose. 

Invert  sugar. 

Volume  completed  with  water  alone  
Volume  completed  with  water  +  5  gms.  I 
urea  ] 

-26.2°  V. 

-27.0 

+56.5°V. 
+56.1 

-10.2°V. 
-10.6 

Volume  completed  with  water  +  5  c.c.  HC1 
Volume  completed  with  water  +5  gms.  / 
urea  +5  c.c.  HC1  ] 

-26.9 
-27.3 

+56.7 
+56.5 

-10.5 
-10.7 

Volume  completed  with  water  +  5  gms.  ) 
urea  +  5  c.c.  HC1  after  2  days  f 

-27.3 

+48.0 

-11.9 

METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION      273 

It  is  seen  that  the  5  gms.  urea  +  5  c.c.  hydrochloric  acid  produce  a 
different  rotation  than  the  5  c.c.  hydrochloric  acid  alone,  this  difference 
being  greater  for  fructose.  On  long  standing,  glucose  in  presence  of  hy- 
drochloric acid  and  urea  shows  a  loss  in  rotation  owing  to  the  formation 
of  glucose  ureide  ([O\D  =  —  23.5).  This  explains  the  high  levorotation  of 
invert  sugar  solutions  prepared  in  presence  of  urea.  (See  Table  LII.) 

The  Andrlik-Stanek  method  is  a  dangerous  one  for  it  may  intro- 
duce greater  errors  than  those  which  it  was  designed  to  correct.  The 
process,  notwithstanding  several  favorable  notices  in  the  literature,  is 
not  to  be  generally  recommended. 

Among  the  modified  methods  belonging  to  Class  II,  which  employ 
for  the  Clerget  determination  inverting  agents  less  open  to  the  objec- 
tions of  hydrochloric  acid,  may  be  mentioned  the  following: 

(1)  Inversion  by  Means  of  Organic  Acids.  —  A  number  of  organic 
acids,  especially  such  as  have  no  pronounced  influence  upon  the  optical 
activity  of  fructose,  have  been  employed  in  place  of  hydrochloric  acid 
for  the  determination  of  sucrose  by  the  Clerget  method.  Weber*  showed 
that  in  presence  of  acetic  acid  invert  sugar  had  the  same  rotatory  power 
as  in  aqueous  solution.  Acetic  acid,  however,  is  an  unsatisfactory  re- 
agent for  the  Clerget  determination  on  account  of  its  very  weak  invert- 
ing action  (%%Q  that  of  hydrochloric  acid,  see  p.  663).  Tolmanf  has 
tested  the  use  of  citric  acid  for  the  Clerget  process  and  found  that  with 
2  gms.  of  this  acid  to  100  c.c.  complete  inversion  of  sucrose  could  be  ac- 
complished in  30  minutes  at  the  temperature  of  boiling  water.  Under 
these  conditions  the  Clerget  factor]  for  the  normal  weight  of  sucrose 
was  141.95  and  for  the  half-normal  weight  141.49.  Tolman  noted, 
however,  that  the  presence  of  soluble  acetates  greatly  retarded  the  in- 
verting action  of  citric  acid  and  that  the  latter  was  consequently  of  no 
value  as  an  inverting  agent  with  products  which  required  previous 
clarification  with  lead  subacetate.  This  same  objection  would  apply  to 
many  other  organic  acids.  Another  serious  objection,  as  with  hydro- 
chloric acid,  against  the  use  of  organic  acids  as  inverting  agents  is  the 
difference  in  optical  activity  of  contaminating  amino  compounds  in 
the  solutions  used  for  direct  and  invert  polarization  —  asparagine,  for 
example,  being  levorotatory  in  aqueous  solution,  but  dextrorotatory  in 
presence  of  strong  acetic  acid. 

Oxalic  acid  |  has  also  been  recommended  as  an  inverting  agent, 
2  gms.  of  the  acid  being  used  for  100  c.c.  of  solution.  This  acid  has 

*  J.  Am.  Chem.  Soc.,  17,  321. 

t  Bull.  73,  U.  S.  Bur.  of  Chem.,  p.  69. 

}  Kulisch.  Z.  ang.  chem.  (1897),  45. 


274  SUGAR  ANALYSIS 

a  much  stronger  inverting  power  than  either  acetic  or  citric  acid,  but 
is  open  to  the  same  objections  previously  stated. 

The  employment  of  organic  acids  as  inverting  agents  in  the  ex- 
amination of  impure  sugar  products  has  not  been  found  upon  the  whole 
to  be  satisfactory. 

(2)  Inversion  by  Means  of  Invertase.  —  The  employment  of  yeast  as 
an  inverting  agent  in  the  Clerget  determination  of  sucrose  was  first  in- 
dicated by  Kjeldahl*  in  1881.  O'Sullivan  and  Tompson,f  in  1891,  and 
Ling  and  Baker  {  in  1898,  extended  the  use  of  the  method  and  more 
recently  Ogilvie  has  applied  it  to  the  analysis  of  sugar-factory  products. 
The  yeast  method  of  O'Sullivan  and  Tompson,  as  modified  by  Ogilvie,  § 
is  as  follows : 

"  Four  times  the  normal  sugar  weight  of  the  sample  are  trans- 
ferred to  a  standardized  200-c.c.  flask,  defecated  with  the  minimum 
amount  of  basic  lead-acetate  solution  (sp.  gr.,  1.26),  a  little  alumina 
cream  added,  then  the  liquid  adjusted  to  bulk  at  standard  temperature, 
well  shaken,  and  filtered;  100  c.c.  of  the  filtrate  are  measured  by  a 
standard  pipette  into  a  small  beaker,  sulphur  dioxide  passed  in  from  a 
siphon  of  the  liquefied  gas  till  a  faint  smell  is  perceptible  (all  the  lead 
thus  being  indicated  to  be  precipitated),  then  the  liquid  transferred  to 
a  200-c.c.  flask,  made  up  to  the  mark,  and  well  mixed.  Now  sufficient 
calcium  carbonate  (dried)  in  fine  powder  to  neutralize  the  excess  of 
acidity,  and  a  little  recently  ignited  kieselguhr  (to  promote  filtration) 
are  added,  after  which  filtration  follows.  In  this  way  a  normal  solu- 
tion is  obtained,  which  is  sufficiently  clarified  to  give  a  distinct  polari- 
metric  reading,  is  free  from  lead  and  excess  of  acidity,  and  is  therefore 
well  suited  for  the  invertase  inversion. 

"  Fifty  cubic  centimeters  of  the  solution,  prepared  in  the  manner 
just  described,  contained  in  a  100-c.c.  flask,  are  raised  in  a  constant- 
temperature  bath  to  between  50°  and  55°  C.,  after  which  0.5  gm.  of  washed 
brewery  yeast  and  2  drops  of  acetic  acid  are  added  and  the  tempera- 
ture maintained  as  near  55°  C.  as  possible  for  4J  to  5  hours.  At  the  end 
of  this  time  the  liquid  is  cooled,  and  a  little  alumina  cream  or  kieselguhr 
added  to  assist  filtration,  and  made  up  to  bulk  at  standard  tempera- 
ture. The  clear  filtrate  is  then  polarized  in  a  lateral-branched  water- 
jacketed  tube  at  exactly  20.0°  C." 

The  Clerget  factor  determined  by  Ogilvie  for  the  above  process 
from  experiments  upon  pure  sucrose  is  141.6. 

*  Compt.  rend.  Lab.  Carlsberg  (1881),  1,  192.    f  J-  Chem.  Soc.  Trans.,  59,  46. 
t  J.  Soc.  Chem.  Ind.,  17,  111.  §  Int.  Sugar  Jour.,  13,  145. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION      275 

Instead  of  employing  yeast,  a  solution  of  invertase  prepared  there- 
from may  be  used  to  advantage.  Hudson*  has  developed  a  method 
upon  this  principle,  which  is  described  as  follows: 

"  Dissolve  26  gms.  of  the  substance  to  be  analyzed  for  cane  sugar 
in  water,  clarify  with  the  usual  substances  (neutral  or  basic  lead  acetate 
or  alumina  cream  or  kaolin)  and  make  up  to  100  c.c.  volume  at  20°  C. 
Filter  and  read  the  polarization  of  the  nitrate  in  a  200-mm.  tube. 
Remove  the  excess  of  lead  from  the  filtrate,  if  lead  has  been  used 
as  clarifying  agent,  with  sodium  carbonate  or  potassium  oxalate,  and 
filter.  To  50  c.c.  of  the  filtrate  add  acetic  acid  by  drops  until  the 
reaction  is  acid  to  litmus,  add  5  c.c.  of  the  stock  invertase  solution 
(p.  669),  and  make  up  the  volume  to  100  c.c.  Add  a  few  drops  of 
toluene  to  the  solution  to  prevent  the  growth  of  microorganisms,  shak- 
ing so  as  to  saturate,  and  allow  to  stand  at  any  temperature  between 
20°  and  40°  C.  over  night.  Under  usual  conditions  about  six  hours' 
time  is  required  to  accomplish  complete  hydrolysis."  When  the  inver- 
sion is  finished,  the  solution  is  read  at  20°  C.  and  the  invert  reading  cal- 
culated to  the  normal  weight  of  substance.  The  Clerget  factor  for  the 
above  method  as  determined  by  Hudson  from  experiments  upon  pure 
sucrose  is  141.7. 

The  invertase  method  is  unquestionably  the  most  ideally  perfect  of 
the  numerous  Clerget  modifications.  No  disturbances  are  produced  in 
the  specific  rotations  of  fructose,  amino  acids,  or  other  optically  active 
substances  which  may  accompany  sucrose  and  no  other  substances 
than  sucrose  are  hydrolyzed  except  in  the  few  special  cases  where 
raffinose,  stachyose  or  gentianose  may  be  present. 

The  complications  involved  in  the  preparation  of  the  invertase 
reagent,  the  uncertainty  of  knowing  whether  a  given  preparation  is 
always  of  constant  strength,  and  the  long  period  of  time  frequently 
necessary  to  accomplish  inversion  are  the  chief  drawbacks  against  the 
use  of  the  method  in  practical  analytical  work. 

The  inverting  power  of  the  stock  invertase  solution  should  be  care- 
fully determined  from  time  to  time  by  experiments  upon  pure  sucrose 
and  with  any  decrease  in  activity  the  quantity  of  reagent  used  for  in- 
version must  be  correspondingly  increased.  The  time  of  inversion  can 
be  shortened  considerably  by  conducting  the  inversion  at  a  tempera- 
ture of  about  55°  C.  To  determine  whether  or  not  inversion  is  com- 
plete the  closed  flask  or  tube  of  solution  may  be  warmed  again  to 
55°  C.  for  an  hour  and  then,  after  cooling  to  20°  C.,  reread.  If  no  change 
in  polarization  is  noted,  the  inversion  is  complete. 
*  J.  Ind.  Eng,  Chem.,  2,  143. 


276  SUGAR  ANALYSIS 

The  invertase  method  will  be  found  of  especial  value  in  research 
work  and  in  controlling  the  results  of  other  methods.  In  this  con- 
nection, however,  it  should  be  noted  that  the  influence  of  salts  and 
other  impurities  upon  the  rotation  of  the  accompanying  sugars  intro- 
duces the  same  error  as  in  other  Clerget  modifications. 

CLARIFICATION  OF  SOLUTIONS  FOR  THE  DETERMINATION  OF  SUCROSE 
BY  THE  CLERGET  METHOD 

In  the  analysis  of  sucrose-containing  products  by  the  Clerget  method, 
clarification  by  means  of  basic  lead  compounds  must  precede  and  not 
follow  the  process  of  inversion.  This  precaution  is  necessary,  owing  to 
the  occlusion  of  a  part  of  the  invert  sugar  in  the  basic  lead  precipitate 
and  the  consequent  diminution  of  the  invert  polarization.  In  so  far  as 
the  work  of  analysis  will  permit,  the  solution  for  the  direct  polarization 
and  that  used  for  inversion  should  both  be  taken  from  the  same  clarified 
filtrate  after  deleading.  The  following  method  of  procedure  is  given  as 
an  example. 

Method  of  Deleading.  —  Transfer  57.20  gins,  of  product  with 
about  100  c.c.  of  water  to  a  graduated  200-c.c.  flask.  After  solution, 
lead-subacetate  reagent  (1.26  sp.  gr.)  is  added  to  the  necessary  point  of 
clarification  and  the  volume  completed  to  200  c.c.  After  mixing  well, 
the  solution  is  filtered  and  100  c.c.  of  the  filtrate  (28.6  gms.  substance) 
treated  in  a  110-c.c.  flask  with  successive  amounts  of  finely  powdered 
potassium  oxalate,  or  sodium  carbonate,  or  sodium  sulphate,  etc.,  until 
no  more  lead  is  precipitated.  If  the  deleaded  solution  is  alkaline  to 
litmus  paper  or  phenolphthalein  it  is  exactly  neutralized  with  acetic 
acid  and  the  volume  completed  to  110  c.c.  The  solution  is  mixed, 
filtered,  and  the  filtrate  (26  gms.  substance  to  100  c.c.)  used  for  the 
direct  polarization.  Fifty  cubic  centimeters  of  the  same  filtrate  are 
then  inverted  in  a  100-c.c.  flask,  according  to  the  method  desired,  and, 
after  completing  the  volume  to  100  c.c.,  polarized  for  the  invert  reading. 
The  latter  multiplied  by  2  gives  the  invert  polarization. 

In  this  connection  it  should  be  remarked  that  with  substances  re- 
quiring large  amounts  of  basic  lead  for  clarification  the  5  c.c.  of  hydro- 
chloric acid  prescribed  for  the  Clerget  or  Herzfeld  inversion  may  be 
insufficient  on  account  of  the  formation  of  chlorides  and  the  liberation 
of  the  weakly  inverting  acetic  acid.  In  such  cases  it  is  usual  to  em- 
ploy 6  c.c.  of  hydrochloric  acid  for  making  the  inversion. 

Instead  of  the  powdered  salts  above  mentioned,  concentrated  sulphur- 
ous acid  (prepared  by  saturating  water  with  sulphur  dioxide)  has  been 
proposed  by  Pellet  for  deleading.  This  reagent  has  certain  advantages, 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION       277 

for,  in  addition  to  precipitating  excess  of  lead,  it  neutralizes  any  free 
alkalinity  and  at  the  same  time  acts  as  a  bleach  upon  any  coloring 
matter  which  might  darken  the  solution  for  reading.  The  sulphur 
dioxide  has  even  been  added  to  excess  for  deleading,  sufficient  quan- 
tity (10  c.c.)  of  the  solution  being  taken  to  complete  the  volume  from 
100  to  110  c.c.  This  excess  does  no  harm,  as  the  acid  in  the  cold  is  a 
very  weak  inverting  agent  and  has  no  immediate  depressing  influence 
upon  the  direct  polarization.  This  excess  of  sulphurous  acid  has  also 
the  advantage  of  preventing  the  troublesome  afterdarkening  which  fre- 
quently results  from  the  inverting  action  of  hydrochloric  acid.  Ogilvie* 
claims  as  another  advantage  an  equalizing  effect  in  the  conditions  before 
and  after  inversion  in  that  both  direct  and  invert  polarizations  are  made 
in  acid  solution.  It  is  evident,  however,  that  the  total  quantity  of  acid 
is  not  the  same  in  both  cases  and  that  these  different  amounts  of  acid 
will  exercise  a  variable  influence  upon  the  rotation  of  fructose,  amino 
compounds,  etc. 

An  objection  against  sulphur  dioxide  as  a  deleading  agent  is  the  very 
troublesome  character  of  the  lead-sulphite  precipitate  which,  on  ac- 
count of  its  finely  divided  colloidal  condition,  is  very  apt  to  pass  through 
the  filter.  Agitating  the  solution  with  paper  pulp,  infusorial  earth 
(kieselguhr),  or  kaolin  previous  to  filtration  has  been  recommended  as 
a  means  of  securing  a  clear  filtrate. 

Decolorization  of  Inverted  Solutions.  —  The  afterdarkening  which 
results  from  the  action  of  the  hydrochloric  acid  upon  coloring  sub- 
stances, caramel,  or  other  organic  impurities,  is  frequently  so  great  as 
to  cause  difficulty  in  reading  the  solution  for  the  invert  polarization. 
In  such  cases  a  number  of  expedients  may  be  followed. 

(1)  Use   of  a  100-wra.   or   50-mm.   Tube.  —  Since   shortening   the 
length  of  the  observation  tube  always  necessitates  a  corresponding 
multiplication  of  any  errors  of  observation  this  method  is  to  be  used 
only  as  a  last  resort. 

(2)  Decolorization  by  Means  of  Bone  Black.  —  Animal  charcoal  or 
bone  black  should  never  be  used  upon  solutions  for  direct  polarization 
on  account  of  its  great  absorptive  power  for  sucrose.     It  may,  how- 
ever, be  employed  with  comparative  safety  upon  solutions  of  invert 
sugar,  provided  the  char  be  previously  purified  by  washing  with  dilute 
hydrochloric  acid  and  water  and  then  dried.     Two  to  five  grams  (de- 
pending upon  the  coloration  of  the  solution)  of  the  finely  ground  bone 
black  are  placed  in  the  apex  of  a  folded  filter  and  the  solution  to  be 
treated  poured  through  in  successive  portions  of  about  10  c.c.    The 

*  Int.  Sugar  Jour.  13,  145. 


278  SUGAR  ANALYSIS 

first  25  to  30  c.c.  of  filtrate  are  discarded  and  the  remainder  used  for 
the  invert  polarization. 

(3)  Decolorization  by  Means  of  Reducing  Agents,  —  Zinc  Dust, 
Sodium  Sulphite,  Etc.  —  A  large  number  of  reducing  agents  have  been 
used  for  decolorizing  acid  solutions  of  invert  sugar.  Zinc  dust  has 
been  frequently  employed  for  this  purpose,  the  destruction  of  coloring 
matter  being  due  to  the  nascent  hydrogen  generated  by  the  action  of 
the  hydrochloric  acid  upon  zinc.  The  powdered  metal  is  added  to 
the  solution  to  be  decolorized  in  successive  small  amounts,  thus  pre- 
venting a  too  violent  evolution  of  gas  with  loss  of  solution. 

Sodium  sulphite  and  bisulphite  have  also  been  employed  for  decol- 
orizing acid  invert  sugar  solutions.  In  this  case  the  bleaching  agent  is 
the  sulphur  dioxide  liberated  by  the  action  of  the  hydrochloric  acid. 

The  use  of  zinc  and  sodium  sulphite  as  decolorizing  agents  is  not 
attended  with  serious  danger,  provided  only  the  minimum  amounts  be 
employed. 

General  Reliability  of  the  Clerget  Method 

While  the  method  of  double,  or  invert,  polarization  gives  perfectly 
reliable  results  upon  pure  sucrose,  it  is  evident  that  the  method  has 
serious  limitations  when  applied  to  the  investigation  of  impure  prod- 
ucts. The  influence  of  mineral  and  organic  impurities  upon  the 
specific  rotations  of  sucrose  and  other  sugars,  and  the  lead-precipitate 
error  affect  all  modifications  of  the  Clerget  process.  The  influence  of 
hydrochloric  acid  upon  the  specific  rotations  of  fructose  and  ammo 
compounds  is  an  additional  source  of  error  in  all  modifications  where 
the  invert  polarization  is  made  in  hydrochloric  acid  solution.  Under 
such  circumstances  the  chemist  need  not  expect,  under  the  most  favor- 
able conditions,  to  obtain  upon  products  containing  a  mixture  of  sucrose 
with  reducing  sugars,  salts,  and  organic  impurities  an  accuracy  much 
greater  than  0.5  per  cent;  in  certain  cases  the  error  may  exceed  1  per 
cent.  The  Clerget  method  gives  therefore  at  best  only  an  approximation, 
the  degree  of  exactness  depending  not  only  upon  the  care  and  skill  of 
the  chemist,  but  also  upon  the  nature  of  the  substance  being  analyzed. 
The  introduction  of  excessive  refinements  in  the  method  has  usually 
proved  a  thankless  labor  and  is  not  to  be  recommended.  The  employ- 
ment, for  example,  of  a  Clerget  factor  elaborated  to  the  fifth  decimal 
(as  in  Tuchschmid's  formula,  p.  264)  is  of  no  possible  value  in  practical 
work. 

In  employing  any  of  the  numerous  Clerget  modifications  it  is 
always  advisable  for  the  chemist  to  establish  his  own  factor  for  the 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION       279 

particular  conditions  of  the  analysis.  This  is  best  done  by  making  a 
blank  determination  upon  pure  sucrose,  or,  better  still,  upon  a  mixture 
of  pure  sucrose  with  approximate  amounts  of  the  accompanying  sub- 
stances which  are  known  to  occur  in  the  product  undergoing  examina- 
tion. By  so  doing  the  chemist  will  gain  an  idea  of  the  reliability  of 
his  method,  such  as  can  be  secured  in  no  other  way. 

APPLICATION  OF  THE  CLERGET  METHOD  TO  THE  DETERMINATION  OF 
SUGARS  IN  PRESENCE  OF  SUCROSE 

When  sucrose  occurs  in  presence  of  another  sugar,  whose  specific 
rotation  is  not  affected  by  the  inverting  agent,  and  no  other  optically 
active  substances  are  present,  the  percentage  (Z)  of  the  accompanying 
sugar  may  be  determined  as  follows: 

If  P  is  the  direct  polarization  for  the  sucrose  normal  weight  of  sub- 
stance, and  S  the  percentage  of  sucrose  by  the  Clerget  method,  then 
P  —  S  is  the  polarizing  power  of  the  accompanying  sugar.  The  per- 
centage Z  may  then  be  determined  as  upon  page  200,  by  dividing  the 
value  100  (P  —  S)  by  the  polarizing  power  of  the  accompanying  sugar 
(Table  XXXVI).  The  calculation  may  also  be  expressed  in  general 
terms  by  the  equation 

„  _  66.5  (P  -  S) 

~wT 

in  which  66.5  is  the  specific  rotation  of  sucrose  and  [ag  that  of  the 
accompanying  sugar.  The  method  of  calculation  may  be  illustrated 
by  several  examples. 

Example  I.  —  A  sirup  containing  sucrose  and  dextrose  gave  a  direct 
polarization  of  -+•  58.0  and  an  invert  polarization  of  —  8.33  at  20°  C.  Required 
the  percentages  of  sucrose  and  dextrose. 

Pe.ee.—  = 


Per  cent  dextrose  =  66-5^  ~  50)  =  10  per  cent. 

O-6.O 

Example  II.  —  A  sirup  containing  sucrose  and  invert  sugar  gave  a  direct 
polarization  of  +  52  and  an  invert  polarization  of  —  21  at  20°  C.  Required 
the  percentages  of  sucrose  and  invert  sugar. 


Per  cent  _e  =      z  -  „  P«  cent. 

(EO 

—(  — 
—  2,0 


Afi  ^  (EO  _  ^i^ 

Per  cent  invert  sugar  =  —  :  —  —(  —  -  *•  =10  per  cent. 

— 


280  SUGAR  ANALYSIS 

Example  III.  —  A  sweetened  condensed  milk  (26  gms.  in  100  c.c.)  gave  a 
direct  polarization  of  -f  51.50  and  after  inversion  in  the  cold  a  polarization  of 
—  4.20  at  20°  C.  Required  the  percentages  of  sucrose  and  lactose. 

100  [51.50-  (-4.20)]       5570 
Per  cent  sucrose  =  -  I  =  =  41.99  per  cent. 


66.5(51.50-41.99)       10n. 

Per  cent  lactose  =  -  s  -  —  —  -  -  =  12.05  per  cent. 

o2.o 

The  percentages  of  sugars  calculated  in  this  manner  have  of  course 
no  greater  degree  of  accuracy  than  the  Clerget  sucrose  determination. 
With  impure  products  clarified  by  means  of  basic  lead  compounds  there 
may  be  an  appreciable  error  due  to  the  occlusion  of  reducing  sugars  in 
the  lead  precipitate. 

Method  of  Dubois  for  Determining  Sucrose  and  Lactose  in  Milk 
Chocolate.  —  Dubois*  has  applied  the  Clerget  method  to  the  deter- 
mination of  sucrose  and  lactose  in  milk  chocolate.  The  usual  procedure 
is  somewhat  modified  in  that  100  c.c.  of  water  are  added  to  the  26  gms. 
of  substance,  a  correction  being  afterwards  applied  for  the  increase  in 
volume  through  solution  of  sugars.  A  preliminary  extraction  of  the 
chocolate  with  ether  to  remove  fat  secures  a  more  rapid  solution  of 
sugars.  The  following  method  of  solution  may  also  be  used. 

Transfer  26  gms.  of  the  finely  ground  chocolate  to  a  flask,  add  100  c.c. 
of  water,  cork  and  heat  in  a  steam  bath  for  20  minutes,  releasing  the 
pressure  occasionally  during  the  first  5  minutes.  Shake  thoroughly 
twice  during  the  heating  so  as  to  emulsify  completely.  Cool  to  room 
temperature,  add  10  c.c.  of  lead-subacetate  solution,  mix  and  filter. 
After  taking  the  direct  polarization  (a),  delead  the  solution  with  dry 
potassium  oxalate.  Invert  the  deleaded  solution  according  to  Herz- 
f  eld's  method  and  take  the  invert  polarization  (6),  correcting  for 
dilution.  Calculate  the  approximate  percentages  of  sucrose  (S)  and 
lactose  (L)  by  the  following  formulae: 

„      (a  -  6)  X  110          r  _  (o  X  1.10)  -  S 

~  " 


The  approximate  grams  (G)  of  total  sugar  in  the  normal  weight  of 
chocolate  are  calculated  from  S  and  L,  and  the  volume  (X)  of  solution 
estimated  by  the  formula  X  =  110  +  (G  X  0.62),  in  which  0.62  is  the 
increase  in  volume  caused  by  dissolving  1  gm.  of  sugar  in  water.  The 
corrected  percentages  of  sucrose  and  lactose  are  then  found  as  follows: 

Q-rr  T  •y 

True  per  cent  sucrose  =  —  —  •    True  per  cent  lactose  =  ^77)' 
*  Or.  66,  U.  S.  Bur.  of  Chem.,  p.  15. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION       281 

The  employment  of  an  expansion  factor,  as  in  the  above  method,  is 
permissible  only  in  case  of  water-free  substances  and  where  no  other  in- 
gredients than  sugars  are  dissolved.  The  factor  0.62  is  not  absolutely 
correct  for  all  concentrations,  as  is  seen  from  the  following  table: 


Sucrose  dis- 

Increase in  vol- 

Sucrose dis- 

Increase in  vol- 

solved in  100 
c.c.  water  at 

Volume  of  resulting 
solution. 

ume  through 
solution  of  1 

solved  in  100 
c.c.  water  at 

Volume  of  re- 
sulting solution. 

ume  through 
solution  of  t 

20°  C. 

gram  sucrose. 

20°  C. 

gram  sucrose. 

Grams. 

c.c. 

c.c. 

Grams. 

c.c. 

c.c. 

1 

100.51 

0.506 

26 

115.98 

0.614 

2 

101  .  12 

0.560 

50 

130.94 

0.619 

5 

102.96 

0.592 

100 

162.37 

0.624 

10 

106.07 

0.607 

200 

225.82 

0.629 

The  error  attending  the  use  of  the  factor  0.62  upon  dilute  solutions 
is  so  small  as  to  be  negligible. 


APPLICATION  OF  THE  CLERGET  PRINCIPLE  TO  THE  DETERMINATION  OP 

RAFFINOSE 

The  principle  of  the  Clerget  inversion  method  may  be  applied  to  the 
analysis  of  any  optically  active  substance  whose  specific  rotation  un- 
dergoes a  known  change  with  a  special  method  of  treatment.  The 
most  common  application  of  the  principle,  outside  of  sucrose,  is  in  the 
determination  of  the  trisaccharide  raffinose,  the  occurrence  of  which  in 
sugar-house  products,  plant  substances,  etc.,  is  referred  to  on  page  732. 

The  hydrolysis  of  raffinose  with  hydrochloric  acid,  under  the  condi- 
tions prescribed  for  the  Clerget  inversion,  proceeds  very  closely  according 
to  the  equation: 


Raffinose 

[a]g=+  104.5  (for 
raffinose  hydrate 
before  hydrolysis) 


d-Fructose 

MS— 


Melibiose 

-  +143 


[a]™=  +  53.5  (for  raffinose  hydrate  after 
hydrolysis) . 

The  specific  rotation  of  raffinose  decreases  during  the  hydrolysis 
from  +104.5  for  the  hydrate  to  +53.5,  which  corresponds  to  that  of 
a  molecular  mixture  of  fructose  and  melibiose  (see  note  p.  737).  The 
normal  weight  of  raffinose  for  the  Ventzke  scale,  using  metric  cubic 
centimeters,  is  16.545  gms.  for  the  hydrate  and  14.037  gms.  for  the 
anhydride  (see  p.  197) .  These  amounts  of  raffinose,  polarizing  + 100°  V., 
show  after  hydrolysis,  following  exactly  the  procedure  of  Herzfeld,  a 
polarization  of  +  51.24°  V.  at  20°  C.,  or  a  decrease  of  48.76°  V.  This 
decrease  for  the  weight  of  raffinose  reading  1°  V.  (0.16545  gm.  hydrate 


282  SUGAR  ANALYSIS 

or  0.14037  gm.  anhydride)  is  0.4876°  V.     The  calculation  of  raffinose 
by  the  hydrolysis  method  may  then  be  expressed  as  follows : 

P-Pr 


R  = 


0.4876 


in  which  R  is  the  percentage  of  raffinose,  P  the  polarization  of  the 
normal  weight  of  product  before  hydrolysis  and  P'  the  polarization  of 
this  normal  weight  after  hydrolysis. 

APPLICATION  OF  THE  INVERSION  METHOD  TO  MIXTURES  OF  SUCROSE 

AND  RAFFINOSE 

Raffinose  is  almost  always  associated  in  nature  with  sucrose,  and 
since  sucrose  undergoes  inversion  simultaneously  with  the  hydrolysis  of 
raffinose,  the  formula  previously  given  for  the  calculation  of  raffinose 
has  but  little  practical  value.  Creydt,*  however,  showed  that  it  was 
possible  to  combine  the  equations  for  the  calculation  of  raffinose  and 
sucrose,  and  in  this  way  obtain  formulae  which  can  serve  for  the  esti- 
mation of  the  two  sugars  in  mixtures.  The  original  formulae  of  Creydt 
were  based  upon  the  old  Clerget  process  of  inversion  and  have  now 
been  largely  replaced  by  formulae  worked  out  for  the  Herzfeldf  modi- 
fication (p.  266).  The  method  of  establishing  these  formulae  may  be 
understood  from  the  following: 

If  the  sucrose  normal  weight  (26.00  gms.)  of  a  substance  contain- 
ing S  per  cent  of  sucrose  and  R  per  cent  of  raffinose  (anhydride)  be 
dissolved  to  100  metric  cubic  centimeters  and  polarized  in  a  200-mm. 
tube,  the  polarization  of  the  sucrose  in  degrees  Ventzke  will  be  repre- 
sented by  S  and  the  polarization  of  the  raffinose  by  1 .852  R  (the  value 

nn   (\f\f\ 

1.852  being  the  ratio  —    r—  of  the  normal  weight  for  raffinose  anhydride 
14.Uo7 

to  that  for  sucrose).  The  direct  polarization  P  (the  sum  of  the  sucrose 
and  raffinose  polarizations)  is  represented  then  by  the  formula 

P  =  S  +  1.852  R,   whence   R  =  ^-^  and  S  =  P  -  1.852/2.      (1) 

l.ooz 

If  the  sucrose  normal  weight  of  the  above  substance  be  inverted 
according  to  the  Herzfeld  method  and  polarized  at  20°  C.,  the  invert 
polarization  of  the  sucrose  will  be  represented  by  -0.3266  S  (since  1°  V. 
sucrose  before  inversion  reads  —0.3266°  V.  at  20°  C.  after  inversion). 
In  the  same  manner  the  polarization  of  the  raffinose  after  hydrolysis  will 
be  1.852  R  x  0.5124  =  0.9490  R  (since  1°  V.  raffinose  before  hydrolysis 
reads  +0.5124°  V.  at  20°  C.  after  hydrolysis  by  Herzfeld's  method). 

*  Z.  Ver.  Deut.  Zuckerind.,  37,  153.  t  Ibid.,  40,  194. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION      283 

The  invert  polarization  Pr  (the  sum  of  the  sucrose  and  raffinose  invert 
polarizations)  is  represented  then  by  the  formula 

P'=-  0.3266  S  +  0.9490  R.  (2) 

p  _   o 

By  substituting  the  quantity  -pcHo"  °f  equation  (1)  for  R  in  equa- 
tion  (2),  we  obtain  the  formula 


whence  „  _  0.5124  P  -  P' 

0.839 
Having  calculated  S  from  P  and  Pf,  the  value  of  R  is  obtained  from 

r>  _   o 

equation  (1),  R  = 


By  substituting  the  quantity  P  —  1.852/2  of  equation  (1)  for  $  in 
equation  (2),  we  obtain  the  formula 

P'  =  -0.3266  (P  -  1.852/2)  +  0.9490  R, 
whence 

p  _  0.3266  P  +  P'  ,  . 

1.554 

By  formula  (4)  the  raffinose  may  be  calculated  at  once,  from  the 
direct  and  invert  polarizations. 

The  method  of  employing  the  formulae  may  be  understood  from 
the  following: 

A  beet-molasses,  free  of  reducing  sugar,  gave  a  direct  polarization  of 
+50°  V.  and  an  invert  polarization  of  —12°  V.  Required  the  percentages  of 
sucrose  and  raffinose. 

By  formula  (3),  per  cent  sucrose  =  °-5124  *  ^~  (~12)  =  44.84  per  cent. 


50  —  44  84 
By  formula  (1),  per  cent  raffinose  =  —         '  -  =  2.79  per  cent,  or 

L.OO& 

By  formula  (4),  per  cent  raffinose  =  0-3266  X  50  +  (-  12)  =  3.79  per  cent. 

I.OO4 

Correction  of  Raffinose  Formula  for  Changes  in  Temperature.  - 

The  determinations  of  sucrose  and  raffinose  by  the  preceding  formulae 
must  be  carried  out  at  exactly  20°  C.  In  case  the  analysis  is  made  at 
other  temperatures  the  formulae  require  to  be  modified.  Several 
formulae  have  been  worked  out  for  correcting  the  invert  polarizations 
of  sucrose  and  raffinose  for  changes  in  temperature.  Among  the 
simplest  of  these  are  the  formulae  of  Herles,*  which  are  derived  as 

follows: 

*  Z.  Zuckerind.  Bohmen,  13,  559;  16,  528. 


284 


SUGAR  ANALYSIS 


26.000  gms.  of  sucrose  and  14.037  gms.  of  raffinose  anhydride  which 
read  100  per  cent  upon  the  saccharimeter  before  inversion,  give  after 
inverting  by  Herzf eld's  method  the  following: 


Temperature. 

Inverted  sucrose 
solution. 

Inverted  raffi- 
nose solution. 

20°  C 

-32  66°  V. 

+51   24 

0°  C 

—42.66 

+47  24 

Difference  for  20°  C  
Difference  for    1  °  C  

10.00 
0.50 

4.00 
0.20 

For  sucrose  and  raffinose  reading  1  per  cent  upon  the  saccharimeter 
before  inversion,  the  reading  after  inversion  is: 

For  1  per  cent  sucrose    =  -0.4266,  at  0°  C. 

For  1  per  cent  sucrose    =  -0.4266  +  0.005  t,  at  t°  C. 

For  1  per  cent  raffinose  =  +0.4724,  at  0°  C. 

For  1  per  cent  raffinose  =  +0.4724  +  0.002  t,  at  t°  C. 

The  invert  polarization  for  S  per  cent  sucrose 

=  £(-  0.4266  +  0.0050- 
The  invert  polarization  for  R  per  cent  raffinose 

=  #(+0.4724  +  0.0020, 

or  for  the  sucrose  normal  weight  (26  gms.)  1.852  R  (+0.4724  +  0.002  t). 
The  invert  polarization  P'  for  S  per  cent  sucrose  and  R  per  cent 
raffinose  for  26.000  gms.  to  100  c.c.  would  be 

P'  =  S  (-0.4266  +  0.005  0  +  1.852  R  (+0.4724  +  0.002 1). 

•p  o 

Substituting  for  R  the  value  in  equation  (1),  R  = 


1.852 
P'  =  S  (-0.4266  +  0.005  0  +  (P  -  S)  (0.4724  +  0.002 1). 


Whence 


and,  as  before,  R 


S  = 


P  (0.4724  +  0.002  0  -' P' 


P-S 


0.899  -  0.003 1 
Equation  (5)  at  20°  C.  becomes  necessaril 


(5) 


1.852 
the  same  as  equation  (3). 

Bone-black  Error  in  Raffinose   Determinations.  —  A  source   o 
error  peculiar  to  certain  applications  of  the  inversion  method  for  d 
termining  raffinose  is  the  increase  in  levorotation  after  decolorizi 
inverted  solutions  by  means  of  bone   black.     This  error  was  fi 
studied  by  Reinhardt,*  who  attributed  the  phenomenon  to  the  ab- 
*  Z.  Ver.  Deut.  Zuckerind.,  62,  114. 


METHODS  OF  INVERT  OR  DOUBLE  POLARIZATION       285 

sorption  of  the  highly  dextrorotatory  melibiose.  Reinhardt's  expla- 
nation is  no  doubt  correct  as  bone  black  shows  a  similar  absorptive 
power  for  other  disaccharides,  such  as  sucrose.  Davoll,*  who  has  made 
a  detailed  study  of  methods  for  estimating  raffinose,  gives  the  follow- 
ing results  upon  a  mixture  containing  94.98  per  cent  pure  cane  sugar 
and  5.02  per  cent  raffinose  hydrate  (4.26  per  cent  raffinose  anhydride). 
The  direct  polarization  for  a  normal  weight  of  this  mixture  was  +102.48. 
The  invert  polarizations  for  different  methods  of  treatment  were  as 
follows : 


Method  of  treatment. 

Invert  polari- 
zation. 

Calculated  sugars. 

Raffinose. 

Sucrose. 

Without  char. 

-27.00 
-27.14 
-27.40 
-28.00 

Per  cent. 
4.16 
4.11 

3.95 
3.56 

Per  cent. 
94.77 

94.87 
95.16 
95.89 

Blood  charcoal  (purified  with  acid)  
Animal  charcoal  (highest  purity)  .... 

Animal  charcoal  (reagent)  

I 

II 


In  the  above  experiments  the  solutions  were  shaken  5  minutes  with 
3  gms.  of  char  before  filtering.  Pouring  the  solutions  in  successive 
portions  through  the  char  with  rejection  of  the  first  runnings  (as  de- 
scribed on  p.  220)  would  no  doubt  reduce  the  error  due  to  absorption 
considerably. 

As  a  remedy  for  the  error  due  to  the  use  of  bone  black  Davoll 
proposes  the  employment  of  zinc  dust  as  a  decolorizing  agent.  At  the 
end  of  the  Clerget  inversion  1  gm.  of  powdered  zinc  was  allowed  to  act 
upon  the  acid  solution  at  69°  C.  for  3  to  4  minutes.  Under  these  con- 
ditions the  zinc  was  not  found  to  affect  the  polarization  of  the  inverted 
solution. 

General  Reliability  of  the  Optical  Method  for  Estimating  Raffinose 

The  remarks  (p.  278)  made  upon  the  limitations  of  the  Clerget 
method  apply  with  even  greater  force  to  the  optical  determination  of 
raffinose.  The  method  does  not  give  accurate  results,  when  optically 
active  substances  other  than  sucrose  and  raffinose  are  present.  In 
cases  where  sucrose  occurs  with  caramelization  products,  gums,  and 
organic  acids,  application  of  the  formula  may  indicate  the  presence  of 
raffinose  when  in  reality  none  is  present.  The  formula  should  only  be 
used  in  the  investigation  of  substances  in  which  raffinose  is  liable  to 
occur  (as  sugar-beet  products,  cotton  seed,  etc.)  and  should  never  be 
*  Proc.  Fifth  Int.  Congr.  Applied  Chem.,  Ill,  p.  135. 


286  SUGAR  ANALYSIS 

employed,  as  is  sometimes  done,  as  a  test  for  the  presence  of  raffinose 
in  unknown  mixtures. 

As  in  the  Clerget  determination  of  sucrose  the  chemist  need  not 
expect  in  the  analysis  of  commercial  products  for  raffinose  an  accuracy 
much  exceeding  0.5  per  cent.  The  indication  of  a  smaller  amount  of 
raffinose  than  0.5  per  cent  is,  in  fact,  not  regarded  by  the  best  author- 
ities as  sufficient  to  justify  reporting  its  presence  (as  in  raw  beet  sugars). 

Before  applying  the  method  to  the  analysis  of  unknown  products 
the  chemist  should  first  satisfy  himself  of  the  presence  of  raffinose  by 
suitable  tests  (see  p.  740);  he  should  also  confirm  the  results  of  his 
analysis  so  far  as  possible  by  making  blank  determinations  upon  known 
mixtures.  A  practical  test  of  this  kind  is  the  best  means  for  testing  the 
reliability  of  the  method  in  particular  cases. 


CHAPTER  XI 

SPECIAL  METHODS  OF  SACCHARIMETRY 

THE  methods  of  inversion,  described  in  the  previous  chapter,  are 
only  special  instances  of  a  more  general  course  of  procedure.  It  is  pos- 
sible to  calculate  the  percentage  of  any  sugar,  provided  its  rotatory 
power,  in  distinction  from  that  of  associated  sugars,  can  be  given  a 
definite  alteration  by  some  special  method  of  treatment.  The  changes 
produced  in  the  rotation  of  sucrose  and  raffinose  by  the  action  of  in- 
vertase  or  acids  are  but  single  illustrations  of  such  special  methods  of 
treatment.  As  other  examples  may  be  mentioned  (1)  the  determina- 
tion of  sugars  by  noting  the  change  produced  in  polarization  under 
different  conditions  of  temperature.  (2)  The  determination  of  sugars, 
by  noting  the  change  in  polarization  after  fermenting  with  yeast. 
(3)  The  determination  of  sugars  by  noting  the  change  in  polarization 
after  destroying  the  optical  activity  of  reducing  sugars.  Numerous 
other  examples  might  be  given  but  the  three  cases  cited  are  sufficient 
to  illustrate  the  general  application  of  the  principle  to  special  problems 
of  saccharimetry. 

DETERMINATION  OF  SUGARS  BY  POLARIZATION  AT  HIGH  TEMPERATURE 
DETERMINATION  OF  INVERT  SUGAR  BY  HIGH-TEMPERATURE 

POLARIZATION 

The  principle  of  this  method  is  based  upon  the  fact  that  solutions 
of  pure  invert  sugar,  when  heated  to  a  temperature  between  85°  and 
90°  C.,  become  optically  inactive.  This  inactivity  is  due  to  the  lowering 
in  specific  rotation  of  fructose  with  increase  in  temperature  (page  179) ; 
the  specific  rotation  of  glucose  being  unaffected  by  temperature,  the 
point  of  optical  inactivity  will  be  the  degree  at  which  the  polarizing 
powers  of  glucose  and  fructose  exactly  neutralize  each  other. 

Temperature  of  Optical  Inactivity  of  Invert  Sugar.  —  The  temper- 
ature of  optical  inactivity  of  invert  sugar  has  been  variously  estimated. 
Dubrunfaut,*  who  made  the  earliest  measurements  of  this  constant, 
set  the  figure  at  90°  C.  Casamajorf  and  Wiley  J  have  given  88°  C., 

*  Compt.  rend.,  42,  901. 
t  Chem.  News,  44,  219. 
j  J.  Am.  Chem.  Soc.,  18,  81. 

287 


288 


SUGAR  ANALYSIS 


Lippmann,*  87.8°  C.,  Wolf,f  87.6°  C.  and  Tuchschmid,t  87.2°  C. 
These  variations  may  be  due  in  part  to  slight  experimental  errors 
(such  as  incipient  destruction  of  sugar  at  the  high  temperature)  and  in 
part  to  the  influence  of  concentration.  Inasmuch  as  the  [O\D  of  glucose 
varies  from  +  52.5  for  a  1  per  cent  solution  to  +  54.0  for  a  40  per  cent 
solution  it  is  evident  that  the  temperatures  at  which  these  different 
polarizations  are  neutralized  must  vary  somewhat. 

The  effect  of  concentration  upon  the  temperature  of  optical  in- 
activity for  invert  sugar  may  be  determined  by  means  of  the  carefully 
established  formulae  of  Gubbe.  || 

I   Concentration  [a]™  =  -  19.657  -  0.0361  c. 
II   Temperature 

(20°  to  100°  C.)    [aYD  =  [a]™  +  0.3246  (t  -  20)  -  0.00021  (t  -  20)2. 

In  Table  LIII,  column  B  gives  the  [a]™  of  invert  sugar,  as  calcu- 
lated by  formula  I,  for  different  concentrations;  column  C  gives  the 
grams  of  invert  sugar  in  100  c.c.  necessary  to  produce  a  reading  of 

1729 


—  1°  V.,  as  calculated  by  the  expression 


1UU 


(page  197);  column  D 


gives  the  temperature  of  optical  inactivity,  as  determined  by  formula  II 
of  Gubbe;  column  E  gives  the  variation  in  degrees  Ventzke,  produced 
by  1  gm.  of  invert  sugar  in  100  c.c.  for  1°  C.  difference  in  temperature 

and  is  calculated  by  the  expression  n  ,„  -  p^-  • 

C  (D  —  20) 

TABLE  LIII. 


A 

B 

C 

D 

B 

Concentration, 
grams  invert  sugar 
in  100  c.c. 

l«l» 

Invert  sugar  in  100 
c.c.  corresponding 
to  -1°  V.  at209C. 

Temperature  of  op- 
tical inactivity. 

Variation  for  1 
gram  invert  sugar 
for  1°C. 

Grams. 

Grams. 

Deg.  C. 

De?.  V. 

2 

-19.72 

0.8768 

83.2 

0.01805 

10 

-20.02 

0.8636 

84.2 

0.01804 

20 

-20.38 

0.8484 

85.4 

0.01802 

30 

-20.74 

0.8336 

86.6 

0.01801 

40 

-21.10 

0.8194 

87.8 

0.01800 

50 

-21.46 

0.8057 

89.0 

0.01799 

60 

-21.82 

0.7924 

90.2 

0.01798 

For  general  purposes  87°  C.  is  usually  taken  as  the  temperature  of 
optical  inactivity  for  invert  sugar. 


*  Ber.,  13,  1823. 

t  Oest.  Ung.  Z.  Zuckerind.,  16,  331. 

t  J.  prakt.  Chem.  [2],  2,  235. 

||   Ber.,  18,  2207. 


SPECIAL  METHODS  OF  SACCHARIMETRY  289 

The  application  of  the  method  to  the  determination  of  invert  sugar 
is  easily  understood.  Since  a  change  of  1°  C.  produces  a  constant 
variation  of  0.018°  V.  for  1  gm.  of  invert  sugar  in  100  c.c.,  regardless  of 
the  concentration,  then  the  grams  of  invert  sugar  in  100  c.c.  of  a  given 
solution  is  found  by  the  formula 

Invert  sugar  =  ~ 


in  which   Pf  =  Ventzke-scale  reading  at  higher  temperature  tf, 
and  P  —  Ventzke-scale  reading  at  lower  temperature  t. 

The  method  of  applying  the  formula  may  best  be  understood  by 
taking  a  typical  example. 

Example.  —  50  gms.  of  a  solution,  containing  a  mixture  of  glucose  and 
fructose  in  unequal  amounts,  were  made  up  to  100  c.c.  at  20°  C.  The  polariza- 
tion was  +  10.20°  V.  at  20°  C.  in  a  200-mm.  tube. 

50  gms.  of  the  same  solution  were  made  up  to  100  c.c.  at  87°  C.  The 
polarization  was  +  20.75°  V.  at  87°  C.  in  a  200-mm.  tube.  Required  the  per- 
centage of  sugars  in  the  original  solution. 


Invert  sugar  --  8.75  gn.. 


Q  7  P\ 

-^—  X  100  =  17.50  per  cent  invert  sugar. 
50 

The  dextrorotation  at  87°  C.  shows  an  excess  of  glucose  over  the  amount 
necessary  to  be  paired  with  the  fructose  for  invert  sugar.  This  excess  of  glucose 
may  be  estimated  as  follows  : 

Since  1°  V.  =  0.3225  gm.  glucose  (page  200)  then  the  grams  of  glucose  cor- 
responding to  the  dextrorotation  at  the  inactivity  of  invert  sugar  is  20.75  X 
0.3225  =  6.69  gms.  (uncorrected  for  concentration),  or  13.38  per  cent.  To 
correct  for  the  influence  of  concentration,  the  true  glucose  value  of  the  Ventzke- 
scale  reading  -f  20.75,  according  to  the  formula  G  =  s  -f  0.02  s  —  0.0002  s2, 
(page  199)  is  21.08.  21.08  X  0.3225  =  6.80  gms.  glucose  or  13.60  per  cent  in 
the  original  solution. 

The  percentage  of  glucose  determined  by  this  method  of  calculation  can,  of 
course,  be  considered  as  only  approximate,  for,  as  shown  in  Table  LIII,  the 
temperature  of  optical  inactivity,  according  to  concentration,  may  be  above  or 
below  87°  C. 

DETERMINATION    OF   COMMERCIAL   GLUCOSE   BY   HIGH-TEMPERATURE 

POLARIZATION 

Method  of  Chandler  and  Ricketts.  —  The  method  of  high-tem- 

perature polarization  as  first  developed  in  1880  by  Chandler  and  Rick- 

etts *  was  not  employed  for  determining  invert  sugar  but  for  detecting 

the  presence  and  estimating  the  amount  of  commercial  glucose  in  cane 

*  J.  Am.  Chem.  Soc.,  2,  428. 


290 


SUGAR  ANALYSIS 


sugar,  molasses,  honey  and  other  products  whose  sugars,  after  inversion, 
consist  almost  wholly  of  invert  sugar.  The  material  under  examina- 
tion was  first  inverted  to  convert  any  sucrose  to  invert  sugar  and  then 
polarized  at  the  temperature  of  optical  inactivity  for  invert  sugar.  Any 
dextrorotation  observed  at  this  temperature  was  attributed  to  com- 
mercial glucose  and  its  percentage  estimated  by  means  of  an  empirical 
factor. 

The  factor  for  converting  the  readings  of  the  Ventzke  sugar  scale 
into  grams  of  commercial  glucose  depends  entirely  upon  the  nature  of 
the  product.  Commercial  glucose,  as  manufactured  in  the  United 
States,  varies  in  density  from  41°  Be.  to  45°  Be.  (sp.  gr.  1.388  to  1.442) 
and  in  specific  rotation  from  about  [a:]^  +  100  to  +  125  for  the  liquid 
product.  The  grams  of  commercial  glucose  corresponding  to  1°  V.  for 
products  of  different  specific  rotation  are  given  in  Table  LIV. 

TABLE  LIV. 


MD  (for 
liquid  prod- 
uct). 

Polarization 
(deg.  V.  of 
26  grams  to 
100  truec.c.). 

Grams  of  liquid 
product  in  100  c.c. 
corresponding  to  a 
polarization  of  1°  V. 

Mo  (for 

liquid  prod- 
uct). 

Polarization 
(deg.  V.  of 
26  grams  to 
100  true  c.c.). 

Grams  of  liquid 
product  in  100  c.c. 
corresponding  to  a 
polarization  of  1°  V. 

+  125 

+  120 
+  115 
+  110 

+  188.0 

+180.5 
+172.9 
+  165.4 

0.1383 
0.1440 
0  1503 
0.1572 

+  108 
+  105 
+  100 

+  162.5 

+157.9 
+150.4 

0.1600 
0.1647 
0.1729 

For  purposes  of  analysis  the  products  of  [oj^  +108  may  be  taken  as 
the  grade  of  commercial  glucose  most  commonly  used.  The  chemist 
should  always  state  the  polarizing  power  of  the  commercial  glucose  in 
terms  of  which  his  results  are  expressed. 

The  form  of  polariscope  devised  by  Chandler  and  Ricketts  for  high- 
temperature  polarization  is  shown  in  Fig.  146.  The  instrument  con- 
sists of  an  ordinary  saccharimeter,  with  trough  removed  and  replaced 
by  a  water  bath  which  is  heated  from  below  by  means  of  gas  or  spirit 
lamps.  The  ends  of  the  water  bath,  before  the  diaphragms  of  the  ana- 
lyzer and  polarizer,  are  provided  with  metallic  caps  containing  small 
windows  of  plate  glass.  The  polarization  tube,  which  in  its  earliest 
form  was  constructed  of  platinum,  is  completely  immersed  in  the 
water  of  the  bath,  and  rests  upon  supports  opposite  the  windows  and  in 
perfect  alignment  with  the  axis  of  the  instrument.  The  tube  is  pro- 
vided with  an  upright  tubule  for  inserting  a  thermometer  and  for  re- 
ceiving any  excess  of  liquid  displaced  by  expansion.  The  cover  of  the 
bath,  which  fits  over  the  tubule,  contains  an  opening  for  a  thermometer 
to  determine  the  temperature  of  the  bath. 


SPECIAL  METHODS  OF  SACCHARIMETRY 


291 


The  use  of  a  special  type  of  saccharimeter  for  high-temperature 
polarization  has  been  largely  discontinued.  At  present  it  is  customary 
to  make  the  polarizations  upon  an  ordinary  type  of  saccharimeter,  em- 
ploying a  metal- jacketed  tube;  the  latter  may  be  insulated  to  advan- 
tage by  a  mantle  of  asbestos  or  other  non-conducting  material.  The 


FIG.  146.  —  Chandler  and  Ricketts's  polariscope  for  high-temperature  polarization. 

hot  water  for  heating  the  tube  is  conveyed  by  rubber  tubing  from  a 
water-heater,  which  should  be  placed  at  a  distance  sufficient  to  prevent 
heating  the  polariscope.  A  convenient  arrangement  for  this  purpose, 
described  by  Leach,*  is  shown  in  Fig.  147. 

Method  of  Leach.  —  The  following  description  of  a  method  for 
determining  commercial  glucose  in  molasses,  sirups,  honey,  etc.,  is  given 
by  Leach. f 

*  "Food  Inspection  and  Analysis"  (1911),  p.  644. 

t  Bull.  81,  U.S.  Bur.  of  Chem.,  p.  73.  Bull.  107  (revised),  U.S.  Bur.  of  Chem., 
p.  74. 


292 


SUGAR  ANALYSIS 


"Invert  a  half-normal  portion  in  the  usual  manner  in  a  100-c.c. 
flask;  after  inversion,  cool,  add  a  few  drops  of  phenolphthalein  and 
enough  sodium  hydroxide  to  neutralize;  discharge  the  pink  color  with  a 
few  drops  of  dilute  hydrochloric  acid,  add  from  5  to  10  c.c.  of  alumina 
cream,  and  make  up  to  the  mark  and  filter.  Multiply  by  2  the  read- 
ing at  87°  C.  in  the  200-mm.  tube;  multiply  this  result  by  100  and 


Fig.  147.  —  Apparatus  for  polarizing  at  high  temperatures. 

divide  by  the  factor  163  to  express  the  commercial  glucose  in  terms  of 
glucose  polarizing  +  175°  V."  * 

In  the  above  method  the  solution  is  made  up  at  room  temperature 
and  polarized  at  87°  C.  When  this  is  done  a  correction  must  be  made 
for  the  expansion  of  the  solution  and  consequent  lowering  of  the 
reading.  The  best  method  of  making  this  correction  is  by  means  of 
an  empirical  test.  Thus  Lythgoe,f  following  the  above  course  of 

*  Provisional  Method  of  the  Association  of  Official  Agricultural  Chemists, 
Bull.  107  (revised),  U.S.  Bur.  of  Chem.,  p.  71. 
t  Bull.  81,  U.S.  Bur.  of  Chem.,  p.  74. 


SPECIAL  METHODS  OF  SACCHARIMETRY 


293 


procedure,  obtained  the  following  results  upon  five  samples  of  commer- 
cial glucose. 


Sample. 

Density. 

Polarization  (26  gms.  in  100  c.c.). 

Ratio  f. 

f 

Ratio  2> 

A 

B 

C 

Direct. 

Invert  at  22°  C. 

Invert  at  87°  C. 

1 
2 
3 
4 
5 

Deg.  Be. 
42 

42 
42 
43 
45 

Deg.  V. 
156.6 

158.6 
169.6 
167.4 
174.0 

Deg.  V. 
153.4 

154.6 
165.4 
162.8 
171.0 

Deg.  V. 
146.6 
149.0 
159.4 
155.0 
161.2 

Average 

0.956 
.964 
.964 
.952 
.943 

0.936 
.940 
.940 
.926 
.927 

.956 

.933 

It  is  seen  that  the  polarization  of  commercial  glucose  is  slightly 
lowered  by  the  action  of  the  acid  during  inversion,  as  well  as  by  the 
expansion  of  the  solution  upon  heating  to  87°  C.  To  correct  for  both 
of  these  influences,  the  polarization  value  of  the  glucose  is  multiplied 
by  the  factor  0.933.  The  Association  of  Official  Agricultural  Chemists 
expresses  glucose  in  terms  of  a  product  polarizing  175°  V.  for  a  weight 
of  26  gms.  in  100  c.c.  and  this  polarization  corrected  gives  175  X  0.933  = 
163  which  is  the  factor  employed  in  the  calculation. 

Example.  — 13  gms.  of  a  sample  of  table  sirup  inverted  according  to  Herz- 
feld's  method  and  made  up  to  100  c.c.  at  20°  C.  polarized  +65.2°  V.at  87°  C. 
Required  the  percentage  of  commercial  glucose  in  terms  of  a  product  polarizing 

+  162.5°  V.for  26  gms.  in  100  c.c. 

65.2 


The  factor  for  162.5  is  162.5  X  0.933 
per  cent  commercial  glucose. 


151.6.    Then 


151.6 


X  100  =  43.0 


Dextrorotation  of  Inverted  Honey  at  87°  C.  —  The  method  of 
estimating  commercial  glucose  in  honeys,  sirups,  molasses,  etc.,  by 
polarizing  at  87°  C.,  can  be  regarded  only  as  an  approximate  one. 
The  chief  limitation  of  the  method  is  the  fact  that  pure  honeys,  mo- 
lasses, sirups,  etc.,  are  more  or  less  dextrorotatory,  after  inversion,  at 
87°  C.,  owing  to  the  presence  of  gums,  dextrins,  or  other  similar  com- 
pounds. 

Table  LV,  which  is  taken  from  the  work  of  Browne,*  gives  the 
polarization  of  various  samples  of  American  honey  at  20°  and  87°  C., 
before  and  after  inversion. 

*  "  Chemical  Analysis  and  Composition  of  American  Honeys,"  Bui.  110;  U.  S. 
Bur.  of  Chem. 


294 


SUGAR  ANALYSIS 


TABLE  LV 


Kind  of  honey. 

Num- 
ber 
samples 
aver- 
aged. 

Direct  polarization. 

Invert  polarization. 

20°  C. 

87°  C. 

20°  C. 

87°  C. 

Difference. 

Levorotatory  Class: 
Mangrove  

1 

3 
4 
8 
2 
2 
15 
3 
2 
3 
2 
6 
1 

1 
1 
1 
1 

92 

7 

Deg.  V. 

-24.80 
-20.93 
-17.61 
-15.10 
-16.80 
-17.50 
-13.01 
-12.33 
-12.40 
-10.47 
-8.55 
-8.90 
-4.90 

+3.60 
+7.80 
+  11.00 

+  17.75 

-14.73 
+9.43 

Deg.  V. 

+0.50 

+4.45 
+6.80 
+9.63 
+8.20 
+6.80 
+11.65 
+10.87 
+  13.00 
+  12.53 
+  17.00 
+  15.05 
+  17.80 

Deg.  V. 

-27.94 
-25.01 
-22.85 
-22.99 
-20.41 
-21.01 
-17.77 
-16.43 
-18.92 
-14.01 
-13.73 
-12.25 
-9.68 

-2.53 
+3.4?. 
+5.17 
+  13.53 

-19.16 

+5.47 

Deg.  V. 

-0.66 
+2.83 
+4.70 
+5.00 
+5.94 
+6.05 
+9.25 
+9.35 
+9.51 
+  11.51 
+  12.76 
+13.62 
+  15.40 

+20.90 
+26.62 
+28.60 
+34.76 

+7.91 
+27.56 

27.28 
27.84 
27.55 
27.99 
26.35 
27.06 
27.02 
25.78 
28.43 
25.52 
26.49 
25.87 
25.08 

23.43 
23.21 
23.43 
21.23 

27.07 
22.09 

JVlesouit 

Sweet  clover  

Alfalfa 

Buckwheat 

Cotton 

White  clover 

Goldenrod 

Dandelion 

Sumac 

Apple 

Basswood 

Whitewood 

Dextrorotatory  Class: 
Poplar 

Hickory  . 

+28.50 
+32.30 

White  oak  . 

Sugar-cane  honey  dew. 

Levorotatory  honeys  
Dextrorotatory  honeys  .  . 

+  10.15 
+32.20 

Average  of  50  varieties 

99 

-13.02 

+10.81 

-17.41 

+9.30 

26.71 

100  P 
Application  of  the  formula      fi<^     to   the  invert   polarizations   at 

87°  C.  would  indicate  nearly  10  per  cent  commercial  glucose  in  some  of 
the  levorotatory  and  nearly  20  per  cent  in  several  of  the  dextrorotatory 
honeys. 

Browne's  Method  for  Estimating  Commercial  Glucose  in  Honey.  - 
Browne*  has  modified  the  application  of  the  high-temperature  polariza- 
tion, for  estimating  commercial  glucose  in  honeys,  by  taking  the  differ- 
ence between  the  invert  polarization  at  20°  and  87°  C.  as  a  basis  of 
calculation.  It  is  seen  from  Table  LV  that  while  the  invert  readings 
at  either  20  °  or  87°  C.  are  subject  to  the  widest  variations,  the  differ- 
ence between  the  polarizations  at  these  two  temperatures  is  a  fairly 
constant  quantity  for  nearly  all  honeys.  The  average  value  of  this 
constant  for  the  99  samples  of  honey  examined  by  Browne  was  26.7. 
Since  this  difference  in  polarization  is  due  entirely  to  the  percentage  of 
invert  sugar  in  the  honey,  the  addition  of  any  commercial  glucose  will 

*  "Chemical  Analysis  and  Composition  of  American  Honeys,"  p.  60,  Bui.  110; 
U.  S.  Bur.  of  Chem. 


SPECIAL  METHODS  OF  SACCHARIMETRY  295 

cause  a  depression  in  the  polarization  difference,  which  will  be  pro- 
portional to  the  amount  of  commercial  glucose  used  but  irrespective  of 
its  specific  rotation.  In  order  to  correct  for  the  variations  in  moisture 
and  non-sugars  of  pure  honey  it  is  better  to  express  the  polarization 
difference  in  terms  of  a  uniform  basis  of  77  per  cent  reducing  sugars, 
which  is  the  average  percentage  of  invert  sugar  after  inversion  for  pure 
honey.  The  formulae  for  making  the  calculation  are  then: 

100  (Pf  -  P)  X  77      288.4  (P'  -  P) 
Per  cent  pure  honey  =          257  XI  ~V~ 

Per  cent  commercial  glucose  =  100 — ^j — 

in  which  P'  =  the  Ventzke  polarization  of  the  inverted  honey  at  87°  C. 
P  =  the  Ventzke  polarization  of  the  inverted  honey  at  20°  C. 
7  =  the  per  cent  of  invert  sugar  in  the  honey  after  inversion. 
Another  method,  used  in  European  countries,  for  estimating  the 
amount  of  commercial  glucose  in  honey  is  based  upon  the  variation  in 
the  invert  polarization  of  the  sample  from  that  of  pure  honey.     Calling 
the  average  invert  polarization  of  pure  honey  —  17.5  at  20°  C.  (Table 
LV)  and  employing  the  official  figure  +  175°  V.  for  the  polarization  of 
commercial  glucose,  then  if 

x  =  per  cent  of  honey  in  sample, 
y  =  per  cent  of  commercial  glucose  in  sample, 
P  =  invert  polarization  of  sample  in  degrees  Ventzke, 
x  +  y  =  100. 
-  0.175 x  +  1.75 y=P 

P  +  17.5 
y=    -T93T 

This  method  of  calculation,  the  same  as  that  based  upon  the  polari- 
zation at  87°  C. ,  makes  no  allowance  for  the  wide  range  in  the  invert 
polarization  of  individual  honeys  (—30  to  +  15),  so  that  a  considerable 
error  may  be  introduced  in  the  final  result. 

In  Table  LVI  the  polarizations  of  5  honeys  and  of  mixtures  of  the 
same,  with  20  per  cent  commercial  glucose,  are  given  together  with  the 
percentage  of  commercial  glucose  as  calculated  by  the  three  methods 
described. 

It  will  be  seen  from  the  results  in  the  table  that  with  admixtures  of 
low-purity  honeys  and  commercial  glucose  there  is  a  considerable  error 
in  the  calculation  of  the  percentage  of  added  adulterant.  The  results 
obtained  by  any  method  for  estimating  commercial  glucose  have  only 
an  approximate  value,  and  in  no  case  ought  such  analytical  results  as 


296 


SUGAR  ANALYSIS 


those  obtained  for  the  pure  basswood  or  white-oak  honey  to  condemn  a 
sample  as  being  adulterated.  In  all  suspicious  or  doubtful  cases  con- 
firmatory qualitative  tests  such  as  that  with  iodine  should  be  employed." 

TABLE  LVI  * 

Polarization  of  Honeys  and  Commercial  Glucose  Mixtures,  with  Calculated  Percent- 
ages of  Glucose  by  Different  Formulce. 


.1 

Invert  polariza- 
tion. 

I 
1 

a 
1 

hi 

Calculated  glucose. 

--.' 

'^u 

P 

P' 

'•3£ 

"3*- 

;3*-  a 

I 

Kind  of  sample. 

~0 

Jl 

k° 

S-*« 

. 

W5 

fl 

€* 

^OH 

If 

1°> 

.2  C-S 

Si 

+  2 

t-i 

c3 

c3  *"*  ^ 

a. 

Csl 

(5 

20°  C. 

87°  C. 

1 

> 

2" 

| 

Deg. 

Deg. 

Deg. 

Deg. 

Per 

Deg. 

Per 

Per 

Per 

V. 

V. 

V. 

V. 

cent. 

V. 

cent. 

cent. 

cent. 

Alfalfa 

—  19  5 

—22  66 

+  3  52 

26  18 

77  84 

25  90 

2  16 

0  00 

^ 

on 

Alfalfa+20  per  cent  glucose  

+19.4 

+16.88 

+35.82 

18.94 

70.01 

20.83 

21.97 

17.82 

21 

!)8 

Hop  vine 

—  12  6 

—  16  83 

+  9  68 

26  51 

75  83 

26  92 

5  94 

35 

00 

Hop  vine+20  per  cent  glucose  

+24.9 

+21  54 

+40  74 

19  20 

68  14 

21  70 

25  00 

20  28 

18 

72 

Whitewood  

-  4.9 

-  9.68 

+15.40 

25.08 

71.88 

26.87 

9.45 

4.06 

00 

Whitewood+20  per  cent  ^lucose 

+31  1 

+27  26 

+45  32 

18  06 

64  99 

21  40 

27  80 

23  25 

U 

^"i 

Basswood  

-     .3 

-  1.32 

+23.21 

24.53 

70.60 

26.75 

14.24 

8.40 

00 

Basswood  +20  per  cent  glucose 

+  3  48 

+33  94 

+51  57 

17  63 

63  97 

21  22 

31  64 

26  72 

80 

53 

White  oak  

+11.0 

+  5  17 

+28  60 

23  43 

70  44 

25  61 

17  56 

11  23 

4 

08 

White  oak+20  per  cent  glucose  

+43.8 

+39.14 

+55.88 

16.74 

63.84 

20.20 

34.28 

29.35 

24 

.35 

1  "  Chemical  Analysis  and  Composition  of  American  Honeys,"  Bui.  110,  U.  S.  Bur.  of  Chem.,  p.  61. 

Dextrorotation  of  Inverted  Molasses  at  87°  C.  —  The  observa- 
tions made  upon  the  dextrorotation  of  inverted  honey  at  87°  C.  also 
pertain  to  sugar-cane  molasses  and  sirups,  but  to  a  much  less  degree. 
Eighteen  samples  of  Louisiana  sugar-cane  molasses,  of  known  purity, 
examined  by  Bryan,f  gave  an  average  direct  polarization  at  20°  C.  of 
+  40.6°  V.,  an  average  invert  polarization  at  20°  C.  of  — 17.8°  V.  and  an 
average  invert  polarization  at  87°  C.  of  +  2.53,  the  range  of  the  latter 
being  from  0.0  to  +  4.18,  or  an  equivalent  of  0  to  2.5  per  cent  commer- 
cial glucose. 

DETERMINATION   OF   FRUCTOSE   BY  POLARIZATION   AT  LOW   AND 
HIGH  TEMPERATURES 

Method  of  Wiley. —  A  second  illustration  of  the  methods  of  high- 
temperature  polarization  is  afforded  by  Wiley's  t  method  for  estimating 
fructose.  In  his  description  of  this  method  Wiley  shows  that  1  gm.  of 
fructose  in  100  c.c.  of  solution  gives  a  variation  of  0.0357°  V.  for  each 
I  C.  difference  in  temperature.  The  grams  of  fructose  present  in 
100  c.c.  of  any  solution  can  be  calculated,  therefore,  from  the  polariza- 

t  Bull.  122,  U.  S.  Bur.  of  Chem,  p.  182. 

t  Wiley's  "Agricultural  Analysis"  (1897),  3,  267. 


SPECIAL  METHODS  OF  SACCHARIMETRY 


297 


tions  made  at  two  widely  separated  temperatures  by  means  of  the 
formula. 

F=       P'~P 

0.0357  (Z'-O' 

in  which    F  =  grams  of  fructose  in  100  c.c.  of  solution. 

P'  =  Ventzke  polarization  at  high  temperature  t'. 
P   =  Ventzke  polarization  at  low  temperature  t. 

The  factor  0.0357  employed  by  Wiley  is  confirmed  by  the  observa- 
tions of  other  investigators  as  shown  in  Table  LVII. 

TABLE  LVII. 
Showing  Change  of  Polarization  of  Fructose  for  1°  C.  Change  of  Temperature 


A 

B 

C 

Observer. 

Change  in  [a}D 
of  fructose  per 
1°C. 

Change  in  rotation 
for  a  fructose  solu- 
tion reading  100°V. 
per  1°  C. 
100  A 

Change  in  rotation 
for  1  gram  fructose 
in  100  c.c.  per  1°  C. 
B 

92.5 

18.692 

Dubrunfaut*  .  . 

0  62 

0  6702 

0  03586 

Honig  and  Jesserf  .  .  . 

0  68 

0  7351 

0  03933 

Jungfleisch  and  Grimberti 

0  56 

0  6054 

0  03239 

Gubbe§  

0  63 

0  6811 

0  03644 

Tuchschmid  ||  

0  64 

0  6919 

0  03702 

Average  

0  626 

0  6767 

0  03621 

The  average  value  0.0362  is  practically  identical  with  that  of  Wiley. 

Another  method  of  determining  the  variation  in  the  Ventzke 
polarization  of  fructose  for  changes  in  temperature  is  by  means  of 
Gubbe's  equations  (page  288).  Since  the  specific  rotation  of  glucose  is 
not  affected  by  changes  in  temperature,  the  results  of  Table  LIII  are 
converted  into  terms  of  fructose  by  dividing  the  values  of  columns  A 
and  C,  and  by  multiplying  those  of  column  E,  by  two.  The  variation 
in  polarization  of  1  gm.  of  fructose  in  100  c.c.  for  1°  C.  change  in  tem- 
perature, as  thus  determined,  is  0.0360°  V.,  which  value  is  constant  for 
all  concentrations.  This  quantity,  which  is  also  the  average  of  Wiley's 
figure  and  that  of  Table  LVII,  may  be  accepted  as  the  most  probable 
value. 

*  Compt.  rend.,  42,  901. 

t  Z.  Ver.  Deut.  Zuckerind.,  (1888),  1028. 

t  Compt.  rend.,  107,  390. 

§  Z.  Ver.  Deut.  Zuckerind.,  34,  1345  ;  calculated  from  results  for  invert  sugar. 

II  J.  prakt.  Chem.  [2],  2,  235;  calculated  from  results  for  invert  sugar. 


298  SUGAR  ANALYSIS 

If  26  gms.  of  product  are  made  up  to  100  c.c.  and  polarized  (P)  at  a 
low  temperature  t,  and  a  second  26  gms.  are  made  up  to  100  c.c.  and 
polarized  (P')  at  a  high  temperature  t',  then  the  percentage  of  fructose 
F  is  determined  by  the  equation 

IQOCP'-P)       _100(P/-P) 
"  26  X  0.036  (tf  -t)=  0.936  («'  -  t)  ' 

Example.  —  26  gms.  of  honey  made  up  to  100  c.c.  and  polarized  at  20°  C. 
gave  a  reading  of  —  14.8°  V.  26  gms.  of  the  same  honey  made  up  to  100  c.c. 
and  polarized  at  87°  C.  gave  a  reading  of  -f-  10.50°  V.  Required  the  percent- 
age of  fructose. 


In  making  polarizations  at  high  temperatures  it  is  desirable  to  make 
the  readings  as  soon  as  the  solution  in  the  tube  has  reached  tempera- 
ture equilibrium,  as  indicated  by  the  thermometer  placed  in  the  solution 
and  by  the  disappearance  of  striations  from  the  field.  After  noting  the 
polarization  the  temperature  is  again  taken  and  the  average  thermom- 
eter reading  used  in  the  calculation.  Prolonged  heating  at  high  tem- 
peratures causes  a  destruction  of  fructose.  A  difficulty  is  sometimes 
experienced  in  obtaining  a  clear  unobscured  field  of  vision  when  using 
the  hot-water  polariscope  tube.  Too  slow  a  circulation  of  hot  water 
through  the  jacket  of  the  tube,  with  production  of  currents  of  unequally 
heated  solution,  is  the  usual  cause  of  the  trouble.  The  hot  water  should 
be  several  degrees  above  the  desired  temperature  and  the  circulation 
must  be  rapid  enough  to  prevent  loss  of  heat  by  radiation. 

Limitations  of  Methods  of  High-temperature  Polarization.  —  The 
method  of  determining  invert  sugar  or  fructose  by  polarization  at 
widely-separated  temperatures,  while  giving  good  results  upon  dilute 
solutions  of  the  pure  sugars,  gives  only  an  approximation  in  case  of 
many  sugar  mixtures.  The  method  is  strictly  applicable  only  when  the 
specific  rotations  of  the  accompanying  sugars  are  unaffected  by  changes 
in  temperature;  in  all  other  cases  there  will  be  a  certain  error  in  the 
determination  depending  upon  the  temperature  coefficient  and  the  per- 
centage of  other  sugars  present.  While  no  other  sugars  are  affected  to 
the  same  extent  as  fructose,  yet  it  must  be  remembered  that  1.5  gms. 
arabinose,  or  3.0  gms.  galactose,  or  7.0  gms.  maltose,  or  9.0  gms.  lactose, 
or  50  gms.  sucrose  produce  approximately  the  same  alteration  in  the 
Ventzke  reading  with  1°  C.  variation  in  temperature  as  1  gm.  of  fructose, 
or  2  gms.  of  invert  sugar. 

But  notwithstanding  this  limitation  the  method  of  high-temperaturo 
polarization  has  a  distinctive  value,  and,  when  employed  with  due 


SPECIAL  METHODS  OF  SACCHARIMETRY  299 

caution,  will  be  found  of  great  service  in  many  problems  of  analysis 
and  research. 

DETERMINATION  OF  SUGARS  BY  POLARIZATION  BEFORE  AND  AFTER 

FERMENTATION 

By  employing  pure  cultures  of  specially  selected  organisms,  it  is 
sometimes  possible  to  ferment  one  or  more  sugars  of  a  given  mixture, 
and  from  the  variation  in  polarization  thus  produced  to  calculate  the 
percentage  of  one  or  more  of  the  members  present. 

Action  of  Pure  Yeast  Cultures  upon  Different  Sugars.  —  The 
fermentative  action  of  various  yeasts  upon  different  sugars  has  been 
studied  by  Tollens  and  Stone,*  Hansen,f  Fischer  and  Thierf elder, J  and 
many  others.  The  results  of  their  experiments  show  a  pronounced 
selective  action  on  the  part  of  different  yeasts.  While  pure  cultures  of 
such  well-known  yeasts,  as  Saccharomyces  cerevisice,  or  Saccharomyces 
Pastorianus,  ferment  completely  d-glucose,  d-fructose,  d-mannose, 
d-galactose,  sucrose,  and  maltose,  these  cultures  are  without  action 
upon  1-xylose,  1-arabinose,  rhamnose,  sorbose  and  lactose.  A  "  milk- 
sugar  yeast,"  employed  by  Fischer  and  Thierf  elder,  fermented  lactose 
and  sucrose  completely  but  did  not  attack  maltose.  Saccharomyces 
apiculatus  ferments  d-glucose,  d-mannose  and  d-fructose  but  not 
galactose,  sucrose,  maltose  or  lactose.  (See  also  Table  CII,  page  714.) 

Method  of  Fermentation.  —  In  carrying  out  experiments  for  the 
separation  of  sugars  by  fermentation  it  is  very  essential  that  the  culture 
of  particular  yeast  be  pure.  The  presence  of  foreign  yeasts,  moulds  or 
bacteria  may  produce  changes  in  sugars,  which  a  pure  culture  would 
leave  unattacked.  The  solution  to  be  fermented  should  be  sterilized 
before  inoculating. 

The  most  favorable  conditions  for  the  action  of  the  yeast  are  obtained 
with  a  solution  containing  about  10  per  cent  sugar  and  kept  at  a  tem- 
perature of  about  30°  C.  It  is  also  necessary,  in  order  to  secure  a 
rapid  and  complete  fermentation,  to  have  a  suitable  supply  of  nutritive 
matter  present  for  the  growth  and  sustenance  of  the  yeast.  A  food 
supply  for  yeast  in  fermentation  experiments  is  generally  furnished  by 
means  of  a  nutritive  salt  solution  or  by  means  of  yeast  extract. 

Hayduck's  Nutritive  Salt  Solution.  —  Dissolve  25  gms.  potassium 
phosphate,  8  gms.  crystallized  magnesium  sulphate  and  20  gms.  aspara- 
gine  in  1000  c.c.  of  spring  water. 

One  cubic  centimeter  of  the  above  solution  to  each  25  c.c.  of  liquid 
to  be  fermented  insures  a  favorable  development  of  yeast. 

*  Ann.,  249,  257.         t  Centralblatt,  88,  1208,  1390.        J  Ber.,  27,  2031. 


300  SUGAR  ANALYSIS 

Yeast  Extract.  —  Wash  100  gms.  of  pure  yeast  (starch-free)  re- 
peatedly with  cold  water  and  repress.  The  residue  of  yeast  is  then 
heated  to  boiling  for  one-fourth  hour  with  500  c.c.  of  water;  the 
liquid  is  then  filtered  through  a  folded  filter,  the  filtrate,  in  case  of 
turbidity,  being  returned  to  the  filter  until  the  extract  runs  through  per- 
fectly clear.  The  extract  is  then  made  faintly  acid  with 
citric  acid,  when  it  is  sterilized  and  preserved  in  flasks  closed 
by  cotton  wadding. 

The  liquid  to  be  fermented  is  diluted  with  an  equal  volume 
of  the  above  extract. 

Fermentation  experiments  are  best  carried  out  in  flasks 
closed  with  a  washing  tube  for  the  escape  of  carbon  dioxide. 
The  apparatus  shown  in  Fig.  148  answers  very  well  for  the 
purpose.  The  fermentation  is  continued  until  bubbles  of  gas 
cease  to  pass  through  the  water  in  the  washing  tube,  when 
the  process  is  considered  to  be  finished.  The  washing  tube 
is  then  removed,  the  solution  heated  to  expel  all  carbon 
dioxide,  and,  after  cooling,  clarified,  and  the  volume  com- 


. 

tion  flask.         The  polarization  of  the  filtered  solution  is  calculated 

to  unfermented  sugar,  and  the  difference  in  polarization, 
before  and  after  fermentation,  calculated  to  fermented  sugar.  The 
application  of  the  method  is  best  understood  from  a  special  case. 

Example.  —  By  hydrolyzing  a  sample  of  sawdust  with  sulphuric  acid, 
treating  the  resultant  liquid  with  an  excess  of  powdered  calcium  carbonate, 
filtering  and  evaporating,  a  sirup  resulted  which  contained  the  two  sugars, 
glucose  and  xylose. 

50  gms.  of  the  sirup,  made  up  to  100  c.c.,  gave  a  polarization  of  +  43.5°  V. 
in  a  200-mm.  tube. 

50  gms.  of  the  sirup  were  then  diluted  in  a  200-c.c.  flask  with  100  c.c.  of 
water  and  5  c.c.  of  nutritive  salt  solution.  After  sterilizing,  cooling  and  in- 
oculating with  pure-yeast  culture,  the  flask  was  closed  with  a  washing  tube  and 
fermented  for  5  days  in  an  incubator  at  30°  C.  The  evolution  of  gas  having 
ceased,  the  solution  was  heated  to  expel  C02,  cooled,  clarified  with  a  little 
normal  acetate  of  lead  solution,  made  up  to  200  c.c.,  and  filtered.  The  polariza- 
tion of  the  filtrate  in  a  400-mm.  tube  was  +  5.2°  V.  Required  the  percentages 
of  glucose  and  xylose  in  the  sirup. 

The  loss  in  polarization  by  fermenting  was  43.5  -  5.2  =  38.3°  V.  Since 
1°  V.  =  0.3225  gms.  glucose  in  100  c.c.  then  the  grams  of  glucose  fermented 
were  38.3  X  0.3225  =  12.35  gms.  or  24.7  per  cent  glucose  (unconnected)  in 
the  sirup. 

Since   1°V.=  0.91   gms.  xylose    in   100  c.c.,    then,   calling  the  residual 


SPECIAL  METHODS  OF  SACCHARIMETRY  301 

polarization  of  +  5.2  as  due  entirely  to  xylose,  5.2  X  0.91  =  4.73  gms.  or  9.46 
per  cent  xylose  (uncorrected)  in  the  sirup. 

Corrections  for  concentration  are  made  as  indicated  on  page  198. 

Determination  of  Dextrin  in  Fruit  Products.  —  The  fermentation 
method  is  sometimes  employed  for  the  determination  of  dextrin  in 
jams,  jellies  and  other  products,  which  might  be  adulterated  with  com- 
mercial glucose.  The  provisional  method  of  the  Association  of  Official 
Agricultural  Chemists  is  as  follows  :  * 

"  Dissolve  10  gms.  of  the  sample  in  a  100-c.c.  flask,  add  20  mgs.  of 
potassium  fluoride,  and  then  about  one-quarter  of  a  cake  of  compressed 
yeast.  Allow  the  fermentation  to  proceed  below  25°  C.  for  two  or 
three  hours  to  prevent  excessive  foaming,  and  then  place  in  an  incuba- 
tor at  a  temperature  of  from  27°  to  30°  C.  for  five  days.  At  the  end 
of  that  time,  clarify  with  lead  subacetate  and  alumina  cream,  make  up 
to  100  c.c.  and  polarize  in  a  200-mm.  tube.  A  pure  fruit  jelly  will 
show  a  rotation  of  not  more  than  a  few  tenths  of  a  degree  either  to  the 
right  or  to  the  left.  If  a  polariscope  having  the  Ventzke  scale  be  used 
and  a  10  per  cent  solution  be  polarized  in  a  200-mm.  tube,  the  number 
of  degrees  read  on  the  sugar  scale  of  the  instrument  multiplied  by 
0.875  will  give  the  percentage  of  dextrin,  or  the  following  formula  may 
be  used: 

Percentage  of  dextrin  =  198  xLXW 

in  which 

C  =  degrees  of  circular  rotation. 
L  =  length  of  tube  in  decimeters. 
W  =  weight  of  sample  in  1  cubic  centimeter." 

The  factor  0.875  is  found  as  follows:  Calling  +  198  the  [a]D  of  dex- 
trin, then  the  grams  of  dextrin  (D)  in  100  c.c.  of  solution  are  found  from 
the  Ventzke  reading  (7)  in  a  200-mm.  tube  by  the  formula: 


If  10  gms.  of  product  are  made  up  to  100  c.c.  then  the  percentage  of 

087^  V 
dextrin  in  the  sample  =      ^      X  100  =  0.875  V. 

The  use  of  potassium  fluoride  in  the  method  just  described  is  to 
prevent  the  development  of  bacteria.  Its  employment  is  not  necessary 
when  pure-yeast  cultures  are  used  and  the  solution  to  be  fermented  has 
been  previously  sterilized. 

*  Bull.,  107  (revised)  U.  S.  Bur.  of  Chem.,  p.  80. 


302  SUGAR  ANALYSIS 

The  work  of  Brown  and  Morris  *  shows  that  the  dextrins  and  malto- 
dextrins  of  starch  conversion  are  not  fermented  by  Saccharomyces  cerevi- 
sice;  their  experiments  prove,  however,  that  other  yeasts,  such  as  Sac- 
charomyces elUpsoideus  and  Saccharomyces  Pastorianus,  strongly  ferment 
these  dextrins.  In  carrying  out  the  fermentation  method  for  the  estima- 
tion of  dextrin,  it  is  best  to  work  with  a  pure  culture  of  Saccharomyces 
cerevisice. 

Limitations  of  Fermentation  Methods.  —  The  methods  of  estimat- 
ing sugars  by  difference  in  polarization,  before  and  after  fermentation, 
give  at  best  only  a  fair  approximation.  Several  dangers  attend  the 
employment  of  the  method,  chief  among  which  are  the  attack  of  sugars, 
or  carbohydrates,  supposed  to  be  unfermented,  and  the  incomplete  de- 
struction of  sugars  supposed  to  be  completely  fermented.  Careful 
attention  to  the  details  of  pure  culture,  sterilization  and  nutrition  will, 
however,  largely  eliminate  these  dangers.  The  formation  of  optically 
active  fermentation  by-products  may  introduce  a  disturbing  factor 
under  certain  irregular  conditions,  but  with  a  normal  alcoholic  fermen- 
tation the  error  from  this  cause  is  insignificant.  The  optical  activity 
of  the  nutritive  solution  used  in  the  experiments  should  of  course  be 
determined,  and  its  value,  if  significant,  should  be  considered  in  the 
calculation. 

The  length  of  time  required  for  completing  a  determination  has 
been  a  strong  objection  against  the  use  of  fermentation  methods  in 
general  sugar  analysis.  The  more  rapid,  and  generally  more  accurate, 
methods  based  upon  polarizing  and  copper-reducing  power  have,  for 
this  reason,  been  given  the  preference. 

POLARISCOPIC  METHODS  BASED  ON  DESTROYING  THE  OPTICAL 
ACTIVITY   OF  REDUCING  SUGARS 

The  determination  of  sugars  by  methods  of  this  class  is  based  upon 
the  fact  that  solutions  of  reducing  sugars,  when  heated  with  alkalies  or 
alkalies  and  hydrogen  peroxide,  or  with  alkalies  and  metallic  oxides  or 
salts,  lose  more  or  less  completely  their  optical  activity.  These  methods 
have  been  applied  not  so  much  to  the  determination  of  reducing 
sugars  themselves,  as  to  the  determination  of  sucrose,  dextrin  and 
other  non-reducing  carbohydrates  in  presence  of  reducing  sugars. 

DESTRUCTION  OF  OPTICAL  ACTIVITY  OF  REDUCING  SUGARS  BY  MEANS 

OF  ALKALIES 

Method  of  Dubrunfaut.  —  The  first  efforts  to  establish  a  quan- 
titative method  in  this  direction  were  made  by  Dubrunfaut  f  in  1850. 
*  J.  Chem.  Soc.  Trans.,  47,  527.  f  Compt.  rend.,  32,  439. 


SPECIAL  METHODS  OF  SACCHARIMETRY 


303 


Later  investigators  found,  however,  that  the  end-products  in  Dubrun- 
faut's  method,  obtained  by  the  action  of  different  alkalies  upon  reducing 
sugars,  were  not  completely  inactive,  so  that  the  polariscopic  reading 
always  required  a  certain  correction.  Efforts  to  establish  a  constant 
correction  factor  for  modifications  of  Dubrunfaut's  method  have  been 
made  by  Pellet,*  Jesser,|  Koydl,}  Bardach  and  Silberstein§  and  others, 
but  the  results,  on  account  of  the  variability  in  conditions,  have  not  been 
wholly  satisfactory. 

Method  of  Lobry  de  Bruyn  and  van  Ekenstein.  —  The  rate  of  de- 
struction of  optical  activity  upon  heating  solutions  of  reducing  sugars 
with  dilute  alkalies  is  illustrated  by  the  following  experiment  taken 
from  the  work  of  Lobry  de  Bruyn  and  van  Ekenstein;  II  20  gms.  of 
anhydrous  glucose  were  heated  with  10  c.c.  of  normal  potassium  hy- 
droxide in  500  c.c.  of  solution  at  63°  C.  The  following  decrease  in 
rotation  was  noted: 


Time. 

Angular  rotation. 

Specific  rotation. 

Time. 

Angular  rotation. 

Specific  rotation. 

Minutes. 
10 

+5°  30' 

[«]/>  =  +  48 

Minutes. 
50 

1°  50' 

20 

4°  20' 

85 

0°  43' 

30 

3°  10' 

135 

±0°  10' 

[a]n  =  -t  1 

40 

2°  20' 

At  the  end  of  the  experiment  the  solution  had  not  darkened  per- 
ceptibly and  the  original  reducing  power  had  only  slightly  diminished. 

Explanation  of  Optical  Inactivity  Produced  by  Alkalies.  —  The  ex- 
planation of  the  change  of  an  optically  active  into  an  optically  inactive 
solution  of  reducing  sugar  by  action  of  alkalies  was  first  given  by  Lo- 
bry de  Bruyn  and  van  Ekenstein.  In  the  experiment  just  quoted  the  op- 
tical inactivity  of  the  solution  is  due  not  to  a  destruction  of  glucose,  but 
to  its  partial  conversion  into  mannose  and  fructose,  the  combined  rota- 
tions of  the  mixture  of  sugars  producing  optical  neutrality.  In  one  ex- 
periment the  authorities,  just  named,  noted  after  heating  with  alkali  a 
loss  of  18  per  cent  in  reducing  power;  the  residue  was  estimated  to  con- 
sist of  49  per  cent  unchanged  glucose,  5  per  cent  mannose  and  28  per 
cent  fructose;  the  calculated  rotation  of  such  a  mixture  would  in  fact 
be  very  nearly  zero. 

*  Bull,  assoc.  chem.  sucr.  dist.,  8,  623. 

t  Oest.  Ung.  Z.  Zuckerind.,  27,  35. 

t  Ibid.,  29,  381. 

§  Z.  Unters.  Nahr.  Genussm.,  21,  540. 

||  Rec.  Trav.  Pays-Bas,  14,  156,  203;  16,  262. 


304 


SUGAR  ANALYSIS 


Method  of  Jolles.  —  Recent  experiments  by  Jolles  *  upon  arabinose, 
glucose,  fructose,  invert  sugar,  lactose  and  maltose  show  that  these 
sugars  in  1  to  2  per  cent  solution  are  rendered  optically  inactive  by  heat- 
ing for  24  hours  at  37°  C.  with  T£o  normal  sodium  hydroxide  while 
sucrose  is  completely  unchanged  by  this  treatment.  Stronger  solutions 
of  reducing  sugars  than  2  per  cent  show  usually  a  residual  activity  after 
the  alkaline  treatment;  it  is  necessary,  therefore,  in  Jolles's  method  to 
dilute  solutions  to  2  per  cent  reducing  sugar  before  making  the  deter- 
mination. With  substances  containing  much  reducing  sugar  such  dilu- 
tion necessarily  involves  a  considerable  multiplication  of  any  errors  in 
the  polariscope  reading. 

Method  of  Bardach  and  Silberstein.  —  Bardach  and  Silbersteinj 
have  modified  Jolles's  method  so  as  to  include  solutions  of  reducing 
sugar  up  to  5  per  cent  concentration.  Their  method  of  procedure  is  as 
follows : 

Take  45  c.c.  of  the  neutralized  sugar  solution  and  make  up  to  50  c.c. 
with  normal  sodium  hydroxide,  thus  making  the  solution  TV  normal 
alkaline.  The  solution  is  then  polarized  and  a  measured  volume  placed 
in  a  small  beaker  (8  to  10  cm.  high  and  5  cm.  diameter)  and  kept 
at  36°  to  39°  C.  for  20  hours  by  means  of  a  thermostat,  the  beaker 
remaining  uncovered.  The  solution  is  then  cooled,  made  up  to  the 
original  volume  and  repolarized.  The  final  polarization  is  corrected  for 
residual  activity  by  means  of  an  empirical  factor,  which  in  case  of 
glucose  was  found  to  be  as  follows: 

TABLE  LVIII 
Showing  Change  in  Polarization  of  Glucose  upon  Warming  ivith  Dilute  Alkali 


Approximate 

Polarization  value. 

Approximate 

Polarization  value. 

glucose  in 
solution. 

Before 
treatment. 

After  treat- 
ment. 

glucose  in 
solution. 

Before  treat- 
ment. 

After  treat- 
ment. 

0.5 

+0.51 

-0.09 

2.5 

+2.54 

-0.36 

1 

+  1.02 

-0.19 

3 

+3.05 

-0.26 

1 

+  1.02 

-0.15 

3 

+3.06 

-0.27 

1.5 

+  1.53 

-0.26 

4 

+4.10 

-0.32 

2 

+2.04 

-0.25 

4 

+4.07 

-0.25 

2 

+2.05 

-0.26 

5 

+5.12 

-0.21 

The  loss  in  polarization,  after  treatment  with  alkali  under  the  pre- 
scribed conditions,  must  be  diminished,  therefore,  by  about  0.25  to 
give  the  correct  polarization  value  of  glucose.     So  also  the  residual 
*  Z.  Unters.  Nahr.  Genussm.,  20,  631.  t  Loc.cit. 


SPECIAL  METHODS  OF  SACCHARIMETRY  305 

polarization  must  be  increased  by  0.25  to  give  the  correct  polarization 
equivalent  of  the  residual  sucrose,  or  other  non-reducing  carbohydrate 
present. 

It  is  evident  that  the  chemist  in  employing  such  methods  as  the 
above  must  establish  his  own  correction  factor  for  the  particular  re- 
ducing sugar  with  which  he  is  working.  The  lack  of  absolute  uni- 
formity of  conditions  in  the  analysis  of  impure  sugar  products,  leaves 
the  general  reliability  of  such  correction  factors  more  or  less  in  doubt. 

DESTRUCTION  OF  OPTICAL  ACTIVITY  OF  REDUCING  SUGARS  BY  MEANS  OF 
ALKALI   AND   HYDROGEN   PEROXIDE 

Other  chemicals  have  been  used  in  connection  with  alkalies  to  pro- 
mote the  destruction  of  reducing  sugars.  Lemeland,*  for  example,  has 
devised  a  method  for  destroying  the  optical  activity  of  reducing  sugars 
in  presence  of  sucrose  by  means  of  alkali,  manganese  dioxide  and  hy- 
drogen peroxide. 

Method  of  Pellet  and  Lemeland.  —  Pellet  and  Lemeland  f  have 
recently  proposed  a  method  for  the  analysis  of  sugar-cane  molasses, 
which  is  based  upon  destroying  the  optical  activity  of  reducing  sugars 
by  means  of  alkali  and  hydrogen  peroxide.  The  details  of  the  method 
are  as  follows: 

"  Make  a  solution  of  the  cane  molasses  that  will  contain  at  most 
5  per  cent  of  reducing  sugars.  Measure  50  c.c.  of  this  solution  into  a 
300-c.c.  flask,  add  7.5  c.c.  of  sodium  hydroxide  (36°  Be.),  then  75  c.c.  of 
hydrogen  peroxide  (12  vols.),  and  60  c.c.  of  water.  Mix  and  place  the 
flask  in  a  boiling  water-bath  for  20  minutes,  cool,  neutralize  the  re- 
maining alkalinity  fairly  exactly  with  acetic  acid,  and  defecate  with 
basic  lead-acetate  solution  (36°  Be.),  the  necessary  amount  of  which 
will  be  found  to  vary  from  15  to  40  c.c.,  according  to  the  weight  of  the 
material  taken,  the  amount  of  reducing  sugars  destroyed  and  the  im- 
purities initially  contained  in  the  liquid.  Complete  the  volume  to 
300-c.c.,  mix  well  and  filter.  First  polarize  directly  in  the  200-mm.  or 
400-mm.  tube.  Then  50  c.c.  of  the  filtered  liquid  may  be  taken,  1  c.c. 
of  glacial  acetic  acid  added  to  it,  the  volume  completed  to  55  c.c.,  and 
after  mixing  a  second  polarization  made,  account  being  taken  of  the 
dilution.  This  is  done  because  the  second  polarization  is  often  a  little 
different  from  the  first,  in  which  the  liquid  is  alkaline.  If  a  difference 
is  observed,  then  the  second,  or  acid  polarization,  should  be  used.  The 
percentage  of  sucrose  is  calculated  on  the  solution,  and  then  on  the 

sample." 

*  J.  Pharm.  Chim.,  2,  298. 
t  Int.  Sugar  J.,  13,  616. 


306  SUGAR  ANALYSIS 

The  authors  state  that  the  results  by  this  method  agree  very  closely 
with  those  obtained  by  the  method  of  inversion,  when  special  pre- 
cautions are  observed  to  insure  the  utmost  accuracy. 

DESTRUCTION  OF  OPTICAL  ACTIVITY  OF  REDUCING  SUGARS  BY  MEANS  OF 
ALKALI    AND    MERCURIC    CYANIDE 

Method  of  Wiley.  —  The  destruction  of  the  optical  activity  of  re- 
ducing sugars  by  means  of  Knapp's  alkali-mercuric-cyanide  solution 
was  first  employed  by  Wiley*  in  the  determination  of  dextrin  in  com- 
mercial glucose.  The  reagent  is  prepared  as  follows: 

Alkali-mercuric-cyanide  Solution.  —  Dissolve  120  gms.  sodium  hy- 
droxide and  120  gms.  mercuric  cyanide  in  separate  portions  of  water; 
the  two  solutions  are  then  mixed  and  made  up  to  1000  c.c.  Any 
precipitate  which  forms  is  removed  by  filtration. 

In  making  the  determination  10  gms.  of  the  commercial  glucose  are 
dissolved  in  water  and  made  up  to  100  c.c.;  10  c.c.  of  this  solution  are 
transferred  to  a  50-c.c.  graduated  flask,  20  to  25  c.c.  of  the  alkali- 
mercuric-cyanide  solution  are  added,  and  the  mixture  boiled  3  minutes 
under  a  well-ventilated  hood.  The  solution  is  cooled,  and  neutralized 
with  concentrated  hydrochloric  acid,  the  latter  being  added  until  the 
brown  color  of  the  liquid  is  just  discharged.  The  solution  is  then  clari- 
fied, made  up  to  volume,  filtered  and  polarized.  The  optical  activity 
of  the  maltose  and  dextrose  being  destroyed,  the  residual  polarization 
is  that  of  the  dextrin. 

In  Wiley's  experiments,  the  specific  rotation  of  the  dextrin  was 
taken  as  +  193.  Adopting  this  figure,  and  taking  the  reading  of  a 
Ventzke-scale  saccharimeter,  the  grams  of  dextrin  in  100  c.c.  of  solu- 
tion =  66-5*°.26  y0  =  Q  Q896  yo  Since  the  golution  p0iarized  con- 

1«7O 

tained  1  gm.  of  original  sample  in  50  c.c.  (or  2  gms.  in  100  c.c.),  then 

0  0896  V° 
— 2 X  100  =  per  cent  dextrin  in  the  commercial  glucose. 

In  concluding  this  chapter  upon  special  methods  of  saccharimetry 
the  chemist  is  advised,  as  in  case  of  the  methods  of  inversion,  to  test  the 
reliability  of  any  untried  process  by  means  of  check  analyses  upon  mix- 
tures of  known  sugars.  It  is  only  in  this  way  that  an  idea  can  be 
formed  of  the  errors  which  are  due  to  defect  of  method  or  to  personal 
equation. 

*  Wiley's  "  Agricultural  Analysis"  (1897),  3,  290. 


CHAPTER  XII 


MISCELLANEOUS  PHYSICAL  METHODS  AS  APPLIED  TO  THE  EXAMINA- 
TION  OF   SUGARS 

IN  addition  to  specific  gravity,  refractive  index  and  specific  rota- 
tion there  are  a  number  of  other  physical  constants,  which,  though  of 
lesser  analytical  importance,  have  nevertheless  a  considerable  value  in 
certain  investigations  of  sugars  and  sugar  solutions.  Among  the  con- 
stants of  this  class  may  be  mentioned  viscosity,  heat  of  combustion, 
osmotic  pressure,  rate  of  diffusion,  surface  tension,  heat  of  solution, 
thermal  conductivity,  specific  heat  and  magnetic  rotation.  It  is  be- 
yond the  scope  of  the  present  volume  to  discuss  the  methods  of  making 
each  one  of  these  physical  measurements.  Viscosity,  heat  of  combus- 
tion and  the  constants  connected  with  osmotic  pressure  have  acquired, 
however,  a  certain  importance  in  general  laboratory  practice  and  the 
present  chapter  will  discuss  their  use  in  the  investigation  of  sugars. 

VISCOSITY  OF  SUGAR  SOLUTIONS 

The  determination  of  viscosity  is  a  measurement  which  is  frequently 
applied  to  solutions  of  sugars  and  other  carbohydrates  for 
special  purposes  of  technology,  analysis  or  research.  The 
viscosity  of  a  liquid  as  ordinarily  determined  is  an  arbitrary 
constant  and  is  usually  taken  as  the  ratio  between  times  of  flow, 
through  a  narrow  tubular  opening,  of  the  same  volumes  of 
water  and  liquid,  all  conditions  of  temperature,  etc.,  being  the 
same. 

Viscosity  Pipette.  —  The  simplest  example  of  this  method 
of  measurement  is  afforded  by  the  viscosity  pipette.     (Fig.  149.) 

The  pipette  is  first  filled  with  water  so  that  its  meniscus 
coincides  with  the  upper  mark  A;    after  holding  in  a  perfectly 
upright  position  the  water  is  released  and  the  interval  of  time 
noted  for  the  passage  of  the  meniscus  from  A  to  the  lower 
mark  B.     The  process  is  repeated  a  number  of  times  and  theFls-149-~ 
average  result  taken  as  the  water  constant  of  the  pipette  at    . 
the    temperature   of  the   experiment.     The   pipette   is    dried 
and  the  process  repeated  in  exactly  the  same  manner  with  a  sugar 
solution.     If  the  average  time  of  flow  at  20°  C.  for  water  be  20.2 

307 


308 


SUGAR  ANALYSIS 


seconds  and  that  of  a  sugar  solution  at  20°  C.  105.1  seconds,  then 
105.1 


20.2 


=  5.2,  the  relative  viscosity  of  the  sugar  solution  at  20   C,  as 


compared  with  water  of  the  same  temperature. 

Engler's  Viscosimeter.  —  The  apparatus  of  Engler*  (Fig.  150)  is 
used  very  generally  for  determining  viscosity.  The  instrument  con- 
sists of  a  bath  B,  which  is  filled  with  water  or  oil  of  the  desired  tempera- 
ture. The  container  A  is  gold  plated,  the  conical  bottom  terminating 


Fig.  150. — Engler's  viscosimeter. 

in  a  narrow  tube  a,  3  mm.  wide  and  20  mm.  long,  which  serves  as  the 
outlet;  the  latter  is  closed  by  the  valve  rod  b.  The  container  holds  at 
the  marks  c  exactly  240  c.c.  of  solution.  After  filling  to  c  with  water 
or  solution,  the  cover  A',  holding  a  thermometer  t,  is  placed  in  position 
and  the  temperature  brought  to  the  desired  point.  The  valve  rod  is 
then  withdrawn  and  the  time  noted  for  the  delivery  of  exactly  200  c.c. 
of  liquid  in  the  flask  C.  The  calculation  of  viscosity  is  made  as  pre- 
viously described. 

*  Konig's  "Untersuchung"  (1898),  p.  432. 


MISCELLANEOUS  PHYSICAL  METHODS 


309 


Coefficient  of  Viscosity.  —  While  the  viscosity,  as  calculated  by 
the  above  method,  is  sufficiently  exact  for  many  purposes,  it  is  necessary 
in  comparing  liquids  of  different  densities  to  employ  the  more  exactly 
defined  coefficient  of  viscosity. 

In  Fig.  151  the  volume  V-oi  liquid  which  is  discharged  in  a  time  t 
through  a  given  capillary  tube  A-B  of  the  length  I  and  radius  r  under  a 
pressure  p  is  found  by  the  equation 

T7      TT  X  p  X  r4  X  t 


SpXl 

in  which  p  is  the  coefficient 
interior  friction  of  the  liquid, 
lows  from  the  foregoing  that 

_irprAt 


(1) 

of  the 
It  fol- 


(2) 


JL 


Fig.  151.  —  Showing  principle  of 

viscosimeter. 

When  Vj  r  and  I  are  unchanged,  as 

happens  in  the  use  of  the  same  viscosity  apparatus,  p  under  constant 
pressure  p  becomes 

P  =  Kt,  (3) 

in  which  K  is  a  single  constant  peculiar  to  each  individual  viscosim- 
eter. 

In  the  previous  figure  the  pressure  p,  with  which  a  given  volume  of 
liquid  M-M'  is  discharged  at  the  beginning  of  flow,  is  equal  to  its  density 
d  multiplied  by  the  height  h  of  its  surface  above  the  outlet  B,  and  at  the 
end  of  the  flow  to  its  density  8  multiplied  by  the  height  h'.  In  the  dis- 
charge of  a  constant  volume  V  of  different  liquids,  between  the  marks 
M  and  M' ',  h  and  h'  are  unchanged,  so  that  for  the  mean  pressure  of 
flow,  p  =  C  X  <5,  in  which  C  is  a  constant.  The  coefficient  of  interior 
friction  for  different  liquids  using  the  same  viscosimeter  is  then  repre- 
sented by  the  formula 

P=KXCX8Xt, 

in  which  K  and  C  are  two  constants. 

For  water  (8  =  1),  p  =  K  XC  Xt.  For  any  liquid  of  density  8  and 
time  of  flow  T,  the  viscosity  coefficient  YJ,  or  ratio  between  the  internal 
friction  of  water  and  liquid,  is 

KXCX8Xr  _8r 
KXCXt       "V 

The  viscosity  coefficients  of  liquids  are,  therefore,  always  proportional 
to  the  products  of  their  densities  and  times  of  flow. 


310 


SUGAR  ANALYSIS 


Viscosity  Coefficients  of  Pure  Sucrose  Solutions.  —  The  viscosity 
coefficients  of  pure  sucrose  solutions,  as  determined  by  Orth*  for  differ- 
ent concentrations  and  temperatures,  are  given  in  Table  LIX. 

TABLE  LIX 
Viscosity  Coefficients  of  Pure  Sucrose  Solutions 


Temperatures. 

Grams  sucrose 

in  100  grams 

20°  C. 

30°  C. 

40°  C. 

50°  C. 

60°  C. 

70°  C. 

80°  C. 

90°  C. 

solution. 

60 

6.29 

4.33 

3.22 

2.54 

2.10 

1.81 

1.61 

1.46 

62 

8.57 

5.54 

3.92 

2.98 

2.39 

2.00 

1.74 

1.55 

64 

12.31 

7.41 

4.94 

3.58 

2.76 

2.25 

1.91 

1.67 

66 

18.80 

10.14 

6.47 

4.43 

3.28 

2.58 

2.13 

1.83 

68 

30.82 

15.40 

8.86 

5.70 

4.01 

3.02 

2.42 

2.02 

70 

54.91 

24.42 

12.79 

7.64 

5.06 

3.65 

2.81 

2.28 

72 

107.85 

41.84 

19.65 

10.76 

6.65 

4.53 

3.34 

2.62 

74 

237.49 

78.50 

32.47 

16.05 

9.15 

5.85 

4.09 

3.08 

76 

596.76 

163.74 

64.16 

25.63 

13.30 

7.88 

5.19 

3.72 

It  is  seen  that  at  low  temperatures  the  viscosity  is  much  higher  and 
that  at  certain  concentrations  it  begins  to  undergo  a  most  marked 
change  in  value.  This  relationship  is  made  more  plain  in  the  opposite 
diagram  (Fig.  152)  which  is  taken  from  the  work  of  Orth. 

Attempts  have  been  made  to  express  the  relationship  between  the 
viscosity  and  concentration  of  sugar  solutions  by  means  of  a  general 
equation.  For  dilute  solutions  the  relationship  according  to  Arrhenius  f 
may  be  expressed  by  the  equation 


Or  logeYJ   =  loge  A(x), 

in  which  A  is  a  constant  and  x  the  concentration.  According  to  this 
equation  the  natural  logarithm  of  the  viscosity  coefficient  is  propor- 
tional to  the  concentration. 

But  for  concentrated  sugar  solutions  the  above  relationship  does 
not  hold.  The  law  for  solutions  of  high  sucrose  content,  according  to 
Orth,  is  expressed  by  the  equation: 


°r  loge  (loge  Y))  =  loge  (fog.  A)  + 

in  which  A  and  B  are  constants. 


*  Bull,  assoc.  chim.  sucr.  dist.,  29,  137. 
t  Z.  physik.  Chem.,  1,  285. 


MISCELLANEOUS  PHYSICAL  METHODS 
For  changes  in  temperature  Orth  gives  the  equation 


311 


or  log,  (loge  ij)  =  loge  (log.  A  )  +  log*  B  (x)  +  loge  C  (t)  ; 

in  which  x  and  t  are  the  concentration  and  temperature  of  the  sugar 
solution,  and  A,  B  and  C  constants. 


300 


250 


200 


150 


Temperature 

Fig.  152.  —  Diagram  showing  viscosity  curves  of  four  sugar  solutions 
at  different  temperatures. 


Viscosity  Coefficients  of  Impure  Sucrose  Solutions.  —  From  the 
viscosity  coefficients  of  solutions  of  different  sugar-house  products  Orth 
has  made  a  compilation,  the  results  of  which  are  shown  in  Table  LX. 


312  SUGAR  ANALYSIS 

TABLE  LX 
Viscosity  Coefficients  of  Sucrose  Solutions  of  Different  Purities. 


Tempera- 
ture. 

Purity  (per 
-cent  sucrose  in 
solids). 

Grams  of  solids  in  100  grams  of  solution. 

65 

70 

75 

80 

85 

20° 

40° 
60° 
80° 

100 
90 

80 
70 
60 

100 
90 
80 
70 
60 

100 
90 
80 
70 
60 

100 
90 
80 
70 
60 

15.09 

15.18 
15.31 
15.41 
15.51 

.  5.62 
5.49 
5.35 
5.23 
5.10 

3.00 
2.90 
2.81 
2.72 
2.64 

2.01 
1.95 
1.89 
1.83 

1.78 

54.91 
52.91 
50.99 
49.16 
47.41 

12.79 
12.25 
11.74 
11.24 
10.78 

5.06 
4.86 
4.67 
4.49 
4.33 

2.81 
2.71 
2.63 
2.54 
2.47 

369.67 
324.0 
283.5 
249.9 
221.1 

43.03 
39.91 
36.96 
34.38 
32.03 

10.95 
10.50 
10.05 
9.65 
9.27 

4.59 
4.48 
4.37 
4.27 
4.17 

4450 
3251 
2400 
1808 

196,600 
102,960 
55,360 
80,770 

225.9 
199.4 
175.7 
155.3 

2,892 
2,334 
1,884 
1,538 

33.03 
31.97 
30.87 
29.90 

184.0 
183.2 
183.2 
183.2 

9.55 
9.65 
9.76 
9.84 

30.41 
33.24 
36.62 
40.33 

The  relation  between  viscosity  and  concentration  of  impure  sugar- 
factory  solutions  is  represented  according  to  Orth  by  the  equation 


in  which  t  is  the  temperature  and  K  a  linear  function  of  t,  x  the  percent- 
age of  sucrose  and  n  the  percentage  of  non-sugar,  and  A,  B  and  C 
constants. 

The  viscosity  of  the  non-sugars  of  sugar-house  products  was  cal- 
culated by  Orth  not  to  differ  greatly  from  that  of  pure  sucrose;  it  was 
somewhat  greater  for  the  cold  dilute  and  hot  concentrated  solutions 
and  a  little  less  for  the  other  solutions,  the  average  value  for  solutions 
of  the  same  concentration  being  about  96  per  cent  that  of  sucrose. 

The  above  conclusions  of  Orth  pertain,  however,  only  to  the  ordi- 
nary impurities  of  sugar-house  products,  such  as  reducing  sugars,  salts 
of  mineral  and  organic  acids,  ammo  compounds,  etc.  The  observation 
does  not  hold  for  dextran,  levan  and  other  gums  which  may  occur  in 
abnormal  products  and  which  greatly  increase  the  viscosity  of  sugar 
solutions  with  consequent  disturbance  in  the  work  of  evaporating  and 
boiling. 


MISCELLANEOUS  PHYSICAL  METHODS  313 

Excessive  viscosities  may  also  occur  in  sugar-house  practice  from 
supersaturation  of  sucrose,  the  result  of  careless  sugar  boiling.  The 
successful  sugar  boiler  aims  to  prevent  supersaturation  and  to  keep  the 
viscosity  of  the  pan  contents  as  low  as  possible,  in  order  that  the  maxi- 
mum yield  of  sugar  crystals  may  be  obtained. 

The  determination  of  viscosity  is  of  great  value  in  certain  branches 
of  analytical  work,  as,  for  example,  the  examination  of  commercial  dex- 
trins,  for  which  see  page  508. 

SPECIFIC  HEAT  OF  COMBUSTION 

Units  Employed  in  Calorimetery.  —  The  number  of  calories  or 
heat  units  which  a  substance  gives  off,  when  burned  in  oxygen  under 
specified  conditions,  is  a  constant  which  has  been  extensively  used  in  the 
investigation  of  sugars.  The  determination  has  been  especially  em- 
ployed in  studying  the  calorific  value  of  the  different  carbohydrates 
which  are  used  in  foods. 

The  Small,  or  Gram,  Calorie  (cal.)  is  defined  as  the  quantity  of  heat 
necessary  to  raise  1  gm.  of  water  through  1°  C.  The  quantity  of  heat 
necessary  to  raise  1  gm.  of  water  from  0°  to  1°  C.  is  not,  however,  ex- 
actly the  same  as  that  necessary  to  raise  1  gm.  of  water  from  99°  to 
100°  C.,  so  that  the  measurement  has  been  defined  more  precisely  as  one 
one-hundredth  of  the  heat  required  to  raise  1  gm.  of  water  from  0°  to 
100°  C. 

The  Large,  or  Kilogram,  Calorie  (Cal.)  contains  1000  small  calories, 
and  may  be  defined,  with  the  limitations  previously  noted,  as  the 
quantity  of  heat  necessary  to  raise  1000  gms.  of  water  through  1°  C. 

The  Centuple  Calorie  (K)  is  defined  as  the  quantity  of  heat  necessary 
to  raise  1  gm.  of  water  from  0°  to  100°  C. 

For  ordinary  purposes  the  ratio  of  the  several  units  may  be  ex- 
pressed as: 

1  Cal  =  10  K  =  1000  cal. 

THE    BOMB    CALORIMETER 

The  determination  of  calories  of  combustion  is  made  in  an  atmos- 
phere of  compressed  oxygen  by  means  of  a  bomb  calorimeter",  the  in- 
vention and  extensive  application  of  which  to  heat  measurements  are 
due  to  Berthelot.*  The  original  bomb  of  Berthelot,  on  account  of  the 
large  amount  of  platinum  which  it  contains,  is  exceedingly  expensive, 
and  has  been  variously  modified  by  Mahler,  Hempel,  Atwater  and 
others  for  the  purpose  of  reducing  the  cost.  The  Berthelot  calorimeter, 
*  "Trait6  pratique  de  Calorimetrie  chimique  ;  "  also  Ann.  chim.  phys,,  [6]  6,  546. 


314 


SUGAR  ANALYSIS 


as  modified  by  Hempel  and  Atwater*  and  improved  by  Blakeslee,  is 

shown  in  Fig.  153. 

Description  of  Calorimeter.  —  The  most  important  feature  of  the 

calorimeter  is  the  steel  bomb,  the  cup  (A)  and  cover  (B)  of  which  are 

lined  with  platinum,  or  heavily 
plated  with  gold.  The  cover  is  pro- 
vided with  a  sunken  lead  gasket  K, 
which  rests  upon  the  rim  of  the  cup, 
and  is  held  in  place  by  the  steel 
collar  C,  which  is  screwed  tightly 
into  position  by  means  of  a  clamp 
and  heavy  spanner.  The  cover  of 
the  bomb  is  provided  with  a  neck 
having  an  opening  leading  from  G 
to  the  interior  of  the  bomb  for  the 
entrance  of  oxygen;  the  inlet  is 
opened  and  closed  by  a  valve  screw 
F.  The  cover  is  also  provided,  on 
its  inner  surface,  with  two  stiff 
platinum  rods  I  and  H,  between 
which  passes  a  small  spiral  of  iron 
wire  for  igniting  the  charge;  the 
latter,  consisting  of  1  to  2  gms.  of 
the  sugar  or  carbohydrate  to  be 
burned,  is  placed  in  a  platinum 
capsule,  with  a  small  piece  of 
naphthalene  to  act  as  a  kindler, 


Fig.  153.  —  Bomb  calorimeter. 


directly  under  the  spiral.  The  rod  /  is  connected  through  the  cover 
with  the  electric  wire  /'  and  the  rod  H,  insulated  from  the  cover,  with 
the  electric  wire  H' '. 

Operation  of  Calorimeter.  —  The  bomb,  after  introducing  the 
charge,  is  filled  with  pure  oxygen  under  20  atmospheres  pressure  and 
then  placed  in  the  brittania-metal  vessel  M,  which  contains  a  weighed 
quantity  of  water,  sufficient  to  cover  all  parts  of  the  bomb.  The  vessel 
M  rests  within  two  buckets,  N  and  0,  which,  with  their  covers,  form 
two  dead-air  spaces,  and  insulate  the  bomb  system  from  the  room  at- 
mosphere. The  temperature  of  the  water  in  M  should  be  2°  to  3°  C. 
below  that  of  the  inner  air-chamber.  A  Beckmann  thermometer,  P, 
passes  through  the  covers  of  the  pails,  and  is  fastened  so  that  its 

*  See  article  by  Atwater  and  Snell,  J.  Am.  Chem.  Soc.,  25,  659,  for  a  very  com- 
plete description  of  this  instrument  and  its  use. 


MISCELLANEOUS  PHYSICAL  METHODS  315 

bulb  is  immersed  in  the  water  about  opposite  the  middle  of  the  bomb. 
The  thermometer  can  be  read,  by  means  of  a  magnifying  lens,  to 
the  thousandth  of  a  degree;  it  should  be  provided  with  a  certificate 
for  correcting  errors  of  construction  and  for  converting  readings  to 
true  centigrade  degrees.  The  mercury  thread  of  the  thermometer  is 
adjusted  at  the  desired  point  by  partly  filling  or  emptying  the  upper 
reservoir. 

When  the  apparatus  is  in  readiness  the  mechanical  stirrer  L  is  set 
in  motion  and  the  thermometer  read  at  intervals  of  one  minute,  tapping 
the  top  gently  with  an  electric  hammer  before  each  reading  to  prevent 
lagging  of  the  mercury  thread.  When  five  successive  readings  show  a 
uniform  rise  in  temperature,  the  electric  switch  is  closed  exactly  at  the 
end  of  the  fifth  minute.  As  soon  as  the  extinction  of  the  lamp  in  a  re- 
sistance circuit  indicates  the  fusion  of  the  iron  wire,  the  switch  is  re- 
opened to  avoid  heating  the  water  by  the  current.  The  readings  of  the 
thermometer  should  be  noted  at  the  end  of  each  minute,  until  the 
maximum  elevation  of  mercury  is  reached  and  the  rate  of  fall  has  be- 
come regular.  With  the  stirring  mechanism  making  40  revolutions  per 
minute  equilibrium  is  obtained  usually  within  5  minutes.  After  stirring 
5  more  minutes  a  final  reading  is  taken,  when  the  calculation  may  be 
made. 

Hydrothermal  Value.  —  The  calories  of  combustion  are  calculated 
from  the  observations  of  a  calorimeter  experiment  by  multiplying  the 
hydrothermal  value  (in  grams)  of  the  calorimeter  system  by  the  cor- 
rected rise  in  temperature  and  dividing  the  product  (after  subtracting 
the  heat  units  due  to  accessory  combustions)  by  the  weight  in  grams  of 
substance  taken. 

The  accuracy  of  all  calorimetric  experiments  is  dependent  upon  the 
exactness  with  which  the  hydrothermal  value  of  the  calorimeter  is 
known.  The  most  common  method  for  computing  the  water  equivalent 
of  the  calorimeter  system  is  to  multiply  the  weight  of  each  part  by  its 
specific  heat  and  take  the  sum  of  these  water  equivalents  as  the  hydro- 
thermal  value  of  the  entire  system.  An  example  of  the  method  is 
given  by  Fries,  in  Table  LXI. 

The  hydrothermal  value  may  also  be  determined  by  measuring  the 
rise  in  temperature  of  the  calorimeter  system  from  burning  a  substance 
of  known  calorific  value,  as  benzoic  acid  (1  gm.  =  6322  cals.).  For  a 
description  of  this  and  other  methods  reference  should  be  made  to  the 
work  of  Fries.* 

*  Fries,  "  Methods  and  Standards  in  Bomb  Galorimetry,"  Bull.  124,  Bur.  of 
Animal  Ind.,  U.  S.  Dept.  of  Agr.,  p.  9. 


316 


SUGAR  ANALYSIS 


TABLE  LXI 
Computed  Water  Value  of  Bomb  Calorimeter 


Material. 

Weight. 

Specific  heats. 

Water  equiva- 
lent. 

Steel  

Grams. 

3236.0 

0'.1114 

Grams. 

360  49 

Platinum  

196.0 

0.0320 

6  27 

Lead 

66  0 

0  0300 

1  98 

German  silver  (approximate) 

4  0 

0  0940 

0  38 

Rubber  (approximate) 

4  0 

0  3310 

1  32 

Iron  (approximate) 

10  0 

0  1114 

1  11 

Mercury  (approximate) 

50  0 

0  0330 

1  65 

Glass  (approximate) 

10  0 

0  1900 

1  90 

Britannia  metal 

855  0 

0  0548 

46  85 

Oxygen  (constant  volume) 

11  4 

0  1570 

1  79 

Water  at  22°  C  

2000.0 

0.9975 

1995  00 

Total  

2418  74 

Correction  for  Radiation.  —  When  the  conditions  of  the  experi- 
ment are  properly  controlled  the  calorimeter  system  at  the  beginning  of 
combustion  is  slightly  cooler,  and  at  the  end  of  combustion  slightly 
warmer,  than  the  surrounding  air.  During  the  first  period  the  calorim- 
eter gains  heat,  and  in  the  second  loses  heat  to  the  surrounding  air; 
the  thermometer  readings  must  be  corrected,  therefore,  for  the  errors 
of  radiation.  This  correction  is  made  by  the  Regnault-Pf  aundler  * 
formula 


) 


where  n  =  number  of  time  units  (minutes)  in  combustion  period. 
V  =  rate  of  fall  of  temperature  of  calorimeter  during  initial  period. 
(The  change  is  actually  a  rise  but  for  convenience  is  expressed  as  a  fall, 
the  value  of  V  thus  being  negative.) 

V  =  rate  of  fall  of  temperature  of  calorimeter  during  final  period. 
6  =  mean  temperature  of  calorimeter  during  initial  period. 

0'  =  mean  temperature  of  calorimeter  during  final  period. 

0i,  Oz,  .  .  .  Bn  =  temperature  at  end  of  first,  second,  .  .  .  nth  min- 
utes of  combustion  period. 

0o  =  temperature  at  moment  of  ignition. 

Illustration  of  Method.  —  The  application  of  "the  formula  is  best 
understood  from  a  special  case  and  the  following  example  of  the  com- 
bustion of  sucrose  is  taken  from  a  paper  by  Atwater  and  Snell.f  The 
calorimeter  employed  had  a  water  equivalent  of  2100  gms.  The  data 


*  Pfaundler.  Pogg.  Ann.,  129,  113. 


t  J.  Am.  Chem.  Soc.,  25,  659. 


MISCELLANEOUS  PHYSICAL  METHODS 


317 


of  the  experiment  are  given  in  the  following  record,  which  is  a  convenient 
form  for  determinations  of  this  kind. 


Sample  No.                                   Description  Cane  Sugar.    Date,  July  13,  1901. 
Bomb  No.  3                                  Observer,  J.  F.  Snell.        Thermometer,  No.  733. 

Capsule  No.  1 
Wt.  caps.  H-  subs. 
Wt.  capsule 

=  4.2501 

=  2.8783 

Correction  foi 
Wt.  Fe  13.0 
Wt.  naphth 
HN03 
Correction  foi 

•  Accessory  Combustions. 
-1.1  =  11.9  mgs.  =  19.0  cal. 
alene=  6.4  mgs.  =61.6  cal. 

Wt.  substance,  W=  1.3718 

•  accessories         =87.2  cal. 

Final  period.  Main  period.  Initial  period. 

' 
' 

Readings. 

1      1.018 
2      1.021 
3      1.025 
4      1.027 
5      1.030 
60o  1.032 

Corrected 
readings. 

1.015 
1.029 

Initial  period. 

Fall            =-   .014 
Rate  V       =-    .0028 
Meanf,  0  =     1.022 

Corrected  reading. 

05                 =     3.646 
00                 =     1.029 

Thermometer  correction. 

770air                  =  25.2 
T°  water             =23.8 
1st  reading         =     1.0 

T°  of  zero           =22.8 
Corr.  for  1°        =+   .001 
Rise  (degrees)   =     2.6 

Thpr    r*nrr             —  -1-     002fi 

70!  2.300 
802  3.650 
903  3.678 
1004  3.662 
1105  3.653 

2.3 
3.7 
3.7 
3.7 

Final  calculations. 

05                          =     3.646 
0o                          =     1.029 

05  +  00 
\ 

Fi 

Fall 
Rate  T 
I 
V     V 

=     4.675 
=     2.3 

nal  period. 

=  +   .013 
rf     =  +   .0026 
r      =  -   .0028 

13.4 
=  2.3 

=  15.7 
=  5.1 

05  +  00 

05-0o                   =     2.617 
Th.  corr.             =+   .0026 
Rad.  corr.           =+   .0079 

2 
Sum 
58 

Corr.  rise            =     2.6275 
Corr.  rise          ) 
X2100            [=  5517.8 
=  total  heat  ) 
Accessories         =       87.2 

Diff.               =10.6 
Log.  diff.       =       0253 
Log.  V'-V  =       7324 
Colog.0/-0  =       5820 

=  +   .0054 

°,0'  =     3.640 
0  =     1.022 

Antilog. 
+5F 
Radiation  ) 
correction) 
16      3.640 
Time  3..  30 

3397 
=  +  .0219 
=  -.014 

Mean  2 
0'-0 

Corrected  heat  =  5430.6 
Log.    corr.  heat  =  73485 
Log.  W               =13729 

=  +  .0079 
3.633 

=     2.618 

59756 
Heat  of  com-  ) 
bustion      per  >  =  3959 
gram                 ) 

Applying  the  formula  to  the  above  example,  where  the  number  of  time 
units,    n,    is    5,    we    obtain    for    the  several    expressions,   F=—  .0028    and 


The  combination  of  these  values  in  the  formula  gives  a  radiation  correction  of 
C=+  0.0079°. 

The  corrected  rise  of  the  Beckmann  scale  was  2.617  degrees  and  this  cor- 
rected to  true  degrees  C.  and  for  radiation  gives  2.6275°  C.  as  the  corrected 
rise  in  temperature,  which,  multiplied  by  2100,  the  water  equivalent  of  the 
calorimeter,  gives  5517.8  calories. 


318  SUGAR  ANALYSIS 

Correction  for  Accessory  Combustions.  —  The  weight  of  the  iron  wire  was 
13  mgs.  The  quantity  unburned  was  1 .1  nig.  The  quantity  burned  was  there- 
fore 11.9  mgs.  The  specific  heat  of  combustion  of  iron  being  1601  calories,  the 
heat  of  combustion  of  11.9  mgs.  is  11.9  X  1.6  =  19  calories.  The  quantity  of 
naphthalene  burned  was  6.4  mgs.,  which  yields  6.4  X  9.63  =  61.6  calories,  the 
specific  heat  of  combustion  of  naphthalene  being  9628  calories.  The  heat  of 
combustion  of  nitrogen  in  the  bomb  as  determined  by  titration  of  the  nitric 
acid  is  6.6  calories.  (N2  +  05  +  H20  =  2  HN03.  0 .004406  gm.  HNOS  =  1 
cal.)  The  total  heat  from  accessory  combustions  is,  therefore,  19  -f-  61.6  +  6.6  = 
87.2  calories. 

Deducting  this  quantity  from  the  total  heat  set  free  in  the  apparatus,  we 
have  5517.8  —  87.2  =  5403.6  calories  as  the  heat  due  to  the  combustion  of  the 
sugar.  The  quantity  of  sugar  burned  was  1.3718  gms.  The  specific  heat  of 
combustion  according  to  this  determination  is,  therefore,  5430.6  •*-  1.3718  = 
3959  calories. 

Gram-molecular  Heat  of  Combustion.  —  The  gram-molecular  heat 
of  combustion  is  found  by  multiplying  the  calories  per  gram  by  the 
molecular  weight  (M ) .  To  avoid  large  figures  it  is  customary  to  express 
this  unit  in  terms  of  large  calories. 

cals.  X  M 


Gm.  mol.  Cals.  = 


1000 


CALORIFIC    CONSTANTS   OF   DIFFERENT    SUGARS 

In  Table  LXII,  compiled  by  Tollens,*  the  calorific  constants  are 
given  for  the  principal  sugars,  polysaccharides  and  sugar  alcohols. 

It  is  seen  from  the  table  that  the  molecular  heat  of  combustion  is 
always  higher  for  the  anhydride  than  for  the  hydrate  of  the  same  sugar. 
The  molecular  heat  of  combustion  of  the  higher  saccharides  is  also 
greater  than  the  sum  of  the  values  of  their  components.     Thus : 
Sucrose  =  1352.7  Gm.  mol.  Cals.   " 

Glucose    =673.7] 

an*  n  r  =  1349.6  Gm.  mol.  Cals. 
Fructose  =  675.9  J      

Difference  3.1  Gm.  mol.  Cals. 

This  difference  may  be  taken  as  the  equivalent  of  heat  which  is  liber- 
ated during  inversion. 

In  the  same  way      Rafnnose  =  2026.1  Gm.  mol.  Cals. 
Glucose     =  673.71 

Fructose    =  675.9  V                   =  2019.5  Gm.  mol.  Cals. 
Galactose  =  669.9  J  


Difference  =        6.6  Gm.  mol.  Cals. 
*  Tollens's  "Handbuch  der  Kohlenhydrate, "  II,  p.  45. 


MISCELLANEOUS  PHYSICAL  METHODS 


319 


TABLE  LXII. 

Giving  Heats  of  Combustion  of  Sugars,  Poly  saccharifies  and  Sugar  Alcohols. 


cal.  1  gram. 


Cal.  (1  Cal.  =  1000  cal.) 
for  1  gram-molecule. 


Sugars 
Arabinose,  C5H1005 

Xylose,  C5H1005 |  3740  (IV 

Rhamnose,  C6H12O5 4379.3  (St. 

Rhamnose  (cryst.),  C6H12O5+H2O  ....  3909.2  (St. 

Fucose,  C6H12O5 4340.9  (St. 

Glucose,  C6H12O6 3742.6  (St.) 

Galactose,  C6H12O6 3721 .5  (St.) 

Fructose,  C6H12O6 3755  (St.) 

Sorbose,  C6H12O6 3714.5  (St. 

Sucrose,  Ci?H22Ou 3955.2  (St. 

Lactose,  Ci2H22On 3951 .5  (St. 

Lactose,  Ci2H22Ou+H2O 3736.8  (St.) 

Maltose,  Ci2H22Ou 3949.3  (St. 

Maltose,  Ci2H22Ou+H2O 3721 . 8  (St. 

Trehalose  (anhydr.),  Ci2H22Ou 3947.0  (St. 

Trehalose  (cryst.),  Ci2H22On+2H2O . .  3550.3  (St. 

Raffinose  (anhydr.),  C18H32Oi6 j  ^'(B^' 

Raffinose  (cryst.),  Ci8H32Oi6+5 H2O. . .  3400.2  (St.) 

Melezitose,  Ci8H32Oi6+H2O 3913.7  (St.) 

Poly  saccharifies: 

Cellulose,  (C6H10O5)n 4185.4  (St.) 

Starch,  (C6H10O5)n 4182.5  (St.) 

Dextran,  (C6H10O5)n.. .  4112.3  (St.) 

Inulin,  C36H62O3i 4133.5  (St.) 

Glycogen,  (C6H10O6)n 4190.6  (St.) 

Sugar  Alcohols: 

Erythrite,  C4H10O4 4132.3  (St.) 

Arabite,  C6H12O5 4024.6  (St.) 

Mannite,  C6HHO6 3997.8  (St.) 

Dulcite,  C6H14O6 3975.9  (St.) 

Perseite,  C7H16O7 3942.5  (St.) 

Quercite,  C6H12O5 4293.6  (St.) 

Inosite,  C6H12OC.  .  3679.6  (St.) 


558.3  (St.) 

557.1  (B.) 
561.9  (St.) 

560.7  (B.) 

718.5  (St.) 

711.8  (St.) 

712.2  (St.) 
673.7  (St.) 
677.2  (B.) 

669.9  (St.) 
675.9  (St.) 

668.6  (St.) 
1352.7  (St.) 

1345.2  (St.) 

1340.6  (Gibson) 

1350.7  (St.) 

1339.8  (St.) 

1349.9  (St.) 

1345.3  (St.) 
2026.5  (St.) 
2026.1  (B.) 
2019.7  (St.) 
2043.0  (St.) 


678.0  (St.) 

673.1  (Gottlieb) 

680.4  (B.) 

677.5  (St.) 

675.6  (Gibson) 

666.2  (St.) 
4092.1  (St.) 

678.9  (St.) 


504.1  (St.) 

502  (Louguinine) 

502.6  (B.) 

612.0  (St.) 
729.9  (St.) 
720.5  (Gibson) 
723.9  (St.) 

836.1  (St.) 
704. 4  (St.) 

710.4  (B.) 
662.3  (St.) 

665.5  (St.) 


St.  =  Stohmann  and  Langbein,  J.  prakt.  chem.  [2],  45,  305. 

B.  =  Berthelot  and  coworkers,  from  results  in  the  Ann.  chim.  phys.  [6],  6,  552;  10,  455;   13,  304, 
341;  21,  409. 


320  SUGAR  ANALYSIS 

The  hydrolysis  of  sugars  may  be  regarded,  therefore,  as  an  exother- 
mic reaction. 

Calculation  of  Calories  from  Chemical  Formulae.  —  Various 
methods  have  been  proposed  for  calculating  the  molecular  heat  of  com- 
bustion from  the  chemical  formula  of  sugars. 

The  calorific  value  for  the  combustion  of  the  elements  carbon  (dia- 
mond) and  hydrogen  have  been  determined  as  follows: 
C  +  O2  =  C02  +  94.3  Cals. 
H2  +  O  =  H20  +  68.3  Cals. 

Welter's  *  rule  for  computing  the  molecular  heat  of  combustion  is  to 
subtract  as  much  O  and  H2  as  will  unite  to  form  water  from  the 
molecular  formula,  and  multiply  the  number  of  remaining  atoms  by 
their  respective  heat  values.  The  sum  of  the  products  is  taken  as  the 
molecular  heat  of  combustion. 

Example.  —  Glucose  C6Hi206.  The  6  atoms  of  0  unite  with  12  atoms  of  H 
to  form  6  H20.  The  Cals.  of  the  6  remaining  C  atoms  =  6  X  94.3  =  565.8  Cals. 
This  value  is  16  per  cent  less  than  the  value  found  experimentally  by  Stoh- 
mann,  viz.  673.7  Cals. 

A  second  method  of  calculating  heat  of  combustion  is  to  combine  all 
the  0  and  C  that  will  unite  to  form  C02,  and  calculate  the  heat  of  the 
remaining  atoms  in  the  manner  just  described. 

To  take  again  the  example  of  glucose :  The  6  atoms  of  0  unite  with  3  atoms 
of  C  to  form  3  C02.    The  remaining  C3  and  Hi2  then  give 
For  C,  3  X  94.3  =  282.9  Cals. 
For  H2,  6  X  68.3  =  409.8  Cals. 


692.7  Cals. 

The  results  by  this  method  are  much  closer  than  those  obtained  by 
Welter's  rule,  being  about  3  per  cent  higher  than  the  value  found  ex- 
perimentally by  Stohmann. 

A  third  method  of  calculating  heat  of  combustion  is  to  distribute 
the  O  of  the  molecule  among  its  C  and  H  atoms  according  to  the  pro- 
portionate number  and  combining  powers  of  the  latter.  Since  the  0 
necessary  to  form  C02  is  represented  by  2  C  and  the  O  to  form  H20  by 

TT 

-g  >  the  uncombined  equivalents  of  C  and  H,  after  deducting  CO2  and 

TT 

H2O,  would  equal  2  C  +  -^  -  O.     The  ratio  of  total  to  uncombined 
*  Walker's  "Introduction  to  Physical  Chemistry,"  (3rd  Ed.),  p.  129. 


MISCELLANEOUS  PHYSICAL  METHODS  321 

H 


\ 
calculation  is  then: 


equivalents  is  then  ( 2  C  +  -=•  -  o)  -r-  ( 2  C  +  5\  -    The  formula  for  the 
\  £  .      /      \  2> 

is  then: 
Gm.  mol.  Cals.  =  ^94.3  C  +  68.3  ^ 


-O 


Applying  this  formula  to  glucose,  we  obtain, 

Gm.  mol.  Cals.  =  (94.3  X  6  +  68.3  X  — ) =  650.4, 

v  '  12+l  | 

a  result  a  little  over  3  per  cent  below  the  value  found  experimentally  by 
Stohmann. 

The  true  molecular  heat  of  combustion  is  about  midway  between  the 
values  calculated  by  the  last  two  methods.  It  is  evident,  however, 
that  absolute  agreement  cannot  be  attained  by  any  method-  of  calcu- 
lation, since  the  experimental  results  are  different  for  different  isomers. 
The  gram-molecule  Calories  for  the  C6Hi206  sugars  were  found  by 
Stohmann  to  vary  from  668.6  for  sorbose  to  675.9  for  fructose. 


OSMOTIC  PRESSURE  AND  RELATED  PHYSICAL  CONSTANTS,  AND  THEIR 
APPLICATION  IN  DETERMINING  MOLECULAR  WEIGHTS  OF  SUGARS 

The  determination  of  the  molecular  weights  of  sugars  and  sugar 
derivatives  is  a  problem  which  may  confront  the  chemist  in  his  examina- 
tion of  unknown  carbohydrates  of  plant  or  animal  origin. 

In  the  case  of  a  reducing  sugar  an  elementary  analysis  of  one  of  its 
osazones  or  hydrazones  (p.  370)  will  serve  to  fix  the  class  to  which  the 
sugar  belongs  and  thus  indicate  the  molecular  weight.  In  the  case, 
however,  of  non-reducing  sugars,  such  as  sucrose,  raffinose,  etc.,  and 
of  the  sugar  derivatives,  which  do  not  form  osazones  and  hydrazones,  a 
determination  of  the  molecular  weight  by  some  physical  method  is 
usually  required. 

The  molecular  weights  of  sugar  derivatives,  which  can  be  distilled 
without  decomposition  or  dissociation,  are  best  determined  by  the  well- 
known  vapor-density  method  of  Victor  Meyer.  All  the  sugars,  how- 
ever, and  most  of  their  compounds  undergo  decomposition  at  or  below 
the  melting  point  so  that  the  vapor-density  method  is  excluded.  Re- 
course is,  therefore,  usually  made  to  some  one  of  the  methods  which  in- 
volve the  principle  of  osmotic  pressure. 


322 


SUGAR  ANALYSIS 


OSMOTIC   PRESSURE   OF   SUGAR   SOLUTIONS 

Pfeffer,*  the  plant  physiologist,  in  1877,  during  his  classical  studies 
upon  osmosis  in  vegetable  cells,  discovered  that  the  osmotic  pressure  of 
dilute  sugar  solutions  was  proportional  to  the  concentration.  Pfeffer's 
experiments  were  performed  by  placing  the  sugar  solutions  in  a  porous 
bulb,  which  had  deposited  within  its  walls  a  semipermeable  membrane 
of  copper  ferrocyanide.  The  bulb,  which  was  connected  with  an  up- 
right tube,  was  then  immersed  in  distilled  water.  The  membrane, 
which  is  permeable  to  water  but  not  to  sugar,  allows  water  to  enter  the 
bulb;  the  sugar  solution  begins  to  rise  in  the  tube  and  the  elevation 
continues  until,  after  many  hours,  a  maximum  is  reached;  at  this  point 
the  difference  between  the  level  of  liquids  within  and  without  the  bulb 
gives  a  pressure  corresponding  to  the  osmotic  pressure  of  the  sugar  solu- 
tion. This  maximum  pressure,  expressed  in  centimeters  or  millimeters 
of  mercury,  was  called  by  Pfeffer  the  osmotic  pressure. 

The  following  results  by  Pfeffer  give  the  osmotic  pressure  of  sucrose 
solutions  at  different  concentrations. 


Concentration 

Pressure  (P)  in 

(C)  of  sucrose 

centimeters  of 

Ratio  J- 

solution. 

mercury. 

C 

Per  cent. 

1 

53.5 

53.5 

2 

101.6 

50.8 

4 

208.2 

52.1 

6 

307.5 

51.3 

p 

The  ratio  -^  is  a  constant,  the  slight  differences  noted  being  due  to 

variations  in  temperature  and  other  experimental  errors. 

Pfeffer  also  showed  that  the  osmotic  pressure  of  sugar  solutions  un- 
derwent a  regular  increase  with  elevation  of  temperature.  The  follow- 
ing experiment  was  made  upon  a  1  per  cent  sucrose  solution. 


Temperature 
C°. 

Absolute  tempera- 
ture (T). 

Osmotic  pres- 
sure (P). 

Ratio  ~. 

14.15 

287.15 

51.0 

.1776 

15.5 

288.5 

52.05 

.1804 

32.0 

305.0 

54.4 

.1784 

36.0 

309.0 

56.7 

.1835 

*  Pfeffer's  "Osmotische  Untersuchungen,"  Leipzig,  1877. 


MISCELLANEOUS  PHYSICAL  METHODS  323 

p 
The  ratio  -^  is  thus  also  found  to  be  constant,  the  slight  variations 

being  due  as  before  to  experimental  errors. 

Relation  of  Osmotic  to  Gas  Pressure.  —  In  1887  van't  Hoff* 
showed  that  Pfeffer's  osmotic  pressures  were  identical  in  value  with 
those  obtained  by  gas  pressure;  in  other  words  that  the  osmotic  pres- 
sure per  gram-molecule  of  substance  is  the  same  as  the  gas  pressure  per 
gram  molecule  at  the  same  temperature  and  volume.  This  identity  is 
expressed  by  the  equation 

pv  =  RT, 

in  which  p  is  the  pressure  and  v  the  volume,  T  the  absolute  temperature 
and  R  a  constant.  Van't  Hoff  showed  that  the  constant  R  is  the  same 
for  substances  in  dilute  solution  as  well  as  in  the  gaseous  state. 

The  molecular  weight  of  a  substance  is  equal  to  the  weight  of  its 
vapor  in  grams  which  would  occupy  the  same  volume,  under  equal 
temperature  and  pressure,  as  2  grams  of  hydrogen  (2  being  the  weight 
of  the  hydrogen  molecule).  This  volume,  called  the  gram-molecular 
volume,  is  22,380  c.c.  at  0°  C.  (273°  abs.)  and  76.0  cm.  of  mercury  pres- 
sure (1  atmosphere). 

Calling  V  the  volume  occupied  by  a  gram-molecule  of  gas  we  obtain 
from  the  previous  equation, 

*-*£• 

The  pressure  p,  per  square  centimeter  of  mercury  (sp.  gr.  =  13.59),  is 
equal  to  76  cm.  X  13.59  =  1033  gms.  We  obtain,  therefore,  for  the 
constant  R, 

„      1033  X  22,380 

~^73~  *4'683' 

To  prove  the  identity  of  this  constant  for  the  osmotic  pressure  of 
sucrose  one  of  the  experiments  of  Pfeffer  may  be  selected.  A  1  per 
cent  solution  of  sucrose  at  0°  C.  (273°  abs.)  gave  an  osmotic  pressure  of 
49.3  cm.  of  mercury.  The  latter  corresponds  to  a  pressure  per  square 
centimeter  of  49.3  X  13.59  =  670  gms.  Since  the  molecular  weight  of 
sucrose  is  342,  the  volume  (V)  of  a  1  per  cent  solution  containing  a 
gram-molecule  would  be  very  closely  34,200  c.c.  Substituting  these 
volumes  in  the  equation,  we  obtain, 


which  value  is  in  substantial  agreement  with  that  derived  by  the  other 
method. 

*  Ostwald's  "  Grundriss  "  (2nd  Ed.),  p.  131. 


324  SUGAR  ANALYSIS 

Application  of  the  Method.  —  If  we  accept  now  the  identity  of  the 
laws  for  gaseous  and  osmotic  pressure,  the  molecular  weight  of  a  sugar 
can  be  determined  from  its  osmotic  pressure  in  a  manner  analogous  to 
that  followed  by  the  vapor-density  method. 

Example.  —  In  one  of  the  experiments  previously  cited  Pfeffer  found  at 
15.5°  C.  (288.5°  abs.)  for  a  1  per  cent  sucrose  solution  an  osmotic  pressure  of 
52.05  cm.  mercury. 

If  1  gm.  of  sucrose  occupies  100  c.c.  at  52.05  cm.  pressure  and  15.5°  C.,  then 
the  number  of  grams  which  would  occupy  22,380  c.c.  at  0°  C.  (273°  abs.)  and 
76  cm.  pressure  would  be: 

1  gm.  X  22,380  c.c.  X  288.5°  X  76  cm.  =  „_ 
100  c.c.  X  273°  X  52.05  cm. 

345  the  number  of  grams  in  the  gram-molecular  volume  is  the  molecular 
weight  of  sucrose.  This  agrees  closely  with  the  actual  value  342  calculated  from 
the  formula  Ci2H22On. 

It  follows  from  the  previous  discussion  that  the  sugars  of  lowest 
molecular  weight  will  show  for  equal  concentration  and  temperature 
the  highest  osmotic  pressure. 

Measurement  of  Osmotic  Pressure  by  Plasmolysis.  —  A  second 
method  of  applying  the  principle  just  described  is  due  to  the  Dutch 
botanist  de  Vries,*  who  discovered  that  the  plasmolysis,  or  loosening  of 
the  protoplasmic  lining  of  plant  cells,  offered  a  simple  and  reliable  means 
of  measuring  osmotic  pressure.  Fig.  154  shows  the  miscroscopic  ap- 
pearance of  a  plant  cell  in  sugar  solutions  of  different  concentration.  In 
such  a  cell  the  thin  layer  p  of  protoplasm  (the  protoplast)  acts  as  a 
semipermeable  membrane.  So  long  as  the  osmotic  pressure  of  the  cell 
liquid  I  exceeds  or  equals  that  of  the  surrounding  sugar  solution  s,  the 
protoplast  is  not  affected.  When,  however,  the  osmotic  pressure  of 
the  sugar  solution  becomes  greater  than  that  of  the  cell  liquid  there  is  a 
diffusion  of  water  outward  through  the  protoplasmic  membrane.  The 
latter,  in  consequence  of  the  loss  of  a  part  of  the  cell  water,  is  loosened 
from  the  cell  wall  and  contracts,  as  shown  in  the  figure. 

The  application  of  the  method  may  be  understood  from  the  follow- 
ing: de  Vries  found  that  the  hair  roots  of  the  frogbit  (Hydrocharis 
Morsus-rance)  showed  no  plasmolysis  in  a  7  per  cent,  but  a  very  pro- 
nounced loosening  of  the  protoplast  in  a  7.1  per  cent,  sucrose  solution. 
For  these  particular  root  hairs  under  the  conditions  of  the  experiment, 
plasmolysis  was  produced  by  a  solution  containing  0.208  gm.  mol.  of 
sucrose  to  1000  gms.  of  solution  (71  gms.  -f-  342,  the  molecular  weight 
of  sucrose). 

*  Bot.  Ztg.,  46,  229,  393. 


MISCELLANEOUS  PHYSICAL  METHODS 


325 


Suppose  that,  using  these  same  root  hairs,  a  solution  containing  3.7 
per  cent  of  glucose  just  produced  plasmolysis.  Then  37  (the  grams  of 
glucose  per  1000  gms.  of  solution)  divided  by  0.208  =  178,  the  molecular 
weight  of  glucose,  which  corresponds  to  the  formula  C6Hi2O6  (molecular 
weight  =180). 


Fig.  154.  —  Illustrating  plasmolysis. 

I.  Condition  of  plant  cell  before  plasmolysis;    II.  Beginning  of  plasmolysis; 
III.  Advanced  stage  of  plasmolysis. 

It  was  by  this  means  that  de  Vries,*  in  1888,  established  the  mo- 
lecular weight  of  raffinose.  The  following  formulae  had  been  proposed 
for  the  constitution  of  this  sugar. 

I.   Ci2H22Oii  +  3  H20  =  396,  molecular  weight. 
II.   Ci8H32016  +  5  H20  =  594,  molecular  weight. 
III.   C36H64O32  +  10H20  =  1188,  molecular  weight. 
De  Vries  found  by  his  method  of  plasmolysis  that,  when  standardized 
against  a  sucrose  solution  for  the  same  plant  cell,  595.7  parts  of  raffinose 
were  equimolecular  with  342  parts  of  sucrose.     This  figure  agrees  with 
the  molecular  weight  of  formula  II;  the  correctness  of  de  Vries's  con- 
clusion was  afterwards  verified  by  chemical  means. 

Owing  to  the  variation  in  composition  of  cell  liquids,  it  is  evident 
that  the  particular  plant  cells  chosen  for  this  method  of  examination 
must  always  be  standardized  before  using. 

FREEZING  AND  BOILING  POINTS  OF  SUGAR  SOLUTIONS 

On  account  of  the  difficulty  of  preparing  a  perfect  semipermeable 
membrane  and  owing  to  the  extreme  liability  of  such  membranes  to 
rupture,  the  determination  of  molecular  weights  by  direct  measurement 
of  osmotic  pressure,  although  most  sound  in  principle,  is  not  generally 
followed.  Use  is  accordingly  made  of  the  measurement  of  some  re- 
lated constant,  such  as  that  of  vapor  pressure,  depression  of  freezing 
*  Compt.  rend.,  106,  751. 


326 


SUGAR  ANALYSIS 


M 


M' 


point  or  elevation  of  boiling  point.  The  freezing  and  boiling  points  of 
sugar  solutions  vary  in  fact  according  to  their  vapor  pressure,  the 
value  of  which,  it  can  be  shown,  is  directly  proportional  to  the  osmotic 
pressure. 

Isotonic  Solutions.  —  In  Fig.  155  suppose  the  closed  vessel  V  to  be 
divided  by  a  semipermeable  membrane  M-M'  into  two  equal  compart- 
ments, which  open  into  one  another  above  M.  Suppose,  next,  equal 

volumes  of  sucrose  and  glucose  solutions 
of  the  same  concentration  to  be  placed 
in  each  of  the  compartments.  Then 
water  will  diffuse  from  the  sucrose  solu- 
tion Sj  where  the  osmotic  pressure  is 
lower,  into  the  glucose  solution  G,  where 
the  osmotic  pressure  is  higher,  until  at 
the  point  of  equilibrium  the  osmotic 
pressures  upon  both  sides  of  the  mem- 
brane are  equal.  The  two  sugar  solu- 
tions are  then  said  to  be  isotonic  and 
Fig.  155.-Illustrating  principle  of  isotonic  solutions  'must  have  the  same 
isotonic  sugar  solutions.  vaPor  pressure.  For  if  the  vapor  pres- 

sures were  unequal,  water  vapor  would 

pass  from  the  solution  of  higher  to  that  of  lower  vapor  pressure,  the 
concentration  of  the  sugar  solutions  would  thus  be  changed,  and  water 
must  again  diffuse  to  the  compartment  of  higher  osmotic  pressure. 
There  would  thus  be  established  a  perpetual  motion  which  is  con- 
trary to  law.  Consequently  isotonic  solutions  must  have  the  same 
vapor  pressure. 

Suppose  next  a  piece  of  ice  /  to  be  placed  in  the  closed  compart- 
ment above  the  partition  M,  and  suppose  this  ice  to  be  of  the  same 
temperature  as  the  freezing  point  of  the  isotonic  sucrose  solution  S. 
Then  the  vapor  pressure  between  7  and  S  must  be  equal,  otherwise 
water  vapor  would  pass  between  the  two  and  change  the  freezing  point 
of  S.  But  since  S  and  G  are  both  isotonic  and  have  the  same  vapor 
pressure,  both  must  also  have  the  same  freezing  point. 

In  the  same  way  the  two  isotonic  solutions  S  and  G  must  have  the 
same  boiling  point,  the  vapor  tension  of  the  aqueous  vapor  at  the  boil- 
ing point  being  the  same  for  both  solutions. 

The  proportionality  between  changes  in  vapor  pressure  and  between 
changes  in  freezing  or  boiling  point  is  easily  illustrated  by  means  of  a 
diagram.  In  Fig.  156,  let  OW  be  the  pressure  curve  of  water  for 
change  in  temperature  and  01  the  pressure  curve  of  ice,  the  projection  of 


MISCELLANEOUS  PHYSICAL  METHODS 


327 


0  at  T  being  the  freezing  point  of  water.  Let  Ss  be  the  corresponding 
curve  of  a  1  per  cent  sucrose  solution  and  Gg  of  a  1  per  cent  glucose 
solution,  the  projection  of  the  points  s  and  g  at  t  and  tf  being  the  re- 
spective freezing  points  of  the  two  solutions.  For  comparatively 
small  areas  the  lines  gO,  ss'  and  ggr  may  be  regarded  as  straight  and  ss' 


t'    t    T 

Temperature 

Fig.  156.  —  Showing  relation  of  vapor  pressure  of  sugar  solutions  to  depression  in 

freezing  points. 

and  gg'  as  parallel.  In  the  A  Ogg',  Osf  :  Ogf  :  :  Os  :  Og  and  so  also 
Os  :  Og  :  :  Tt  :  Tt' .  Therefore  the  lowerings  in  vapor  pressure  (and 
hence  osmotic  pressure)  Os'  and  Og'  of  the  two  sugar  solutions  as  com- 
pared with  the  solvent  water  are  directly  proportional  to  the  correspond- 
ing depressions  in  freezing  point  Tt  and  Tt' . 

Raoult's  Method  for  Determining  Depression  of  Freezing  Point.  — 
For  determining  the  depression  of  freezing  points  by  Raoult's  *  method 
the  apparatus  of  Beckmann  f  (Fig.  157)  is  generally  used.  This  con- 
sists of  a  large  tube  A  (2.5  cm.  X  21  cm.)  provided  with  a  side  tube  A'. 
The  main  opening  is  provided  with  a  stopper  through  which  pass  the 
Beckmann  thermometer  D  and  a  small  stirrer,  provided  with  a  cork 
handle  r.  The  thermometer  has  a  range  of  about  6  degrees  and  the 
scale  is  divided  into  hundredths,  the  thousandths  of  a  degree  being 
estimated  by  aid  of  a  magnifying  glass.  The  tube  A  fits  through  a 
cork  into  the  larger  tube  B,  which  serves  as  an  air-jacket,  and  the 
whole  sets  in  the  cover  of  a  large  glass  cylinder  which  is  filled  with  a 
freezing  mixture  a  few  degrees  lower  than  the  freezing  point  of  the 
solution  to  be  examined. 


*  Compt.  rend.,  94,  1517;  101,  1056;  103,  1125. 
t  Z.  physik.  Chem.,  2,  638. 


328 


SUGAR  ANALYSIS 


In  making  an  experiment,  using  water  as  the  solvent,  the  freezing 
bath  is  set  at  about  —5°  C.  and  the  mercury  of  the  Beckmann  ther- 

mometer adjusted  by  means  of 
its  regulating  device  c,  so  that 
the  top  of  the  column  falls  within 
the  proper  range  of  the  scale. 
A  weighed  quantity  of  water, 
sufficient  to  cover  the  bulb  of 
the  Beckmann  thermometer,  is 
placed  in  A,  the  thermometer 
and  stirrer  are  inserted  and  the 
tube  plunged  through  the  small 
opening  b  into  the  freezing  mix- 
ture. When  signs  of  freezing 
begin  to  appear,  the  tube  is 
withdrawn  from  the  freezing 
mixture,  wiped  dry  and  then 
inserted  in  the  air-jacket  B. 
The  water  and  forming  ice  are 
now  stirred  vigorously  by  r;  the 
temperature  after  reaching  a 
certain  minimum  begins  to  in- 
crease suddenly  with  the  lib- 
eration of  latent  .heat.  The 
mercury  soon  ceases  to  rise  and 
the  point  at  which  it  stops,  after 
tapping  to  prevent  any  lag,  is 
taken  as  the  freezing  point  of 
the  water.  The  operation  is 
repeated  several  times  and  the 
average  of  the  observations 
taken  as  the  final  value.  The 
same  operations  are  now  re- 
peated after  introducing  through 

A'  known  weights  of  the  sugar 
be  examined  (1  to  5 

"  . 

100  gms.  of  water),  the  maxi- 


Fig. 157.  —  Beckmann's    apparatus  for  de- 
termining depression  of  freezing  point. 


mum  point  to  which  the  mercury  rises  after  overcooling  being  taken  as 
the  freezing  point  of  the  solution.  The  corrected  difference  between 
the  freezing  point  of  water  and  that  of  water  +  sugar  is  the  depression 
of  freezing  point. 


MISCELLANEOUS  PHYSICAL  METHODS 


329 


Molecular  Depression  of  Freezing  Point.  —  According  to  what 
was  said  under  osmotic  and  vapor  pressure,  solutions  of  undissociated 
substances  (non-conducting  solutions),  which  contain  the  same  num- 
ber of  gram-molecules  per  liter,  should  show  the  same  depression  of 
freezing  point.  The  depression  for  1  gm.  mol.  of  undissociated  sub- 
stance per  1000  gms.  of  solvent,  according  to  van't  Hoff,*  is  expressed  by 

0  002  T2 
the  formula       w —  >  in  which  T  is  the  absolute  temperature  of  melting, 

and  W  the  latent  heat  of  melting  for  the  solvent.     This  expression  in 
case  of  water,  whose  latent  heat  of  melting  is  80  calories  and  temper- 


ature of  melting  273°  abs.,  would  give 


0.002  X  2732 
80 


=  1.86.     Loomis,  as 


a  matter  of  fact,  in  the  examination  of  solutions  of  some  25  different  sub- 
stances obtained  a  depression  in  freezing  point  for  1  gm.  mol.  to  1000 
gms.  of  water  of  almost  exactly  1.86°  C.  The  following  experiments  by 
Loomis  f  give  the  results  of  6  tests  upon  maltose.  (M,  the  molecular 
weight  of  maltose  anhydride  C^H^Ou  =  342.) 


Grams  maltose  to  1000 
grams  water  (P). 

Gram-molecules  of  mal- 
tose to  1000  grams  water 

(PV 

WA 

Depression  of  freezing 
point  (A), 
degrees  C. 

Molecular  depression 
of  freezing  point 
f./P       AM\ 

(*/M  =  -p-y 

3.431 

0.0100 

0.0193 

1.86 

6.879 

0.0201 

0.0378 

1.88 

10.350 

0.0302 

0.0560 

1.85 

17.316 

0.0506 

0.0946 

1.87 

35.004 

0.1023 

0.1919 

1.876 

71.548 

0.2091 

0.3946 

1.887 

Applications  of  Freezing-point  Method.  —  The  application  of  the 
freezing-point  method  to  the  determination  of  molecular  weights  may 
be  understood  from  the  following  example: 


20  gms.  of  water  in  the  apparatus  gave 
20  gms.  of  water  +  0.3647  gms.  fructose  gave 
Depression  of  freezing-point  ( A)  = 


Corrected  freezing  point 
upon  Beckmann  scale. 

4.320° 
4.131 


0.189°  G. 

The  grams  of  fructose  calculated  to  1000  gms.  of  water  would  be 
0.3647  X  1000 


20 


Since 


=  18.235  gms.  =  P. 

1.86P 


~  =  the  constant  1.86,  M  = 

P  a 

*  Ostwald's  "Grundriss"  (2nd  Ed.),  p.  142. 
t  Z.  physik.  Chem.,  37,  407. 


330  SUGAR  ANALYSIS 

Substituting  the  values  obtained  for  the  A  and  P  of  fructose  we  obtain 


which  agrees  closely  with  the  value  180,  required  by  the  formula  C6Hi206. 

If  w  is  the  weight  of  sugar  taken  and  W  the  weight  of  water,  the 
various  steps  of  the  calculation  are  represented  by  the  general  equation : 

w  X  1000  X  1.86 
M=          JFXA 

The  method  of  determining  molecular  weight  by  the  depression  of 
freezing  point  is  one  that  requires  considerable  care  in  manipulation, 
and  the  inexperienced  chemist  should  thoroughly  test  the  method  upon 
substances  of  known  molecular  weight  before  applying  it  to  the  exami- 
nation of  unknown  compounds.  The  method  is  open  to  a  large  number 
of  experimental  errors,  such  as  too  low  a  temperature  of  freezing  bath, 
too  high  a  room  temperature,  radiation  of  heat  from  the  observer, 
faulty  thermometer  or  error  in  reading,  solution  of  air  by  the  water, 
careless  handling  of  the  instrument,  etc.  For  a  thorough  discussion 
of  these  various  points  the  chemist  is  referred  to  the  original  papers 
by  Raoult,  Beckmann,  Loomis  and  others.*  Owing  to  the  small  value 
of  A  any  slight  error  in  its  determination  becomes  greatly  magnified  in 
the  final  calculation. 

The  freezing-point  method  has  been  successfully  employed  by  Tollens 
and  Mayer,  Brown  arid  Morris,  and  others  in  determining  the  molecular 
weights  of  many  sugars.  The  following  examples  of  determinations  for 
nine  sugars  are  selected  from  a  compilation  of  results  by  Tollens.  f 


Sugar. 

Formula. 

Molecular  weight. 

Authority. 

Calculated. 

Found. 

Arabinose  

CEH1005 
CsHioOa 
CeH^Os 
C6H1206 
C6H1206 

Cl2H22Oll 

C^HaaOn 

(^12il  22^11  ,  H.2V-) 

CisH32Oi6,5H2O 

150.08 
150.08 
'  180.10 
180.10 
180.10 
342.18 
342.18 
360.19 
594.32 

150.3 
154.1 
179 
174.3 
177 
352 
322 
353 
594 

Brown  and  Morris 
Tollens  and  Mayer 
Tollens  and  Mayer 
Brown  and  Morris 
Brown  and  Morris 
Raoult 
Brown  and  Morris 
Tollens  and  Mayer 
Tollens  and  Mayer 

Xylose  

Glucose  

Invert  sugar 

Galactose..         ... 

Sucrose  
Maltose 

Lactose 

Raffinose  .  .  . 

The  freezing-point  method  can  be  applied  to  the  examination  of 
sugar  solutions  for  other  purposes  than  those  of  molecular  weight  de- 

*  For  a  complete  review  and  bibliography  of  the  subject  see  Lippmann's 
"Chemie  der  Zuckerarten,"  1126.  f  "Handbuch  der  Kohlenhydrate,"  II,  p.  26. 


MISCELLANEOUS  PHYSICAL  METHODS 


331 


termination.  Kahlenberg,  Davis  and  Fowler,*  for  example,  have  em- 
ployed it  in  measuring  the  speed  of  inversion  of  sucrose.  Table  LXIII, 
by  the  above  authorities,  gives  a  comparison  of  the  inversion  coefficient 
of  sucrose  as  determined  by  the  polariscope  and  freezing-point  methods. 
One-half  gram  molecule  of  sucrose  to  1000  c.c.  was  inverted  at  55.5°  C. 
by  T&<J  gni.  mol.  of  hydrochloric  acid. 

TABLE  LXIII 

Giving  Rate  of  Inversion  of  Sucrose  as  Determined  by  Bolariscope  and  by  Depression 

in  Freezing  Point 


Time. 

Polariscope  read- 
ing. 

Inversion  coeffi- 
cient K  by  polar- 
iscope. 

Depression  in 
freezing  point. 

Inversion  coefficient 
K  by  freezing  point. 

Hours. 
0  0 

22  62 

Degrees  C. 
175 

1.0 
2.0 

2.5 
3.0 
4.0 
4.5 
7.0 
17.5 
26.5 

16.58 
9.92 
7.68 
5.94 
2.54 
1.42 
-2.40 
-6.90 
-7.20 

0.0983 
0.1205 
0.1208 
0.1186 
0.1215 
0.1198 
0.1130 
0.1142 

.393 
.635 
.705 
.809 
.912 
.954 
2.105 
2.230 
2.247 

0.0977 
0.1217 
0.1185 
0.1296 
0.1263 
0.1252 
0.1254 
0.1028 

Average  

0.1158 

0.1147 

It  is  seen  that  the  value  of  the  constant  K,  as  determined  by  the 


Wilhelmy  equation  K  =  -  log 

t 


(p.  660),  is  identical  by  the  two 


methods  of  measurement. 

Beckmann's  Method  for  Determining  Elevation  of  Boiling  Point 

—  Beckmann'sf  method  of  determining  molecular  weights  by  the  eleva- 
tion of  boiling  point  is  the  same  in  principle  as  that  by  depression  of 
freezing  point.  A  gram-molecule  solution  of  an  undissociated  sub- 

002  T2 

stance  should  show  according  to  van't  HofFs  formula  '- — yy —  On  which 

T  =  373  degrees,  the  absolute  boiling  point  of  water  and  W  =  536  cals., 
the  latent  heat  of  evaporation),  an  elevation  in  boiling  point  of 
.002  X  3732 


536 


0.519°  =  A. 


Beckmannt  found  in  one  experiment  an  elevation  in  boiling  point 

*  J.  Am.  Chem.  Soc.,  21,  1. 

t  Z.  physik.  Chem.,  3,  603;  4,  532;  6,  76;  6,  437;  8,  223. 

t  Ibid.,  6,  459. 


332  SUGAR  ANALYSIS 

of  0.315°  C.  for  a  solution  containing  216.8  gms.  of  sucrose  to  1000 

216  8 
gms.  of  water,  or        '     =  0.634  gm.  mols.     The  elevation  in  boiling 


point  for  a  1  gm.  mol.  solution  would  then  be   'OA  =  0.497°  C.,  which 


is  slightly  lower  than  the  value  calculated  by  van't  Hoff's  formula. 

The  general  formula  for  calculating  molecular  weights  from  the 
elevation  in  boiling  point  (A)  is  similar  to  the  formula  for  the  freezing 
point  method  (p.  330)  and  is 

w  X  1000  X  0.52 

M-        JFXA 

The  boiling-point  method,  upon  the  whole,  is  open  to  more  sources  of 
error  than  the  freezing-point  method  and  has  proved  much  less  satis- 
factory as  a  means  of  establishing  the  molecular  weights  of  sugars. 


CHAPTER  XIII 

QUALITATIVE  METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS 

PEOBABLY  no  other  class  of  organic  compounds  gives  such  a  variety 
of  reactions,  or  forms  so  large  a  number  of  chemical  derivatives  as  the 
sugars.  Owing  to  the  great  extent  of  the  field  it  will  be  possible  to 
describe  only  a  few  of  the  more  general  tests  and  reactions. 

In  describing  the  various  chemical  tests,  the  sugars  will  be  classified 
for  convenience  under  two  general  groups:  I.  The  reducing  sugars. 
II.  The  non-reducing  sugars.  The  reducing  sugars  are  distinguished 
by  the  fact  that  they  cause  a  marked  precipitation  of  cuprous  oxide 
when  warmed  with  Fehling's  alkaline  copper  solution,  whereas  the  non- 
reducing  sugars  do  not  exhibit  this  property,  or  only  to  a  very  slight 
extent  after  prolonged  boiling.  The  reducing  sugars  constitute  by  far 
the  larger  group;  of  the  some  one  hundred  known  natural  or  synthetic 
sugars,  about  ninety  are  reducing  and  only  about  ten  non-reducing. 

Reactions  of  the  Reducing  Sugars 

The  characteristic  chemical  properties  of  the  reducing  sugars  are 
due  for  the  most  part  to  the  occurrence  of  a  common  carbonyl-alcohol 

H-C-OH 

group        I          .     The  reducing  sugars,  as  aldoses  or  ketoses,  give  in 
C  =  O 
I 

fact  nearly  all  the  reactions  peculiar  to  aldehydes  and  ketones.  The 
chemist  must,  therefore,  first  of  all,  guard  against  deciding  as  to  the 
presence  oi^a  sugar  from  a  reaction  which  would  also  be  given  by 
formaldehyde,  acetaldehyde  or  acetone.  A  number  of  confirmatory 
tests  must  usually  be  applied,  before  it  can  be  stated  definitely  whether 
a  sugar  is  or  is  not  present. 

The  qualitative  reactions  for  reducing  sugars  are  divided  for  con- 
venience into  I.  General  tests;  II.  Special  tests;  III.  Individual 
tests.  After  it  has  been  determined  from  general  tests  that  a  sugar  is 
present,  special  tests  must  be  applied  in  order  to  determine  what  classes 
or  groups  of  sugars  are  present,  whether  hexoses  or  pentoses,  aldoses  or 
ketoses,  monosaccharides  or  disaccharides.  After  the  class  or  group  of 
sugars  has  been  ascertained,  individual  tests  must  be  applied  in  order 

333 


334  SUGAR  ANALYSIS 

to  determine  what  particular  sugars  are  present.  Only  the  general 
and  special  tests  are  taken  up  in  the  present  chapter.  The  individual 
tests  are  given  under  the  description  of  the  different  sugars  in  Part  II. 

GENERAL  TESTS  FOR  REDUCING  SUGARS 

Among  the  general  tests  which  are  sometimes  given  for  sugars  may 
be  mentioned  the  familiar  property  which  all  carbohydrates  have  of 
giving  off  a  characteristic  sweetish  odor  upon  heating  over  a  flame  in  a 
closed  tube.  This  odor,  which  is  usually  designated  as  caramel-like,  is 
given  off,  however,  by  many  polyatomic  alcohols  and  acids  (as  by  tar- 
taric  acid)  so  that  the  test  is  not  characteristic  of  sugars  alone.  Among 
the  decomposition  products  obtained  by  heating  sugars  in  a  closed  tube 
may  be  mentioned  (besides  water  and  the  gaseous  products  carbon  di- 
oxide and  carbon  monoxide)  formic  acid,  acetic  acid,  acetone,  furfural 
and  various  products  of  an  aldehyde  nature.  It  is  to  the  furfural 
and  aldehyde  products  that  the  characteristic  odor  of  burnt  sugar  is 
largely  due. 

The  general  tests  for  reducing  sugars  may  be  divided  for  conven- 
ience into  four  general  groups  of  reactions. 
I.   Reducing  reactions  with  alkaline  solutions  of  metallic  salts. 
II.   Color  reactions  with  alkalies,  acids  and  phenols. 

III.  Hydrazone  and  osazone  reactions  with  phenylhydrazine  and  its 

substituted  derivatives. 

IV.  Miscellaneous  reactions. 

I.     REDUCING  REACTIONS  OF  SUGARS  WITH  ALKALINE  SOLUTIONS  OF 
METALLIC    SALTS 

The  simple  sugars  and  certain  of  the  disaccharides,  as  maltose  and 
lactose,  have  the  property  of  reducing  alkaline  solutions  of  many 
metallic  salts,  such  as  those  of  copper,  silver,  mercury  and  bismuth. 
'This  reaction,  which  is  common  to  most  aldehydes,  is  due  to  the  with- 
drawal of  oxygen  from  the  metallic  base,  the  latter  being  precipitated 
either  as  a  suboxide  or  in  the  metallic  form.  The  aldehyde  group  of 
the  sugar  molecule  is  oxidized  by  the  oxygen  withdrawn  from  the 
metallic  base  to  the  acid  carboxyl  group,  as  indicated  by  the  following 
general  equation: 

H-C:O         +          2CuO  =      H-O-C:O         +          Cu2O. 

Aldehyde  Copper  Oxide  Acid  Copper  Suboxide. 

The  above,  however,  marks  only  the  beginning  of  the  reaction,  for,  upon 
heating,  the  oxidation  of  the  sugar  molecule  usually  proceeds  with  the 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      335 

conversion  of  alcohol  into  carboxyl  groups  as  in  the  following  reaction 
for  glycol  aldehyde : 
H 

H-C-O-H       +        3Ag20         =    0:C-0-H       +       6Ag        +  H2O. 
H-C:O  O:C-O-H 

Glycol  Silver  oxide  Oxalic  Metallic  Water, 

aldehyde  acid  silver 

This  oxidation  in  the  case  of  the  higher  monosaccharides  is  usually  at- 
tended by  a  breaking  down  of  the  carbon  chain  as  by  the  oxidation  of 
glucose  in  ammoniacal  silver  solution : 

C6H1206  +  9  Ag2O  =  3(COOH)2       +  18  Ag  +  3  H20. 

The  reaction  between  sugars  and  alkaline  salts  of  metals,  as  ordinarily 
carried  out,  gives  rise  to  a  number  of  monobasic  and  dibasic  acids 
(formic,  oxalic,  etc.)  in  varying  proportions  according  to  the  conditions 
of  the  experiment.  It  is  not  possible,  therefore,  to  express  the  reaction 
.by  chemical  equations  except  in  a  very  general  way. 

The  most  common  of  the  alkaline  salt  solutions  employed  in  test- 
ing sugars  are  those  of  copper.  The  sulphate  and  acetate  of  copper 
are  the  salts  most  generally  used  and  sugar  literature  is  filled  with 
descriptions  of  modifications  for  making  the  test.  Only  a  few  of  these 
will  be  described. 

Fehling's  Copper  Solution.  —  This  is  the  most  common  chemical 
reagent  employed  in  testing  sugars.  As  ordinarily  prepared  the  reagent 
consists  of  two  solutions:  solution  A  containing  34.64  gms.  crystallized 
copper  sulphate  to  500  c.c.  and  solution  B  containing  173  gms.  Rochelle 
salts  and  51.6  gms.  sodium  hydroxide  to  500  c.c.  The  solutions  are  the 
same  as  those  used  in  quantitative  analysis  and  are  to  be  kept  separate 
until  just  before  using.  By  mixing  5  c.c.  each  of  solutions  A  and  B  in 
a  test  tube,  adding  a  few  c.c.  of  the  solution  to  be  examined  and  heat- 
ing to  boiling  for  2  minutes,  a  brick-colored  precipitate  of  cuprous  oxide, 
Cu20,  will  form,  if  reducing  sugars  are  present,  the  intensity  of  coloration 
and  amount  of  precipitate  being  proportional  to  the  amount  of  sugar 
present.  The  test  is  sensitive  to  about  0.01  mg.  of  glucose  to  1  c.c. 

Products  Obtained  by  Heating  Reducing  Sugars  with  Fehling's  Solu- 
tions. —  The  chemical  reactions  which  take  place  in  the  oxidation  of 
sugars  by  means  of  Fehling's  solution  are  exceedingly  complex.  Nef,* 
who  has  made  the  most  complete  studies  in  this  field,  found  that  in 
case  of  1-arabinose,  the  oxidation  proceeds  along  three  separate  lines. 

*  Ann.,  357,  214-312. 


336  SUGAR  ANALYSIS 

I.   From  10  to  25  per  cent  of  sugar  are  oxidized  to  form  pentonic 
acids. 

C5Hi005  +  0  =  C5Hi006. 

II.  From  35  to  45  per  cent  of  sugar  are  oxidized  to  form  formic  and  tri- 

oxybutyric  acids. 

C5H1005  +  2O  =  HCOOH  +  C4H805. 

III.  From  30  to  38  per  cent  of  sugar  are  oxidized  to  form  formic  and 

glycollic  acids. 

C5Hio05  +  30  =  HCOOH  +  2  C2H403. 

In  case  of  the  hexose  sugars,  d-glucose,  d-mannose  and  d-fructose, 
Nef  obtained  analogous  reactions  with  formation  of  carbonic,  formic, 
glycollic,  glyceric,  trioxybutyric  and  hexonic  acids.  The  amount  of  the 
different  acids  was  found  to  vary  according  to  the  amount  of  alkali 
present. 

In  testing  solutions  containing  much  foreign  organic  matter  such  as 
urine,  the  reaction  with  Fehling's  solution  may  be  interfered  with. 
Uric  acid,  creatine,  creatinine,  albumin,  peptones  and  other  substances 
may  either  check  the  precipitation  of  cuprous  oxide,  when  reducing  sugars 
are  present,  or  in  some  cases  cause  a  precipitate  of  copper  in  the  com- 
plete absence  of  sugars.  Solutions  containing  xanthine  bases,  such  as 
low-grade  molasses,  distillery  waste,  etc.,  when  heated  with  Fehling's 
solution  may  precipitate  greenish-yellow  copper  compounds,  which  may 
be  mistaken  for  cuprous  oxide.  In  all  such  cases  the  impure  solution 
should  be  clarified  with  a  little  normal  acetate  of  lead  and  filtered ;  any 
excess  of  lead  is  removed  from  the  filtrate  with  sodium  carbonate  and 
the  clear  solution  tested  with  Fehling's  reagent  in  the  usual  way. 
Filtering  the-  impure  solution  through  animal  charcoal  is  also  of  ad- 
vantage when  foreign  coloring  matter  masks  the  reaction. 

Barfoed's  Copper  Solution.  —  Instead  of  the  sulphate,  solutions 
of  other  copper  salts  have  been  employed  in  testing  for  sugars.  Bar- 
foed  *  has  prepared  a  solution  containing  one  part  crystallized  neutral 
copper  acetate  in  15  parts  of  water;  5  c.c.  of  38  per  cent  acetic  acid  are 
added  to  200  c.c.  of  the  copper-acetate  solution  before  use.  On  boiling 
the  solution  a  basic  acetate  of  copper  is  formed,  the  liberated  cupric 
oxide  being  reduced  in  presence  of  monosaccharides.  Barfoed's  reagent 
is  not  reduced  to  any  great  extent  by  the  disaccharides,  lactose  and 
maltose,  and  is,  therefore,  of  value  in  distinguishing  these  sugars  from 
monosaccharides. 

*  Z.  analyt.  Chem.,  12,  27. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       337 

Soldaini's  Copper  Solution.  —  Carbonate  of  copper  solution  has 
also  been  used  in  testing  for  sugars.  Soldaini  *  has  prepared  a  solution 
containing  15  gms.  precipitated  copper  carbonate,  CuGO3,  and  416  gms. 
potassium  bicarbonate,  KHCO3,  dissolved  to  1400  c.c.  Instead  of  start- 
ing with  copper  carbonate,  copper  sulphate  may  be  used;  a  solution  of 
the  latter  is  added  to  the  KHCOs  solution,  the  precipitate  of  CuCOs 
first  formed  being  dissolved  in  the  excess  of  bicarbonate.  A  solution 
containing  3.464  gms.  copper  sulphate  and  297  gms.  potassium  bicar- 
bonate to  1000  c.c.  is  especially  adapted  for  detecting  small  amounts  of 
reducing  sugars. 

Among  other  copper  solutions  recommended  for  testing  sugars  may 
be  mentioned  copper  ammonium  tartrate  and  ammoniacal  copper  sul- 
phate or  acetate.  None  of  these  preparations  has  been  found,  how- 
ever, to  equal  Fehling's  reagent  for  general  usefulness  in  practical 
sugar  analysis. 

Tollens's  Silver  Solution. — The  most  sensitive  of  metallic-salt  solu- 
tions for  detecting  sugars  is  ammoniacal  silver  solution,  first  employed 
by  Tollens  f  and  hence  usually  known  as  Tollens's  reagent.  This  is  pre- 
pared by  dissolving  one  part  silver  nitrate  in  10  parts  of  water;  a  second 
solution  is  then  made  containing  one  part  sodium  hydroxide  in  10  parts 
of  water.  Before  making  the  test  equal  parts  of  the  two  solutions  are 
mixed  and  then  ammonia  added  drop  by  drop  until  the  precipitate  of 
silver  oxide  is  completely  dissolved.  A  solution  containing  one  part  of 
glucose  in  1000  parts  of  water  will  cause  a  strong  reduction  of  Tollens's 
reagent  in  the  cold,  a  mirror  of  silver  being  deposited  within  15  min- 
utes. A  solution  containing  one  part  glucose  to  100,000  parts  of  water 
will  also  produce  a  perceptible  reduction. in  the  cold,  but  the  solution 
must  stand  one  to  two  days.  The  reduction  takes  place  more  rapidly 
upon  warming,  but  warming  or  heating  the  solution  is  to  be  avoided 
owing  to  the  danger  of  forming  explosive  silver  compounds.  For  the 
latter  reason  the  reagent  should  be  prepared  only  just  before  using. 
Tests  should  be  carried  out  in  the  dark  and  solutions  containing  the 
reagent  should  not  be  kept  for  any  length  of  time. 

Tollens's  silver  reagent  is  also  reduced  by  all  aldehyde  substances; 
it  is  affected  not  only  by  the  sugars  which  reduce  Fehling's  solution 
but  also  by  sucrose,  raffinose  and  all  other  soluble  carbohydrates. 
Even  the  alcohol  derivatives  of  the  sugars  produce  reduction,  glycerol, 
for  example,  causing  the  formation  of  a  silver  mirror.  The  readiness 
with  which  ammoniacal  silver  solution  is  reduced  by  soluble  organic 

*  Z.  Ver.  Deut.  Zuckerind.,  39,  933;  40,  792. 
t  Ber.,  15,  1635;  16,  921. 


338  SUGAR  ANALYSIS 

non-sugars  has  proved  a  serious  objection  against  the  use  of  this  reagent 
in  ordinary  analytical  work. 

Knapp's  Mercury  Solution. — A  third  reagent  which  has  been  used 
for  testing  sugars  is  Knapp's*  alkaline  mercuric-cyanide  solution.  The 
latter  contains  10  gms.  of  mercuric  cyanide  dissolved  in  100-c.c.  sodium 
hydroxide  solution  of  1.145  specific  gravity.  Similar  alkaline  solutions 
have  been  prepared  by  Sachsse  f  from  mercuric  iodide  and  by  Bauer  J 
from  mercuric  chloride.  These  solutions  are  reduced  upon  warming 
with  sugar  solutions  giving  grayish  deposits  of  metallic  mercury. 
The  mercury  solutions  have  the  same  objection,  however,  as  those  of 
silver  in  being  reduced  by  different  organic  non-sugars,  such  as  creatine, 
creatinine  and  glycerol  and  even  under  certain  conditions  by  alcohol. 
Alkaline  solutions  of  mercury  salts  are,  therefore,  of  but  little  value  in 
detecting  sugar  in  urine  and  other  liquids  rich  in  organic  non-sugars. 

Nylander's  Bismuth  Solution.  —  A  fourth  reagent,  which  has  been 
used  considerably  for  detecting  reducing  sugars  in  urine,  is  an  alkaline 
solution  of  bismuth  sub-nitrate,  known  as  Nylander's  §  (or  Almen's) 
reagent.  This  solution  as  prepared  by  Nylander  is  made  by  dissolving 
2  gms.  of  bismuth  sub-nitrate  and  4  gms.  of  Rochelle  salts  in  100  gms. 
of  8  per  cent  sodium  hydroxide  solution.  After  standing  for  a  few  days 
the  solution  is  filtered  through  glass  wool  and  the  clear  filtrate  preserved 
in  a  stoppered  bottle.  The  solution  will  keep  indefinitely.  When 
Nylander's  reagent  is  heated  with  a  solution  containing  reducing  sugars 
a  precipitate  of  dark  metallic  bismuth  is  produced.  Heating  with  TV  its 
volume  of  0.01  per  cent  glucose  solution  will  cause  a  perceptible  darken- 
ing. In  testing  urine  1  c.c.  of  the  reagent  and  10  c.c.  of  urine  are 
heated  in  a  test  tube  2  to  5  minutes  over  the  flame;  after  standing 
for  5  minutes  the  solution  is  examined  for  the  appearance  of  a  dark- 
colored  sediment. 

Nylander's  reagent,  however,  is  open  to  the  same  objections  noted 
for  the  alkaline  silver  and  mercury  solutions.  The  presence  of  albu- 
min, nuclein,  glucuronic  acid  and  other  organic  non-sugars  in  urine 
will  also  cause  a  precipitation  of  bismuth,  even  when  glucose  is  com- 
pletely absent.  While  the  failure  of  a  precipitate  with  Nylander's  re- 
agent may  indicate  the  absence  of  reducing  sugars,  the  occurrence  of  a 
precipitate  may  be  said  to  indicate  the  presence  of  sugar  only  when  re- 
ducing non-sugars  are  proved  to  be  absent. 

*  Z.  analyt.  Chem.,  9,  395. 
t  Z.  Ver.  Deut.  Zuckerind.,  26,  872. 
t  Landw.  Vers.-Stat.,  36,  304. 
§  Z.  physiol.  Chem.,  8,  175. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      339 

Miscellaneous  Solutions.  —  Of  other  alkaline  solutions  of  metallic 
salts  proposed  for  sugar  testing  may  be  mentioned  alkaline  nickel  sul- 
phate and  tartaric  acid  which  gives  a  dark-red  precipitate  of  nickel  sub- 
oxide  in  presence  of  reducing  sugars,  and  alkaline  ferric  chloride  and 
sodium  tartrate  which  gives  a  brown-colored  precipitate  on  heating 
with  reducing  sugars.  None  of  these  reagents,  however,  or  any  of  the 
other  alkaline  solutions  of  metallic  salts  previously  mentioned,  has  been 
found  to  equal  Fehling's  copper  reagent  for  all-around  usefulness  and 
reliability. 

II.  COLOR  REACTIONS  OF  SUGARS  WITH  ALKALIES,  ACIDS  AND  PHENOLS 

As  a  second  general  reaction  of  reducing  sugars  may  be  mentioned 
certain  color  effects  which  nearly  all  soluble  carbohydrates  give  when 
brought  into  contact  with  different  reagents.  The  reagents  employed 
may  be  divided  into  three  groups: 

I.   Alkalies. 

II.   Concentrated  mineral  acids. 
III.   Phenols. 

Color  Reactions  of  Sugars  with  Alkalies.  —  All  reducing  sugars 
have  the  property  of  coloring  solutions  of  the  alkalies  and  alkaline 
earths  yellow,  the  application  of  heat  turning  the  color  a  dark  brown. 
This  reaction  is  common  to  all  aldehydes.  The  exact  nature  of  the 
coloring  matter  formed  by  the  action  of  alkalies  upon  sugars  in  solution 
is  not  understood.  Considerable  oxygen  is  absorbed  from  the  air  dur- 
ing the  reaction  and  a  variety  of  products  of  an  acid  nature  are  among 
the  substances  formed. 

Products  Obtained  by  Heating  Reducing  Sugars  with  Alkali.  —  Lactic 
acid  is  produced  in  considerable  amount  by  the  action  of  alkalies  upon 
many  reducing  sugars  such  as  xylose,  arabinose,  glucose  and  fructose. 
The  presence  of  calcium  lactate  in  certain  sugar-cane  molasses  is  ex- 
plained by  the  action  of  an  excess  of  lime  during  clarification  upon  the 
reducing  sugars  of  the  juice.  Formic,  acetic  and  oxalic  acids  have  also 
been  found  among  the  products  resulting  from  the  action  of  alkalies 
upon  sugars  in  solution.  Certain  phenol  bodies  such  as  pyrocatechin 
and  protocatechuic  acid  have  also  been  detected  among  the  oxidation 
products  of  sugars  resulting  from  treatment  with  alkalies. 

Nef  *  has  studied  the  action  of  J  normal  sodium  hydroxide  upon  dif- 
ferent sugars  and  obtained  in  case  of  d-glucose,  d-mannose,  and  d-fruc- 

*  Ann.,  376,  1-119. 


340  SUGAR  ANALYSIS 

tose  a  yield  of  from  40  to  45  per  cent  d,l-lactic  acid,  from  10  to  15  per 
cent  d,l-l-hydroxybutyrolactone,  about  25  per  cent  of  saccharin,  meta- 
saccharin  and  isosaccharin  and  a  small  quantity  of  tarry  decomposition 
products. 

The  action  of  dilute  alkalies  in  causing  transformations  of  sugars  into 
one  another  by  molecular  rearrangement  is  referred  to  elsewhere. 

Color  Reactions  of  Sugars  with  Mineral  Acids.  —  Treatment  of 
solutions  of  sugars  and  carbohydrates  with  concentrated  mineral  acids 
gives  rise  to  a  number  of  decomposition  products,  the  color  of  which 
frequently  throws  some  light  upon  the  nature  of  the  sugars  present. 
The  acids  most  commonly  used  for  this  purpose  .are  sulphuric  and 
hydrochloric.  The  character  of  the  color  generated  will  depend  partly 
upon  the  kind  of  sugar,  partly  upon  the  strength  of  acid  used  and 
partly  upon  the  temperature  of  the  reaction. 

Products  Obtained  by  Heating  Sugars  with  Acids.  —  The  darkening 
produced  in  all  sugar  solutions  upon  warming  with  concentrated  sul- 
phuric or  hydrochloric  acid  is  due  largely  to  the  formation  of  insoluble 
so-called  "humus"  substances  of  relatively  high  carbon  content  (C  =  62 
to  67  per  cent  and  H  =  3.5  to  4.5  per  cent),  the  percentage  of  carbon  and 
depth  of  color  increasing  with  the  strength  of  acid  used.  Attempts  have 
been  made  to  classify  the  humus  substances  formed  by  the  action  of 
acid  upon  sugars  into  ulmin  and  humin  and  ulmic  and  humic  acids, 
to  which  various  formulae  have  been  assigned  by  different  authorities. 
The  constitution  of  the  humus  substances  has  not  been  definitely 
settled,  however,  and  until  considerable  more  work  has  been  done  the 
formulae  of  these  must  remain  more  or  less  a  matter  of  conjecture. 

In  addition  to  the  insoluble  humus  substances  a  number  of  soluble 
and  volatile  products  are  formed  by  the  action  of  sulphuric  and  hydro- 
chloric acids  upon  sugars.  Among  such  products  may  be  mentioned 
formic  acid,  levulinic  acid,  furfural,  methylfurfural,  oxymethylfurfural 
and  a  number  of  dextrin-like  condensation  or  reversion  products  of  high 
specific  rotation.  The  nature  and  amount  of  these  various  products 
depend  largely  upon  the  kind  of  sugar,  and  a  number  of  methods  of 
group  distinction  are  based  upon  the  separation  of  characteristic  de- 
compositfon  products.  Further  reference  will  be  made  to  these  under 
the  special  reactions. 

The  ketoses  are  much  more  easily  decomposed  by  strong  mineral 
acids  than  the  aldoses  and  their  solutions  give  rise  to  color  reactions 
with  corresponding  greater  facility.  This  offers  one  means  of  dis- 
tinguishing between  a  ketose  and  aldose  or  of  detecting  a  ketose  sugar 
in  presence  of  an  aldose.  If  a  cold  sugar  solution  be  treated  in  a  test 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       341 

tube  with  a  few  cubic  centimeters  of  concentrated  sulphuric  acid,  allow- 
ing the  latter  to  flow  down  the  walls  of  the  tube  to  the  bottom  without 
shaking,  a  brown  ring  will  quickly  form  at  the  junction  of  the  acid  and 
sugar  solution  if  fructose,  sucrose  or  a  sugar  containing  the  ketone 
group  is  present;  with  glucose,  lactose,  maltose  and  the  aldoses  in 
general  no  such  coloration  will  develop. 

Color  Reactions  of  Sugars  with  Phenols.  —  The  most  distinctive 
color  reactions  of  the  sugars  are  those  obtained  by  treatment  with 
different  phenols  in  presence  of  concentrated  hydrochloric  or  sulphuric 
acid.  The  development  of  a  color  in  this  case  is  due  to  the  formation 
of  condensation  products  between  the  phenol  derivatives  and  the  de- 
composition products  obtained  from  the  sugar  (humus  substances, 
furfural,  aldehydes,  etc.).  a-Naphthol,  thymol,  resorcin,  orcin,  naph- 
thoresorcin  and  phloroglucin  are  among  the  more  important  phenol  de- 
rivatives used  for  making  color  reaction  with  sugars. 

The  color  reactions  with  the  phenols  are  performed  in  various 
ways.  The  test  with  a-naphthol,  for  example,  which  is  perhaps  used 
more  frequently  than  any  of  the  others,  is  made  as  follows:  1  to  2 
cubic  centimeters  of  the  sugar  solution  are  treated  in  a  test  tube  with 
1  to  2  drops  of  a  10  to  20  per  cent  alcoholic  solution  of  a-naphthol.  A 
few  cubic  centimeters  of  concentrated  sulphuric  acid  (must  be  free  from 
nitric  acid)  are  then  carefully  added  so  as  to  flow  down  the  walls  of  the 
tube  to  the  bottom.  If  sugars  containing  a  ketone  group  are  present 
a  violet  ring  will  form  instantly  at  the  junction  of  the  two  liquids;  in 
presence  of  aldoses  a  gentle  warming  of  the  test  tube  is  usually  neces- 
sary in  order  to  bring  out  the  full  intensity  of  color.  The  a-naphthol 
test,  which  is  of  extreme  delicacy,  is  frequently  employed  in  sugar 
houses  and  refineries  in  testing  the  condensation  water  from  the  vacuum 
pan  for  presence  of  sucrose  lost  by  entrainment. 

If  the  reaction  described  for  a-naphthol  is  carried  out  with  thymol, 
menthol,  resorcin  and  other  phenols  similar  colorations  are  produced, 
the  tints  varying  from  cherry  red  to  deep  purple. 

The  tests  with  phenols  and  hydrochloric  acid  are  usually  made  by 
warming  a  few  cubic  centimeters  of  the  sugar  solution  with  a  solution 
of  the  phenol  (resorcin,  orcin,  phloroglucin,  etc.)  in  concentrated  hydro- 
chloric acid.  The  colorations  thus  obtained  are  usually  very  brilliant, 
varying  in  tint  from  a  bright  red  to  a  bluish  violet.  The  colors  formed 
are  not  permanent,  however;  they  rapidly  darken  and  the  clear-colored 
solution  soon  becomes  turbid  with  the  precipitation  of  a  dark-colored 
condensation  product. 


342 


SUGAR  ANALYSIS 


USE  OF  THE  SPECTROSCOPE  IN  STUDYING  COLOR  REACTIONS  FOR  SUGARS 

The  spectroscope  has  been  used  with  great  success  by  Tollens  and 
his  coworkers  in  studying  the  colors  obtained  by  treating  sugars  with 
different  reagents.  The  appearance  of  characteristic  absorption  bands 
in  different  parts  of  the  spectrum,  when  the  colored  solution  is  viewed 
through  the  spectroscope  against  white  light,  is  peculiar  of  many  sugars. 

Description  of  Direct-vision  Spectroscope.  —  A  simple  type  of 
spectroscope  for  studying  absorption  spectra  is  the  direct  vision  in- 


Fig.  158. 


—3- — 


Fig.  159. 
Showing  outer  and  inner  construction  of  a  direct-vision  spectroscope. 

strument  illustrated  in  Fig.  158,  the  interior  construction  of  which  is 
shown  in  Fig.  159. 

The  essential  parts  of  the  apparatus  consist  of  a  telescopic  tube  con- 
taining an  Amici  prism  P  and  an  achromatic  objective  0.  At  one  end 
of  the  tube,  protected  by  the  screw  cap  K,  a  diaphragm  is  situated  con- 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      343 

taining  a  narrow  slit  S,  the  width  of  which  can  be  adjusted  by  turning 
the  milled  ring  B.  The  upper  half  of  the  slit  is  covered  with  a  small 
prism  V;  a  mirror  D,  which  can  be  rotated  through  a  small  angle  about 
the  axis  of  the  tube,  is  also  attached  to  the  slit  end  of  the  instrument. 

At  the  prism  end  of  the  spectroscope  there  is  fixed  a  small  lateral 
tube  T  containing  a  graduated  scale  E.  The  latter  is  attached  to  a 
small  prism  b  to  which  is  fixed  a  converging  lens  a.  At  R  is  a  right 
angle  prism,  from  the  hypotenuse  surface  of  which  the  image  of  the 
scale  E  is  reflected  through  the  achromatic  objective  0'  upon  the  cut 
surface  cc  of  the  Amici  prism. 

If  the  slit  end  of  the  spectroscope  be  pointed  towards  a  sodium 
flame  the  rays  of  light  will  pass  into  the  spectroscope  along  the  paths  1, 
2  and  3.  The  telescope  is  first  focused  by  turning  the  milled  ring  G 
until  a  sharply  defined  image  of  the  lower  uncovered  half  of  the  slit 
is  obtained  by  the  light  passing  along  2  upon  the  surface  cc.  The  image 
of  the  scale  E  is  reflected  at  the  same  time,  by  the  light  passing  along 
3;  also  upon  cc.  The  position  of  the  sodium  line  is  noted  upon  the 
graduated  scale,  the  latter  being  in  this  way  standardized.  If  the 
spectroscope  be  now  directed  towards  the  sky  a  continuous  spectrum 
is  obtained  upon  the  surface  cc;  the  mirror  D  is  next  turned  until  the 
light  passing  along  1  is  reflected  through  an  opening  in  the  cap  K  upon 
the  small  prism  V  and  thence  through  the  upper  half  of  the  slit  S',  in 
this  way  a  continuous  spectrum  is  obtained  upon  cc  the  width  of  which 
is  equal  to  the  total  length  of  the  slit  S. 

If  the  slit  has  been  sufficiently  reduced  in  width,  the  spectrum  of 
sunlight  is  seen  to  be  crossed  by  a  number  of  dark  lines,  the  so-called 
Fraunhofer  lines,  which  are  due  to  the  absorption  of  certain  rays  of 
light  from  the  incandescent  mass  of  the  sun  by  the  vaporized  elements 
of  the  solar  atmosphere.  A  dark  line  (the  D  line  of  Fraunhofer's  scale), 
for  example,  corresponds  to  the  position  of  the  bright-yellow  line 
obtained  with  the  sodium  flame  and  so  of  the  other  elements.  The 
position  and  wave-length  of  the  more  important  Fraunhofer  lines  is 
shown  in  Fig.  165  (p.  384) ;  their  presence  is  very  helpful  in  defining  the 
position  of  absorption  spectra. 

For  studying  absorption  spectra  the  spectroscope  is  mounted  upon 
a  stand  as  shown  in  Fig.  160,  a  screen  L  being  attached  to  the  tube  to 
shade  the  eye  of  the  observer.  The  solution  to  be  examined  is  placed 
in  a  small  cell  T,  before  the  front  opening  in  the  screw  cap  and  viewed 
against  white  light.  The  rays  of  light  absorbed  by  the  solution  will 
cause  characteristic  dark-colored  bands  to  appear  upon  that  part  of  the 
spectrum  corresponding  to  the  lower  half  of  the  slit.  The  part  of  the 


344 


SUGAR  ANALYSIS 


spectrum  corresponding  to  the  half  of  the  slit  covered  by  the  prism  V 
meanwhile  remains  continuous  and  together  with  the  scale,  or  Fraun- 
hofer  lines,  serves  for  the  exact  location  of  the  absorption  bands. 


_™...    -  ::  —» 

Fig.  160.  Fig.  161. 

Methods  of  mounting  apparatus  for  study  of  absorption  spectra. 

Solutions  which  arc  only  weakly  absorptive  are  best  examined  through 
a  large  tube  H,  in  the  manner  shown  in  Fig.  161.  The  spectroscope  is 
turned  and  clamped  in  a  vertical  position  and  the  light  reflected  upward 
from  the  mirror  F  through  the  glass  bottom  of  the  support  G. 

Tollens's  Method  of  Studying  Absorption  Spectra. — In  preparing 
color  tests  of  sugar  solutions  for  spectroscopic  examination  it  is  im- 
portant that  the  color  remain  permanently  in  solution  and  that  no  tur- 
bidity develop  which  would  obscure  the  visible  parts  of  the  spectrum. 
This  is  sometimes  accomplished  by  carrying  out  the  reaction  in  presence 
of  alcohol  or  some  other  solvent  to  hold  the  color  compound  in  solu- 
tion. A  better  way  is  by  use  of  Tollens's*  deposit  method  ("Absatz- 
methode  ")•  In  this  method  the  deposit  of  insoluble  condensation  prod- 

*  Ber.,  29,  1202. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       345 

ucts  obtained  by  treating  the  sugar  solution  with  hydrochloric  acid 
and  the  phenol  (orcin,  phloroglucin,  naphthoresorcin,  etc.)  is  filtered  off, 
washed  several  times  with  water  and  then  dissolved  in  alcohol.  Bright- 
colored  solutions  are  thus  obtained  which  can  be  brought  by  dilution  with 
alcohol  to  the  degree  of  intensity  suitable  for  spectroscopic  examination. 
Descriptions  of  characteristic  absorption  spectra  will  be  given  under  the 
reactions  for  groups  and  individual  sugars. 

.  Of  less  importance  than  the  color  reactions  with  phenols  are  the 
color  tests  obtained  by  treating  sugars  with  aromatic  amines  (aniline, 
xylidine,  diphenylamine,  etc.)  in  presence  of  concentrated  hydrochloric 
acid.  The  colors  in  this  instance  are  due  to  a  combination  between  the 
aromatic  amine  and  the  furfural,  methylfurfural,  and  oxymethyl- 
furfural  derived  from  the  decomposition  of  the  sugar. 

III.     HYDRAZONE  AND   OSAZONE  REACTIONS  OF  REDUCING  SUGARS  WITH 
PHENYLHYDRAZINE  AND  ITS  SUBSTITUTED  DERIVATIVES 

In  many  respects  the  most  important  of  the  qualitative  tests  for 
sugars  are  those  obtained  with  phenylhydrazine  and  its  substituted 
derivatives.  Phenylhydrazine  was  introduced  as  a  reagent  in  sugar 
chemistry  by  Emil  Fischer*  in  1884;  it  has  been  of  immense  service 
not  only  as  a  means  of  separation  and  identification  but  also  in  first 
opening  a  way  to  a  thorough  understanding  of  the  molecular  constitu- 
tion of  sugars. 

Hydrazone  Reaction.  —  The  reaction  with  phenylhydrazine  is 
limited  to  such  sugars  as  contain  a  free  carbonyl  group  and  proceeds  in 
two  phases  with  production  of  two  entirely  different  classes  of  com- 
pounds. The  first  phase  of  the  reaction  is  common  to  all  aldehydes 
and  ketones,  the  0  of  the  carbonyl  group  combining  with  H2  of  the 
amino  group  in  the  phenylhydrazine  with  formation  of  a  group  of 
compounds  called  hydrazones.  With  formaldehyde,  for  example,  the 
reaction  proceeds  as  follows: 

H2C:0          +        H2N-NHC6H6      =      H2C:N-NHC6H5        +        H2O 

Formaldehyde  Phenylhydrazine  Formaldehyde-  Water 

phenylhydrazone 

With  the  carbonyl  group  of  a  sugar  the  reaction  would  be  for  a 
diose : 

CH2OH  CH2OH 

HC:0          +        H2N-NHC6H6      =       HC:N-NHC6H6        +       H2O 

Diose  Phenylhydrazine  Dioae-phenylhydrazone  Water 

*  Ber.,  17,  579. 


346  SUGAR  ANALYSIS 

The  hydrazone  reaction  is  carried  out  by  treating  the  sugar  solution 
in  the  cold  with  a  solution  containing  one  volume  of  phenylhydrazine, 
one  volume  of  50  per  cent  acetic  acid,  and  three  volumes  of  water.  A 
little  more  of  the  phenylhydrazine  is  used  in  making  the  test  than  the 
theoretical  quantity  corresponding  to  the  supposed  amount  of  sugar 
present.  In  place  of  the  above  solution  the  crystalline  chloride  of 
phenylhydrazine  may  be  used  to  advantage,  a  few  grams  of  sodium 
acetate  being  also  added  to  promote  the  reaction.  After  the  above 
treatment  the  hydrazones  of  the  sugars  will  separate  sooner  or  later 
as  well-defined  crystalline  compounds,  the  length  of  time  for  separation 
depending  upon  the  solubility  of  the  hydrazones  formed.  The  phenyl- 
hydrazone  of  mannose,  for  example,  being  very  insoluble,  will  separate 
almost  immediately;  those  of  the  methylpentoses,  fucose,  rhamnose 
and  rhodeose  also  deposit  readily;  the  phenylhydrazone  of  glucose,  on 
the  other  hand,  which  is  quite  soluble  in  water,  may  require  one  or  two 
days  for  its  precipitation.  By  filtering  off  the  hydrazones  as  they  are 
formed  a  separation  of  sugars  in  mixtures  may  often  be  accomplished. 

After  separation  of  the  hydrazones  the  latter  are  filtered  off  and  re- 
crystallized  either  from  water  or,  in  case  of  difficultly  soluble  hydrazones, 
from  alcohol  or  pyridine. 

Use  of  Substituted  Derivatives  of  Phenylhydrazine.  —  In  place  of 
phenylhydrazine  any  of  its  substituted  derivatives  may  be  used  for  the 
purpose  of  precipitating  sugars.  The  substituted  phenylhydrazines 
yield  in  many  cases  characteristic  hydrazones  with  sugars  and  their  use 
in  sugar  chemistry  in  recent  years  has  been  of  the  greatest  service.  Of 
the  various  substituted  phenylhydrazines  the  following  are  among  the 
most  important. 


1.  Methylphenylhydrazine  H2N  — N 

XC6H5 

2.  Ethylphenylhydrazine  H2N  — Nx 

NC6H5 


3.  Amylphenylhydrazine  H2N  — N 

XC6H5 

C  H 

4.  Allylphenylhydrazine  H2N  —  N 

N  C6H5 


XC6H5 


5.  Diphenylhydrazine  H2N— N 

•\ 

C*  TT 

6.  Benzylphenylhydrazine  H2N— N/ 

xCeH6 


TT 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      347 

7.  Parabromophenylhydrazine  H2N  —  N 

8.  Paranitrophenylhydrazine  H2N  —  N 


C6H4Br 

TT 

C6H4N0 


Other  hydrazines  than  those  of  the  phenyl  group  are  also  employed 
as,  for  example, 

TT 

9.   Naphthylhydrazine  H2N-N^ 

CloHj 

The  reactions  with  the  substituted  hydrazines  are  usually  best 
carried  out  in  alcoholic  solution,  the  hydrazones  formed  being  for  the 
most  part  much  less  soluble  than  those  of  ordinary  phenylhydrazine. 

In  the  examination  of  the  hydrazones  obtained  from  sugar  solutions 
a  melting  point  of  the  product  is  taken  before  and  after  recrystalliza- 
tion.  If  the  melting  point  remains  unchanged  the  hydrazone  is  pure. 
Should  a  difference  in  the  temperature  of  melting  be  obtained  the 
hydrazone  should  be  recrystallized  until  successive  determinations  show 
no  change  in  melting  point.  A  table  of  melting  points  will  then  usually 
identify  the  hydrazone  of  the  sugar.  (See  Table  24,  Appendix.) 

Separation  of  Sugars  from  Hydrazones.  —  When  a  sufficient  quantity 
of  hydrazone  is  available  it  is  always  well  to  decompose  the  compound 
and  make  a  direct  examination  of  the  separated  sugar.  For  the  separa- 
tion of  sugars  from  their  hydrazones  two  processes  are  available: 
•First,  by  means  of  concentrated  hydrochloric  acid  as  originally  used  by 
Fischer.  Second,  by  means  of  benzaldehyde  and  formaldehyde  as  rec- 
ommended by  Herzfeld*  and  by  Ruff.f 

When  the  hydrazone  of  a  sugar  is  treated  with  concentrated  hydro- 

chloric acid  the  chloride  of  the  hydrazine  and  free  sugar  are  formed:  — 

C6H1205N-NHC6H5    +    HC1    +    H20     =     C6H12O6    +    HC1  H2N-NHC6H5 

Hexose-pheny  I  hydrazone  Hexose  Phenylhydrazine 

chloride 

The  phenylhydrazine  chloride  is  almost  insoluble  in  concentrated  hydro- 
chloric acid  and  is  removed  by  filtration.  The  filtrate  is  neutralized  with 
lead  carbonate;  the  lead  chloride  is  filtered  off  and  the  filtrate  evapo- 
rated to  a  syrup.  The  latter  is  shaken  with  95  per  cent  alcohol,  any 
remaining  lead  chloride  filtered  off  and  the  alcoholic  filtrate  evaporated 
to  a  sirup  which  is  set  aside  for  the  sugar  to  crystallize. 

*  Ber.,  28,  442. 
t  Ber.,  32,  3234. 


348  SUGAR  ANALYSIS 

The  separation  of  sugars  from  their  hydrazones  by  means  of  alde- 
hydes is  much  simpler  than  by  use  of  hydrochloric  acid  and  this  is  the 
process  most  generally  used  at  present.  For  this  purpose  benzaldehyde 
is  usually  employed  for  the  hydrazones  of  phenylhydrazine  and  formal- 
dehyde for  the  hydrazones  of  the  substituted  hydrazines.  The  reaction 
between  the  aldehyde  and  hydrazone  is  a  simple  one,  the  aldehyde  dis- 
placing the  sugar  with  formation  of  aldehyde  hydrazone. 


+    CeHsCHO     =     C6H1206     +    C6H6CHN-NHC6H5 

Hexose-phenylhydrazone  Benzaldehyde  Hexose  Benzaldehyde- 

phenylhydrazone 

C6Hi2O5N-N(C6H5)2     +         CH2O        =     C6Hi2O6     +  CH2N-N(C6H5)2 

Hexose-diphenylhydrazone  Formaldehyde  Hexose  Formaldehyde- 

diphenylhydrazone 

The  reaction  is  best  carried  out  by  treating  a  solution  of  the  hydra- 
zone  in  50  per  cent  alcohol  in  a  flask  with  an  amount  of  the  aldehyde 
slightly  in  excess  of  the  theoretical  quantity  necessary  to  effect  de- 
composition. The  flask  is  then  attached  to  a  reflux  condenser  and 
the  solution  gently  boiled  for  an  hour.  After  cooling,  the  solution  is 
filtered  from  the  aldehyde  hydrazone,  the  filtrate  shaken  out  several 
times  with  ether  in  a  separatory  funnel,  the  sugar  solution,  after  de- 
colorizing with  animal  charcoal,  evaporated  to  a  sirup  and  set  aside  for 
crystallization.  Should  crystallization  not  take  place  immediately, 
the  process  may  be  promoted  by  priming  the  sirup  with  a  minute 
crystal  of  the  sugar  suspected  to  be  present.  After  crystallization  the 
sugar  crystals  are  filtered  off,  washed  with  alcohol  and  ether  (using 
suction)  and  dried  between  filter  paper  in  a  desiccator  over  concen- 
trated sulphuric  acid.  The  identity  of  the  sugar  thus  obtained  is  then 
established  by  determination  of  its  specific  rotation. 

If  the  filtrate  obtained  from  filtration  of  a  hydrazone  be  shaken  out 
with  ether  to  remove  excess  of  hydrazine,  the  solution  can  be  treated  a 
second  time  with  a  different  hydrazine.  In  this  manner  a  qualitative 
separation  of  several  mixed  sugars  may  be  accomplished. 

Osazone  Reaction.  —  While  the  hydrazone  reaction  is  of  pre- 
eminent value  in  the  isolation  of  sugars,  the  osazone  test  with  phenyl- 
hydrazine is  usually  of  more  qualitative  significance  owing  to  the 
greater  insolubility  of  the  osazones  in  water  and  the  consequent 
greater  rapidity  and  ease  of  their  separation  as  compared  with  hydra- 
zones. 

If  a  solution  of  a  reducing  sugar  be  treated  with  an  excess  of  phenyl- 
hydrazine and  then  warmed,  two  molecules  of  phenylhydrazine  unite 
with  the  sugar  molecule  forming  an  osazone.  The  aldehyde  or  ketorffe 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      349 

group  of  the  sugar  and  the  adjacent  alcohol  group  are  the  ones  which 
always  participate  in  this  reaction. 

CH2OH  CH2OH 

(HCOH)s_  (HCOH)3 

HCOH       +  ^N-NHCeHs      =      C:N-NHC6H6    +    2H2O      + .  H, 
HC:O  HC:N-NHC6H6 

Hexose  Phenylhydrazine  Hexose-phenylosazone  Water  Hydrogen 

The  free  hydrogen  liberated  in  the  above  reaction  acts  upon  a  part 
of  the  excess  of  phenylhydrazine  reducing  this  to  aniline  with  liberation 
of  ammonia. 

H2N-NHC6H5  +  H2  NH2C6H5  +  NH3 

Phenylhydrazine  Hydrogen  Aniline  Ammonia 

Since  the  first  stage  in  the  reaction  with  phenylhydrazine  is  the  for- 
mation of  a  hydrazone,  it  follows  that  all  phenylhydrazones  when 
treated  with  phenylhydrazine  in  excess  are  changed  to  the  correspond- 
ing osazones. 
C6H1205N-NHC6H5  +  H2N-NHC6H5  =  C6H10O4(N-NHC6H5)2  +  H2O  +    H2 

Hexose-phenylhydrazone  Phenylhydrazine  Hexose-phenylosazone  Water  Hydrogen 

In  conducting  the  reaction  for  osazones  the  original  method  of 
Fischer*  is  usually  followed.  For  1  gm.  of  sugar,  2  gms.  of  phenyl- 
hydrazine chloride  and  3  gms.  crystallized  sodium  acetate  (CH3COONa  + 
3  H2O)  and  20  c.c.  of  water  are  heated  together  for  f  to  1J  hours  in  a 
large  test  tube  of  about  50  c.c.  capacity  placed  in  a  boiling-water  bath. 
The  contents  of  the  tube  are  stirred  occasionally  to  promote  crystalliza- 
tion. Instead  of  the  chloride  one  may  employ  a  solution  of  phenyl- 
hydrazine acetate,  prepared  by  adding  concentrated  acetic  acid  drop  by 
drop  to  phenylhydrazine  until  the  turbid  emulsion  clears.  The  osa- 
zone  reaction  with  the  substituted  hydrazines  is  conducted  in  the  same 
way  as  with  phenylhydrazine. 

The  osazones  of  the  sugars  are  yellowish-colored  crystalline  com- 
pounds of  variable  solubility.  The  osazones  of  the  monosaccharides 
crystallize  out  from  the  hot  solutions;  those  of  the  disaccharides,  maltose 
and  lactose,  however,  separate  only  after  cooling.  A  separation  of  the 
osazones  of  the  mono-  and  disaccharides  can  be  accomplished  in  this 
manner,  a  second  crystallization  usually  rendering  the  separation  com- 
plete. While  the  osazones  of  the  monosaccharides  are  nearly  all  of 
much  lower  solubility  than  the  corresponding  hydrazones,  the  osazone . 
separation  is  never  complete. 

*  Ber.,  17,  579. 


350 


SUGAR  ANALYSIS 


Yield  and  Time  for  Formation  of  Osazones.  —  Sugars  differ  greatly  in 
the  amount  of  osazone  which  is  formed  under  a  definite  method  of 
treatment,  and  this  property  has  been  utilized  as  a  means  of  identifica- 
tion. Maquenne,*  for  example,  has  determined  the  yield  of  osazones 
obtained  by  heating  1  gm.  of  different  sugars  in  100  c.c.  of  water  with 
5  c.c.  of  a  solution,  containing  40  gms.  phenylhydrazine  and  40  gms. 
glacial  acetic  acid  in  100  c.c.,  for  1  hour  in  a  boiling- water  bath.  The 
sugars  studied  by  Maquenne  are  arranged  in  Table  LXV  in  the  order 
of  yield  of  osazone. 

TABLE  LXV 

Showing  Yield  of  Osazones  and  Time  of  Precipitation  for  Different  Sugars 


Sugar. 

Phenylosazone 
from  1  gram 
sugar. 

Time  for  precipitation. 

Sorbose  
Fructose    

Gram. 

0.82 
0.70 

Turbid  in  12  min. 
Precipitate  in  5  min. 

Xylose  
Glucose  

0.40 
0.32 

Precipitate  in  13  min. 
Precipitate  in  8  min. 

Arabinose 

0.27 

Turbid  in  30  min 

Galactose 

0.23 

Precipitate  in  30  min 

Rhamnose 

0.15 

Precipitate  in  25  min 

Lactose 

0.11 

Precipitate  only  on  cooling. 

Maltose  

0.11 

Precipitate  only  on  cooling. 

It  is  noted  that  the  ketoses,  sorbose  and  fructose  are  characterized 
by  a  much  greater  yield  of  osazone.  The  theoretical  yield  of  osazone 
from  1  gm.  of  sugar  is  2.19  gms.  for  pentoses,  1.99  gms.  for  hexoses  and 
1.53  gms.  for  disaccharides.  This  shows  how  large  a  part  of  even  the 
more  insoluble  osazones  were  unprecipitated  in  Maquenne's  experi- 
ments. The  latter,  however,  were  not  intended  to  give  the  conditions 
of  maximum  yield  and  were  designed  simply  for  purposes  of  comparison. 

Fischer  by  heating  one  part  glucose  with  two  parts  phenylhydrazine 
chloride,  three  parts  sodium  acetate  and  20  parts  of  water  for  1J  hours 
upon  the  water  bath  obtained  85  to  90  per  cent  of  the  weight  of  sugar  as 
osazone.  This  is  nearly  three  times  the  amount  obtained  by  Maquenne, 
but  is  still  less  than  50  per  cent  of  the  theoretical  yield. 

Mulliken  f  has  based  a  scheme  for  the  identification  of  pure  sugars 
upon  the  time  of  separation  of  the  osazones.  Fischer's  method  of  mak- 
ing the  test  is  followed,  0.1  gm.  sugar,  0.2  gm.  pure  phenylhydrazine 
chloride,  0.3  gm.  sodium  acetate  and  2  c.c.  water  being  mixed  in  a 

*  Maquenne's  "Les  Sucres,"  p.  266;  Compt.  rend.,  112,  799. 
t  Mulliken's  "Identification  of  pure  Organic  Compounds." 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      351 

small  test  tube,  corked  loosely  to  prevent  evaporation  and  heated  in 
boiling  water.  The  tube  is  shaken  occasionally  without  removing  from 
the  bath  and  the  time  noted  for  the  separation  of  a  precipitate.  Under 
the  above  conditions  Mulliken  noted  the  following: 


Sugar. 

Time  for 
osazone 
separation. 

Sugar. 

Time  for  osazone  separation. 

Fructose  
Sorbose 

Minutes. 

2 

01 

Arabinose  
Galactose 

Minutes. 
10 
1  1;  iq 

Glucose  

02 
4K 

Sucrose  - 

30  (due  to  sliffht  inversion) 

Xylose    .  . 

7 

Maltose 

Rhamnose 

Lactose 

The  relation  of  the  sugars  as  regards  time  of  osazone  formation  agrees 
closely  with  that  noted  by  Maquenne. 

Sherman  and  Williams  *  give  the  following  time  of  osazone  forma- 
tion for  different  quantities  of  sugar  under  the  conditions  followed  by 
Mulliken,  but  with  double  the  quantity  of  reagents  and  water. 

Time  for  Precipitation  of  Osazones 


Weight  of  sugar 
taken. 

Glucose. 

Fructose. 

Invert  sugar. 

Sucrose. 

Gram. 

Minutes. 

Minutes. 

Minutes. 

Minutes. 

0.2 

4-5 

H-H 

1MI 

31 

0.1 

5 

lf-2 

2 

35 

0.05 

6£ 

2£ 

3 

78 

0.01 

17 

5| 

6-6| 

No  ppt. 

0.005 

34 

10 

14 

0.0025 

65 

17 

Sherman  and  Williams  found  that  with  mixtures  of  different  sugars 
the  time  of  osazone  formation  was  greatly  modified.  The  following  re- 
sults were  noted. 


Influence  of  Maltose  on  Glucose 


Weight  of 
glucose. 

Weight  of  maltose. 

In  absence  of 
maltose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 
0.01 
0.02 

Minutes. 
No.  ppt. 
26-28 

Minutes. 
40 

Minutes. 
30 

Minutes. 
22 

Minutes. 
17  . 
12-13 

*  J.  Am.  Chem.  Soc.,  28,  629. 


352 


SUGAR  ANALYSIS 


Influence  of  Lactose  on  Glucose 


Weight  of 
glucose. 

Weight  of  lactose. 

In  absence  of 
lactose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 

0.01 
0.02 

Minutes. 

No  ppt. 
45-48 

Minutes. 

50 

Minutes. 

32 

Minutes. 

25 

Minutes. 
17 
12-13 

Influence  of  Sucrose  on  Glucose 


Weight  of  sucrose. 

Weight  of 

In  absence  of 

glucose. 

sucrose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 
0.005 

Minutes. 
15-17 

Minutes. 

15-17 

Minutes. 
22 

Minutes. 
30 

Minutes. 

33-39 

0.01 

14-16 

16 

17 

17 

17 

0.2 

9 

12-13 

Influence  of  Raffinose  on  Glucose 


Weight  of 
glucose. 

Weight  of  raffinose. 

In  absence  of 
raffinose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 

0.005 

Minutes. 

27-30 

Minutes. 

33-37 

Minutes. 

36-38 

Minutes. 

37-39 

Minutes. 

33-39 

Influence  of  Maltose  on  Fructose 


Weight  of 
fructose. 

Weight  of  maltose. 

In  absence  of 
maltose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 
0.01 

Minutes. 

7-8 

Minutes. 
5£-6 

Minutes. 

5H* 

Minutes. 

5^ 

Minutes. 

5£ 

Influence  of  Lactose  on  Fructose 


Weight  of 
fructose. 

Weight  of  lactose. 

In  absence  of 
lactose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 

0.01 

Minutes. 
9i-10 

Minutes. 

7| 

Minutes. 

ef 

Minutes. 
6 

Minutes. 

5| 

METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      353 


Influence  of  Sucrose  on  Fructose 


Weight  of 
fructose. 

Weight  of  sucrose. 

In  absence  of 
sucrose. 

0.2  gram. 

0.1  gram. 

0.05  gram. 

0.01  gram. 

Gram. 

0.005 

Minutes. 

8^ 

Minutes. 

8f 

Minutes. 

9* 

Minutes. 

9i 

Minutes. 

9£ 

The  results  show  that  sucrose  accelerates,  while  maltose  and  lactose 
retard  the  separation  of  osazone  from  solutions  containing  glucose  and 
fructose. 

A  scheme  of  identification,  based  upon  yield,  or  time  of  formation  of 
osazone  under  a  prescribed  method  of  treatment,  is  of  value  only  in 
working  with  a  known  quantity  of  pure  sugar.  In  case  of  products 
containing  foreign  organic  and  mineral  matter,  or  a  mixture  of  several 
sugars,  the  presence  of  impurities  or  of  other  osazones  influences  crys- 
tallization to  a  very  marked  degree.  This  fact  prevents  the  employ- 
ment of  .the  osazone  reaction  for  exact  quantitative  purposes. 

The  osazones  of  sugars  after  precipitation  require  to  be  purified. 
The  crystalline  precipitate  is  filtered  off,  well  washed  with  cold  water, 
and  then  pressed  as  dry  as  possible  between  filter  paper.  The  product 
is  then  recrystallized  from  boiling  50  per  cent  alcohol  to  which  a  few 
drops  of  pyridine  may  be  added,  in  case  of  very  insoluble  osazones,  to 
promote  solubility.  Recrystallization  may  also  be  effected  from  ace- 
tone and  other  organic  solvents  and  in  case  of  easily  soluble  osazones, 
as  of  maltose  and  lactose,  from  hot  water.  After  dissolving  the  osa- 
zones, the  hot  solution  is  filtered  and  set  aside  in  the  cold  until  crystalli- 
zation is  complete.  The  purified  osazone  is  then  filtered  off  and  dried 
at  a  gentle  heat.  A  melting  point  is  then  taken  which,  if  the  osazone 
is  pure,  will  remain  unchanged  after  further  crystallization.  A  table  of 
melting  points  is  then  consulted  and  this  in  many  cases  is  sufficient  to 
identify  the  osazone.  (See  Table  24,  Appendix.) 

Limitations  of  the  Osazone  Reaction.  —  The  osazone  reaction  with 
phenylhydrazine,  while  invaluable,  is  not  always  an  absolute  test  of  the 
identity  of  a  sugar,  owing  to  the  fact  that  a  number  of  isomeric  sugars 
give  the  same  osazone.  The  pentose  sugars  d-lyxose  and  1-xylose,  for 
example,  yield  the  same  phenylosazone  of  melting  point  160°-161°  C. 
Similarly  the  hexose  sugars,  d-glucose,  d-mannose  and  d-fructose,  yield 
the  same  phenylosazone  of  melting  point  206°  C.  In  fact  any  of  the 
isomeric  sugars  which  are  mutually  transformable  (as  in  contact  with 


HO-C-H 
H-C-OH 
H-C-OH 


This  circumstance,  although  nullifying  the  use  of  phenylosazones  in 
certain  cases  as  a  means  of  identification,  has  yet  thrown  a  flood  of 
light  upon  the  molecular  constitution  of  sugars. 

Test  for  Ketoses  with  Methylphenylhydrazine.  —  In  distinction  from 
phenylhydrazine  the  substituted  hydrazines  do  not  always  give  the 
same  osazone  reaction  with  sugars  which  are  mutually  transformed. 
The  osazone  reaction  with  substituted  hydrazines  has,  therefore,  a  dis- 
tinct qualitative  value.  Methylphenylhydrazine,  for  example,  forms 
very  readily  a  characteristic  osazone  with  d-fructose,  but  does  not  form 
an  osazone  with  d-glucose  or  d-mannose  or  any  of  the  other  aldose 
sugars.  The  osazone  reaction  with  methylphenylhydrazine  is,  there- 
fore, serviceable  in  distinguishing  aldoses  from  ketoses. 

Decomposition  of  Osazones  into  Osones.  —  While  hydrazones,  upon 
decomposition  with  strong  hydrochloric  acid  or  with  benzaldehyde  or 
formaldehyde,  yield  the  component  sugar,  the  osazones  cannot  be  re- 
solved in  this  manner.  The  osazone  reaction  is  consequently  of  value 


354  SUGAR  ANALYSIS 

alkalies)  give  the  same  osazone.     This  is  made  more  clear  from  the  fol- 
lowing stereoformulse  of  glucose,  mannose  and  fructose. 

H-C=0  H-C  =  0  CH2OH 

H-C-OH  HO-C-H  C=O 

I  I  ! 

••••HO-C-H'"  ••"HO-C-H"  HO-C-H 

H-C-OH  H-C-OH  H-C-OH 

H-C-OH  H-C-OH  H-C-OH 

CH2OH  CH2OH  CH2OH 

d-Glucose  d-Mannose  d-Fructose 

The  part  of  the  molecule  below  the  dotted  line  has  the  same  spatial 
arrangement  in  all  three  sugars.  The  part  of  the  molecule  above  the 
dotted  line  is  the  only  part  of  the  molecule  affected  in  the  osazone  re- 
action, this  in  all  three  sugars  giving  rise  to  an  osazone  which  has  the 
same  structural  formula: 

H-C=N-NH-C6H5 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      355 

only  as  a  means  of  identifying  and  not  of  separating  sugars.  The  de- 
composition of  osazones  with  acids  and  aldehydes  has,  however,  a  con- 
siderable theoretical  interest  which  may  be  considered  briefly  in  this 
connection. 

Treatment  of  osazones  with  concentrated  hydrochloric  acid  or  with 
certain  aldehydes  causes,  as  in  the  case  of  hydrazones,  a  separation  of 
the  phenylhydrazine  ;  the  product  remaining  behind,  however,  is  not  the 
original  sugar,  but  a  compound  with  two  adjacent  carbonyl  groups  called 
an  osone.  The  reaction  of  glucosazone  with  hydrochloric  acid,  for  ex- 
ample, is: 

CH2OH  CH2OH 

(CHOH)3  +  2  HC1  +  2  H2O      =      (CHOH)3  +  2  CeHsNH  -  NH2HC1 

C  :  N  -  NHC6H5  C  :  O 


HC  :  N  - 


NHC6H5  HC  :  O 

Glucosazone  Hydrochloric  acid.  Glucosone  Phenylhydrazine  chloride. 

In  case  of  osazones  soluble  in  hot  water  the  conversion  into  osones 
can  be  easily  effected  with  benzaldehyde  in  presence  of  sufficient  al- 
cohol, the  phenylhydrazine  being  separated  as  benzaldehyde-phenyl- 
hydrazone  and  the  osone  remaining  behind  in  solution. 

Osones  upon  treatment  with  zinc  dust  and  acetic  acid  are  reduced 
by  the  nascent  hydrogen  to  a  sugar,  the  end  carbonyl  group  being  con- 
verted always  to  an  alcohol  group,  as  shown  in  the  following  equation 
for  glucosone. 

CH2OH  CH2OH 

(CHOH)3  +                H2                              (CHOH)3 

C:O  C:0 

HC  :  O  CH2OH 

Glucosone  Hydrogen  Fructose 

It  will  be  seen  from  the  above  reaction  that  the  sugar  obtained  by  re- 
duction of  an  osone  is  always  a  ketose.  By  this  means  glucose  and 
mannose  can  be  transformed  into  fructose,  and  this  type  of  reaction  is 
true  for  the  conversion  of  any  aldose  into  the  corresponding  ketose,  the 
steps  of  the  transformation  being  always 

Aldose »  Osazo'ne >  Osone  >  Ketose. 

The  osones,  while  of  great  service  in  establishing  the  relationship  of 
different  sugars  to  one  another,  have  no  value  either  in  qualitative  or 
quantitative  sugar  analysis. 


356 


SUGAR  ANALYSIS 


THE  IDENTIFICATION  OF  HYDRAZONES  AND  OSAZONES 

The  identification  of  hydrazones  and  osazones,  by  examination  of 
their  physical  properties,  although  belonging  strictly  to  the  tests  for 
individual  sugars,  is  introduced  for  convenience  at  this  point. 

Determination  of  Melting  Point  of  Hydrazones  and  Osazones.  — 
The  determination  of  melting  point  is  the  principal  physical  method 
for    identification    of    hydrazones    and 
osazones. 

Capillary-tube  Method.  —  The  capil- 
lary-tube method  is  the  one  most  gener- 
ally employed  for  determining  melting 
points.  The  essential  requirements  in 
way  of  apparatus  are  shown  in  Fig.  162. 
A  long-neck  flask  with  a  small  body 
of  about  20-c.c.  capacity  is  filled  about 
two-thirds  with  pure  concentrated  sul- 
phuric acid;  to  prevent  discoloration  of 
the  acid  through  accidental  contamina- 
tion with  organic  matter  a  small  crystal 
of  potassium  nitrate,  the  size  of  a  pin- 
Fig.  162.— Ap-  head,  is  dropped  in.  The  flask  is  clamped 
paratus  for  de-  ^o  a  lamp-stand  in  the  manner  shown. 
The  opening  of  the  flask  is  fitted  with  a 
perforated  cork  containing  a  groove  upon 
the  side  to  allow  escape  of  expanding  air.  The  perfora- 
tion in  the  cork  should  be  of  such  a  size  as  to  hold  a 
thermometer,  graduated  to  300°  C.,  tightly  in  position; 
the  bulb  of  the  latter  should  be  above  the  bottom  of 
the  flask  and  yet  be  submerged  entirely  in  the  acid. 

The  capillary  tubes  for  holding  the   hydrazone  or 
osazone  are  best  prepared  by  thoroughly  softening  a 
piece  of  glass  tubing  by  turning  it  in  the  flame  and  then 
drawing  it  out  to  about  1   to   1.5-mm.  diameter.     By 
continuing   this   process  backwards  along  the  tube  aFig-163-—  Show- 
number  of  sections  are  obtained  similar  to  Fig.  163a;  ing 
the  sections  are  then  filed  off  at  the  points  indicated 
and  the  smaller  ends  melted   together  in  the  flame,   melting  points. 
Small  tubes  of  the  size  and  shape  shown  in  Fig.  1636  are  thus  obtained. 
A  small  amount  of  finely  powdered  hydrazone  or  osazone  is  then  in- 
troduced into  the  open  end  of  the  tube  and  the  latter  gently  tapped  until 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      357 

the  substance  has  settled  to  the  bottom.  To  prevent  the  powdered 
material  from  forming  too  loose  a  layer  it  is  usually  well  to  push  it 
tightly  down  by  means  of  a  platinum-wire  or  thin-glass  rod.  The  depth 
of  substance  in  the  tube  should  not  exceed  2  mm.  The  capillary  tube 
containing  the  substance  is  then  attached  to  the  thermometer  either  by 
binding  it  with  a  piece  of  fine  platinum  wire  or  by  dipping  it  first  in  con- 
centrated sulphuric  acid  and  allowing  it  to  stick  to  the  thermometer 
bulb  by  adhesion.  The  tube  is  placed  so  that  the  layer  of  substance  is 
even  with  the  center  of  the  mercury  bulb. 

After  placing  the  thermometer  and  tube  in  position,  as  shown  in  Fig. 
162,  a  small  flame  is  placed  beneath  the  flask  and  the  temperature  raised 
until  the  liquefaction  of  the  powdered  crystals  indicates  the  tempera- 
ture of  melting.  Hydrazones  and  osazones  at  the  point  of  melting  de- 
compose with  darkening  of  color,  the  evolution  of  gas  causing  the 
liquefied  substance  to  foam  upwards  in  the  stem  of  the  tube.  The  first 
determination  of  melting  point  is  only  preliminary  and  a  second  and 
third  trial  should  always  be  made  with  fresh  tubes  and  material.  The 
acid  in  the  subsequent  tests  is  heated  rapidly  to  about  5°  C.  below 
the  melting  point  first  observed  and  then  the  temperature  raised 
gradually  so  that  the  thread  of  mercury  in  the  thermometer  comes  to 
rest  just  at  the  point  of  liquefaction.  The  entire  operation  for  glucosa^ 
zone,  for  example,  melting  at  204°  to  205  °C.,  should  not  consume  over 
4  minutes.  Undue  protraction  of  the  time  of  heating  affects  the  result 
of  the  determination  very  markedly  and  the  wide  discrepancies  noted 
in  the  literature  between  melting-point  determinations  of  the  same 
osazone  by  different  authorities  are  due  largely  to  this  cause. 

Maquenne's  Block.  —  A  second  method  for  determining  melting 
points  of  hydrazones  and  osazones  is  employed  considerably  by  French 
chemists.  This  method  involves  the  use  of  the  Maquenne  Block,  an 
apparatus  invented  by  Maquenne  in  1887,  the  essential  features  of 
which  are  shown  in  Fig.  164. 

The  important  part  of  Maquenne's  apparatus  consists  of  a  prismatic 
block  (A)  of  brass,  weighing  about  2  kilos,  which  is  placed  in  a  frame 
with  one  of  its  edges  resting  above  the  openings  of  a  long  gas  burner  (B). 
In  one  end  of  the  block  about  5  mm.  below  the  upper  surface  a  hole  is 
bored,  extending  nearly  the  length  of  the  block,  into  which  a  thermom- 
eter (T)  can  be  inserted.  In  the  upper  level  surface  of  the  block  are  a 
number  of  small,  round  cavities.  In  conducting  a  determination  a  small 
amount  of  substance  is  placed  in  one  of  the  cavities,  which,  to  prevent 
disturbances  from  air  drafts,  is  covered  with  a  small  glass;  the  thermom- 
eter is  then  inserted  so  that  its  bulb  is  about  underneath  the  cavity  and 


358  SUGAR  ANALYSIS 

the  burner  started  with  a  low,  uniform  flame.  The  temperature  is 
slowly  elevated  until  the  substance  begins  to  melt  when  the  thermometer 
is  drawn  out  or  pushed  in  until  just  the  end  of  the  mercury  thread  pro- 
jects and  the  temperature  noted.  The  block  is  now  cooled  slightly  and 
a  second  determination  made  more  slowly  than  before,  using  a  cavity 
above  the  bulb  of  the  thermometer  in  its  second  position.  Owing  to 
the  fact  that  the  block  has  nearly  the  same  temperature,  the  entire 
column  of  mercury  is  brought  to  the  same  temperature  as  that  of  the 
melting  substance  and  no  correction  due  to  contraction  of  the  thread 
outside  the  unheated  portion  of  the  thermometer  is  necessary  as  by  the 
method  of  melting-point  determination  previously  described. 


Fig.  164.  —  Maquenne's  block  for  determining  melting  points. 

A  comparison  of  melting  points  of  glucose-phenylosazone  by  the 
two  methods  shows  the  following:  capillary  tube  205°  C.  (Fischer), 
Maquenne  Block  230°  to  232°  C.  (Bertrand).  From  this  it  would 
appear  that  the  Maquenne  Block  gives  considerably  higher  melting 
points  than  the  capillary-tube  method.  A  critical  comparison  of  the 
two  methods  by  Miither  *  (see  Table  LXVI,  opposite  page)  shows,  how- 
ever, that  this  is  not  always  the  case. 

It  will  be  seen  that  Miither  obtained  for  glucosazone  results  by  the 
block  agreeing  very  closely  with  those  by  the  tube,  the  range  found  by 
the  block  being  200°  to  206°  C.  and  by  the  tube  203.5°  to  205°  C. 
The  greater  variation  by  the  block  is  attributed  by  Miither  to  the 
unequal  distribution  of  heat  through  the  brass,  the  outer  surface  being 
more  quickly  warmed  than  the  center;  differences  from  3°  to  6°  C. 
were  also  noted  for  different  positions  of  the  thermometer  inside  the 
block.  The  slowness  with  which  the  block  is  heated  and  cooled  and 
the  difficulty  with  which  the  cavities  are  cleaned  are  also  serious  objec- 
tions. With  substances  which  sublime,  the  Maquenne  Block  cannot 
*  Dissertation,  Gottingen,  1903. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      359 


be  used  on  account  of  the  rapid  condensation  of  material  from  the 
cavity  upon  the  cover  glass.  These  objections  together  with  the  high 
cost  of  the  apparatus  (about  $15.00,  duty  free)  render  it  much  less 
desirable  for  determining  melting  points  than  the  simpler  capillary-tube 
method. 

TABLE  LXVI 

Showing  Melting  Points  of  Hydrazones  and  Osazones  by  Different  Methods.  (Miither.) 


Compound. 

Method  of  melting  point. 

Capillary  tube. 

Maquenne  block. 

Arabinose-methylphenylhydrazone  

Deg.  C. 
164  ' 

203-204 
177 

172-173 

188-189 
188-189 
203.5 
204-205 
203.5 
203-204 
203.5 

Deg.  C. 
158-160 
159-160 
159-160 
162 
198 
199-200 
174-175 
172-173 
170-171 
165-167 
173-174 
187 
191-192 
202-203 
*       200-201 
204-205 
205-206 
205 

Arabinose-diphenylhydrazone  

Fucose-methylphenylhydrazone. 

Fucose-benzylphenylhydrazone  .      .    . 

Mannose-phenylhydrazone. 

Fructose-osazone  (glucosazone)  

Isomerism  and  Variability  in  Melting  Points  of  Hydrazones.  —  A 
peculiarity  of  a  number  of  hydrazones  is  the  existence  of  two  isomers  of 
different  crystalline  form,  melting  point  and  specific  rotation.  Thus 
in  case  of  d-glucose-phenylhydrazone  the  following  properties  were 
noted  by  Fischer  and  Tafel,*  and  by  Simon  and  Benard.f 


I. 

II. 

Crystalline  form  

Fine  needles. 

Long  needles. 

Melting  point 

144M460 

115°-116^ 

Specific  rotation  after  solution 

-66.57 

-15.3 

Specific  rotation  after  standing  

-52.00 

-52.9 

It  is  seen  that  the  isomeric  hydrazones  each  possess  mutarotation, 
and  in  solution  undergo  transformation  into  the  same  compound. 

*  Ber.,  20,  2566. 

t  Compt.  rend.,  132,  564. 


360  SUGAR  ANALYSIS 

The  isomerism  has  been  attributed  to  the  existence  of  hydrazones  of  a- 
and  jS-glucose,  but  the  conditions  for  their  separate  formation  have  not 
been  definitely  established. 

Similar  differences  have  been  noted  in  the  case  of  other  hydrazones, 
but  whether  the  variation  in  properties  is  due  to  isomerism  or  to  a 
difference  in  purity  is  not  always  certain. 

Optical  Activity  of  Hydrazones  and  Osazones  as  a  Means  of  Iden- 
tification. —  In  addition  to  melting  point  the  optical  activity  of  hydra- 
zones  and  osazones  is  sometimes  employed  as  a  means  of  identification. 

Owing  to  the  low  solubility  of  some  of  the  compounds  and  the  high 
color  of  some  of  the  solutions  the  polarization  of  hydrazones  and  osa- 
zones can  not  always  be  measured  with  exactness.  In  the  case  of 
hydrazones  the  existence  of  different  isomers,  as  in  the  case  of  glucose- 
phenylhydrazone  just  cited,  may  cause  wide  differences  in  polarization. 
Mutarotation,  which  was  noted  in  the  case  of  glucose-phenylhydrazone, 
has  also  been  observed  with  some  of  the  osazones.  Thus  Allen  and 
Tollens*  found  for  1-arabinose-phenylosazone  [a]o  =+18.9  after  dis- 
solving in  alcohol,  but  after  standing  a  short  time  the  solution  became 
optically  inactive. 

The  rotatory  power  of  hydrazones  and  osazones  also  varies  greatly 
for  different  solvents.  Thus  Lobry  de  Bruyn  and  van  Ekenstein  f 
found  the  following  rotations  for  different  0-naphthylhydrazones  in 
methyl  alcohol  and  glacial  acetic  acid. 


Methyl  alcohol. 

Glacial  acetic  acid. 

Rhamnose-/3-naphthylhydrazone  .  . 

+  8.4 

-11.8 

Glucose-/8-naphthylhydrazone.               

+40.2 

0 

Mannose-/3-naphthylhydrazone  
Galactose-/8-naphthylhydrazone  

+  16.8 
+24.8 

0 
+  2 

For  purposes  of  comparison  and  identification  the  rotations  of 
hydrazones  and  osazones  must  be  measured,  therefore,  under  exactly 
similar  conditions  as  to  quantity  of  material  and  nature  of  solvent. 
Neubergt  recommends  dissolving  0.2  gm.  of  osazone  in  a  mixture  of 
4  gms.  pyridine  and  6  gms.  absolute  alcohol,  and  reading  the  solution 
in  a  200-mm.  tube  in  a  polarimeter.  The  following  rotations  were 
obtained  by  Neuberg  for  different  osazones  when  working  under  the 
above  conditions: 

*  Z.  Ver.  Deut.  Zuckerind.,  40,  1033. 
t  Rec.  Trav.  Pays  Bas,  16,  226. 
t  Ber.,  32,  3384. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       361 


TABLE  LXVII 
Giving  Polarization  of  Different  Osazones 


1-Arabinose-phenylosazone   

1-Arabinose-p-bromophenylosazone 

Xylose-phenylosazone   

Xylose-p-bromophenylosazone 

Rhamnose-phenylosazone 

d-Glucose-phenylosazone 

d-Glucose-p-bromophenylosazone. 

d-Galactose-phenylosazone 

Sorbose-phenylosazone 

Maltose-phenylosazone 

Lactose-phenylosazone 


+0°28' 
-0°15' 
±0° 


+0°48' 
-0°15' 
+1°30' 
±0° 


The  rotations  are  small  and  in  some  cases  uncertain  so  that  this 
method  of  identification  upon  the  whole  is  less  satisfactory  than  a  melt- 
ing-point determination. 

In  case  of  the  hydrazones  and  osazones  of  optically  opposite  isomeric 
sugars  (which,  as  regards  melting  point  and  solubility,  behave  alike  ex- 
cept in  the  special  case  where  optically  active  hydrazines  are  used),  a 
determination  of  the  optical  activity  of  the  compound  is  the  only  ready 
means  of  identification.  Thus  Fischer  *  gives  for  the  phenylhydra- 
zones  of  d-  and  1-galactose  the  following  constants. 

Melting  point.        [a]^ 

d-Galactose-phenylhydrazone 158°    —21.6 

1-Galactose-phenylhydrazone 158°    +21.6 

Fischer  also  gives  for  the  phenylhydrazones  of  d-  and  1-mannose 

M£'Sf       Station. 

d-Mannose-phenylhydrazone    195°     - 1.2 

1-Mannose-phenylhydrazone    195°    +1.2 

The  rotations  in  the  latter  case  were  the  angular  readings  obtained 
in  a  100-mm.  tube  upon  a  solution  of  0.1  gm.  hydrazone  in  1  c.c.  cold 
concentrated  hydrochloric  acid  and  diluted  with  5  c.c.  of  water. 

Employment  of  Optically  Active  Hydrazines  for  Separating 
Sugars  from  Racemic  Mixtures.  —  Neuberg  f  has  recently  employed 
optically  active  hydrazines  for  analyzing  racemic  mixtures  of  sugars. 

If  two  optically  opposite  isomeric  sugars  ("  antipodes  ")  +  S  and  — S 
form  hydrazones  with  an  optically  inactive  hydrazine  H,  the  result- 
ing compounds,  which  may  be  represented  by  the  symbols  +SH  and 
— SH  are  also  antipodes,  and,  although  of  exactly  opposite  rotations, 

*  Fischer's  "  Untersuchungen  uber  Kohlenhydrate." 
t  Ber.,  36,  1192;  38,  866,  868. 


362  SUGAR  ANALYSIS 

have  in  other  respects,  such  as  specific  gravity,  melting  point,  solubility, 
etc.,  the  same  physical  properties.  A  separation  of  two  such  hydra- 
zones  is  consequently  not  possible  by  the  ordinary  methods  of  analysis. 

If,  however,  the  two  sugars  +S  and  —  S  combine  with  an  optically 
active  hydrazine  as  +H,  the  resulting  hydrazones  +  S  +  H  and 
—  S  +  H  are  not  optical  antipodes  and  show  well-defined  differences 
in  solubility,  melting  point  and  other  properties.  A  separation  of  the 
two  hydrazones  is  thus  made  possible  by  the  ordinary  methods  of 
fractional  crystallization. 

The  hydrazines,  which  have  been  used  by  Neuberg  and  his  co- 
workers  for  this  method  of  separating  sugars,  are  1-menthylhydrazine 
and  d-amylphenylhydrazine,  the  structural  formulae  of  which  are  as 

follows  : 

CH3  CH3 


i 


n  )cH-CH2 


CH2   CH-NH-NH2 

\  / 

CH 

CH3-CH-CH3 

l-Menthylhydrazine.  d-Amylphenylhydrazine 

The  method  has  been  employed  successfully  by  Neuberg  in  resolv- 
ing the  racemic  sugar  d,l-arabinose,  which  occurs  in  the  urine  of  many 
persons  suffering  from  pentosuria;  d,l-arabinose  gives  with  1-menthyl- 
hydrazine an  easily  soluble  1-arabinose-l-menthylhydrazone  and  a  very 
insoluble  d-arabinose-1-menthylhydrazone.  The  latter  is  filtered  off  and 
upon  treatment  with  formaldehyde  (p.  348)  is  easily  decomposed  with 
liberation  of  the  free  sugar  d-arabinose. 

IV.     MISCELLANEOUS  REACTIONS  OF  SUGARS 

Reactions  of  Sugars  with  Reducing  Agents.  —  The  simple  reducing 

sugars,  in  their  character  of  aldehydes  or  ketones,  are  easily  transformed 

by  reducing  agents  into  the  corresponding  alcohols.     The  sugar  man- 

nose,  for  example,  is  reduced  by  sodium  amalgam  to  the  alcohol  mannite. 

CH2OH  CH2OH 

(CHOH)4          +          H2  (CHOH)4 

CHO  CH2OH 

Mannose  Hydrogen  Mannite 

A  more  general  type  of  equation  would  be: 

CnH2nOn  +  H2  CnH2n+2On 

Sugar  Hydrogen  Sugar  alcohol 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      363 


The  reactions  of  the  different  sugars  with  reducing  agents  are  of 
comparatively  minor  importance  as  regards  use  in  sugar  analysis. 

A  description  of  the  different  sugar  alcohols,  with  reactions  and 
methods  of  identification,  is  given  in  Chapter  XXIII. 

Reactions  of  Sugars  with  Weak  Oxidizing  Agents.  —  Reducing 
sugars  belonging  to  the  aldoses  are  changed  by  means  of  the  less  power- 
ful oxidizing  agents,  such  as  bromine  water,  into  the  corresponding 
monobasic  acids.  Thus: 


CH2OH 

I 
(CHOH)< 


4-        2Br 


H20 


CH2OH 
(CHOH)4 


Aldo-hexose 


Bromine  water 


Hexonic  acid 


2HBr 


Hydrobromic  acid 


In  carrying  out  the  reaction  1  part  sugar  is  treated  with  5  parts 
of  water  and  2  parts  of  bromine,  and  the  solution  kept  at  room  tempera- 
ture for  1  to  3  days. 

Ketose  sugars,  upon  treatment  with  bromine  water,  undergo  but 
little  oxidation  during  the  first  few  days.  Prolonged  action,  or  eleva- 
tion of  temperature,  will,  however,  oxidize  ketoses  with  a  breaking  up 
of  the  molecule  into  several  acids  of  fewer  carbon  atoms. 

Rate  of  Oxidation  with  Bromine  as  a  Test  for  Aldoses  and  Ketoses.  — 
The  rate  of  oxidation  of  several  aldose  sugars  with  bromine  water,  as 
compared  with  fructose,  is  shown  in  the  following  experiments  by 
Votocek  and  Nemecek;*  0.5  gm.  of  pure  sugar  was  dissolved  in  a  50-c.c. 
flask  in  9  c.c.  of  water,  40  c.c.  of  bromine  water  (saturated  at  room 
temperature)  were  then  added  and  the  volume  made  up  to  50  c.c.  After 
standing  at  room  temperature  (21°  C.)  for  24  hours,  the  unoxidized 
sugar  was  determined  in  each  flask  with  the  following  results: 


Sugar. 

Per  cent  sugar 
unoxidized. 

Sugar. 

Per  cent  sugar 
unoxidized. 

d-Galactose  .. 

5   10 

1-Xylose                 ..,,..  vv 

25.68 

1-Arabinose    . 

7  56 

Rhamnose           

39.19 

d-Glucose.  .  . 

22  20 

d-Fructose  

100.00 

Votocek  and  Nemecek  propose  their  method  as  a  means  for  dis- 
tinguishing aldoses  from  ketoses  and  also  as  a  method  for  examining 
sugar  mixtures.  In  case  of  the  latter  the  aldoses  are  oxidized  away  with 
bromine  water,  leaving  the  ketoses  in  better  condition  for  isolation. 

Reactions  of  Sugars  with  Strong  Oxidizing  Agents.  —  Reducing 
sugars  belonging  to  the  normal  unsubstituted  aldoses  are  changed  upon 
*  Z.  Zuckerind.  Bohmen,  34,  399. 


364  SUGAR  ANALYSIS 

warming  with  stronger  oxidizing  agents,  as  30  per  cent  nitric  acid,  into 
the  corresponding  dibasic  acids.     Thus 

CH2OH  COOH 

(CHOH)4          +          2HN03        =        (CHOH)4  +  2H20+2NO 
CHO  COOH 

Galactose  Nitric  acid  Mucic  acid 

In  carrying  out  the  reaction  one  part  of  sugar  is  heated  with  2|  parts 
nitric  acid  of  1.2  sp.  gr.  and  gently  warmed  at  40°  to  50°  C.  until  no 
more  nitrous  fumes  are  evolved.  The  solution  is  then  heated  upon  the 
water  bath  until  all  nitric  acid  is  expelled  and  then  evaporated,  when 
the  acid  or  its  lactone  will  in  many  cases  crystallize;  when  crystalliza- 
tion does  not  occur  separation  from  impurities  is  effected  by  forming  an 
insoluble  salt  or  other  derivative  from  which  the  acid  can  afterward  be 
liberated  in  the  pure  condition. 

Ketose  sugars,  upon  oxidation  with  nitric  acid,  are  degraded  into 
lower  oxidation  products,  of  which  oxalic  acid  is  usually  formed  in 
largest  amount. 

The  substituted  aldose  sugars,  as  the  methyltetroses,  methylpen- 
toses,  methylhexoses,  etc.,  lose  the  methyl  group  upon  oxidation  with 
nitric  acid  and  are  degraded  into  dibasic  acids  of  one  less  carbon  atom. 
CH3 

CHOH  COOH 

(CHOH)2  +  5  O      =       (CHOH)2      +      HCOOH      +      H2O 
CHO  COOH 

Methyltetrose  Tartaric  acid  Formic  acid  Water 

In  the  same  way  the  methylpentoses,  rhamnose,  rhodeose  and 
fucose  are  oxidized  into  trioxyglutaric  acids,  the  methylhexoses  into 
tetraoxyadipic  acids,  etc. 

Oxime  Reaction  of  Sugars.  —  Many  of  the  reducing  sugars  react 
with  hydroxylamine,  after  the  manner  of  all  aldehydes  and  ketones, 
with  formation  of  oximes.     The  following  combination  of  glucose  with 
hydroxylamine  is  an  illustration  of  this  type  of  reactions. 
CH2OH  CH2OH 

(CHOH)4  (CHOH)4  +'  H20 

H-C:O        +        H2N-OH        =        H-C:N-OH 

Glucose  Hydroxylamine  Glucose-oxime  Water 

The  oximes  of  the  sugars  are  often  difficult  to  isolate  and  the  reac- 
tion, for  this  reason,  has  but  little  value  in  sugar  analysis.  In  sugar 
synthesis,  however,  the  oxime  reaction  has  considerable  importance,  for 
by  its  means  a  monosaccharide  may  be  changed  into  another  sugar  con- 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      365 

taining  one  less  carbon  atom.  This  is  done  by  first  making  the  oxime  of 
the  sugar  and  then  heating  the  latter  with  acetic  anhydride;  the  result- 
ing acetyl-nitrile  derivative  is  then  heated  with  an  ammoniacal  solu- 
tion of  silver  oxide  which  splits  off  the  acetic  acid  and  hydrocyanic 
acid  groups  with  formation  of  a  lower  sugar  (Wohl's*  synthesis).  The 
reaction  in  its  simplest  phase  is  represented  as  follows: 
CH2OH  CH2OH  CH2OH 

(CHOH)4  (CHOH)3        =        (CHOH)3         +         HCN 

HC  :  NOH  CHOH  CHO 

i-N 

d-Glucose-oxime  d-Gluconic  acid  nitrile  d-Arabinose  .       Hydrocyanic  acid 

The  hexose  sugar  d-glucose  is  thus  converted  into  the  pentose  sugar 
d-arabinose.  In  the  same  manner  d-arabinose  can  be  converted  into 
the  tetrose  sugar  d-erythrose. 

Cyanhydrine  Reaction  of  Sugars.  —  The  reducing  sugars,  similar 
to  all  aldehydes  and  ketones,  react  with  hydrocyanic  acid  forming  a 
characteristic  group  of  compounds  known  as  cyanhydrines. 
CH2OH  CH2OH 

(CHOH)4        +  HCN  (CHOH)4 

CHOH 


C  :  O 


d-Glucose  Hydrocyanic  acid  d-Glucose-cyanhydrine  (d-glucoheptonic  acid  nitrile) 

The  Cyanhydrine  reaction,  as  that  of  the  oximes,  while  having  but 
little  value  in  sugar  analysis,  has  very  great  importance  in  sugar  synthesis 
for  by  its  means  a  monosaccharide  may  be  'built  up  into  another  sugar 
having  one  more  carbon  atom.  This  is  done  by  first  making  the 
cyanhydrine,  saponifying  this  to  form  the  corresponding  acid,  and  then 
reducing  the  latter  with  sodium  amalgam  which  produces  the  corres- 
ponding sugar.  The  formation  of  glucoheptose  from  glucose  is  given 
as  an  illustration  of  this  type  of  reaction. 

CH2OH  CH2OH 

(CHOH)6  +        3H/)  (CHOH)6          +        NH4OH 

C  =  N  COOH 

d-Glucose-cyanhydrine  d-Glucoheptonic  acid  Ammonia 

CH2OH  CH2OH 

(CHOH)5  +        H2       =  (CHOH)5          +          H2O 

COOH  HC  :  O 

d-Glucoheptonic  acid  (lactone)  Hydrogen  d-Glucoheptose  Water 

*  Ber.,  26,  730. 


366  SUGAR  ANALYSIS 

In  the  same  manner,  starting  from  the  hexoses,  mannose  and  galac- 
tose,  mannoheptose  and  galaheptose  can  be  derived.  The  heptoses  by 
the  same  cyanhydrine  synthesis  have  been  built  up  into  the  correspond- 
ing octoses  CsHieOg  and  the  latter  in  turn  into  the  corresponding  nonoses 
CgHisOg.  For  details  as  to  this  method  of  forming  sugars  the  work  of 
Fischer  *  should  be  consulted. 

Ureide  Reaction  of  Sugars.  —  Nearly  all  reducing  sugars,  with  ex- 
ception of  the  ketoses,  react  at  moderately  warm  temperatures  with 
urea  in  presence  of  dilute  sulphuric  or  hydrochloric  acid  to  form  a 
group  of  compounds  called  ureides.  The  reaction  is  analogous  to  that 
with  phenylhydrazine,  the  hydrogen  of  the  amino  group  withdrawing 
the  oxygen  from  the  aldehyde  group  of  the  sugar.  The  reaction  with 
glucose  and  urea  is  given  by  way  of  example. 

CH2OH  CH2OH 

(CHOH)4  (CHOH)4 

HC:0     +      H2N-CO-NH2    =          HC:N-CO-NH2      +     H2O 

Glucose  Urea  Glucose-ureide  Water 

The  ureides  are  partly  crystalline  and  partly  amorphous  bodies.  In 
aqueous  solution  they  are  decomposed  upon  heating  with  evolution  of 
ammonia  and  liberation  of  the  free  sugar. 

Semicarbazone  Reaction  of  Sugars.  —  Very  similar  to  the  reaction 
of  sugars  with  urea  is  that  with  semicarbazide;  the  latter  in  alcoholic 
solution  combines  with  the  aldoses  to  form  a  group  of  substances  called 
semicarbazones.     The  reaction  with  glucose  is  given  as  illustration. 
CH2OH  CH2OH 

(CHOH)4  (CHOH)4 

I  H  I  H 

HC:O      +      H2N-N-CONH2       =        HC  :  N  -  N  -  CONH2     +  H2O 

Glucose  Semicarbazide  Glucose-semicarbazone  Water 

The  semicarbazones  are  well-defined  crystalline  compounds;  when 
warmed  with  benzaldehyde  in  alcohol  solution  they  are  decomposed  into 
free  sugar  with  formation  of  benzaldehyde  semicarbazone. 

Thiosemicarbazone  Reaction  of  Sugars.  —  Exactly  similar  to  the 
previous  reaction  is  the  behavior  of  aldose  sugars  with  thiosemicarbazide. 
The  reaction  with  glucose  proceeds  as  follows: 

CH2OH  CH2OH 

(CHOH)4  (CHOH)4 

H  H 

HC:O    +    H2N-N-CSNH2        =        HC:N-N-CSNH2    +    H2O 

Glucose  Thiosemicarbazide  Glucose-thiosemicarbazone  Water 

*  Ann.,  270,  64;  288,  139. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      367 

The  thiosemicarbazones  are  well-defined  crystalline  compounds  simi- 
lar in  many  properties  to  the  semicarbazones. 

Reactions  of  Sugars  with  Aromatic  Amines.  —  The  ease  with 
which  reducing  sugars  unite  with  compounds  containing  an  amino 
group,  as  shown  in  the  case  of  the  hydrazones,  oximes,  ureides,  semi- 
carbazones, etc.,  is  further  exemplified  by  the  reactions  of  sugars  with 
different  aromatic  amines,  such  as  aniline,  toluidine,  etc.  Glucose,  for 
example,  reacts  with  aniline  in  alcoholic  solution  as  follows: 

CH2OH  CH2OH 

(HCOH)4  (HCOH)4 

H-C:0     +     H2NC6H5        =    H-C:N-C6H5     +     H20 

Glucose  Aniline  Glucose  anilide  Water 

Reactions  of  Sugars  with  Alcohols.  —  By  leading  dry  hydro- 
chloric-acid gas  into  the  solution  of  a  reducing  sugar  in  an  alcohol  the 
corresponding  alcohol  derivative  of  the  sugar  is  formed.  The  com- 
pounds thus  prepared  are  called  glucosides  from  their  resemblance  to 
the  group  of  plant  substances  known  under  this  name.  The  reaction 
of  glucose  with  methyl  alcohol  is  given  as  illustration. 
CH2OH  CH2OH 

CHOH                 CHOH 
7  CHO FH""  7  CH , 


/3  CHOH 


HOH 


H-C  :  !O  +  H 


/SCHOHJ) 


a.  CHOH 


OCH3 


=  H-C=0~- 


-CH3    +    H20 


Glucose  Methyl  alcohol  Methyl  glucoside  Water 

In  the  same  manner  glucosides  of  the  other  sugars  have  been  made 
as  methyl  arabinoside,  methyl  xyloside,  methyl  rhamnoside,  methyl 
fructoside,  also  of  the  other  alcohols  as  ethyl  glucoside,  etc.  The  com- 
pounds thus  prepared  are  well-defined  crystalline  substances,  easily 
soluble  in  water,  do  not  reduce  Fehling's  solution  and  do  not  react  with 
phenylhy  drazine . 

The  reactions  of  the  reducing  sugars  with  alcohols  are  but  little 
used  as  a  means  of  identification.  The  synthetic  glucosides  have, 
however,  a  great  interest  for  the  sugar  chemist  in  other  ways. 

Mercaptal  Reaction  of  Sugars.  —  Nearly  all  reducing  sugars,  ex- 
cept ketoses,  react  with  the  mercaptans  in  presence  of  concentrated 
hydrochloric  acid  to  form  mercaptals.  The  reaction  with  glucose  and 
ethyl-mercaptan  is  given  as  illustration. 


368  SUGAR  ANALYSIS 

CH2OH  CH2OH 

(CHOH)4  (CHOH)4 

H-C:O    4-     H-S-C2H5  TT     i/S-C2Hs 

H  -  S  -  C2H5  °  \  S  -  C2H6 

Glucose  Ethyl-mercaptan  LGlucose-mercaptal  Water 

The  mercaptals  of  the  sugars  are  well-defined  crystalline  compounds, 
soluble  in  hot  water;  they  do  not  reduce  Fehling's  solution  and  do  not 
react  with  phenylhydrazine. 

Reactions  of  Sugars  with  Aldehydes.  —  The  simple  reducing 
sugars  react  with  a  large  number  of  aldehydes  (formaldehyde,  acetal- 
dehyde, benzaldehyde,  salicylaldehyde,  furfural,  etc.)  to  form  a  variety 
of  condensation  products.  The  latter,  for  the  most  part,  are  of  a 
gummy  or  sirupy  nature  and  do  not  crystallize  readily.  The  combi- 
nation of  glucose  with  acetaldehyde  is  given  as  an  illustration  of  this 
type  of  reaction. 

CH2OH  CH2OH 

(CHOH)4  (CHOH)4 


M  |  XK    u 

H-C:O        +        O:C-CH3        =         H-C(       >  C  -  CH3 


Glucose  Acetaldehyde  Glucose-acetaldehyde 

Reactions  of  Sugars  with  Polyvalent  Phenols.  —  The  simple  re- 
ducing sugars  unite  with  different  polyvalent  phenols  (resorcin,  orcin, 
hydroquinone,  phloroglucin,  pyrogallol,  etc.)  to  form  a  series  of  amor- 
phous ill-defined  condensation  products.  The  reaction  is  carried  out  in 
the  cold  in  presence  of  hydrochloric  acid.  The  following  combination 
of  arabinose  with  resorcin  is  given  as  an  illustration  of  this  type  of 
reaction. 

CsHioOs        -j-        CeHeC^        —  CnHwOe          ~h          H^O. 

Arabinose  Resorcin  Arabinose-resorcin  Water 

The  condensation  products  of  the  sugars  with  polyvalent  phenols 
when  heated  with  concentrated  hydrochloric  acid  are  decomposed,  show- 
ing the  color  and  spectral  reactions  characteristic  for  each  class  of  sugar 
(see  p.  341). 

Reactions  of  Sugars  with  Acid  Radicals.  —  In  the  many  different 
reactions  previously  described  the  aldehyde  or  ketone  group  of  the 
sugar  molecule  is  the  one  mostly  involved.  In  the  reactions  of  sugars 
with  acid  radicals,  as  acetic  and  benzoic,  the  alcohol  groups  of  the  mole- 
cule are  affected;  the  aldehydic  characteristics  of  the  sugar  are  also 
usually  modified  in  the  higher  derivatives.  The  number  of  acid  de- 
rivatives obtainable  with  a  sugar  is  dependent  upon  the  number  of 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      369 

alcohol  groups.  In  the  case  of  hexoses  having  five  such  groups  there 
are  mono-,  di-,  tri-,  tetra-  and  penta-  acetates  and  benzoates;  with 
sugars  of  fewer  alcohol  groups  the  number  of  these  combinations  is 
correspondingly  less. 

Reaction  of  Sugars  with  Acetic  Anhydride.  —  Acetates  of  the  sugars 
are  formed  by  heating  with  acetic  anhydride.  A  mixture  of  different 
acetates  usually  results  during  the  reaction,  the  separation  of  these 
being  effected  by  fractional  crystallization  or  by  the  use  of  different 
solvents.  To  obtain  the  highest  acetates,  the  reaction  must  be  carried 
out  in  presence  of  zinc  chloride  or  some  other  condensing  agent.  The 
formation  of  glucose  pentacetate  is  given  as  illustration  of  this  type  of 
reaction : 

CH2OH  CH3  -  CO  CH2OCOCH3 

1  \  I 

(CHOH)4      +5  O  (CHOCOCH3)4     +        5CH3COOH 

HC:O  CH3-CO  HC :  O 

Glucose  Acetic  anhydride  Glucose-pen tacetate  Acetic  acid 

The  lower  acetates  of  the  sugars  are  amorphous,  easily  soluble  sub- 
stances; the  higher  acetates  are  crystalline  and  less  soluble  in  water. 
By  warming  with  alcoholic  potassium  or  sodium  hydroxide,  the  acetates 
are  all  easily  saponified  with  regeneration  of  the  sugar.  The  lower  ace- 
tates of  the  sugars  are  copper  reducing  and  exhibit  other  aldehydic  prop- 
erties; the  higher  acetates,  as  glucose-pentacetate,  lack,  however,  many 
aldehyde  characteristics,  such  as  formation  of  hydrazones  and  oximes. 
This  is  probably  due  to  a  stable  lactonic  rearrangement  of  the  molecule 
as  shown  by  the  following  formula  of  Erwig  and  Konigs  *  for  glucose 
pentacetate. 

,CHOCOCH3 


/CHOCOC] 
0    CHOCOCH3 


HOCOCH3 


Reaction  of  Sugars  with  Benzoyl  Chloride.  —  The  acetates  of  the 
sugars  owing  to  their  solubility  are  not  well  adapted  for  the  identifi- 
cation of  sugars;  the  sugar  benzoates,  however,  are  marked  by  a  high 
insolubility  in  water  and  their  formation  is  sometimes  used  as  a  quali- 
tative test  for  sugars. 

*  Ber.,  22,  1464,  2209. 


370  SUGAR  ANALYSIS 

The  test,  according  to  the  method  of  Baumann,*  is  carried  out  by 
treating  a  solution  of  the  sugar  with  benzoyl  chloride  in  presence  of 
sodium  hydroxide;  the  benzoic  radical  displaces  the  H  of  the  hydroxyl 
groups  with  formation  of  sodium  chloride  and  water.  A  number  of 
benzoates  are  usually  formed  in  the  reaction.  In  the  case  of  glucose- 
pentabenzoate  the  formation  proceeds  as  follows: 

CH2OH  CH2OCOC6H5 

(CHOH)4  +  5  C6H5COC1  +  5  NaOH  =        (CHOCOC6H5)4  +  5  NaCl  +  5  H2O 

CHO  CHO 

Glucose  Benzoyl  chloride      Sodium  hydroxide  Glucose-pentabenzoate          Salt  Water 


The  Baumann  reaction  is  sufficiently  delicate  to  detect  1  to  2  mgs. 
glucose  in  100  c.c.  of  water  and  is  sometimes  employed  for  testing  urine; 
100  c.c.  of  solution  are  well  shaken  with  2  c.c.  of  benzoyl  chloride. 

SPECIAL  TESTS  FOR  REDUCING  SUGARS 

To  the  second  class  of  reactions  for  examining  sugars  belong  the 
special  tests  pertaining  to  group  identification;  the  reactions  chosen  for 
description  may  be  divided  for  convenience  into  three  general  classes. 
I.   Analysis  of  hydrazones  and  osazones. 

II.   Separation  of  products  obtained  by  decomposition  with  concen- 
trated hydrochloric  acid. 

III.   Color  reactions  with  phenols  in  presence  of  concentrated  mineral 
acids. 

I.    ANALYSIS  OF  HYDRAZONES  AND  OSAZONES  AS  A  MEANS  OF  IDENTIFYING 

SUGAR   GROUPS 

If  the  hydrazone  or  osazone  of  a  sugar  has  been  separated  in  a  pure 
condition,  an  elementary  analysis  of  the  compound  will  serve  to  identify 
the  group  to  which  the  sugar  belongs.  The  osazones,  owing  to  their 
greater  insolubility  and  ease  of  preparation,  are  best  adapted  for  this 
purpose.  The  determinations  necessary  for  the  identification  of  an 
osazone  are  those  of  the  elements  nitrogen  and  carbon;  a  determina- 
tion of  hydrogen  is  also  usually  included  since  this  element  can  be 
determined  with  little  extra  trouble  at  the  same  time  as  the  carbon 
determination. 

The  elementary  analysis  of  osazones  and  hydrazones  is  carried  out  by 
burning  about  0.2  gin.  of  the  substance  over  cupric  oxide  in  a  com- 

*  Ber.,  19,  3220. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       371 


bustion  tube.  For  nitrogen  the  combustion  is  carried  out  by  Dumas 's 
method  in  a  current  of  carbon  dioxide  after  complete  displacement  of 
the  air.  The  evolved  nitrogen  is  received  in  a  eudiometer  over  strong 
potassium  hydroxide  solution  and  its  volume  measured.  From  the  vol- 
ume of  gas  the  weight  of  nitrogen  is  calculated,  making  the  necessary 
corrections  for  atmospheric  pressure  and  temperature. 

For  carbon  and  hydrogen  the  combustion  is  carried  out  by  Liebig's 
method  in  a  current  of  air  or  oxygen  which  must  be  perfectly  dry  and 
free  from  carbon  dioxide.  The  evolved  water  is  collected  in  weighed 
tubes,  or  spirals,  containing  concentrated  sulphuric  acid,  and  the  evolved 
carbon  dioxide  absorbed  in  weighed  Liebig  bulbs  containing  concentrated 
potassium  hydroxide  solution,  or  in  U-tubes  filled  with  soda  lime  (NaOH 
+  CaO).  From  the  weights  of  water  and  carbon  dioxide  obtained  the 
percentages  of  carbon  and  hydrogen  are  calculated.  The  percentage  of 
oxygen  in  osazones  and  hydrazones  is  determined  by  subtracting  the 
sum  of  the  percentages  of  the  other  elements  from  100. 

In  the  elementary  analysis  of  osazones  and  hydrazones,  as  of  all 
other  nitrogen  compounds,  a  spiral  of  copper  should  be  placed  in  the 
combustion  tube  at  the  exit  end  in  order  to  effect  the  reduction  of 
oxides  of  nitrogen.  For  complete  details  as  to  methods  of  combustion 
the  chemist  is  referred  to  the  standard  textbooks  upon  organic  analysis. 

Having  determined  the  elementary  composition  of  an  osazone  or 
hydrazone,  reference  to  a  table  of  percentage  composition  will  usually 
locate  the  class  of  sugar  to  which  the  compound  belongs.  In  the  fol- 
lowing table  the  formula  and  percentage  composition  of  phenylosazones 
are  given  for  various  groups  of  sugars. 


Phenylosazone. 

Formula. 

Composition. 

C 
per  cent. 

H 

per  cent. 

N 
per  cent. 

O 

per  cent. 

Diose  
Triose 

C14H14N4 
C15H16N40 
C16H18N402 
Ci7H2oN403 
C18H22N403 
Ci8H22N404 
Ci9H24N406 
C20H26N406 
C2iH28N407 
C24H32N40, 

70.54 

67.12 
64.39 
62.16 
63.12 
60.30 
58.73 
57.38 
56.22 
55.35 

5.93 
6.01 
6.08 
6.14 
6.48 
6.19 
6.23 
6.27 
6.29 
6.20 

23.53 
20.90 
18.80 
17.08 
16.38 
15.64 
14.43 
13.40 
12.50 
10.77 

'5.'97 
10.73 
14.62 
14.02 
17.87 
20.61 
22.95 
24.99 
27.68 

Tetrose 

Pentose. 

Methylpentose  
Hexose  
Heptose 

Octose 

Nonose 

Disaccharide  

372  SUGAR  ANALYSIS 

II.    SEPARATION  OF  PRODUCTS  OBTAINED  BY  DECOMPOSITION  WITH  CON- 
CENTRATED  HYDROCHLORIC   ACID   AS   A   MEANS   OF   IDENTIFYING 
SUGAR   GROUPS 

While  an  elementary  analysis  of  osazones  is  one  of  the  best  means 
of  determining  the  class  to  which  a  sugar  belongs  there  are  a  number 
of  other  special  group  reactions  which  are  of  great  value.  The  most 
important  of  these  is  the  separation  and  identification  of  some  char- 
acteristic decomposition  product  obtained  by  treating  the  sugar  with 
concentrated  sulphuric  or  hydrochloric  acid.  The  latter  acid  is  less 
drastic  in  its  action  and  is  the  one  most  commonly  used. 

The  varied  nature  of  the  decomposition  products  —  humus  sub- 
stances, aldehydes,  acids,  etc.  —  obtained  upon  heating  sugars  with 
concentrated  hydrochloric  acid  has  already  been  mentioned.  It  is 
found,  however,  that  when  this  treatment  is  carefully  controlled  some 
one  characteristic  decomposition  product  will  predominate  for  each 
particular  group  of  sugar.  The  following  equations,  representing  ideal 
types  of  reaction,  are  given  as  illustrations : 

I.   C6H1206  =       C5H803  +    HCOOH     +     H2O 

Hexose  Levulinic  acid  Formic  acid  Water 

II.   C5H1005  =       C5H4O2  +     3H2O 

Pentose  Furfural  Water 

III.   C5H9(CH3)05     =       C5H3(CH3)02      +     3  H2O 

Methylpentose  Methylfurfural  Water 

The  above  types  of  reaction  hold  true  not  only  of  the  simple  sugars 
above  named,  but  also  of  the  higher  saccharides  which  yield  these 
sugars  upon  hydrolysis.  In  fact  the  initial  phase  of  the  reaction  in 
case  of  the  polysaccharides  (sucrose,  maltose,  lactose,  raffinose,  starch, 
pentosans,  methylpentosans,  etc.),  is  purely  hydrolytic,  the  simple 
sugars  formed  being  subsequently  decomposed  after  the  manner  just 
indicated. 

Levulinic  Acid  Reaction  for  Hexose  Groups.  —  This  reaction, 
which  is  due  to  Tollens  *  and  has  been  extensively  studied  by  his  co- 
workers,  has  been  employed  with  great  success  in  detecting  hexose 
groups  in  a  large  variety  of  plant  and  animal  substances  (cellular  tis- 
sues of  plants,  nucleic  acids  of  animal  origin,  etc.)  Owing  to  the  much 
greater  predominance  of  hexose-producing  substances  in  nature  the 
levulinic  acid  reaction  is  usually  among  the  first  tests  applied  in  in- 
vestigating materials  of  unknown  composition. 

Description  of  Test.  —  In  carrying  out  the  reaction  5  to  10  gms.  of 

*  Ann.,  206,  207,  226;  243,  314;  Ber.,  33,  1286. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      373 


material  are  treated  with  20  to  50  c.c.  of  hydrochloric  acid  of  1.09  to 
1.10  sp.  gr.  (18  to  20  per  cent)  in  a  flask  provided  with  a  rubber  stopper 
and  condensing  tube,  and  heated  in  a  boiling-water  bath  for  5  to  20 
hours.  The  brownish-colored  liquid  is  then  cooled  and  filtered  from  the 
precipitate  of  humus  substances;  the  filtrate  is  shaken  out  in  a  sep- 
aratory  funnel  four  times  with  ether,  and  the  ether  extract,  after  pouring 
through  a  dry  filter,  evaporated.  The  sirupy  residue  is  then  gently  heated 
in  an  open  dish  to  expel  the  formic  acid  (see  previous  equation  I).  If 
levulinic  acid  is  present  a  drop  of  the  sirup  dissolved  in  water  in  pres- 
ence of  sodium  carbonate  and  iodine  will  give  a  precipitate  of  iodoform, 
which  can  also  be  recognized  by  its  characteristic  odor. 

The  main  portion  of  the  sirup  is  dissolved  in  water,  boiled  with  an 
excess  of  zinc  oxide  (ZnO),  and  then,  after  decolorizing  with  animal 
charcoal,  filtered  and  evaporated.  The  zinc  salt  of  levulinic  acid  will 
soon  crystallize;  the  crystals  are  filtered  off,  washed  with  absolute 
alcohol  and  ether,  and  then  converted  into  the  silver  compound.  This 
is  done  by  dissolving  the  zinc  salt  in  5  to  10  c.c.  of  water,  adding  silver 
nitrate  slightly  in  excess  of  the  equivalent  amount  and  heating  nearly 
to  boiling,  with  addition  of  a  little  water  until  the  precipitated  silver 
salt  has  completely  dissolved.  A  little  animal  charcoal  is  then  added 
and  the  solution  filtered.  The  levulinate  of  silver,  CsHyOsAg,  which 
crystallizes  will  show  under  the  microscope,  in  case  the  compound  is 
pure,  hexagonal  crystals  or  plates;  if  the  compound  is  less  pure  the 
crystals  will  be  feather-like  in  appearance.  The  silver  salt  is  filtered 
off,  washed  with  cold  water,  pressed  between  filter  paper  and  dried  in  a 
dark  place  over  concentrated  sulphuric  acid.  The  per  cent  of  silver  in 
the  salt  is  determined  by  strongly  igniting  a  weighed  portion  in  a  por- 
celain crucible.  The  theoretical  amount  is  48.39  per  cent  Ag. 

The  yield  of  levulinic  acid  obtained  by  treating  hexose  sugars  with 
hydrochloric  acid  will  vary  greatly  according  to  the  time  of  heating  and 
other  conditions  of  the  experiment.  Conrad  and  Guthzeit  *  obtained 
upon  heating  10.5  gms.  each  of  fructose,  glucose,  and  galactose,  with  50 
c.c.  of  acid  (containing  4.87  gms.  HC1  gas)  for  17  hours  the  following  yield 
of  products. 


Sugar. 

Humua. 

Levulinic  acid. 

Formic  acid. 

Fructose  
Glucose  

Grams. 
2.12 
1.00 

1.77 

Per  cent. 
20.19 

9.52 
16.86 

Grams. 
4.09 
3.12 

2.85 

Per  cent. 
38.95 

29.71 
27.14 

Grams. 
1.73 
1.35 
1.11 

Per  cent. 
16.48 
12.86 

10.57 

Galactose  .... 

*  Ber.,  19,  2575. 


374  SUGAR  ANALYSIS 

From  these  results  it  appears  that  of  the  three  hexose  sugars  fruc- 
tose gives  the  largest  yield  of  levulinic  acid  and  galactose  the  least. 
That  this  is  due  largely  to  the  greater  resistance  of  glucose  and  galac- 
tose toward  the  acid  was  shown  by  the  fact  that  at  the  end  of  the  above 
experiments  considerable  quantities  of  these  sugars  were  still  unde- 
composed  (in  case  of  glucose  26  per  cent).  The  yield  of  levulinic  acid 
is  too  variable  for  the  method  to  be  of  any  quantitative  value. 

Furfural  Reaction  for  Pentose  Groups.  —  This  reaction,  which  is 
also  due  to  Tollens,*  has  been  of  the  greatest  value  not  only  as  a  means 
of  detecting  the  presence  of  pentose  carbohydrates  but  also  as  a  means 
of  their  quantitative  estimation. 

The  reaction  of  the  pentose  sugars  with  hydrochloric  acid  proceeds 
much  more  nearly  according  to  the  equation  (II,  p.  372)  than  the 
reaction  of  the  hexoses,  the  formation  of  humus  substances  being  cor- 
respondingly less.  The  following  graphic  equation  shows  the  decom- 
position of  a  pentose  sugar  into  furfural. 


I  CH:CH 

CH-CH-iOHi       -  v 

I         xOjH  !  in-p'0    +   3H2° 

„    CH-CV,   ........  CH'C\C-0 

J  ......  :lxc:o  M 

JQH...H!  * 

Pentose  (150  parts)  Furfural  (96  parts)        Water  (54  parts) 

The  theoretical  yield  of  furfural,  according  to  the  above  equation, 
is  64  per  cent;  actual  determinations  of  the  furfural,  obtained  by  dis- 
tilling weighed  amounts  of  the  pentose  sugars,  arabinose  and  xylose, 
with  hydrochloric  acid,  give  about  47  per  cent  in  case  of  arabinose  and 
about  57  per  cent  in  case  of  xylose  —  yields  which  are  about  75  per  cent 
and  90  per  cent  respectively  of  the  theoretical. 

Description  of  Test.  —  In  carrying  out  the  qualitative  test  about 
5  gms.  of  substance  are  heated  in  a  distillation  flask  with  100  c.c.  of 
hydrochloric  acid  of  1.06  sp.  gr.  and  successive  portions  of  about  30  c.c. 
distilled  into  a  receiver,  new  portions  of  acid  being  added  to  the  flask  for 
each  quantity  distilled.  The  distillates  are  then  tested  for  the  presence 
of  furfural;  the  latter  in  large  amounts  can  usually  be  detected  by  its 
pleasant  aromatic  odor  somewhat  resembling  that  of  bitter  almond  oil. 
The  presence  of  very  small  amounts  of  furfural  is  best  indicated  by 
Schiff's  reaction  with  aniline  or  xylidine  acetate.  Aniline  acetate  re- 
agent is  best  prepared  according  to  Tollens  by  mixing  in  a  test  tube 
equal  volumes  of  aniline  and  water  and  then  adding  with  constant  shak- 
*  Landw.  Vers.-Stat.,  39,  425. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      375 

ing  glacial  acetic  acid  drop  by  drop  until  the  milky  solution  becomes 
clear.  Test  paper  is  prepared  by  moistening  strips  of  filter  paper  with 
the  aniline-acetate  solution.  Application  of  a  drop  of  distillate  con- 
taining furfural,  even  in  minute  traces,  will  cause  the  aniline-acetate 
paper  to  turn  a  bright  cherry  red. 

The  presence  of  furfural  in  the  distillate  may  also  be  indicated  by 
first  neutralizing  the  acid  solution  with  sodium  carbonate  and  then  add- 
ing a  solution  of  phenylhydrazine  acetate  and  stirring.  Furfural  if  pres- 
ent is  precipitated  as  furfural-phenylhydrazone,  C4H3OCHN2HC6H5, 
which  melts  at  97°  to  98°  C. 

A  better  precipitating  agent  for  furfural  than  phenylhydrazine  is 
phloroglucin.  A  solution  of  this  compound  in  hydrochloric  acid  when 
added  to  a  distillate  containing  furfural  will  cause  an  immediate  dark- 
ening of  the  solution  with  final  precipitation  of  furfural-phloroglucide, 
according  to  equation: 

C5H402          +          C6H603      =          CnH8O4          +          H2O 

Furfural  Phloroglucin  Furfural-phloroglucide  Water 

Limitations  of  Furfural  Reaction  for  Pentoses.  —  While  all  carbohy- 
drates containing  a  pentose  group  yield  large  amounts  of  furfural  upon 
distillation  with  hydrochloric  acid,  it  must  also  be  borne  in  mind  that 
other  substances  have  the  same  property.  All  hexose  carbohydrates  such 
as  starch,  cellulose,  sucrose,  glucose,  etc.,  give  small  amounts  of  furfural 
upon  distillation  with  hydrochloric  acid  but  the  yield  is  too  small  to  in- 
terfere seriously  with  the  test  for  pentoses.  Two  substances,  however, 
of  a  non-pentose  nature  are  especially  marked  by  their  property  of 
yielding  furfural  upon  distilling  with  acids  and  hence  require  brief 
mention.  These  are  glucuronic  acid  and  oxycellulose. 

Glucuronic  acid  is  an  aldehyde-acid  derivative  of  glucose  and  has 
the  formula  COH(CHOH)4  COOH.  By  the  action  of  putrefactive 
bacteria  it  is  converted  into  the  pentose  sugar  1-xylose. 

C6H10O7  C5H1005        +          C02 

Glucuronic  acid  Xylose  Carbon  dioxide 

The  intimate  relationship  of  glucuronic  acid  to  the  pentoses  is  also 
shown  by  the  reaction  upon  distilling  with  hydrochloric  acid. 

C6H10O7      =     C5H402     +     3H2O     +      C02 

Glucuronic  acid  Furfural  Water  Carbon  dioxide 

Glucuronic  acid  is  sometimes  found  in  the  urine,  especially  after  the 
ingestion  of  chloral,  menthol,  camphor,  turpentine,  acetanilide,  alka- 
loids and  many  other  compounds.  Under  such  conditions  a  combina- 
tion takes  place  in  the  animal  organism  between  the  ingested  compound 


376 


SUGAR  ANALYSIS 


and  the  glucuronic  acid,  the  latter  apparently  being  formed  as  an  oxi- 
dation product  of  glycogen.  The  glucuronic-acid  derivative,  which  is 
excreted  in  the  urine,  may  be  mistaken  for  a  pentose  sugar  if  the  chemist 
relies  solely  upon  such  tests  as  the  furfural  reaction  and  reduction  of 
metallic  salt  solutions. 

One  means  of  determining  the  presence  of  glucuronic  acid  is  by 
means  of  p-bromophenylhydrazine,  which  was  found  by  Neuberg  *  to 
give  a  characteristic  glucuronic-acid  derivative,  C^HnOr^Br.  The 
exact  nature  of  the  compound,  whether  hydrazone  or  hydrazide,  was 
not  determined.  The  solution  to  be  tested  is  heated  in  a  water  bath  at 
60°  C.  with  5  gms.  of  p-bromophenylhydrazine  chloride  and  6  gms.  of 
sodium  acetate.  If  glucuronic  acid  is  present  yellowish  needle-like  crys- 
tals will  separate  in  5  to  10  minutes.  The  solution  is  cooled,  the  crystals 
filtered  off  and  the  filtrate  again  heated  as  before;  a  second  crop  of 
crystals  may  thus  be  obtained  which  are  filtered  off  again  and  the 
process  continued  until  no  more  crystals  form.  The  combined  precipi- 
tates are  thoroughly  washed  with  warm  water  and  then  with  absolute 
alcohol.  Recrystallized  from  60  per  cent  alcohol  the  crystals  melt  at 
236°  C.  The  crystals  dissolved  in  a  mixture  of  6  c.c.  absolute  alcohol 
and  4  c.c.  pyridine  have  a  strong  levorotation,  [O\D  =  —  369. 

Spectroscopic  methods  for  distinguishing  between  pentoses  and  glu- 
curonic acid  will  be  described  under  the  color  reactions  for  sugar  groups. 

Cellulose,  when  treated  with  different  oxidizing  agents,  such  as  nitric 
acid,  chromic  acid,  hypochlorous  acid  and  permanganate,  undergoes  a 
partial  oxidation.  The  oxycellulose  derivatives  formed  under  such 
conditions  have  the  property  of  yielding  furfural  upon  distillation  with 
hydrochloric  acid. 

According  to  the  researches  of  Tollens  and  Faber  f  oxycelluloses 
consist  of  mixtures  of  cellulose  (CeHioOs^  in  different  porportions  with 
an  oxy-derivative  celloxin  (C6H806)n.  The  greater  the  amount  of  cel- 
loxin  in  the  oxycellulose  the  greater  the  yield  of  furfural  upon  distilla- 
tion with  hydrochloric  acid.  Cotton,  for  example,  upon  treatment  with 
nitric  acid  at  100°  C.  for  different  periods  of  time,  gave  the  following 
results : 


Time  of  treatment. 

Composition. 

Yield  of  furfural. 

Hours. 

2* 

4 

4  C6HioO5,  C6H8O6 
3  CeHioOs,  C6H8O6 

Per  cent. 
2.3 
3.2 

*  Ber.,  32,  2395. 
t  Ber.,  32,  2589. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      377 

The  yield  of  furfural  calculated  to  pure  celloxin  (which  has  not  as 
yet  been  isolated)  is  about  12  per  cent. 

The  oxycelluloses  are  widely  distributed  in  nature  and  if  reliance 
is  based  exclusively  upon  the  furfural  reaction  erroneous  conclusions 
may  be  formed  as  to  the  occurrence  of  pentose  carbohydrates  in  plant 
materials.  The  oxycelluloses  may  be  easily  distinguished,  however, 
from  pentosans  by  the  fact  that  they  yield  glucose  exclusively  upon 
hydrolysis  with  acids,  the  hydrolytic  products  giving  none  of  the  re- 
actions (osazone,  color  tests,  etc.)  characteristic  of  the  pentoses. 

Methylfurfural  Reactions  for  Methylpentose  Groups.  —  In  the 
same  way  that  all  substances  containing  pentose  groups  yield  furfural 
upon  distilling  with  hydrochloric  acid,  those  materials  containing  methyl- 
pentose  groups  yield  methylfurfural.  The  reaction  is  perfectly  anal- 
ogous to  that  described  upon  page  374. 


iOH    H; 
|  >CH, 

-C-iOHi  =    yH-% 


|         |XC:O  H 

jpH"H|H 

Methylpentose  (164  parts)  Methylfurfural  (110  parts)  Water  (54  parts) 

The  theoretical  yield  of  methylfurfural  from  methylpentose  accord- 
ing to  the  above  reaction  is  67.07  per  cent.  In  actual  distillation  ex- 
periments with  the  methylpentoses,  fucose  and  rhamnose,  only  from 
35  to  40  per  cent  methylfurfural  is  obtained  or  50  to  60  per  cent  of  the 
theoretical  amount. 

In  testing  natural  products  for  the  presence  of  methylpentose 
groups,  the  material  is  distilled  with  hydrochloric  acid  of  1.06  sp.  gr.  in 
exactly  the  same  manner  as  described  for  pentoses  and  the  distillate 
tested  for  methylfurfural.  If  no  furfural  is  present  in  the  distillate  the 
presence  of  methylfurfural  will  be  indicated  by  aniline-acetate  paper, 
which  in  this  instance  is  colored  yellow.  If  pentosans  are  also  present 
in  the  plant  material  being  examined,  as  is  nearly  always  the  case,  the 
presence  of  furfural  in  the  distillate  will  color  the  aniline-acetate  paper 
red  and  completely  mask  the  yellow  color  of  the  methylfurfural  re- 
action. Other  tests  must,  therefore,  be  employed  to  detect  the  presence 
of  methylfurfural. 

Maquenne  *  has  devised  a  reaction  by  which  1  part  methylfur- 
fural can  be  detected  in  presence  of  9  parts  furfural.  A  small  amount 
of  the  solution  to  be  tested  is  added  to  a  mixture  containing  3  volumes 

*  Compt.  rend.,  109,  573. 


378  SUGAR  ANALYSIS 

95  per  cent  alcohol  and  1  volume  concentrated  sulphuric  acid  and  the 
whole  gently  warmed.  The  development  of  a  bright  grass-green  color 
throughout  the  body  of  the  solution  indicates  the  presence  of  methyl- 
furfural. 

Spectral  reactions  for  methylfurfural  will  be  described  in  a  succeed- 
ing section. 

Reactions  for  Tetrose  and  Triose  Groups.  —  Excepting  the  hexoses, 
pentoses  and  methylpentoses,  but  few  experiments  have  been  made 
concerning  the  reactions  of  other  sugar  groups  with  hydrochloric  acid. 

Experiments  of  Tollens  and  Ellett  *  show  that  1-erythrose  is  de- 
composed upon  heating  with  hydrochloric  acid  into  lactic  acid.  The 
reaction  may  proceed  as  follows: 

C4H804        =         C3H603        +          CH20 

Tetrose  Lactic  acid  Formaldehyde 

Tollens  and  Ellett  suggest  that  the  above  may  be  a  general  reaction 
for  tetrose  groups,  just  as  levulinic  acid  is  formed  from  hexoses,  fur- 
fural from  pentoses,  and  methylfurfural  from  methylpentoses. 

The  formation  of  considerable  methylglyoxal  CH3  — CO  — COH  by 
heating  dioxyacetone,  CaHeOa,  with  sulphuric  acid  has  been  observed 
by  Pinkus.f  This  may  perhaps  be  a  group  reaction  of  trioses. 

Further  investigations  require  to  be  made  upon  the  tetroses  and 
trioses  before  any  results  from  the  above  observations  can  be  applied  to 
sugar  analysis. 

III.    COLOR    AND    SPECTRAL    REACTIONS    AS    A    MEANS    OF    IDENTIFYING 

SUGARS 

A  study  of  the  color  reactions  and  absorption  spectra  which  solu- 
tions of  different  sugars  give  with  various  phenols  as  a-naphthol,  orcin, 
resorcin,  naphthoresorcin  and  phloroglucin,  in  presence  of  concentrated 
sulphuric  or  hydrochloric  acids  offers  frequently  a  most  rapid  as  well 
as  most  reliable  method  for  detecting  sugar  groups. 

Color  Reactions  of  Ketoses.  —  Reference  has  already  been  made 
(p.  340)  to  the  greater  ease  with  which  solutions  of  ketoses  show  colora- 
tion phenomena  in  contact  with  concentrated  sulphuric  acid.  The  same 
fact  has  been  noted  with  the  colorations  produced  with  sugars  and 
a-naphthol  and  sulphuric  acid,  and  this  has  been  utilized  as  one  means 
of  detecting  the  presence  of  ketose  sugars  in  mixtures. 

a-Naphthol  Test. — Pinoff  {  has  modified  the  a-naphthol  test  for  sugars 
by  using  a  mixture  of  750  c.c.  96  per  cent  alcohol  and  200  gms.  con- 
centrated sulphuric  acid  as  the  condensing  agent.  By  treating  in  a  test 

*  Ber.,  38,  499.  f  Ber.,  31,  31.  t  Ber.,  38,  3314. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      379 


tube  0.05  gm.  of  sugar  with  10  c.c.  of  the  alcohol-acid  mixture  and 
0.2  c.c.  of  alcoholic  a-naphthol  (5  gms.  a-naphthol  dissolved  in  100  c.c. 
96  per  cent  alcohol)  and  heating  in  boiling  water,  Pinoff  obtained  red 
colorations  which  in  case  of  sugars  containing  ketone  groups  appeared 
almost  immediately;  with  the  aldose  sugars  20  minutes  or  more  elapsed 
before  coloration  developed.  The  following  table  for  1 1  different  sugars 
by  Pinoff  gives  the  time  of  heating  before  coloration,  the  number  of 
absorption  bands  shown  by  the  solution  before  the  spectroscope  and 
the  position  of  the  bands  with  reference  to  the  wave  length  of  the  light 
absorbed. 

TABLE  LXVIII 

Giving  Absorption  Spectra  of  Sugars  with  a-Naphthol  and  Sulphuric  Acid  in  Alcohol 


Sugar. 

Time  for 
develop- 
ment of 
color. 

Number  of 
absorption 
bands. 

Wave  length  in  nn  and  position  of  bands. 

Arabinose    .  .  . 

Minutes. 
20 

Rhamnose  . 

20 

1 

562.5  (in  yellow) 

Glucose  

35 

532  5  (between  yellow  and  green) 

Mannose  

31 

1 

532  .  5  (between  yellow  and  green) 

Galactose  

31 

1 

532.5  (between  yellow  and  green) 

Fructose  

1 

2 

573.6  (in  yellow),  508.8  (in  green) 

Sorbose  

1 

2 

573.6  (in  yellow),  508.8  (in  green) 

Sucrose  

1 

2 

573.6  (in  yellow),  508.8  (in  green) 

Lactose 

31 

1 

532  5  (between  yellow  and  green) 

Maltose  .    . 

31 

1 

532  5  (between  yellow  and  green) 

Raffinose  

1 

o 

573.6  (m  yellow),  508.8  (in  green) 

It  will  be  noted  that  for  the  ketose  sugars  fructose  and  sorbose  and 
for  the  di-  and  tri-saccharides  sucrose  and  raffinose,  which  give  the 
ketose  sugar  fructose  upon  hydrolysis,  a  red  coloration  is  obtained  in 
1  minute,  while  for  the  other  sugars  20  to  35  minutes  must  elapse 
before  coloration.  By  diluting  the  10  c.c.  of  sulphuric-acid  alcohol 
mixture  with  10  c.c.  of  96  per  cent  alcohol  before  making  the  test, 
Pinoff  obtained  no  coloration  sufficient  to  show  absorption  bands  with 
any  of  the  aldose  sugars.  For  the  ketose  sugars  he  obtained  the  fol- 
lowing results: 


Sugar. 

Time  for  de- 
velopment of 
color. 

Number  of 
bands. 

Wave  length  in  MM  and 
position  of  bands. 

Fructose  .  .  . 

Minutes. 
13 

1 

508.8  (in  green) 

Sorbose  

30 

1 

508.8  (in  green) 

Sucrose  

15 

1 

508.8  (in  green) 

Raffinose  

19 

1 

508.8  (in  green) 

380  SUGAR  ANALYSIS 

While  diluting  the  acid-alcohol  mixture  has  practically  eliminated 
the  aldoses  from  the  reaction,  it  has  also  materially  lessened  the  sen- 
sibility of  the  test  for  the  ketoses. 

Resorcin  Test.  —  The  most  convenient  color  test  for  distinguishing 
ketose  from  aldose  sugars  is  the  color  reaction  with  resorcin  and  hydro- 
chloric acid  —  generally  known  as  Seliwanoff's  *  test.  The  test  was 
originally  regarded  as  peculiar  to  fructose,  but  later  experiments  have 
shown  that  it  is  given  by  sorbose,  tagatose,  the  keto-pentoses  and  all 
other  sugars  having  a  ketone  group. 

The  reaction  is  carried  out  by  mixing  in  a  test  tube  10  c.c.  of  the 
clarified  solution  to  be  tested  with  10  c.c.  of  25  per  cent  hydrochloric 
acid,  then  adding  a  little  resorcin  (about  the  tip  of  a  knifebladeful),  and 
heating  gently  over  a  small  flame.  If  fructose  or  other  ketose  is  present 
a  fiery  eosin-red  color  will  develop,  which  upon  cooling  and  standing 
will  deposit  as  an  amorphous  powder  mixed  with  humus  decomposition 
products. 

If  the  acid  solution  is  made  alkaline  with  soda  and  then  shaken  with 
amyl  alcohol,  the  red  coloring  matter  is  dissolved  with  a  greenish 
fluorescence.  If  a  few  drops  of  absolute  alcohol  be  now  added  the 
color  becomes  a  beautiful  rose  red. 

If  the  red-colored  solutions  obtained  by  Seliwanoff's  reaction  be  ex- 
amined before  the  spectroscope  a  distinct  absorption  band  will  be  noted 
in  the  blue  near  the  F  line.  (See  Fig.  165.) 

It  is  important  in  making  the  test  with  resorcin  that  an  excess  of 
hydrochloric  acid  be  avoided.  The  percentage  of  acid  in  the  final  mix- 
ture should  be  about  12 J  per  cent.  If  too  much  strong  acid  is  present, 
glucose  and  other  aldoses  will  also  react  with  resorcin  and  form  pink- 
colored  solutions;  the  latter,  while  lacking  the  intensity  of  color  obtained 
with  the  ketoses,  may  nevertheless  lead  to  erroneous  conclusions.  The 
resorcin  reaction  obtained  with  glucose  may  be  due  to  a  slight  trans- 
formation of  this  sugar  into  fructose.  Ost,  as  a  matter  of  fact,  has 
succeeded  in  effecting  such  a  transformation  by  treating  glucose  in 
the  cold  with  strong  sulphuric  acid. 

Pinoff  f  has  modified  the  resorcin  test  for  ketoses  by  using  the 
alcohol-sulphuric-acid  mixture  previously  described  as  the  condensing 
agent.  In  making  the  test  0.05  gm.  of  sugar  was  treated  in  a  test 
tube  with  5  c.c.  of  the  alcohol-sulphuric-acid  reagent,  5  c.c.  alcohol  and 
0.2  c.c.  of  a  5  per  cent  resorcin  solution  and  the  mixture  placed  in  boil- 
ing water.  The  following  table  for  11  different  sugars  by  Pinoff  gives 
the  length  of  time  required  for  development  of  color,  the  number  of 
*  Ber.,  20,  181.  t  Ber.,  38,  3314. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       381 


absorption  bands  and  the  position  of  the  bands  with  reference  to  wave 
length  of  light  absorbed. 

TABLE  LXIX 

Giving  Absorption  Spectra  of  Sugars  with  Resorcin  and  Sulphuric  Acid  in  Alcohol 


Sugar. 

Time  for  de- 
velopment of 
color. 

Number  of  ab- 
sorption bands. 

Wave  lengths  in  nn  and 
position  of  bands. 

Arabinose                     ... 

Minutes. 
35 

Rhamnose  

35 

Glucose  

32 

1 

487.5  (in  blue) 

Mannose  

35 

Galactose  

35 

Fructose  

1 

1 

487.5  (in  blue) 

Sorbose  

1 

1 

487.5  (in  blue) 

Sucrose 

1 

1 

487  5  (in  blue) 

Lactose 

32 

1 

487  5  (in  blue) 

Maltose 

32 

1 

487  5  (in  blue) 

Raffinose 

1 

1 

487  5  (in  blue) 

Naphthoresorcin  Test.  —  Tollens  and  Rorive  *  have  employed  in 
place  of  resorcin  naphthoresorcin  or  1 :  3  dioxynaphthalin.  The  ketose 
sugars  fructose  and  sorbose  and  the  di-  and  trisaccharides  sucrose 
and  raffinose  show  upon  heating  with  a  little  naphthoresorcin  in  pres- 
ence of  hydrochloric  acid  (1  vol.  acid  1.19  sp.  gr.  and  1  vol.  water)  beauti- 
ful red-colored  solutions  which  show  a  weak  absorption  band  in  the 
green.  The  sensibility  of  this  test  is  about  the  same  as  that  obtained  in 
Seliwanoff's  reaction,  but  the  color  has  more  of  a  violet  tinge  than  the 
fiery  red  obtained  with  resorcin.  The  red-colored  solutions  obtained 
with  naphthoresorcin  soon  become  turbid  with  formation  of  a  deposit. 
If  the  latter  is  filtered  off  and  dissolved  in  alcohol  a  yellowish-brown 
solution  with  green  fluorescence  is  obtained  which  shows  a  weak  absorp- 
tion band  in  the  green. 

Color  Reactions  of  Pentoses  (and  Glucuronic  Acid) .  —  The  pentoses 
are  distinguished  above  all  other  sugar  groups  for  the  depth  and  variety 
of  the  color  reactions  obtained  with  different  polyvalent  phenols  in 
presence  of  concentrated  hydrochloric  acid.  Phloroglucin,  orcin  and 
naphthoresorcin  are  the  three  compounds  most  used  for  this  purpose, 
and  the  reactions  for  each  of  these  will  be  described  in  the  order 
named. 

Phloroglucin  Test.  —  Ihl  f  discovered  that  solutions  of  the  pentose 
sugars,  or  of  hydrolytic  products  derived  from  substances  containing 

*  Ber.,  41,  1783.  t  Chemiker  Ztg.  (1885),  231. 


382  SUGAR  ANALYSIS 

pentosans,  gave,  upon  heating  with  an  equal  volume  of  concentrated 
hydrochloric  acid  and  a  little  phloroglucin,  a  beautiful  violet-red  color. 
The  colored  solution  thus  obtained  when  viewed  before  the  spectro- 
scope was  found  by  Tollens  and  Allen  *  to  show  a  sharp  black  absorp- 
tion band  in  the  yellow  of  the  spectrum  between  the  D  and  E  lines. 

The  violet-red  solution  obtained  in  the  phloroglucin  reaction  for 
pentoses  soon  becomes  turbid  with  deposition  of  a  dark-colored  precipi- 
tate. If  the  turbid  solution  is  allowed  to  stand  3  to  5  minutes,  then 
cooled,  filtered  and  the  precipitate  washed  with  cold  water  on  a  small 
rapid  filter  and  then  dissolved  in  95  per  cent  alcohol,  a  permanent  red 
solution  is  obtained  which  is  perfectly  adapted  to  the  study  of  ab- 
sorption spectra.  If  the  color  is  too  deep  it  can  be  reduced  by  careful 
dilution  with  96  per  cent  alcohol.  (Tollens's  "  absatz  "  method.) 

The  same  color  reaction  of  the  pentoses  with  phloroglucin  and 
hydrochloric  acid  is  given  by  glucuronic  acid  and  its  derivatives,  but 
not  by  oxycellulose.  The  test,  therefore,  while  enabling  the  chemist  to 
distinguish  between  such  furfural-yielding  substances  as  pentosans  and 
oxycellulose,  does  not  permit  the  distinction  between  glucuronic  acid 
and  pentoses  (as  for  example  in  urine). 

Orcin  Test.  —  If  the  reaction  for  the  pentoses  just  described  be 
carried  out  with  orcin  in  place  of  phloroglucin  a  violet-blue  coloration 
is  obtained.  The  solution,  however,  becomes  rapidly  turbid  with  de- 
position of  a  bluish-colored  flaky  precipitate.  If  the  latter  is  filtered 
off  and  dissolved  in  alcohol  by  Tollens's  "  absatz "  method  a  blue- 
colored  solution  is  obtained  which  shows  before  the  spectroscope  a  very 
sharp  dark  band  almost  exactly  over  the  D  line  of  the  spectrum.  The 
same  reaction  is  also  obtained  with  glucuronic  acid. 

Bial  f  has  made  the  orcin  reaction  more  sensitive  by  carrying  out 
the  test  in  presence  of  a  little  ferric  chloride.  In  this  manner  it  is 
found  possible  to  distinguish  between  pentoses  and  glucuronic  acid. 

Bial's  orcin  reagent  is  prepared  by  dissolving  1  gm.  orcin  in  500  c.c. 
hydrochloric  acid  of  1.15  sp.  gr.  (30  per  cent)  to  which  20  drops  of 
an  officinal  solution  of  ferric  chloride  (liquor  ferri  sesquichloridi)  are 
added. 

In  making  the  test  4  to  5  c.c.  of  the  reagent  are  heated  in  a  test 
tube  to  boiling;  the  solution  is  removed  from  the  flame  and  a  few  drops 
(never  over  1  c.c.)  of  the  solution  to  be  tested  added.  If  pentoses  are 
present  a  vivid  green  color  will  develop  almost  immediately;  the  re- 
action is  not  given  under  the  above  conditions  with  glucuronic  acid. 

*  Ann.,  260,  289. 

t  Biochem.  Zeitschrift.,  3,  323. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS       383 

BiaFs  test  has  been  studied  and  generally  confirmed  by  Sachs,*  and 
also  by  Tollens  and  Lefevre.f  The  last-named  authorities  found  that 
a  dilute  solution  of  glucuronic  acid  produced  no  perceptible  coloration 
under  the  conditions  prescribed  by  Bial,  but  that  if  the  solution  was 
heated  for  any  length  of  time  a  green  color  speedily  developed.  The 
cause  of  the  retardation  is  explained  by  the  slower  decomposition  of 
glucuronic  acid  by  hydrochloric  acid  as  compared  with  the  pentoses; 
such  a  difference  in  the  rate  of  decomposition  is  also  noted  between  the 
pentose  sugars  themselves,  xylose,  for  example,  giving  a  coloration  with 
Dial's  reagent  in  a  shorter  time  than  arabinose. 

The  green  solution  obtained  by  BiaFs  reaction  shows  before  the 
spectroscope  a  dark  absorption  band  in  the  red  between  the  lines  B  and 
C  and  a  second  band  in  the  yellow  covering  the  position  of  the  D  line 
of  the  spectrum. 

Naphthoresorcin  Test  for  Pentoses  and  Glucuronic  Acid.  —  Tollens  and 
Rorive  J  have  found  that  when  solutions  of  different  sugars  are  heated 
with  a  little  naphthoresorcin  in  presence  of  an  equal  volume  of  concen- 
trated hydrochloric  acid  (1.19  sp.  gr.)  characteristic  colored  solutions 
and  deposits  are  formed. 

With  the  pentoses  arabinose  and  xylose  a  red  color  develops  on 
heating  followed  by  a  bluish  turbidity.  The  deposit  dissolves  in  alco- 
hol to  a  reddish-brown  solution  with  beautiful  green  fluorescence,  show- 
ing a  weakly-defined  absorption  band  in  the  green. 

Glucuronic  acid  gives  with  naphthoresorcin  and  hydrochloric  acid 
a  bluish  turbid  solution  with  blue  deposit.  The  alcoholic  solution  of 
the  latter  is  a  beautiful  blue,  only  slightly  fluorescent,  and  shows  a 
dark  absorption  band  in  the  yellow  covering  the  D  line  of  the 
spectrum. 

The  naphthoresorcin  test  for  glucuronic  acid  has  been  improved  by 
Tollens  §  in  the  following  way.  The  deposit  of  coloring  matter  is 
treated  with  ether  instead  of  alcohol;  if  glucuronic  acid  is  present  the 
ether  is  colored  a  violet  blue  and  shows  before  the  spectroscope  an 
absorption  band  in  the  yellow,  its  center  lying  a  little  to  the  right  of  the 
D  sodium  line  (i.e.,  toward  the  green). 

The  naphthoresorcin  deposits  obtained  with  sugars  (pentoses, 
hexoses,  etc.)  in  presence  of  hydrochloric  acid  are  insoluble  in  ether 
and  so  do  not  appear  in  the  reaction.  The  presence  of  sugar  and  also 
of  foreign  organic  matter,  as  in  urine,  may  change  the  color  of  the  ether 
solution  from  the  violet  blue  characteristic  of  pure  glucuronic  acid  to  a 

*  Biochem.  Zeitschrift.,  1,  384.  {  Ber.,  41,  1783. 

t  Ber.,  40,  4520.  §  Ber.,  41,  1788. 


384 


SUGAR  ANALYSIS 


violet,  red,  or  reddish  brown.     The  characteristic  absorption  band  in 
the  yellow  part  of  the  spectrum  will  not,  however,  be  interfered  with. 


B  C 


Indigo 


Violet 


Fructose,     resorcin    and    hydro- 
chloric acid. 


Sucrose,  a-naphthol  and  sulphuric 
acid. 


Arabinose,  phloroglucin  and  hy- 
drochloric acid. 


Methylfurfural,  phloroglucin  and 
hydrochloric  acid. 


Methylfurfural  and  hydrochloric 
acid. 


Fig.  165.  —  Absorption  spectra  given  by  different  sugars. 

The  naphthoresorcin  test  as  prescribed  by  Tollens  is  made  as  fol- 
lows: 5  to  6  c.c.  of  the  solution  (urine,  etc.)  to  be  tested  are  treated  in 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      385 

a  16  mm.  wide  test  tube  with  \  to  1  c.c.  of  a  1  per  cent  solution  of 
naphthoresorcin  in  alcohol  and  an  equal  volume  of  hydrochloric  acid 
of  1.19  sp.  gr.  added.  The  solution  is  carefully  heated  to  boiling  and 
then  kept  for  1  minute  over  a  small  flame.  The  dark-colored  solution 
is  set  aside  for  4  minutes  and  then  cooled  under  a  stream  of  cold  water; 
an  equal  volume  of  ether  is  then  added  and  the  whole  thoroughly 
shaken.  After  the  acid  solution  has  settled  the  ether  layer  will  be 
colored  blue  or  bluish  violet  to  red,  in  case  glucuronic  acid  is  present, 
and,  if  the  tube  is  held  before  the  spectroscope,  will  show  the  character- 
istic absorption  band  near  the  D  line.  In  case  the  ether  does  not  sepa- 
rate readily  a  drop  or  two  of  alcohol  will  hasten  the  process.  If  the 
ether  solution  is  too  deeply  colored  for  spectroscopic  examination  more 
ether  is  added  until  the  color  is  reduced  and  the  unabsorbed  part  of  the 
spectrum  made  visible. 

The  naphthoresorcin  deposits  of  the  pentoses  and  other  sugars 
being  insoluble  in  ether  separate  as  a  layer  between  the  colored  ether 
and  the  lower  acid  solution. 

Color  Reactions  of  Methylpentoses.  —  The  color  reactions  for 
detection  of  methylpentoses  may  be  divided  into  two  classes:  (1)  color 
reactions  made  upon  the  distillate  obtained  by  distilling  methylpentoses 
or  methylpentosans  with  hydrochloric  acid;  (2)  color  reactions  made 
directly  upon  these  substances  without  distillation.  The  color  reactions 
of  the  first  class  are  in  reality  color  reactions  of  methylfurfural  to 
which  reference  has  already  been  made.  It  remains,  however,  to  describe 
some  of  the  spectral  reactions  of  methylfurfural. 

Spectral  Reactions  of  Methylfurfural.  —  Tollens  and  Widtsoe  *  have 
detected  the  presence  of  methylfurfural  in  the  hydrochloric  acid  dis- 
tillate from  various  plant  materials  by  mixing  a  few  cubic  centimeters 
of  the  solution  with  an  equal  volume  of  concentrated  hydrochloric  acid 
and  gently  warming.  If  the  solution  is  colored  yellow  methylfurfural  is 
present.  The  yellow  solution  viewed  before  the  spectroscope  will  show 
a  dark  absorption  band  between  the  green  and  blue  of  the  spectrum 
near  the  F  line.  If  much  methylfurfural  is  present  the  band  will  grad- 
ually darken  and  broaden,  the  increase  in  width  extending  toward  the 
violet  and  leaving  the  green  unaffected.  With  considerable  methyl- 
furfural  the  violet  end  of  the  spectrum  is  completely  extinguished,  the 
green,  however,  always  remaining  clear  and  transparent.  Furfural  does 
not  give  this  reaction  although  it  may  affect  the  delicacy  of  the  test  if 
present  in  large  amount.  The  reaction,  however,  will  indicate  1  part  of 
methylfurfural  in  presence  of  64  parts  furfural  (^V  drop  methylfurfural 

*  Ber.,  33,  146. 


386  SUGAR  ANALYSIS 

in  presence  of  2  drops  furfural  in  10  c.c.  of  hydrochloric  acid).  By  use 
of  this  test  Tollens  and  Widtsoe  were  able  to  detect  methylpentosans 
in  different  gums,  sea  weed,  leaves  of  different  kinds  of  trees  and  a 
large  variety  of  other  plant  substances. 

Tollens  and  Oshima  *  have  rendered  the  spectral  reaction  for 
methylfurfural  more  sensitive  by  carrying  out  the  test  in  presence  of 
phloroglucin;  5  c.c.  of  the  hydrochloric  acid  distillate  are  treated  with 
5  c.c.  of  concentrated  hydrochloric  acid  and  a  few  cubic  centimeters  of 
a  solution  of  phloroglucin  (in  hydrochloric  acid  of  1.06  sp.  gr.)  added. 
After  5  minutes  the  solution  is  filtered  from  the  greenish-black  precipi- 
tate of  furfural  phloroglucide;  if  the  filtrate  is  colored  yellow  or  reddish 
yellow  methylfurfural  is  present.  The  solution  gives  before  the  spectro- 
scope a  dark  absorption  band  in  the  blue.  On  long  standing  the  solu- 
tion deposits  a  red  precipitate  of  methylfurfural  phloroglucide  which 
is  readily  distinguished  from  the  dark-green  furfural  compound.  Ab- 
sorption spectra  of  methylfurfural  are  shown  in  Fig.  165. 

The  vivid  color  reactions  of  the  pentoses  with  orcin  and  phloroglucin 
are  not  obtained  with  the  methylpentoses.  Naphthoresorcin,  however, 
was  found  by  Tollens  and  Rorive  to  give  a  deposit  of  coloring  sub- 
stance with  the  methylpentoses,  rhamnose  and  fucose,  when  heated  in 
presence  of  hydrochloric  acid.  The  alcoholic  solution  of  the  deposits 
showed  a  violet  blue  color  with  an  exceedingly  brilliant  green  fluores- 
cence, which  showed  before  the  spectroscope  an  absorption  band  in  the 
yellow  over  the  D  line  and  a  second  band  in  the  green. 

There  are  a  number  of  other  color  spectral  reactions  which  have  not 
been  described;  these  belong,  however,  more  to  the  reactions  of  individ- 
ual sugars  and  will  be  given  under  the  description  of  these. 

A  few  characteristic  absorption  spectra,  useful  in  testing  for  sugars, 
are  shown  in  Fig.  165. 

Reactions  of  the  Non-reducing  Sugars 

The  comparatively  small  number  of  sugars,  which  do  not  reduce 
Fehling's  solution,  all  belong  to  the  higher  di-,  tri-  and  tetrasaccharides 
and  include  sucrose,  trehalose,  raffinose,  melezitose,  gentianose,  lacto- 
sinose,  secalose,  lupeose  and  stachyose.  The  soluble  polysaccharides, 
such  as  dextrin,  inulin,  glycogen,  etc.,  although  not  classified  as  sugars, 
are  sometimes  included  for  convenience  in  the  group  of  non-reducing 
saccharides. 

A  free  aldehyde,  or  ketone  group,  to  which  the  reducing  sugars  owe 
their  peculiar  reactivity  in  the  formation  of  hydrazones,  oximes,  ureides, 

*  Ber.,  34,  1425. 


METHODS  FOR  THE  IDENTIFICATION  OF  SUGARS      387 

mercaptals,  etc.,  is  lacking  in  the  non-reducing  sugars,  and  the  in- 
ability of  the  latter  to  reduce  Fehling's  solution,  or  to  react  with  phe- 
nylhydrazine,  dilute  alkalies,  hydroxylamine,  etc.,  is  thus  explained. 

The  non-reducing  sugars  give  many  of  the  color  and  spectral  re- 
actions of  the  reducing  sugars,  sucrose  and  raffinose,  for  example,  giv- 
ing the  a-naphthol  reaction  with  sulphuric  acid  and  Seliwanoff  s  reaction 
with  resorcin  and  hydrochloric  acid.  But  as  previously  explained  these 
reactions  are  not  given  by  the  original  non-reducing  sugar,  but  by  the 
reducing  sugars  derived  from  this  by  the  hydrolytic  action  of  the  acid 
used  in  making  the  test. 

A  carefully  controlled  hydrolysis  by  means  of  acids  or  enzymes, 
combined  with  quantitative  measurements  of  changes  in  polarization 
or  in  copper-reducing  power,  is  the  most  reliable  test  for  the  presence  of 
non-reducing  sugars.  Methods  involving  this  principle  have  been  de- 
scribed under  the  inversion  methods  for  determining  sucrose  and  raffinose, 
and  other  examples  will  be  given  under  quantitative  chemical  methods. 
Individual  tests  will  be  described  under  the  heading  of  each  single  sugar 
in  Part  II  of  this  Handbook. 


CHAPTER  XIV 

REDUCTION  METHODS  FOR  DETERMINING  SUGARS 

THE  principal  chemical  methods  for  determining  sugars  are  based 
upon  the  property  which  all  aldehydes  and  ketones  have  of  reducing 
alkaline  solutions  of  certain  metallic  salts.  The  reducing  action  of 
glucose,  lactose  and  other  sugars  upon  alkaline  solutions  of  copper, 
silver,  mercury,  bismuth  and  other  metals  has  already  been  mentioned. 
In  the  case  of  silver  and  glucose,  for  example,  the  reaction  when  care- 
fully controlled  proceeds  as  follows: 

C6H12O6  +  9  Ag2p    =  18  Ag  +  3  (COOH)2  +  3  H20. 

Glucose  Silver  oxide  Silver  Oxalic  acid  Water. 

If  the  weight  of  reduced  silver  be  determined  for  this  reaction,  the 
amount  of  glucose  can  easily  be  estimated.  But  unfortunately  the  re- 
ducing action  of  sugars  upon  metallic  salts  does  not  proceed  with  the 
quantitative  precision  of  the  above  equation;  the  reduction  is  rarely 
complete  and  the  amount  of  reduced  metal  varies  with  the  conditions 
of  the  experiment.  The  latter  difficulty  is  obviated,  however,  in  prac- 
tice by  controlling  the  process  so  that  the  same  weight  of  reduced 
metal  is  always  obtained  for  the  same  weight  of  sugar. 

Of  the  various  alkaline  solutions  of  metals  those  of  copper  are  em- 
ployed almost  exclusively  in  sugar  analysis. 

COPPER  REDUCTION  METHODS 

Early  Methods.  —  The  reducing  action  of  sugars  upon  different 
salts  of  copper  has  been  known  since  the  first  beginning  of  chemistry. 
Trommer,*  in  1841,  first  noted  the  value  of  alkaline  copper-sulphate 
solution  as  a  means  of  distinguishing  grape  from  cane  sugar.  Trom- 
mer's  method  was  improved  in  1844  by  Barreswil  f  who  made  the  im- 
portant discovery  that  addition  of  potassium  tartrate  to  the  alkaline 
copper-sulphate  solution  greatly  increased  its  stability.  Barreswil's 
method  was  volumetric;  the  sugar  solution  was  slowly  added  to  the 
boiling  copper  reagent,  which  had  previously  been  standardized  against 
pure  glucose,  until  the  blue  color  was  just  discharged. 

*  Ann.,  39,  360. 

t  Journal  de  Pharmacie  [3],  6,  301. 
388 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS      389 

Fehling's  Method.  —  Pehling,*  in  1848,  first  worked  out  the  details 
of  the  alkaline  copper  method,  as  they  now  stand,  and  the  copper-sul- 
phate and  alkaline-tartrate  reagent  has  since  been  called  by  his  name. 

The  copper  solution  employed  by  Fehling  consisted  of  40.00  gms. 
copper  sulphate,  CuS04.5  H2O,  160  gms.  neutral  potassium  tartrate  and 
600-700  gms.  sodium  hydroxide  sol.  of  1.12  sp.  gr.  dissolved  in  water  to 
1154.4  c.c.  This  is  equivalent  to  34.65  gms.  CuS04.5  H20  dissolved 
to  1000  c.c.,  the  proportion  used  by  nearly  all  subsequent  workers  down 
to  the  present  time. 

Fehling's  solution  contains  8.822  gms.  copper  to  1000  c.c.  or  0.008822 
gm.  to  1  c.c.  According  to  Fehling's  experiments  1  c.c.  of  his  solu- 
tion was  exactly  reduced  by  0.005  gm.  of  anhydrous  glucose,  or  1  part 
glucose  reduced  1.765  parts  copper.  In  terms  of  the  molecular  weight 
of  glucose  the  ratio  would  be  180  X  1.765  =  317.6.  Dividing  this 
value  by  63.6,  the  atomic  weight  of  copper,  the  atoms  of  copper  reduced 
by  one  molecule  of  glucose  is  found  to  be  five.  The  reduction  ratio 
1  :  5  was  regarded  as  constant  by  Fehling  and  was  so  employed  by  all 
chemists  until  Soxhlet  f  showed  in  1878  that  the  ratio  between  sugar 
and  amount  of  copper  reduced  was  not  a  constant  but  varied  according 
to  the  excess  of  copper  which  is  present  during  the  reaction. 

The  more  modern  methods  of  sugar  determination,  which  employ 
Fehling's  solution,  may  be  divided  into  two  general  classes.  I.  Volu- 
metric methods  based  upon  the  complete  reduction  of  a  measured 
volume  of  standard  solution.  II.  Methods  based  upon  a  gravimetric 
or  volumetric  determination  of  the  reduced  copper. 

VOLUMETRIC  METHODS  BASED  UPON  THE  COMPLETE  REDUCTION  OF  A 
MEASURED  VOLUME  OF  FEHLING'S  SOLUTION 

Soxhlet's  Method.  —  Owing  to  the  decomposition  which  takes 
place  in  the  mixed  copper-sulphate  and  alkaline-tartrate  solution  upon 
standing,  the  two  solutions  employed  in  the  Soxhlet  and  all  other 
modern  methods  are  mixed  only  just  before  using.  The  solutions  con- 
sist of  the  following:  Solution  A,  34.639  gms.  of  pure  crystallized 
CuSO4.5  H20  are  dissolved  in  water  and  made  up  to  500  c.c.  Solution 
B,  173  gms.  of  Rochelle  salts  are  dissolved  in  water,  100  c.c.  of  a  solu- 
tion of  caustic  soda,  containing  516  gms.  NaOH  per  liter  are  added, 
and  the  volume  completed  to  500  c.c.  Previous  to  analysis  mix  equal 
volumes  of  solutions  A  and  B. 

Before  using  the  mixed  copper  reagent,  it  shoulc}  be  standardized 
against  glucose,  invert  sugar,  lactose,  etc.,  according  to  the  needs  of 
*  Ann.,  72,  106;  106,  75.  t  J-  prakt.  Chem.  [2],  21,  227. 


390  SUGAR  ANALYSIS 

analysis.  Since  reducing  sugar  in  sugar-cane,  sugar-beet  and  most 
other  food  products  is  most  usually  expressed  as  invert  sugar,  the  latter 
is  most  commonly  used  for  standardization.  A  standard  solution  of 
invert  sugar  has  also  an  advantage  in  being  easily  prepared. 

Standard  Invert  Sugar  Solution.  Method  of  the  Association  of 
Official  Agricultural  Chemists.*  —  Dissolve  4.75  gms.  of  pure  sucrose  in 
75  c.c.  of  water,  add  5  c.c.  of  38.8  per  cent  hydrochloric  acid  and  set 
aside  during  a  period  of  24  hours  at  a  temperature  not  below  20°  C. 
Neutralize  the  acid  exactly  with  dilute  sodium  hydroxide  and  make  up 
to  1000  c.c.;  100  c.c.  of  this  solution  contains  0.500  gm.  of  invert  sugar. 

The  amount  of  standard  invert  sugar  solution  necessary  to  reduce 
100  c.c.  of  the  mixed  copper  reagent  is  determined  according  to  the 
details  described  in  the  next  paragraph. 

Application  to  Analysis  of  Sugar  Products.  Method  of  the  Associa- 
tion of  Official  Agricultural  Chemists.^  —  Make  a  preliminary  titration 
to  determine  the  approximate  percentage  of  reducing  sugar  in  the  ma- 
terial under  examination.  Prepare  a  solution  which  contains  approx- 
imately 1  per  cent  of  reducing  sugar.  Place  in  a  beaker  100  c.c.  of  the 
mixed  copper  reagent  and  approximately  the  amount  of  the  sugar 
solution  for  its  complete  reduction.  Boil  for  two  minutes.  Filter 
through  a  folded  filter  and  test  a  portion  of  the  filtrate  for  copper  by 
use  of  acetic  acid  and  potassium  ferrocyanide.  Repeat  the  test,  vary- 
ing the  volume  of  sugar  solution,  until  two  successive  amounts  are 
found  which  differ  by  0.1  c.c.,  one  giving  complete  reduction  and  the 
other  leaving  a  small  amount  of  copper  in  solution.  The  mean  of  these 
two  readings  is  taken  as  the  volume  of  the  solution  required  for  the 
complete  precipitation  of  100  c.c.  of  the  copper  reagent. 

Under  these  conditions  100  c.c.  of  standard  copper  reagent  require 
0.475  gm.  of  anhydrous  glucose  or  0.494  gm.  of  invert  sugar  for  com- 
plete reduction.  Calculate  the  glucose  by  the  following  formula: 

V  =  the  volume  of  the  sugar  solution  required  for  the  complete 

reduction  of  100  c.c.  of  standard  copper  reagent. 
W  =  the  weight  of  the  sample  in  1  c.c.  of  the  sugar  solution. 

rp,  100  X  0.475 

I  hen  — _  —  =  per  cent  of  glucose, 

r    X    W 

100  X  0.494  „  . 

or  —  —  =  per  cent  of  invert  sugar. 

-  v  /\  w 

In  making  the  test  for  unreduced  copper  a  few  drops  of  the  filtered 
solution  are  placed  upon  a  white  test  plate,  acidified  with  a  few  drops  of 

*  Bull.  107  (revised)  U.  S.  Bur.  of  Chem.,  p.  42.  f  Ibid. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     391 

10  per  cent  acetic  acid  and  a  drop  of  2  per  cent  potassium-ferrocyanide 
solution  added.  A  brown  coloration  indicates  the  presence  of  unre- 
duced copper. 

Volume  of  Fehling's  Solution  Reduced  by  Different  Sugars.  - 
The  ratio  between  volume  of  standard  Fehling's  solution  and  the  amount 
of  different  sugars,  just  sufficient  to  cause  complete  reduction,  was  de- 
termined by  Soxhlet  *  to  be  as  follows: 

TABLE  LXX 


Volume  of  Fehling's  solution  reduced  by  different  sugars. 

Reducing 
power  in  terms 
of  glucose. 

0.5000 
0.5000 
0.5000 
0.5000 
0.5000 

gm.  'glucose           reduces  105.2  c.c.  Fehling's 
"      in  vert  sugar        "        101.2    " 
"      fructose               "         97.2    " 
"      lactose                 "         74.0    " 
"      maltose               "         64.2    " 

solution. 

1.000 
0.962 
0.924 
0.703 
0.610 

u 

it 

tc 
It 

The  above  results  calculated  to  equal  volumes  of  copper  reagent 
show  that  100  c.c.  of  mixed  standard  Fehling's  solution  are  reduced  by 
0.4753  gm.  of  glucose,  0.4941  gm.  of  invert  sugar,  0.5144  gm.  of  fructose, 
0.6757  gm.  of  lactose  and  0.7788  gm.  of  maltose. 

Modifications  of  Soxhlet's  Method. — Instead  of  employing  100  c.c. 
of  Fehling's  solution  for  the  Soxhlet  determination,  it  is  more  customary 
to  use  10  c.c.,  20  c.c.  or  50  c.c.,  the  quantity  thus  used  being  measured 
into  a  casserole,  beaker  or  flask,  and  diluted,  according  to  require- 
ments, with  a  measured  volume  of  water.  In  case  of  very  dilute  sugar 
solutions,  as  small  a  quantity  as  5  c.c.  of  Fehling's  solution  may  be  used 
to  advantage. 

In  using  any  of  the  numerous  modifications  of  Soxhlet's  method,  it 
is  important  that  the  Fehling  solution  be  standardized  under  exactly 
the  same  conditions  as  in  analysis.  The  same  degree  of  dilution  should 
be  followed  for  the  mixed  copper  reagent  in  all  experiments.  Soxhlet 
found  that  0.5  gm.  of  glucose  reduced  105.2  c.c.  of  Fehling's  solution 
when  undiluted  and  only  101.1  c.c.  when  diluted  with  4  parts  of  water; 
similar  results  were  also  obtained  with  other  sugars.  Such  differences 
as  these  might  produce  a  variation  of  several  per  cent  in  the  estimation 
of  reducing  sugars. 

It  is  also  evident  that  to  obtain  the  most  concordant  results  the 
sugar  solutions  should  always  contain  about  the  same  percentage  of 
reducing  sugar.  This  is  accomplished  in  practice  by  making  a  rough 
*  J.  prakt.  Chem.  [2]  21,  227. 


392  SUGAR  ANALYSIS 

preliminary  determination  and  then  making  up  a  fresh  sugar  solution 
so  that  the  percentage  of  reducing  sugar  shall  be  0.1  per  cent,  0.5  per 
cent  or  1.0  per  cent,  etc.,  according  to  the  volume  of  Fehling's  solution 
taken  and  the  individual  preference  of  the  chemist.  In  this  manner 
approximately  the  same  volume  of  sugar  solution  is  always  used  for 
reducing  the  same  volume  of  copper  reagent,  and  under  such  con- 
ditions, with  a  uniform  method  of  boiling,  the  most  accurate  results  are 
obtained. 

A  difference  in  reducing  power  is  also  obtained  whether  the  sugar 
solution  be  added  to  the  copper  reagent  in  small  portions,  with  suc- 
cessive periods  of  boiling,  or  only  in  one  portion  with  one  period  of 
boiling.  The  most  accurate  results  are  secured  where  the  test  is  made 
with  the  entire  volume  of  sugar  solution,  necessary  for  complete  reduc- 
tion, with  only  one  period  of  boiling. 

The  following  example  will  give  an  illustration  of  the  application  of 
the  method: 

Example.  —  20  c.c.  of  Fehling's  solution  diluted  with  80  c.c.  of  water  were 
found  to  require  for  reduction  exactly  20.2  c.c.  of  standard  invert  sugar  solu- 
tion or  0.101  gm. 

50  gms.  of  sugar-cane  molasses  were  diluted  to  1000  c.c.  Of  this  solution 
about  8  c.c.  were  required  to  discharge  the  blue  color  of  20  c.c.  Fehling's  solu- 
tion. 

80  c.c.  of  the  sugar  solution  (4  gms.  molasses)  were  then  made  up  to  200  c.c. 
(1  c.c.  =  0.02  gm.  molasses).  Of  this  solution  19.6  c.c.  when  boiled  with 
20  c.c.  Fehling's  solution  and  80  c.c.  of  water  for  2  minutes  showed  incomplete 
reduction  by  the  ferrocyanide  test  and  19.8  c.c.  complete  reduction. 

Calling  19.7  c.c.  the  volume  of  sugar  solution  necessary  to  reduce  the 

20  c.c.  of  Fehling's  solution,  then  ^^        ^  =  25.64  per  cent  invert  sugar  in 

U.U.Z  X  19.7 

the  molasses. 

The  Ferrocyanide  Test  for  Copper.  —  Several  methods  are  fol- 
lowed for  making  the  ferrocyanide  test  for  unreduced  copper.  It  some- 
times happens  that  the  cuprous  oxide  is  precipitated  in  a  very  finely 
divided  form,  and  gives  annoyance  by  running  through  the  filter. 

One  method  of  making  the  test  is  to  superimpose  several  small  strips 
of  filter  paper  and  allow  a  few  drops  of  the  solution  to  fall  upon  the 
upper  paper.  The  moistened  area  upon  the  second  or  third  underlying 
strip  is  then  treated  with  a  drop  of  ferrocyanide  solution  acidified  with 
acetic  acid.  The  appearance  of  a  brown  spot  indicates  the  presence  of 
unreduced  copper. 

Another  method  of  removing  the  portion  of  solution  to  be  tested  is 
by  means  of  a  Wiley  or  Knorr  filtering  tube,  which  is  prepared  as  fol- 
lows: 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     393 


Wiley's  Filter  Tube.  —  The  Wiley  *  filter  tube,  Fig.  166a,  consists  of 
a  piece  of  glass  tubing,  5  to  7  mm.  in  diameter  and  20  to  25  cm.  long, 
one  end  of  which  has  been  softened  in  a  flame  and 
then  pressed  out  so  as  to  form  a  shoulder.  A  piece 
of  fine  linen  is  then  stretched  tightly  over  the  end  and 
tied  securely  by  a  thread.  In  using  the  tube  the 
covered  end  is  dipped  into  water  containing  in  suspen- 
sion finely  divided  asbestos,  and  a  film  of  the  latter 
spread  over  the  surface  of  the  filter  by  suction  at  the 
upper  end.  A  small  portion  of  the  liquid  to  be  tested 
is  sucked  into  the  tube  and  then  poured  from  the 
open  end  onto  the  test  plate.  Knorr's  f  modification 
of  the  Wiley  tube  is  of  smaller  diameter  and  contains 
a  perforated  platinum  disk  in  place  of  the  linen  (Fig. 
1666).  The  disk  is  coated  with  asbestos  and  the  liquid 
withdrawn  for  testing  as  with  the  Wiley  tube.  The 
filter  tubes  should  not  be  reused  until  after  cleaning 
in  dilute  nitric  acid  and  washing  with  water. 

Method  of  Ross.  —  A  method  due  to  Ross,|  and 
employed  quite  extensively  in  Louisiana,  is  to  dip  the 
point  of  a  small  folded  filter,  held  by  means  of  for- 
ceps, below  the  surface  of  the  hot  solution  in  the  cas- 
serole and  withdraw  a  few  drops  of  the  clear  liquid 
from  the  interior  of  the  filter  by  means  of  a  medicine 
dropper  (Fig.  167).  The  method  is  simple,  and  par- 
ticularly useful  where  there  is  a  large  amount  of 
routine. 

Conveniences  for  making  the  determination  by 
Soxhlet's  method,  such  as  2-minute  sand  glass  for 

regulating  time  of  boiling,  test  plate,  dropping  bottles  pjg     166  Filter 

for  ferrocyanide  solution  and  acetic  acid,  are  shown  in      tubes  for  deter- 
Fig.  167.  mining    reducing 

Violette's  Method.  —  The  volumetric  method  of      susars- 
copper  reduction,  which  is  used  most  extensively  in  France,  is  that 
of  Violette.§      The  proportions  of  copper  sulphate,  Rochelle  salts  and 
alkali  employed  in  the  Soxhlet  method  may  be  used  in  the  Violette 
determination,  or  the  Violette  solution  may  be  taken  which  consists  of 

*  Wiley's  "Agricultural  Analysis"  (1897),  III,  130. 
t  Ibid. 

j  Journal  of  Analytical  Chemistry,  4  (1890),  p.  427. 
§  Sidersky's  "Manuel"  (1909),  p.  95. 


394 


SUGAR  ANALYSIS 


Fig.  167.  —  Ross's  method  for  determining  reducing  sugars. 

36.46  gms.  CuS04.5  H20,  200  gms.  Rochelle  salts  and  500  gms.  sodium 
hydroxide  solution  of  1.2  sp.  gr.  made  up  to  1000  c.c. 

The  Violette  solution  takes  a  slightly  larger  amount  of  copper  sul- 
phate than  the  Soxhlet  solution  in  order  that  1  c.c.  may  correspond  to 
the  invert  sugar  derived  from  5  mgs.  of  sucrose  or  §||  X  5  =  5.263  mgs. 
of  invert  sugar.  The  ratio  of  invert  sugar  and  copper  Sulphate  for  the 
Soxhlet  and  Violette  solutions  is  accordingly  5  :  34.64  ::  5.263  :  36.46. 

The  Violette  solution  is  preferred  by  some  chemists  for  convenience 
in  determining  sucrose  by  the  method  of  inversion  and  copper  reduc- 
tion. 

The  end  point  of  the  reduction  in  Violette's  method  is  determined, 
as  in  the  early  process  of  Barreswil,  by  the  disappearance  of  blue  color 
from  the  copper  solution.  The  details  of  the  method  are  as  follows: 

Ten  cubic  centimeters  of  the  mixed  copper  solution  are  transferred 
to  a  large  test  tube  20  to  22  mm.  in  diameter  and  22  to  24  cm.  long; 
5  c.c.  of  distilled  water  are  added  in  case  the  solution  is  rich  in  reducing 
sugars  and  a  few  small  pieces  of  pumice  stone,  which  have  been  ignited 
and  then  washed  in  acid  and  water.  The  copper  solution  is  then 
heated  to  boiling,  the  grains  of  pumice  stone  giving  a  smooth  ebullition 
and  preventing  the  sudden  ejection  of  liquid  from  the  tube.  The  sugar 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     395 

solution  to  be  tested,  which  should  have  been  previously  clarified  and 
diluted  to  about  0.5  to  1.0  per  cent  invert  sugar,  is  then  added  from  a 
burette,  a  few  cubic  centimeters  at  a  time,  the  copper  solution  being 
boiled  for  2  minutes  after  each  addition.  As  the  reduction  proceeds 
the  blue  color  of  the  solution  becomes  more  of  a  reddish  violet,  due  to 
the  diminishing  intensity  of  the  blue  and  the  increasing  amount  of  the 
red  cuprous  oxide.  Towards  the  end  of  the  reduction  it  is  necessary 
to  hold  the  tube  against  a  white  wall  or  paper  and  observe  the  color  of 
the  clear  solution,  after  the  red  oxide  begins  to  settle.  When  the  final 
drop  of  sugar  solution  discharges  the  last  trace  of  blue  color,  the  read- 
ing of  the  burette  is  noted,  and  the  calculation  of  sugar  made  as  pre- 
viously described. 

A  little  practice  is  required  in  the  Violette  method  in  following  the 
disappearance  of  the  blue  color.  The  chemist  should  standardize  his 
solution  against  invert  sugar,  following  the  same  procedure  in  deter- 
mining end  point  as  in  making  an  analysis. 

The  Violette  method  is  much  simpler  than  the  Soxhlet  method  and 
is  for  this  reason  preferred  by  many  chemists.  The  Soxhlet  method,  on 
the  other  hand,  owing  to  the  more  sensitive  method  of  determining  the 
end  point  of  reduction,  has  a  much  greater  degree  of  accuracy. 

The  Violette  method  has  been  modified  by  Spencer,*  so  as  to  in- 
clude the  ferrocyanide  test  for  unreduced  copper.  Some  chemists  have 
also  sought  to  improve  the  method  by  employing  larger  test  tubes  and 
using  20  c.c.  of  the  mixed  copper  solution.  The  possibilities  of  modi- 
fication in  this  direction  are  of  course  unlimited  and  do  not  require 
special  description. 

Pavy's  Method.  —  Another  volumetric  process,  using  the  disap- 
pearance of  blue  color  as  end  point,  is  the  method  of  Pavy,f  which  is 
based  upon  the  fact  that  when  Fehling's  solution  is  reduced  in  presence 
of  ammonia  the  precipitated  cuprous  oxide  is  dissolved  as  a  colorless 
solution,  any  unreduced  copper  being  indicated  by  the  characteristic 
blue  color  of  the  cuprammonium  compounds.  The  disturbing  influence 
of  the  precipitated  cuprous  oxide  upon  the  color  of  the  solution  is  thus 
avoided  and,  in  the  absence  of  air,  the  change  from  blue  to  colorless  at 
the  end  point  becomes  quite  sharp. 

Pavy's  copper  solution  is  prepared  as  follows:  34.65  gms. 
CuS04.5H20,  170  gms.  Rochelle  salts  and  170  gms.  potassium  hy- 
droxide are  dissolved  in  water  to  1000  c.c.  It  is  preferable,  however, 
as  in  Soxhlet's  method  to  make  up  the  copper  and  alkali-tartrate  solu- 

*  Spencer's  "Handbook  for  Cane  Sugar  Manufacturers"  (1906),  p.  131. 
t  Pavy's  "Physiology  of  the  Carbohydrates"  (London,  1894),  p.  71. 


396 


SUGAR  ANALYSIS 


tions  separately  to  500  c.c.,  and  to  mix  equal  quantities  of  the  two  just 
before  using;  120  c.c.  of  the  mixed  copper  solution  are  transferred  to  a 
liter  flask,  300  c.c.  of  ammonia  of  specific  gravity  0.880  are  added  and 
the  volume  completed  to  1000  c.c. ;  20  c.c.  of  the  ammoniacal  Fehling's 
solution  are  reduced  by  0.01  gm.  glucose. 

The  reduction  is  carried  out  in  a  flask  of  about  150  c.c.  capacity, 
provided  with^a  two-hole  stopper,  one  opening  of  which  is  connected 
with  the  tip  of  the  burette  containing  the  sugar  solution  and  the  other 
with  a  bent  glass  tube  for  the  escape  of  air  and  steam  (Fig.  168). 


Fig.  168. — Pavy's  method  for  determining  reducing  sugars. 

Forty  cubic  centimeters  of  the  ammoniacal  copper  solution  are  placed 
in  the  flask,  and  after  inserting  the  stopper  the  solution  is  brought  to  a 
gentle  boil.  The  sugar  solution  is  then  added  at  the  rate  of  60  to  100 
drops  per  minute,  the  discharge  being  regulated  by  a  Pavy  pinch  cock 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     397 

(C);  the  ebullition  must  be  maintained  without  interruption.  When 
the  blue  color  begins  to  lighten,  the  sugar  solution  is  added  drop  by 
drop  until  the  last  trace  of  color  is  just  discharged.  The  end  point  is 
made  more  sensitive  by  looking  through  the  solution  against  a  white 
plate  (P). 

The  reduction  must  be  made  in  complete  absence  of  air,  otherwise 
the  dissolved  cuprous  oxide  will  be  reoxidized.  A  precaution  sometimes 
used  to  prevent  the  entrance  of  air,  through  momentary  cooling,  is  to 
use  a  bent-glass  exit  tube,  fitted  with  a  rubber  valve,  dipping  into  a 
beaker  of  water.  Care  must  also  be  taken  not  to  prolong  the  time  of 
reduction,  otherwise  all  the  ammonia  will  be  expelled  and  the  cuprous 
oxide  not  be  dissolved. 

In  Pavy's  method  1  molecule  of  glucose  reduces  6  molecules  of 
cupric  oxide  instead  of  5  molecules  as  by  Fehling's  solution.  These 
proportions  vary  somewhat,  however,  according  to  concentration  and 
other  conditions  of  experiment.  The  solution  should,  therefore,  be 
standardized  against  glucose  or  invert  sugar  following  the  exact  method 
employed  in  analysis. 

Pavy's  method  gives  good  results,  when  the  reduction  is  carried  out 
with  complete  exclusion  of  the  air.  The  extra  precautions  necessary 
for  making  the  determination,  and  the  failure  of  the  method  to  give 
good  results  with  colored  solutions,  have  prevented  the  process  from 
becoming  generally  employed. 

Conversion  Tables  for  Volumetric  Determination  of  Sugars.  - 
The  calculation  of  reducing  sugars  by  any  of  the  volumetric  methods 
is  much  simplified  by  the  use  of  appropriate  conversion  tables.  If  a 
volume  of  Fehling's  solution  be  taken,  which  always  corresponds  to  a 
fixed  amount  of  reducing  sugar,  as,  for  example,  0.5  gm.  in  Table  LXX, 
and  the  sugar  solution  for  titration  be  made  up  so  as  to  contain  this 
same  amount  of  substance  (as  0.5  gm.)  in  1  c.c.,  then  the  formula  for 
determining  reducing  sugar  becomes 

_  0.5  X  100  _  100 
:   0.5  XV         V 

in  which  R  is  the  per  cent  of  reducing  sugar  in  the  substance  and  V  the 
cubic  centimeters  of  sugar  solution  necessary  for  the  reduction. 

If  the  substance  be  very  high  or  very  low  in  reducing  sugar,  an  even 
fraction  or  multiple  of  0.5  gm.  may  be  taken  for  the  amount  of  sub- 
stance to  be  dissolved  in  1  c.c.  Thus  for  0.05  gm.  of  substance  in  1  c.c. 

R  =  -'  and  for  1  gm.  of  substance  in  1  c.c.  R  =      * 


398 


SUGAR  ANALYSIS 


Under  the  above  conditions  of  analysis  a  table  giving  different 
multiples  of  the  reciprocals  of  the  burette  readings  will  give  the  cor- 
responding percentages  of  reducing  sugars.  The  following  example 
will  illustrate  the  method  for  constructing  such  a  table. 

Fehling's  solution  taken  =  0.2  gram  of  reducing  sugar 


Volume  of 
sugar  solution 
for  reduction. 

Reciprocal. 

Weight  of  substance  in  1  c.c.  of  sugar  solution. 

0.40  gm. 

0.20  gm. 

0.10  gm. 

0.04-gm. 

0.02  gm. 

V 

1 
V 

50 

V 

100 

'T 

200 
V 

500 
V 

1000 
V 

c.c. 
20.0 
20.1 
20.2 
20.3 
20.4 

30  io 
40.0 
50.0 

0.05000 
0.04975 
0.04950 
0.04926 
0.04902 

Per  cent. 
2.50 

2.49 
2.48 
2.46 
2.45 

i'.G7 
1.25 
1.00 

Per  cent. 
5.00 

4.98 
4.95 
4.93 
4.90 

3~33 
2.50 
2.00 

Per  cent. 
10.00 
9.95 

9.90 
9.85 
9.80 

6^67 
5.00 
4.00 

Per  cent. 

25.00 
24.88 
24.75 
24.63 
24.51 

Per  cent. 
50.00 

49.75 
49.50 
49.26 
49.02 

33^33 
25.00 
20.00 

0.03333 
0.02500 
0.02000 

16.67 
12.50 
10.00 

The  table  can  of  course  be  modified  in  a  great  variety  of  ways  to 
suit  individual  requirements.  A  list  of  reciprocals  for  assistance  in  cal- 
culating such  a  table  is  given  in  the  Appendix  (Table  25). 

Reischauer  and  Kruis's  Method.  —  In  the  methods  previously 
described  a  constant  volume  of  Fehling's  solution  was  taken  and  the 
amount  of  sugar  solution  noted  necessary  to  complete  the  reduction. 
In  a  process  first  proposed  by  Lippmann  *  and  elaborated  by  Reischauer 
and  Kruis  f  the  opposite  procedure  is  followed.  A  constant  volume  of 
sugar  solution  is  taken  and  the  amount  of  Fehling's  solution  determined 
necessary  to  oxidize  the  reducing  sugar. 

In  the  Reischauer-Kruis  method  the  sugar  solution  is  made  up  so 
as  not  to  contain  over  0.58  gm.  glucose  in  100  c.c.  Six  numbered  test 
tubes  holding  from  20  to  30  c.c.  are  taken  and  5  c.c.  of  the  sugar 
solution  measured  into  each;  1,  2,  3,  4,  5  and  6  c.c.  respectively  of 
Fehling's  solution  are  then  added  to  the  different  tubes,  which  are 
afterwards  shaken  and  immersed  in  boiling  water  for  20  minutes.  At 
the  end  of  this  time  the  tubes  are  examined  and  the  two  tubes  noted  in 
which  reduction  is  just  completed  and  in  which  the  least  amount  of 
unreduced  copper  is  left.  Having  noted  the  limits  between  which  the 
true  copper  equivalent  lies,  the  volume  of  Fehling's  solution  is  varied 

*  Oester.  Ungar.  Z.  Zuckerind.,  7,  256. 
t  Oester.  Ungar.  Z.  Zuckerind.,  12,  254. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS      399 

within  this  interval  until  the  exact  amount  necessary  for  oxidizing  all 
the  reducing  sugar  is  found. 

The  pipettes  employed  for  this  method  are  graduated  in  their 
lower  part  from  1  c.c.  to  5  c.c.  and  in  the  stem  contain  an  extra  1  c.c. 
graduated  into  hundredths.  With  three  trials  and  employment  of  the 
ferrocyanide  test,  the  volume  of  Fehling's  solution  can  be  determined 
to  0.01  c.c.  The  following  example  illustrates  the  application  of  the 
method. 


First  trial. 

Second  trial. 

Third  trial. 

1  c.c.  Cu 

all  reduced 

4 

15  c.c.  Cu 

all  reduced 

4 

32  c.c.  Cu 

all 

reduced 

2   ' 

it 

(4.30 

S( 

4 

34 

t 

« 

3 

" 

14 

45 

Cu  in  solution 

J4 

36 

1 

< 

' 

j  4    ' 

11 

4 

60 

11 

14 

38 

'    Cu 

in  solution 

I  5   ' 

Cu 

in  solution 

4 

75 

" 

4 

40 

' 

* 

' 

6   ' 

n 

4 

90 

4 

42     ' 

The  quantity  of  Fehling's  solution  which  exactly  oxidizes  the  reducing 
sugar  in  the  5  c.c.  of  solution  may,  therefore,  be  placed  at  4.37  c.c. 

The  amount  of  glucose  corresponding  to  each  0.01  c.c.  between 
1  c.c.  and  6  c.c.  of  Fehling's  solution  is  found  from  a  table  calculated 
by  Kruis  (Appendix,  Table  9). 

The  Reischauer-Kruis  method  possesses  certain  advantages  over  the 
methods  previously  described  in  point  of  exactness;  the  error  due  to 
variation  in  reducing  power  with  changes  in  concentration  is  avoided, 
the  amount  of  reducing  sugar  in  5  c.c.  corresponding  to  different  volumes 
of  Fehling's  solution  being  definitely  known  for  the  conditions  of  ex- 
periment. The  large  amount  of  labor  and  time  necessary  for  com- 
pleting a  determination  has  been,  however,  a  serious  obstacle  against 
the  general  use  of  the  method. 


METHODS  BASED  UPON  A   GRAVIMETRIC  OR  VOLUMETRIC  DETERMINATION 

OF    REDUCED    COPPER 

In  the  methods  of  this  class  an  excess  of  copper  is  present  in  the 
Fehling's  solution  at  the  end  of  reduction.  The  precipitated  cuprous 
oxide  after  a  fixed  period  of  heating  is  filtered  off,  and  the  amount  of 
copper  determined  by  any  of  the  numerous  gravimetric  or  volumetric 
processes.  The  weight  of  reducing  sugar  corresponding  to  a  definite 
weight  of  precipitated  copper  is  then  determined  by  means  of  formulae 
or  tables  which  have  been  calculated  from  results  obtained  upon  known 
amounts  of  pure  sugar  under  similar  conditions  of  experiment. 


400 


SUGAR  ANALYSIS 


Variability  in  Reducing  Power  of  Monosaccharides.  —  Soxhlet* 
showed  that  when  a  solution  of  glucose  acted  upon  Fehling's  solution 
the  first  portion  added  reduced  most  strongly  and  the  succeeding  por- 
tions gradually  less  so.  This  variability  in  reducing  power  is  found  to 
be  different,  however,  for  the  monosaccharides,  glucose,  fructose,  invert 
sugar,  galactose,  etc.,  than  for  the  disaccharides,  lactose  and  maltose. 

As  examples  of  the  variability  in  reducing  power  of  monosaccharides 
the  following  results  are  given.  The  values,  which  were  calculated 
from  Bertrand's  sugar  tables,  represent  the  milligrams  of  copper  re- 
duced by  each  succeeding  10-milligram  portion  of  added  sugar. 

TABLE  LXXI 

Shouting  variability  in  reducing  power  of  monosaccharides 


Number  of  series. 

Invert  sugar. 
Milligrams 
copper. 

Glucose. 
Milligrams 
copper. 

Galactose. 
Milligrams 
copper. 

First         10  m 
Second     10 
Third       10 
Fourth     10 
Fifth        10 
Sixth        10 
Seventh   10 
Eighth     10 
Ninth       10 
Tenth       10 

gS.  Of  SUj 

< 
< 

;ar  red 

<  - 
i 

uce 

20.6 

19.8 
18.9 
18.4 
17.7 
17.2 
16.6 
16.1 
15.8 
15.4 

20.4 
19.7 
19.0 

18.4 
17.9 
17.4 
17.0 
16.3 
15.9 
15.8 

19.3 

18.6 
18.3 
17.7 
17.3 
16.9 
16.7 
16.3 
16.3 
16.0 

It  is  seen  that  each  succeeding  10  mgs.  of  added  glucose  undergoes  a 
loss  in  reducing  power  of  about  3  per  cent. 

Law  of  Reducing  Action.  —  The  reducing  action  of  a  monosac- 
charide  upon  Fehling's  solution  may  be  expressed  in  general  terms  as 
follows : 

If  for  the  first  minute  quantity  s  of  a  given  sugar  a  definite  amount 
c  of  copper  is  reduced,  then  for  any  multiple  n  of  s  the  weight  of  copper 
would  be  nc,  if  the  same  amount  of  copper  in  the  Fehling's  solution  were 
always  maintained.  The  latter  condition,  however,  is  never  realized 
in  practice,  and  with  the  continuous  removal  of  copper  from  solution 
the  value  nc  becomes  nc  —  (n  —  1  -{-  n  —  2  +  n  —  3  +  •  •  •  n  —  ri)k. 
When  working  with  weighable  quantities  of  sugar,  this  expression 
should  be  modified  to  c  +  (n  —  l)d  —  (n  —  2  +  n  —  3  +  •  •  •  n  —  ri)k 
in  which  d  is  the  difference  between  the  weights  of  copper  for  the  first 
two  members  of  the  series  s  and  2s.  The  values  of  d  and  of  the  constant 

*  J.  prakt.  Chem.  [2],  21,  227; 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     401 

k  are  easily  determined  empirically,  and  knowing  these  it  is  possible  to 
construct  tables  for  any  of  the  reducing  sugars. 

As  an  example  of  this  method  of  calculation  the  following  values  are  taken 
from  the  experimental  work  of  Allihn :  * 

No.  of  series  (ra) . 

1 10  mgs.  of  glucose  reduce    18.0  mgs.  copper 

2 20  mgs.  of  glucose  reduce    38.2  mgs.  copper 

25 250  mgs.  of  glucose  reduce  463.0  mgs.  copper. 

18.0  =  c. 

38.2  -  18.0  =  20.2  =  d. 

Substituting  the  above  values  for  c  and  d  in  the  equation  for  n  =  25, 
18  +  (25  -  1)  20.2  -  (25  -  2  +  25  -  3  .  .  .  )  k  =  463.0 

whence   k  =  0.14. 

The  equation  18  +  (n  -  1)  20.2  -(n-2  +  n-3+-  •  •  n  —  n)  0.14  will 
give  the  milligrams  of  copper  reduced  by  any  multiple  n  of  10  mgs.  of  glucose 
under  the  conditions  of  Allihn's  experiments. 

Suppose  it  is  required  to  find  the  milligrams  of  copper  reduced  by  100  mgs. 
of  glucose. 

18  +  (10  -  1)  20.2  -  (10  -  2  + -10  -  3  .  .  .  )  0.14  =  194.8  mgs.  Cu. 
Allihn  obtained  by  actual  experiment  195  mgs.  of  copper  by  the  reducing 
action  of  100  mgs.  of  glucose. 

Calculation  of  Reduction  Tables.  —  The  calculation  of  tables  for 
the  copper-reducing  power  of  different  sugars  is  usually  made  by  the 
method  of  least  squares,  according  to  the  general  formula: 

y  =  A  +  Bx  +  Cx\ 

in  which  x  is  the  milligrams  of  copper  reduced  by  y  milligrams  of  sugar 
and  A,  B  and  C  constants.  Having  determined  by  experiment  the 
values  of  x  for  10  or  more  values  of  y,  the  calculation  of  A,  B  and  C  is 
made  in  the  same  manner  as  described  on  page  175. 

As  an  example  of  the  method  of  least  squares  the  work  of  Allihn  is  again 
quoted.  Allihn  found  that  different  amounts  of  glucose  under  constant  con- 
ditions of  experiment  reduced  the  following  amounts  of  copper. 


Mgs.  of  glucose  (y)  .  .  . 
Mgs.  of  copper  (x)  

10.0 
18.0 

20.0 

38.2 

25.0 
47.5 

50.0 
99.0 

100.0 
195.0 

125.0 
242.5 

150.0 

287.7 

175.0200.0 
333.0377.7 

225.0 
421.2 

250.0 
463.0 

Substitution  of  the  above  values  for  x  and  y  in  the  formula  y  =  A  +  Bx  +  Cx2 
gives  the  general  equation 

y  =  -  2.5647  -f  2.0522  x  -  0.0007576  xz, 

by  means  of  which  Allihn  constructed  his  table  giving  the  milligrams  of  glucose 

corresponding  to  any  weight  of  reduced  copper  between  10  mgs.  and  463  mgs. 

*  J.  prakt.  Chem.  [2],  22,  46. 


402 


SUGAR  ANALYSIS 


Variability  in  Reducing  Power  of  Disaccharides.  —  The  variability 
in  reducing  power  of  maltose  and  lactose  is  different  from  that  noted  for 
the  monosaccharides.  According  to  the  amount  of  free  alkali,  time  of 
boiling  and  other  conditions,  succeeding  portions  of  maltose  and  lactose, 
while  usually  showing  a  slight  loss,  may  show  either  no  change  at  all,  or 
even  a  slight  gain  in  reducing  power  over  preceding  portions  of  the  same 
sugar.  This  peculiarity  of  maltose  and  lactose  is  explained  by  a  slight 
hydrolysis  of  the  sugar  into  monosaccharides  of  higher  reducing  power. 
A  slight  inversion  of  this  kind  takes  place  with  sucrose,  which  is  strictly 
speaking  a  non-reducing  sugar,  and  it  no  doubt  occurs  to  a  greater  or 
less  extent  with  all  higher  saccharides  upon  boiling  with  Fehling's  solu- 
tion. 

As  an  illustration  of  the  reducing  power  of  successive  portions  of 
maltose,  the  following  results  are  taken  from  the  tables  of  Wein  and  of 
Munson  and  Walker. 

TABLE  LXXII 
Showing  variability  in  reducing  power  of  maltose 


Number  of  Series. 

Wein. 

Munson  and 
Walker. 

First       30  m 
Second    30 
Third      30 
Fourth    30 
Fifth       30 
Sixth       30 
Seventh  30 

gs.  of  mal 

^ose  rec 

uce 

Mgs.  Cu. 
35.4 
34.5 
34.0 
33.4 
33.4 
33.8 
33.5 

Mgs.  Cu. 

35.9 
33.6 
33.5 
33.8 
33.6 
33.7 
33.6 

It  is  seen  that  in  both  series  of  experiments  there  is  at  first  a  marked 
decrease  and  then  a  slight  increase  in  the  reducing  power  of  the  suc- 
cessive portions  of  added  sugar.  Changes  of  a  similar  nature  are 
noted  in  some  of  the  tables  for  lactose. 

The  reducing  power  of  the  disaccharides  upon  Fehling's  solution  is 
much  more  subject  to  change  with  difference  in  conditions  than  the 
monosaccharides.  Kjeldahl,*  for  example,  found  that  increasing  the 
amount  of  alkali  in  Fehling's  solution  caused  the  reducing  power  of 
maltose  and  lactose  to  gain  with  ten  times  the  rate  of  increase  noted  for 
glucose.  The  same  effect  is  also  produced  by  prolonging  the  time  of 
boiling.  This  greater  sensibility  of  the  disaccharides  to  disturbing  in- 
fluences during  reduction  involves  a  greater  experimental  error  in  the 
determination  when  the  details  of  the  method  are  not  carefully  followed. 
*  Neue  Z.  Riibenzuckerind.,  37,  13,  23. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     403 

Methods  and  tables  for  estimating  different  sugars  from  the  amount 
of  copper  reduced  from  Fehling's  solution  have  been  devised  by  Soxhlet; 
Allihn;  Wein;  Meissl;  Herzfeld;  Lehmann;  Kjeldahl;  Pfluger;  Ost; 
Honig  and  Jesser;  Brown,  Morris  and  Millar;  Bertrand;  Defren; 
Munson  and  Walker;  Kendall;  and  many  others.  It  is  impossible  to 
describe  all  these  processes  and  only  a  few  of  the  more  typical  methods 
will  be  selected.  The  method  of  Allihn,*  which  is  one  of  the  widest 
known,  illustrates  well  the  various  principles  involved  and  will  be 
described  first  in  somewhat  fuller  detail. 

Allihn's  Method  for  the  Determination  of  Glucose.  —  The  follow- 
ing details  of  Allihn's  method  with  the  description  of  several  processes 
for  determining  the  amount  of  reduced  copper  are  taken  from  the 
Methods  of  Analysis  of  the  Association  of  Official  Agricultural 
Chemists,  f 

PREPARATION   OF   REAGENTS 

Copper-sulphate  Solution.  —  Dissolve  34.639  gms.  of  CuS04.5H20  in 
water  and  dilute  to  500  c.c. 

Alkaline-tartrate  Solution.  —  Dissolve  173  gms.  of  Rochelle  salts  and 
125  gms.  of  potassium  hydroxide  in  water  and  dilute  to  500  c.c. 

DESCRIPTION   OF   METHOD 

Place  30  c.c.  of  the  copper  solution,  30  c.c.  of  the  alkaline-tartrate 
solution  and  60  c.c.  of  water  in  a  beaker  and  heat  to  boiling.  Add 
25  c.c.  of  the  solution  of  the  material  to  be  examined,  which  must  be  so 
prepared  as  not  to  contain  more  than  0.250  gm.  of  glucose,  and  boil  for 
exactly  two  minutes  keeping  the  beaker  covered.  Filter  immediately 
through  asbestos  without  diluting,  and  obtain  the  weight  of  copper  by 
one  of  the  methods  described  in  the  following  section.  The  correspond- 
ing weight  of  glucose  is  found  from  Allihn's  table  (Appendix,  Table  10). 

METHODS  FOR  DETERMINING  REDUCED  COPPER 

Reduction  of  the  Cuprous  Oxide  in  Hydrogen.| — "Filter  the 
cuprous  oxide  immediately  through  a  weighed  filtering  tube  made  of 
hard  glass,  using  suction.  Support  the  asbestos  film  in  the  filtering  tube 
with  a  perforated  disk  or  cone  of  platinum,  and  wash  free  from  loose 
fibers  before  weighing;  moisten  previous  to  the  filtration.  Provide  the 
tube  with  a  detachable  funnel  during  filtration,  so  that  none  of  the 
precipitate  accumulates  near  the  top,  where  it  could  be  removed  by 

*  J.  prakt.  Chem.  [2],  22,  46. 

t  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  pp.  49-53. 

t  Ibid. 


404 


SUGAR  ANALYSIS 


i  ii  in 

Fig.  169.  —Forms  of  tubes  for  filtering  cuprous  oxide. 


Fig.  170.  —  Showing  methods  of  filtering  cuprous  oxide  with  filter  tube  or 
Gooch  crucible. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     405 

the  cork  used  during  the  reduction  of  the  cuprous  oxide.  Transfer  all  the 
precipitate  to  the  filter  and  thoroughly  wash  with  hot  water,  following 
the  water  by  alcohol  and  ether  successively.  After  being  dried,  con- 
nect the  tube  with  an  apparatus  for  supplying  a  continuous  current  of 
dry  hydrogen,  gently  heat  until  the  cuprous  oxide  is  completely  re- 
duced to  the  metallic  state,  cool  in  the  current  of  hydrogen  and  weigh." 
Several  forms  of  tubes  for  filtering  cuprous  oxide  are  shown  in 
Fig.  169.  Glass  wool  is  sometimes  used  in  place  of  a  platinum  disk  for 
holding  the  asbestos,  but  makes  a  less  resistant  support  (see  Fig.  169  III). 


Fig.  171.  — Apparatus  for  reducing  cuprous  oxide  to  copper.    A,  hydrogen  generator; 
B  and  C,  gas  driers;  D,  filter  tube  containing  cuprous  oxide. 

A  convenient  method  of  filtering  cuprous  oxide  by  means  of  suction 
is  shown  in  Fig.  170.  A  continuous  filtration  should  be  maintained 
and  all  the  precipitate  should  be  transferred  to  the  tube  before  the 
liquid  above  the  asbestos  is  allowed  to  run  completely  through.  Too 
rapid  or  too  irregular  filtration  may  cause  particles  of  cuprous  oxide  to 
run  through  the  asbestos.  A  fine  jet  of  water  will  usually  bring  all  the 
cuprous  oxide  into  the  filter  tube;  should  any  of  the  precipitate  remain 
adhering  to  the  beaker  a  feather,  or  a  rubber-tipped  rod,  will  assist  the 
removal. 

The  reduction  of  the  cuprous  oxide  to  copper  by  means  of  hydrogen 
is  shown  in  Fig.  171.  All  air  must  be  expelled  from  the  tube  before 


406 


SUGAR  ANALYSIS 


Fig.  172.  —  Desiccator  for 
filter  tubes. 


heating,  otherwise  there  is  danger  of  explosion.     The  heating  should  be 
continued  until  all  water  is  expelled  from  the  tube.     A  desiccator  of  the 
form  shown  in  Fig.  172  is  convenient  for  hold- 
ing filter  tubes  before  weighing. 

The  asbestos  used  for  loading  the  filter  tubes 
should  be  of  a  kind  which  is  not  attacked  by 
hot  Fehling's  solution.  The  following  method 
of  preparation  used  by  Munson  and  Walker  * 
is  recommended. 

Preparation  of  Asbestos.  —  Prepare  the 
asbestos  which  should  be  the  am  phi  bole 
variety  by  first  digesting  with  1 :  3  hydro- 
chloric acid  for  two  or  three  days.  Wash  free 
from  acid  and  digest  for  a  similar  period  with 
soda  solution,  after  which  treat  for  a  few  hours 
with  hot  alkaline  copper-tartrate  solution  of 
the  strength  employed  in  sugar  determinations. 
Then  wash  the  asbestos  free  from  alkali,  finally 
digest  with  nitric  acid  for  several  hours,  and 
after  washing  free  from  acid  shake  with  water  for  use.  In  preparing 
filter  tubes  or  Gooch  crucibles  load  with  a  film  of  asbestos  one-fourth 
inch  thick,  wash  this  thoroughly  with  water  to  remove  fine  particles  of 
asbestos;  finally  wash  with  alcohol  and  ether,  dry  for  30  minutes  at 
100°  C.,  cool  in  a  desiccator  and  weigh.  It  is  best  to  dissolve  the  cop- 
per with  nitric  acid  each  time  after  weighing  and  use  the  same  felts  over 
and  over  again,  as  they  improve  with  use. 

The  method  of  estimating  copper  by  reduction  of  the  precipitated 
cuprous  oxide,  although  not  so  exact  as  the  electrolytic  method,  is 
nevertheless  sufficiently  accurate  for  most  purposes  of  analysis.  In  the 
case  of  impure  sugar  products  the  cuprous  oxide  is  frequently  con- 
taminated with  mineral  or  organic  matter,  and  in  such  cases  the 
method  gives  too  high  results. 

Determination  of  Reduced  Copper  by  Electrolysis.  —  Deposition 
from  Sulphuric-acid  Solution.^  —  Filter  the  cuprous  oxide  in  a  Gooch 
crucible  (as  shown  in  Fig.  1 70) ,  wash  the  beaker  and  precipitate  thoroughly 
with  hot  water  without  any  effort  to  transfer  the  precipitate  to  the  filter. 
Wash  the  asbestos  film  and  the  adhering  cuprous  oxide  into  the  beaker 
by  means  of  hot  dilute  nitric  acid.  After  the  copper  is  all  in  solution, 
refilter  through  a  thin  film  of  asbestos  and  wash  thoroughly  with  hot 

*  J.  Am.  Chem.  Soc.,  28,  666. 

t  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  pp.  49-53. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     407 

water.  Add  10  c.c.  of  dilute  sulphuric  acid,  containing  200  c.c.  of  sul- 
phuric acid  (sp.  gr.  1.84)  per  liter,  and  evaporate  the  filtrate  on  the 
steam  bath  until  the  copper  salt  has  largely  crystallized.  Heat  care- 
fully on  a  hot  plate  or  over  a  piece  of  asbestos  board  until  the  evolution 
of  white  fumes  shows  that  the  excess  of  nitric  acid  is  removed.  Add 
from  8  to  10  drops  of  nitric  acid  (sp.  gr.  1.42)  and  rinse  into  a  platinum 
dish  of  from  100  to  125  c.c.  capacity.  Precipitate  the  copper  by  elec- 
trolysis. Wash  thoroughly  with  water,  alcohol  and  ether  successively, 
dry  at  about  50°  C.  and  weigh.  If  preferred  the  electrolysis  can  be 
conducted  in  a  beaker,  the  copper  being  deposited  upon  a  weighed 
platinum  cylinder. 

Deposition  from  Sulphuric-  and  Nitric-acid  Solution.*  —  Filter  and 
wash  as  previously  described.  Transfer  the  asbestos  film  from  the 
crucible  to  the  beaker  by  means  of  a  glass  rod  and  rinse  the  crucible 
with  about  30  c.c.  of  a  boiling  mixture  of  dilute  sulphuric  and  nitric 
acids,  containing  65  c.c.  of  sulphuric  acid  (sp.  gr.  1.84)  and  50  c.c.  of 
nitric  acid  (sp.  gr.  1.42)  per  liter.  Heat  and  agitate  until  solution  is 
completed;  filter  and  electrolyze. 

Deposition  from  Nitric-acid  Solution.^  —  Filter  and  wash  as  pre- 
viously described.  Transfer  the  asbestos  film  and  adhering  oxide  to 
the  beaker.  Dissolve  the  oxide  still  remaining  in  the  crucible  by 
means  of  2  c.c.  of  nitric  acid  (sp.  gr.  1.42),  adding  it  with  a  pipette 
and  receiving  the  solution  in  the  beaker  containing  the  asbestos  film. 
Rinse 'the  contents  of  the  beaker  until  the  copper  is  all  in  solution, 
filter,  dilute  the  filtrate  to  a  volume  of  100  c.c.  or  more  and  electrolyze. 
When  a  nitrate  solution  is  electrolyzed,  the  first  washing  of  the  deposit 
should  be  made  with  water  acidulated  with  sulphuric  acid  in  order  that 
the  nitric  acid  may  all  be  removed  before  the  current  is  interrupted. 

Leach's  Electrolytic  Apparatus.  —  A  convenient  apparatus  for 
the  electrolytic  deposition  of  copper  in  sugar  analysis  is  that  of  Leach  £ 
shown  in  Fig.  173.  A  is  a  hard  rubber  plate  50  cm.  long  and  25  cm. 
wide  provided  with  four  insulated  metal  binding  posts  B,  each  carry- 
ing at  the  top  a  thumb  screw  by  which  a  coiled-platinum-wire  electrode 
may  be  attached.  In  front  of  each  post  is  a  copper  plate  about  4  cm. 
square  covered  with  thin  platinum  foil  P,  which  is  bent  around  the 
edges  of  the  copper  plate  and  so  held  in  place,  the  copper  plate  being 
screwed  to  the  rubber  from  beneath.  On  the  square  platinum-covered 
plate  is  set  the  platinum  evaporating  dish  which  holds  the  solution 

*  Bull.  107  (revised),  U.S.  Bur.  of  Chem.,  pp.  49-53. 

t  Ibid. 

j  Leach's  "Food  Inspection  and  Analysis"  (1911),  p.  608. 


408 


SUGAR  ANALYSIS 


from  which  the  copper  is  to  be  deposited,  the  inside  of  the  dish  forming 
the  cathode,  while  the  coiled  platinum  wire,  dipping  below  the  surface 
of  the  solution,  forms  the  anode.  In  front  of  each  platinum-covered 
plate  is  a  switch  S,  and  at  either  end  of  the  hard-rubber  plate  is  a  bind- 
ing post  R,  for  connection  with  the  electric  current. 


Fig.  173.  —  Leach's  electrolytic  apparatus  for  determining  reduced  copper. 

,  Four  determinations  may  be  carried  on  simultaneously  in  four 
platinum  dishes,  if  desired,  the  wiring  and  the  switches  being  so  ar- 
ranged that  beginning  at  one  end  of  the  plate  either  the  first  dish,  or 
the  first  two  or  the  first  three,  may  be  thrown  in  or  out  of  the  circuit  at 
will  without  interrupting  the  current  through  the  remaining  dishes.  A 
cover  with  wooden  sides  and  glass  top  fits  closely  over  the  whole  ap- 
paratus as  a  protection  from  dust,  but  may  easily  be  lifted  off  to  manipu- 
late the  dishes  when  desired.  The  sides  of  the  cover  are  perforated  to 
permit  the  escape  of  the  gas  formed  during  the  electrolysis. 

The  ordinary  street  current  is  used  when  available,  and  the  strength 
of  the  current  may  be  varied  within  wide  limits  by  means  of  a  number 
of  16-  or  32-candle-power  lamps  K,  coupled  in  multiple,  and  a  rheostat 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     409 

L,  consisting  of  a  vertical  glass  tube  sealed  at  the  bottom,  containing  a 
column  of  dilute  acid,  the  resistance  being  changed  by  varying  the 
length  of  the  acid  column  contained  between  the  two  platinum  ter- 
minals immersed  therein,  one  of  which  is  movable.  A  gravity  battery 
of  four  cells  may  be  employed  if  the  laboratory  is  not  equipped  with 
electric  lights. 

In  using  the  apparatus  the  plating  process  should  go  on  till  all  the 
copper  is  deposited,  which  requires  several  hours  or  over  night  with  a 
current  of  about  0.25  ampere.  Before  stopping  the  process  the  absence 
of  copper  in  the  solution  should  be  proved  by  removing  a  few  drops 
with  a  pipette,  adding  first  ammonia,  then  acetic  acid  and  testing  with 
ferrocyanide  of  potassium.  If  no  brown  coloration  is  produced,  all  the 
copper  has  been  plated  out.  Throw  the  dish  out  of  circuit  by  means  of 
the  switch,  pour  out  the  acid  solution  quickly  before  it  has  a  chance  to 
dissolve  any  of  the  copper,  wash  the  dish  first  with  water  and  then  with 
alcohol,  dry  and  weigh. 

The  copper  may  be  removed  from  the  platinum  dish  by  strong 
nitric  acid. 

The  electrolytic  process  for  determining  reduced  copper  is  the  most 
exact  of  all  methods.  The  determination,  however,  involves  a  con- 
siderable expenditure  of  time  and  for  this  reason  is  but  little  used  in 
sugar  laboratories  where  there  is  a  large  amount  of  routine. 

Electrolytic  Method  of  Peters.  —  Peters  *  has  devised  a  rapid  elec- 
trolytic method  for  the  determination  of  copper,  whereby  the  metal 
is  deposited  from  an  alkaline-tartrate  solution,  such  as  is  used  in 
preparing  Fehling's  solution.  The  electrolysis  is  carried  out  either 
in  platinum  dishes  placed  upon  plates  of  sheet  brass  to  which  the 
cathode  connection  is  made,  or  in  glass  beakers  or  large  test  tubes, 
in  which  case  large  cylindrical  strips  of  sheet  copper  may  be  used  for 
the  cathode.  The  anode  consists  of  a  flat  or  cylindrical  spiral  of 
platinum  wire,  which  should  be  placed  at  a  distance  of  1  cm.  or  less 
from  the  cathode  surface.  A  volume  of  10  c.c.  copper  solution 
(which  may  be  slightly  acid  or  alkaline)  is  usually  taken,  to  which  is 
added  an  approximately  equal  volume  of  a  solution  containing  35  gms. 
pure  Rochelle  salts  and  25  gms.  potassium  hydroxide  (purified  by 
alcohol)  in  100  c.c.  For  copper  solutions  containing  free  sulphuric 
or  nitric  acid,  two  volumes  of  the  alkaline-tartrate  solution  may  be 
used.  From  0.4  to  1.0  c.c.  of  a  saturated  aqueous  potassium-cyanide 
solution  is  then  added  according  to  the  amount  of  copper  present; 
the  amount  of  cyanide  solution  should  be  less  than  sufficient  to  dis- 
*  J.  Am.  Chem.  Soc.,  34,  426. 


410  SUGAR  ANALYSIS 

charge  the  blue  color.  If  the  copper  deposit  should  be  found  to  be 
too  soft  or  dark  colored,  more  cyanide  should  be  used;  an  excess  of 
the  latter,  however,  greatly  lengthens  the  time  for  complete  deposition 
of  the  copper. 

In  making  the  determination  the  direct  110- volt  current  of  a  light- 
ing system  is  used  with  three  32-candle-power  lamps  interposed  as 
resistance;  under  these  conditions  the  voltage  measures  2.6  and  the 
amperage  2.85.  During  the  electrolysis  the  solution  is  warmed  by  a 
small  burner  placed  under  the  brass  plate  to  one  side  of  the  cathode 
vessel;  if  test  tubes  are  used  they  are  placed  upon  wire  gauze  over  a 
small  flame.  The  evolution  of  gas  and  the  circulation  of  warm 
liquid  cause  a  very  rapid  deposition  of  copper,  which  is  usually  com- 
plete in  less  than  30  minutes.  The  solution  should  be  covered  during 
electrolysis  to  prevent  loss  by  spraying. 

To  determine  the  completion  of  electrolysis,  Peters  recommends 
the  Endemann-Prochazka  *  hydrobromic  acid  test.  One  volume  of 
concentrated  sulphuric  acid  is  diluted  with  2  to  3  volumes  of  distilled 
water.  About  1  c.c.  of  the  dilute  acid  is  placed  in  a  narrow  test  tube, 
a  few  crystals  of  potassium  bromide  added  and  the  whole  heated  to 
boiling.  A  drop  of  the  solution  to  be  tested  is  then  added;  as  small 
an  amount  as  0.007  mg.  copper  will  cause  a  red  color  to  develop. 

If  the  deposition  of  copper  is  complete,  the  solution  in  the  cathode 
vessel,  without  breaking  the  current,  is  displaced  by  a  small  stream 
of  water  until  the  resistance  lamps  are  extinguished;  under  this  pro- 
cedure no  copper  is  lost  by  solution.  The  electrode  containing  the 
deposit  of  copper  is  then  washed  in  alcohol  and  ether,  dried  and 
weighed. 

On  account  of  the  similarity  in  composition  of  the  electrolyte 
employed  by  Peters  to  that  of  the  alkaline-tartrate  solution  used  in 
Allihn's  method,  the  process  recommends  itself  for  the  determination 
of  copper  in  the  original  Fehling's  solution  or  in  the  filtrate  from  the 
reduced  cuprous  oxide  obtained  in  the  analysis  of  sugar  solutions. 

Several  volumetric  processes  have  been  devised  for  determining 
copper  in  the  precipitate  of  cuprous  oxide.  Of  these  the  permanganate, 
the  iodide  and  thiocyanate  methods  will  be  described. 

Volumetric  Permanganate  Method,  f  —  Filter  and  wash  the  cuprous 
oxide  as  in  the  previous  methods.  Transfer  the  asbestos  film  to  the 
beaker,  add  about  30  c.c.  of  hot  water  and  heat  the  precipitate  and 
asbestos  thoroughly.  Rinse  the  crucible  with  50  c.c.  of  a  hot  saturated 

*  Chem.  News,  42,  8. 

t  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  pp.  49-53. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     411 

solution  of  ferric  sulphate  in  20  per  cent  sulphuric  acid,  receiving  the 
rinsings  in  the  beaker  containing  the  precipitate.  After  the  cuprous 
oxide  is  dissolved,  wash  the  solution  into  a  large  Erlenmeyer  flask  and 
immediately  titrate  with  a  standard  solution  of  potassium  permanga- 
nate. One  cubic  centimeter  of  the  permanganate  solution  should  equal 
0.010  gm.  of  copper.  In  order  to  standardize  the  permanganate  solu- 
tion, make  six  or  more  determinations  with  the  same  sugar  solution, 
titrating  one-half  of  the  precipitations  and  determining  the  copper  in 
the  others  by  electrolysis.  The  average  weight  of  copper  obtained  by 
electrolysis,  divided  by  the  average  number  of  cubic  centimeters  of 
permanganate  solution  required  for  the  titration,  is  equal  to  the  weight 
of  copper  equivalent  to  1  c.c.  of  the  standard  permanganate  solution. 

The  reaction  between  the  ferric  sulphate  and  cuprous  oxide  is  ex- 
pressed as  follows: 

Fe2(SO4)3  +  Cu20  +  H2S04  =  2  FeS04  +  2  CuSO4  +  H20. 

Since  1  atom,  or  16  parts,  of  0  is  required  to  oxidize  the  iron  reduced 
by  2  atoms,  or  127.2  parts,  of  Cu,  and  1  c.c.  of  n/10  permanganate 
contains  0.0008  gm.  of  active  0,  then  1  c.c.  of  n/10  permanganate  is 
equivalent  to  0.00636  gm.  Cu.  For  a  solution  containing  5  gms.  of 
potassium  permanganate  to  the  liter,  1  c.c.  will  be  equivalent  very 
closely  to  0.01  gm.  of  copper.  Owing  to  slight  deviations  in  practice 
from  the  above  theoretical  equation,  the  copper  value  of  the  perman- 
ganate must  always  be  determined  by  direct  experiment. 

Volumetric  Iodide  Method,*  Low's  Modification.^ — Standardization 
of  the  Thiosulphate  Solution.  —  Prepare  a  solution  of  sodium  thiosul- 
phate  containing  19  gms.  of  pure  crystals  to  1000  c.c.  Weigh  accu- 
rately about  0.2  gm.  of  pure  copper  foil  and  place  in  a  flask  of  250  c.c. 
capacity.  Dissolve  by  warming  with  5  c.c.  of  a  mixture  of  equal 
volumes  of  strong  nitric  acid  and  water.  Dilute  to  50  c.c.,  boil  to  expel 
the  red  fumes,  add  5  c.c.  strong  bromine  water  and  boil  until  the 
bromine  is  thoroughly  expelled.  Remove  from  the  heat  and  add  a 
slight  excess  of  strong  ammonium  hydroxide  (about  7  c.c.  of  0.90  sp.  gr.). 
Again  boil  until  the  excess  of  ammonia  is  expelled,  as  shown  by  a  change 
of  color  of  the  liquid,  and  a  partial  precipitation.  Now  add  a  slight  ex- 
cess of  strong  acetic  acid  (3  or  4  c.c.  of  80  per  cent  acid)  and  boil  again 
for  a  minute  to  redissolve  the  copper.  Cool  to  room  temperature  and 
add  10  c.c.  of  a  solution  of  pure  potassium  iodide  containing  300  gms. 

*  For  a  critical  study  of  the  iodide  method  for  determining  copper  in  sugar 
analysis  see  paper  by  Peters,  J.  Am.  Chem.  Soc.,  34,  422. 
f  J.  Am.  Chem.  Soc.,  24,  1082. 


412  SUGAR  ANALYSIS 

of  potassium  iodide  to  1000  c.c.  Titrate  at  once  with  the  thiosulphate 
solution  until  the  brown  tinge  has  become  weak,  then  add  sufficient 
starch  liquor  to  produce  a  marked  blue  coloration.  Continue  the  ti- 
tration  cautiously  until  the  color  due  to  free  iodine  has  entirely  van- 
ished. The  blue  color  changes  toward  the  end  to  a  faint  lilac.  If  at 
this  point  the  thiosulphate  be  added  drop  by  drop  and  a  little  time  be 
allowed  for  complete  reaction  after  each  addition  there  is  no  difficulty 
in  determining  the  end  point  within  a  single  drop.  One  cubic  centi- 
meter of  the  thiosulphate  solution  will  be  found  to  correspond  to  about 
0.005  gm.  of  copper. 

Determination  of  Copper.  —  After  washing  the  precipitated  cuprous 
oxide,  cover  the  Gooch  crucible  with  a  watch  glass  and  dissolve  the 
oxide  by  means  of  5  c.c.  of  warm  nitric  acid  (1  :  1),  poured  under  the 
watch  glass  with  a  pipette.  Catch  the  filtrate  in  a  flask  of  250  c.c. 
capacity,  wash  watch  glass  and  crucible  free  of  copper;  50  c.c.  of 
water  will  be  sufficient.  Boil  to  expel  red  fumes,  add  5  c.c.  of  bromine 
water,  boil  off  the  bromine  and  proceed  exactly  as  in  standardizing  the 
thiosulphate. 

In  a  later  modification  of  the  above  method,  Low  has  found  it 
possible  to  dispense  with  the  use  of  bromine,  the  nitrous  acid  being 
expelled  from  the  copper  solution  by  boiling,  adding  ammonia,  heat- 
ing, acidifying  with  acetic  acid  and  again  boiling. 

The  reaction  between  the  copper  acetate  and  potassium  iodide  is 
expressed  as  follows: 

2  Cu(C2H3O2)2  +  4  KI  =  Cu2I2  +  4  KC2H302  +  I2. 

Since  1  atom,  or  63.57  parts,  of  copper  liberates  1  atom,  or  126.92 
parts,  of  iodine  and  1  c.c.  of  n/10  thiosulphate  solution  (24.8  gms.  Na2S2Oa 
+  5  H20  to  1000  c.c.)  reacts  with  0.01269  gm.  I,then  1  c.c.  n/W  thiosul- 
phate corresponds  to  0.00636  gm.  Cu.  For  a  solution  containing  19.5 
gms.  of  pure  sodium  thiosulphate  to  the  liter,  1  c.c.  will  be  equivalent 
very  closely  to  0.005  gm.  of  copper.  In  actual  practice  the  above 
reaction  does  not  proceed  with  absolutely  quantitative  precision,  the 
results  of  the  determination  varying  somewhat  according  to  concen- 
tration of  acid,  excess  of  reagents,  temperature  and  other  conditions. 
It  is,  therefore,  important  always  to  standardize  the  thiosulphate 
solution  against  pure  copper  under  the  exact  conditions  which  are 
followed  in  analysis. 

Kendall's  Modification  of  the  Iodide  Method.  —  The  removal  of  the 
nitrous  acid,  formed  in  dissolving  the  copper,  is  the  chief  difficulty  in 
the  iodide  method.  Kendall  *  has  modified  the  method  by  removing 

*  J.  Am.  Chem.  Soc.,  33,  1947. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     413 

the  nitrous  acid  with  hypochlorite,  the  free  chlorine,  which  is  evolved, 
being  afterwards  removed  with  phenol. 

The  cuprous  oxide,  after  filtering  and  washing  upon  a  Gooch  cru- 
cible, is  dissolved  in  10  to  15  c.c.  of  30  per  cent  nitric  acid  into  a 
300  c.c.  Erlenmeyer  flask.  The  volume  of  solution  and  washings 
should  be  between  50  and  60  c.c.  with  an  acidity  of  4  to  5  c.c.  con- 
centrated nitric  acid;  5  c.c.  of  sodium  hypochlorite  solution  are  then 
added  of  such  strength  that  the.  iodine  liberated  by  5  c.c.  is  equivalent 
to  30  c.c.  of  n/10  thiosulphate.  The  solution  is  allowed  to  stand 
2  minutes,  when  10  c.c.  of  a  5  per  cent  colorless  phenol  solution  are 
quickly  added.  The  chlorine  gas  above  the  liquid  is  removed  by 
blowing  into  the  flask  and  the  sides  are  washed  down  with  a  jet  of 
water.  The  solution  is  then  made  slightly  alkaline  with  sodium 
hydroxide  and  acidified  with  acetic  acid;  10  c.c.  of  30  per  cent  potas- 
sium iodide  solution  are  then  added  and  the  free  iodine  titrated  with 
standard  sodium  thiosulphate,  as  under  Low's  modification,  using  sol- 
uble starch  as  indicator.  The  thiosulphate  is  previously  standardized 
against  pure  copper  under  the  same  conditions  as  those  of  the  method. 

In  working  with  known  weights  of  copper  between  20  and  340 
nigs.,  Kendall  found  the  error  of  his  method  to  exceed  in  no  case  0.3  mg. 

Peters' s  Modifications  of  the  Iodide  Method. — Peters*  has  found  that 
boiling  the  nitric-acid  solution  of  copper  in  the  presence  of  talcum 
powder  will  remove  completely  all  lower  oxides  of  nitrogen  and  leave 
the  solution,  after  cooling  and  diluting,  in  suitable  condition  for  titra- 
tion.  The  copper,  or  its  compound,  is  dissolved  in  an  Erlenmeyer 
flask  in  the  least  possible  volume  of  concentrated  nitric  acid,  to  which 
one-half  its  volume  of  water  has  been  added;  5  to  10  c.c.  of  dilute 
acid  are  sufficient  for  0.5  gm.,  or  less,  of  copper.  After  solution  15  to 
25  c.c.  of  distilled  water  and  a  little  pure  powdered  talcum  are  added, 
and  the  mixture  boiled  vigorously  for  5  to  10  minutes.  After  cooling 
to  room  temperature  distilled  water  is  added  and  10  c.c.  of  a  saturated 
potassium-iodide  solution,  the  dilution  being  so  regulated  that  the 
final  volume  of  liquid  at  the  end  of  the  thiosulphate  titration  is  about 
120  c.c. 

Peters  has  also  employed  the  iodide  method  in  the  determination 
of  copper  in  the  alkaline-tartrate  solutions,  or  filtrates,  occurring  in 
sugar  analysis.  In  the  modification  employed,  20  c.c.  of  Allihn's 
alkaline-tartrate  solution,  20  c.c.  of  Fehling's  copper-sulphate  solution 
and  20  c.c.  of  water  (as  in  a  blank  determination),  or  of  the  aqueous 
reducing-sugar  solution,  were  taken,  making  the  total  volume  for 
*  J.  Am.  Chem.  Soc.,  34,  422. 


414  SUGAR  ANALYSIS 

reduction  always  60  c.c.  After  the  reduction  the  cuprous  oxide  is 
filtered,  washed  and  the  nitrate,  which  has  a  volume  of  70  to  75  c.c., 
acidified  with  4  to  5  c.c.  of  concentrated  sulphuric  acid.  After  cool- 
ing to  about  20°  C.,  10  c.c.  of  saturated  potassium  iodide  are  added 
and  the  solution  titrated  with  standard  thiosulphate  in  the  usual 
way. 

The  end  point  of  the  titration  in  the  iodide  method  is  best  deter- 
mined according  to  Peters  by  noting  the  point  at  which  a  drop  of  the 
thiosulphate  solution  ceases  to  produce  a  perceptible  white  area  upon 
the  quiet  surface  of  the  titration  liquid.  As  in  the  case  of  all  other 
modifications  of  the  iodide  method,  the  thiosulphate  solution  must 
be  standardized  against  pure  copper  under  the  exact  conditions  of 
the  analysis. 

Potassium  iodide  is  an  expensive  reagent  and  where  many  deter- 
minations of  copper  are  made  by  this  method,  the  waste  titration 
liquids  and  cuprous  iodide  precipitates  should  be  saved  for  recovery 
of  the  iodine. 

Volumetric  Thiocyanate  Method  (Volhard-Pfluger).*  — The  fol- 
lowing solutions  are  required:  (a)  n/W  silver-nitrate  solution,  (6)  n/10 
ammonium-thiocyanate  solution,  (c)  a  cold  saturated  solution  of  sulphur 
dioxide  (S02)  in  water,  (d)  nitric  acid  of  sp.  gr.  1.2,  free  from  nitrous 
acid,  (e)  a  saturated  solution  of  ferric  alum,  (/)  normal  sulphuric-acid 
solution. 

The  filter  tube,  or  Gooch  crucible,  containing  the  cuprous  oxide  is 
weighed  and  the  approximate  amount  of  copper  determined.  The  cuprous 
oxide  is  then  dissolved  from  the  asbestos  with  nitric  acid,  the  solution 
treated  with  a  slight  excess  of  normal  sulphuric  acid  solution  (/)  necessary 
to  convert  all  the  copper  into  copper  sulphate  and  evaporated  to  dryness. 
The  copper  sulphate  is  then  dissolved  in  water  and  washed  into  a  300-c.c. 
graduated  flask.  Sodium  carbonate  solution  is  added  to  the  point  of 
turbidity  and  then  50  c.c.  of  the  sulphurous  acid  reagent  (c).  The 
solution  is  boiled  for  1  minute  and  then  n/10  thiocyanate  (6)  added 
until  there  is  an  excess  of  about  5  c.c.  above  the  calculated  amount 
necessary  for  precipitating  the  copper  as  cuprous  thiocyanate  Cu2(SCN)2. 
The  solution  is  then  cooled,  made  up  to  300  c.c.,  shaken  and  filtered 
through  dry  filter  paper.  Should  the  first  runnings  appear  turbid,  they 
are  returned  to  the  filter;  100  c.c.  of  the  clear  filtrate  are  diluted  with 
100  c.c.  of  water,  50  c.c.  of  nitric  acid  (d)  and  10  c.c.  of  ferric-alum  solution 
(e)  are  added,  and  the  solution  titrated  with  n/10  silver  nitrate  (a)  until 
the  red  color  is  discharged.  The  addition  of  silver  solution  is  continued 

*  Pfliiger's  Archiv,  69,  423. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     415 

to  the  next  even  number  of  c.c.,  and  then  the  solution  titrated  back 
with  n/10  thiocyanate  until  the  white  liquid  just  begins  to  turn  pink. 

Let  A  be  the  cubic  centimeters  of  n/10  thiocyanate  added  to  the 
300  c.c.  of  solution,  B  the  cubic  centimeters  of  n/10  silver  nitrate  added 
to  the  100  c.c.  of  nitrate,  and  C  the  cubic  centimeters  of  n/10  thio- 
cyanate to  titrate  back  excess  of  B. 

Since  1  c.c.  n/10  thiocyanate  =  6.357  mgs.  copper  then  the  total  milli- 
grams of  copper  (Cu)  are  found  by  the  formula  Cu  =  6.357  (A  +3  C  —  3 B) . 
The  thiocyanate  solution  should  be  standardized  against  pure  copper 
under  the  conditions  of  analysis,  as  in  the  permanganate  and  iodide 
methods. 

Volumetric  Cyanide  Method. — Of  other  volumetric  processes  which 
are  used  for  determining  reduced  copper  may  be  mentioned  the  well- 
known  cyanide  method.  The  unreduced  copper  in  the  filtrate  from  the 
cuprous  oxide  is  titrated  with  standard  potassium  cyanide  solution  until 
the  blue  color  disappears.  The  difference  between  the  copper  in  the 
volume  of  Fehling's  solution  taken,  and  that  found  in  the  filtrate  after 
reduction,  is  the  amount  of  copper  reduced  by  the  sugar. 

Determination  of  Copper  by  Weighing  as  Cupric  Oxide.  —  In  this 
method  the  cuprous  oxide,  after  collecting  upon  a  Gooch  crucible,  is 
heated  to  redness  for  about  15  minutes,  when  it  is  converted  to  black 
cupric  oxide.  To  insure  complete  oxidation  care  must  be  taken  that 
the  oxide  is  not  exposed  to  the  reducing  action  of  the  illuminating  gas 
during  ignition.  For  this  reason  the  operation  is  best  carried  out  in  a 
muffle. 

If  porcelain  Gooch  crucibles  are  used  they  should  have  open  bottoms 
with  loose  perforated  disks  for  supporting  the  asbestos  (CaldwelPs 
crucible,  Fig.  174).  The  one-piece  porcelain  Gooch 
crucible  is  liable  to  crack  at  high  temperatures  of 
ignition. 

Finely-divided  cupric  oxide  is  hygroscopic  and, 
after  cooling  in  a  desiccator,  should  be  weighed  as 
quickly  as  possible.  The  weight  of  cupric  oxide  Fig.  174. — Gooch  cru- 
multiplied  by  the  factor  0.7989  gives  the  weight  of  cible  with  detach- 
metallic  copper.  Several  sugar  tables,  as  KjeldahPs 
and  Defren's,  express  results  in  terms  of  cupric  oxide,  thus  avoiding 
the  labor  of  calculation,  when  this  method  of  determining  copper  is 
used. 

The  method  of  estimating  copper  from  the  weight  of  cupric  oxide 
is  one  of  the  most  accurate  of  the  indirect  methods.  With  impure  pro- 
ducts, however,  the  precipitate  of  cuprous  oxide  frequently  carries 


416 


SUGAR  ANALYSIS 


down  mineral  matter  and  this  contamination  will  impair  somewhat  the 
accuracy  of  the  method  (see  Table  LXXIII). 

Determination  of  Copper  by  Direct  Weighing  of  the  Cuprous 

Oxide.  —  In  this  method  the  precipitated  cuprous  oxide  is  collected 
in  a  filter  tube  or  Gooch  crucible  in  the  usual  way.  Wash  thoroughly 
with  hot  water,  then  with  10  c.c.  of  alcohol  and  finally  with  10  c.c.  of 
ether.  Dry  the  precipitate  30  minutes  in  a  water  oven  at  tlie  tem- 
perature of  boiling  water;  cool  and  weigh.  The  weight  of  cuprous 
oxide  multiplied  by  0.8882  gives  the  weight  of  metallic  copper.  The 
sugar  tables  of  Munson  and  Walker  express  results  in  terms  of  cuprous 
oxide,  and  the  use  of  these  tables  will  save  much  labor  of  calculation 
when  this  method  of  determining  copper  is  used. 

Contamination  of  Cuprous  Oxide.  —  Direct  weighing  of  the  cuprous 
oxide  is  the  simplest  of  the  gravimetric  methods  for  estimating  reduced 
copper  in  sugar  analysis.  The  process,  however,  is  less  accurate  than 
the  other  methods  previously  described.  The  method  gives  good  re- 
sults with  sugar  solutions  of  high  purity,  but  with  impure  products  the 
cuprous  oxide  is  contaminated  with  mineral  and  organic  impurities, 
which  may  affect  considerably  the  accuracy  of  the  determination. 

The  extent  of  the  error  in  estimating  copper  from  the  weight  of 
cuprous  oxide  is  shown  by  the  following  comparative  analyses  made  by 
Sherwood  and  Wiley  *  upon  a  variety  of  sugar-containing  products. 

TABLE  LXXIII 
Comparison  of  Methods  for  Determining  Reduced  Copper 


Reduced  Copper 

Material. 

From  weight 
of  cuprous  oxide 

From  weight 
of  cupric  oxide. 

Volumetric 
iodide 
method  (Low). 

Molasses  residuum  

Gram. 

0  3753 

Gram. 

0.3594 

Gram. 

0.3494 

«    , 

0.3905 

0.3634 

0.3470 

u 

0  2517 

0.2348 

0.2242 

n 

0  3287 

0.3130 

0.3034 

n 

0  3291 

0.3134 

0.3029 

(i 

0  .  2768 

0.2698 

0.2688 

(t 

0.2709 

0.2620 

0.2612 

Pure  dextrose 

0  4619 

0.4617 

(i           « 

0  2449 

0.2444 

(i           u 

0  1251 

0.1257 

Beer.  .  . 

0  0755 

0.0753 

n 

0  0746 

0.0748 

Molasses  .... 

0  4628 

0.4520 

Corn  juice  

0  3360 

0.3134 

Malt  extract.. 

0  3322 

0.3048 

«         (i 

0  3160 

0.2933 

«         i< 

0  2093 

0.1934 

*  Bun.  105,  U.  S.  Bur.  of  Chem.,  p.  120. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS       417 

The  results  upon  the  molasses  residuum  show  a  contamination  of 
the  cuprous  oxide  with  organic  matter  as  shown  by  the  differences  in 
copper  as  calculated  from  the  suboxide  and  oxide,  and  with  mineral 
matter  as  shown  by  the  differences  in  copper  as  calculated  from  the 
oxide  and  by  the  volumetric  method. 

With  solutions  of  pure  sugar  and  such  liquids  as  beer,  where  the 
organic  matter  consisted  largely  of  carbohydrates,  the  calculation  of 
copper  from  the  weight  of  cuprous  oxide  gave  accurate  results.  In  the 
case  of  the  malt  extracts,  which  contained  added  peptones,  the  precipi- 
tated cuprous  oxide  seemed  to  carry  down  a  considerable  amount  of 
albuminoid  matter  from  solution;  in  the  case  of  the  molasses  the  precipi- 
tated copper  seemed  to  be  in  partial  combination  with  certain  nitro- 
genous bases  such  as  xanthine. 

Similar  comparisons  upon  methods  of  determining  copper  in  the 
analysis  of  cane-sugar  products  are  given  in  Table  LXXX. 

The  chemist  is  usually  able  to  form  an  opinion  of  the  purity  of  the 
cuprous  oxide  from  its  physical  appearance.  If  the  precipitate  is  yel- 
low or  greenish-red  in  color,  or  has  a  flaky  appearance,  there  is  evidence 
of  contamination,  in  which  case  the  reduced  copper  must  be  determined 
by  one  of  the  direct  methods.  • 


CAUSES  AFFECTING  THE  ACCURACY  OF  ESTIMATING  SUGARS  FROM  A 
DETERMINATION  OF  REDUCED  COPPER 

In  addition  to  the  errors  in  determining  reduced  copper,  there  are  a 
number  of  other  causes  which  affect  the  accuracy  of  the  analytical 
methods  belonging  to  this  class. 

Purity  of  Reagents.  —  A  frequent  cause  of  inaccuracy  in  deter- 
mining sugars  by  the  methods  of  copper  reduction  is  the  presence  of 
organic  or  mineral  impurities  in  the  Fehling's  solution.  The  copper 
sulphate,  the  caustic  alkali  and  especially  the  Rochelle  salts  should  be 
of  the  purest  quality.  The  copper  sulphate  and  alkali-tartrate  solu- 
tions should  be  filtered  separately  through  glass  wool,  or  asbestos,  and 
the  mixed  reagent  should  be  perfectly  clear  and  show  no  trace  of  cuprous 
oxide  after  boiling.  A  blank  determination  should  be  made  upon  each 
fresh  lot  of  solution;  the  crucibles,  or  filter  tubes,  used  in  the  blank 
test  should  show  no  increase  in  weight  under  the  conditions  of  experi- 
ment followed  in  analysis. 

Degree  of  Dilution  and  Time  of  Boiling.  —  The  effect  of  varying 
the  dilution  of  Fehling's  solution,  or  the  time  of  boiling,  is  shown  by 
the  following  comparison  of  results  from  Allihn's  table  with  those 


418 


SUGAR  ANALYSIS 


obtained  by  Wein's,  and  by  Koch  and  Ruhsam's  modifications   of 
Allihn's  method. 


2  minutes'  heating. 

30  minutes'  heating. 

Reduced  cop- 

per. 

Diluted  (Allihn). 
Glucose. 

Undiluted  (Wein). 
Glucose. 

Diluted  (Koch  and 
Ruhsam)  .    Glucose. 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

10 

6.1 

4.5 

4.1 

50 

25.9 

24.6 

21.3 

100 

50.9 

49  9 

46.9 

150 

76.5 

75.5 

72.0 

200 

102.6 

101.7 

96.8 

250 

129.2 

128.3 

122.7 

300 

156.5 

155.6 

149.0 

350 

184  3 

182  3 

176.2 

400 

212.9 

212.0 

205.0 

450 

242.2 

240.6 

235.9 

It  is  seen  that  considerably  more  copper  is  reduced  by  using  a  more 
concentrated  Fehling's  solution  or  by  heating  for  a  longer  time. 

Incomplete  reduction  of  the  copper  solution  has  been  raised  as  an 
objection  against  such  methods  as  Allihn's,  which  boil  for  only  2  min- 
utes. If  the  time  of  filtration  be  too  prolonged  an  additional  amount 
of  copper  is  sometimes  precipitated,  thus  increasing  the  results.  It  is 
important,  therefore,  with  methods  which  boil  for  only  2  minutes  to 
filter  immediately,  and  as  rapidly  as  permissable,  at  the  end  of  the  time 
limit. 

Atmospheric  Pressure  and  Temperature  of  Boiling.  —  Variable 
temperature  of  boiling,  due  to  difference  in  altitude  above  sea-level, 
has  been  suggested  by  Traphagen  and  Cobleigh  *  as  a  cause  of  differ- 
ences in  determining  reducing  sugars.  Rosenkranz  f  has  recently 
studied  the  influence  of  pressure  upon  the  reducing  power  of  invert 
sugar  with  the  following  results: 


Pressure. 

Temperature  of 
boiling. 

25  c.c.  invert  sugar  solution  plus 

25  c.c.  water. 
50  c.c.  Fehling's 
solution. 

25  c.c.  10%  sucrose 
solution.     50  c.c. 
Fehling's  solution. 

Millimeters. 
J775 

1600 
J760 
)  925 

Deg.  C. 
103-105 

90-  96 
103-104 
109-110 

Mgs.  Cu. 

236.5 
232.5 
235.6 
236.1 

Mgs.  Cu. 
260.4 

244.9 

277.7 
296.3 

*  J.  Am.  Chem.  Soc.,  21,  369.  f  Z.  Ver.  Deut.  Zuckerind.,  61  (1911),  426. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     419 

The  results  show  for  pure  invert  sugar  a  slight  tendency  towards 
increase  in  reducing  power  with  increase  in  pressure;  the  error  due  to 
this  cause,  however,  is  slight  and  may  be  neglected  for  ordinary  at- 
mospheric conditions.  When  sucrose  is  present  the  increase  in  pressure 
causes  a  marked  increase  in  the  amount  of  reduced  copper,  owing  to  the 
much  greater  degree  of  inversion. 

Surface  Area  of  Solution.  —  The  diameter  of  the  vessel  in  which 
the  Fehling's  solution  is  heated  has  been  found  to  influence  the  amount 
of  reduced  copper.  With  wide  beakers,  which  expose  a  larger  area  of 
solution  to  the  air,  more  cuprous  oxide  is  lost  by  oxidation  (through 
being  redissolved  in  the  alkaline-tartrate  solution)  than  in  narrower 
beakers.  Kjeldahl  has  eliminated  the  error  due  to  oxidation  by  mak- 
ing the  reduction  in  an  atmosphere  of  hydrogen  or  of  oxygen-free  illumi- 
nating gas. 

Under  the  same  set  of  conditions  the  oxidation  error  is  a  constant 
one  and  the  discrepancies  due  to  this  cause  are  eliminated  by  making 
the  reduction  always  in  beakers  of  the  same  size.  A  350-400-c.c. 
lipped  beaker  of  Jena,  or  Non-sol  glass,  7-8  cm.  in  diameter  is  about 
the  proper  size. 

SPECIAL    COPPER-REDUCTION   METHODS 

Modifications  of  Allihn's  Method.  —  Allihn's  method  gives  the 
most  accurate  results  upon  sugar  solutions  containing  0.4  to  1.0  per 
cent  glucose,  i.e.,  0.10  to  0.25  gm.  glucose  in  the  25  c.c.  of  solution. 
When  less  than  50  mgs.  of  glucose  are  present  the  method  is  apt  to 
show  wide  discrepancies  in  the  hands  of  different  chemists.  Several 
modifications  of  Allihn's  method,  involving  a  longer  period  of  heating, 
have  been  devised  for  the  purpose  of  increasing  the  accuracy  of  the 
determination  with  dilute  sugar  solutions. 

Pfliiger's  Method.  —  Pfliiger,*  who  uses  the  same  reagents  and 
volumes  of  solutions  as  in  Allihn's  method,  has  modified  the  determina- 
tion by  heating  the  mixed  sugar  and  Fehling's  solutions  (145  c.c.  in  all) 
in  a  boiling- water  bath  for  exactly  30  minutes  and  then  diluting  with 
130  c.c.  of  cold  water  before  filtering.  The  cuprous  oxide  is  filtered  upon 
asbestos  and,  after  washing  and  drying,  the  weight  of  precipitate  deter- 
mined. Owing  to  the  frequent  occurrence  of  impurities  in  the  cuprous 
oxide,  especially  when  working  with  fluids  or  extracts  of  animal  origin, 
Pfliiger  advises  to  make  also  a  direct  determination  of  the  copper  by 
means  of  the  thiocyanate  method. 

*  Pfliiger's  Archiv,  69,  399. 


420  SUGAR  ANALYSIS 

Pfliiger's  table  giving  the  weights  of  glucose  corresponding  to  dif- 
ferent weights  of  cuprous  oxide  and  copper,  is  found  in  the  Appendix 
(Table  11). 

Koch  and  Ruhsam's  *  Method.  —  In  this  modification  the  same 
reagents  and  volumes  of  solutions  are  used  as  in  Allihn's  and  Pfliiger's 
methods.  The  mixed  sugar  and  Fehling's  solutions  (145  c.c.  in  all) 
are  first  brought  to  a  boil  and  then  set  in  a  boiling-water  bath  for  ex- 
actly 30  minutes.  The  solution  without  diluting  is  then  filtered  through 
asbestos  in  a  Gooch  crucible  and  the  reduced  copper  determined  by  any 
of  the  usual  methods. 

The  glucose  table  for  Koch  and  Ruhsam's  method  is  given  in  the 
Appendix  (Table  12). 

Koch  and  Ruhsam's  modification  was  designed  for  determining 
glucose  in  tannin  extracts,  etc.,  and  is  the  official  method  of  the  Ameri- 
can Leather  Chemists  and  other  similar  associations. 

The  modifications  of  Allihn's  method,  using  30-minute  heating,  are 
considerably  more  accurate  than  the  original  process  upon  dilute  glu- 
cose solutions  and  should  be  employed  for  determining  small  amounts 
of  sugar  in  urine,  tannin  extracts  and  other  animal  and  vegetable  sub- 
stances of  low  glucose  content.  When,  however,  the  25  c.c.  of  sugar 
solution  contain  over  0.10  gm.  of  glucose,  Allihn's  original  method  of 
2-minute  boiling  may  be  followed  with  perfect  safety,  and  with  a  con- 
siderable economy  of  time.  The  fact  that  more  copper  is  reduced  upon 
longer  heating  does  not  affejt  the  accuracy  of  the  method,  since  the 
tables  were  standardized  under  exactly  similar  conditions. 

Application  of  Allihn's  Method  to  the  Determination  of  Other  Re- 
ducing Sugars.  —  Allihn's  method  has  been  employed  for  determining 
other  reducing  sugars  besides  glucose.  Honig  and  Jesser  f  have  used 
the  method  for  determining  fructose  and  have  constructed  a  table  giv- 
ing the  copper-reducing  power  of  fructose  for  different  weights  of  sugar. 
In  Table  LXXIV  the  fructose  values  of  Honig  and  Jesser,  and  the 
corresponding  glucose  values  of  Allihn,  are  given  for  several  weights  of 
reduced  copper.  The  ratio  of  fructose  to  glucose,  for  the  same  weight 
of  copper,  is  also  given. 

For  equal  weights  of  sugar  the  amount  of  copper  reduced  by  fructose 
is  about  92  per  cent  of  that  reduced  by  glucose.  Soxhlet  found  by  his 
volumetric  method  (p.  391)  that  for  equal  weights  of  sugar  the  reducing 
power  of  fructose  was  92.4  per  cent  that  of  glucose. 

*  J.  Soc.  Chem.  Ind.,  13,  1227. 
t  Monatshefte,  9,  562. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     421 


TABLE  LXXIV 
Showing  Comparative  Reducing  Power  of  Fructose  and  Glucose 


Reduced  copper. 

Fructose  (Honig 
and  Jesser). 

Glucose  (Allihn). 

Ratio  ,gluc08e. 
fructose 

Mgs. 

32.7 

20 

17.4 

0.870 

70.2 

40 

35.9 

0.898 

107.1 

60 

54.6 

0.910 

143.2 

80 

73.0 

0.912 

178.9 

100 

91.5 

0.915 

213.9 

120 

110.0 

0.917 

248.3 

140 

128.3 

0.916 

282.2 

160 

146.7 

0.917 

315.3 

180 

165.0 

0.917 

347.9 

200 

183.1 

0.916 

379.9 

220 

201.3 

0.915 

411.3 

240 

219.5 

0.915 

Average  ratio  (excluding  first  2  of  the  series)     0.915 

Reducing  Ratios  of  Sugars.  —  It  is  seen  from  Table  LXXIV  that 
if  the  values  are  eliminated  for  weights  of  sugar  under  50  mgs.,  for 
which,  as  previously  stated,  Allihn's  method  gives  uncertain  results, 
the  ratio  of  fructose  to  glucose  for  the  same  weight  of  reduced  copper  is 
a  constant  quantity  0.915.  Other  monosaccharides  show  a  similar 
constancy  of  ratio.  The  following  ratios  are  given  by  Browne  *  for  a 
number  of  other  sugars,  the  copper-reducing  power  in  all  cases  being 
determined  by  Allihn's  method: 

Glucose 


Arabinose 
Glucose 
Xylose 
Glucose 
Invert  Sugar 
Glucose 
Galactose 


=  1.032. 


=  0.983. 


=  0.958. 


=  0.898. 


Relative  Copper-reducing  Power.  —  Instead  of  using  the  ratios 
of  the  weights  of  sugars  for  the  same  amount  of  reduced  copper,  the 
ratios  of  the  weights  of  copper  reduced  by  the  same  amount  of  the  two 
sugars  are  frequently  used.  O'Sullivan  f  expressed  the  relative  copper- 
reducing  power  of  a  sugar  by  the  symbol  K  and  adopted  as  his  standard 
(K  =  100)  the  cupric  oxide  reduced  by  a  given  weight  of  glucose  under 
the  conditions  of  his  method.  O'Sullivan  found,  for  example,  that  1  gm. 


*  J.  Am.  Chem.  Soc.,  28,  439. 
t  J.  Chem.  Soc.  (1879),  72,  275. 


422  SUGAR  ANALYSIS 

of  glucose  reduced  2.205  gms.  CuO  and  1  gm.  of  maltose  1.345  gms. 
CuO.     The  relative  copper,  or  cupric  oxide,  reducing  power  of  maltose 


would  then  be  K  =  X  100  =  61. 


In  the  examination  of  starch-conversion  products  the  copper-re- 
ducing power  of  maltose,  expressed  by  the  symbol  R,  is  sometimes 
taken  as  the  standard.  Taking  the  previous  values  of  0  'Sullivan  the 


2 

R  of  glucose  would  be  =•         X  100  =  164. 


In  place  of  the  constant  K,  Brown,  Morris  and  Millar  *  have  sub- 
stituted the  value  K,  which  is       :  K.    According  to  this  system  the  rela- 


tive copper-reducing  power  of  maltose  (using  O'Sullivan's  results)  is  0.61 
K.  The  values  for  K,  when  determined  for  the  same  absolute  weights  of 
the  two  sugars,  are  practically  identical  with  the  reducing  ratios  as  cal- 
culated in  the  previous  section. 

Thus  from  Defren's  table  for  glucose  and  maltose  44.4  mgs.  of  glucose 
reduce  100  mgs.  CuO  and  44.4  mgs.  of  maltose  reduce  61.1  mgs.  CuO  then 

—  -J-  =  0.611,  K  for  maltose. 
lUU 

Using  again  Defren's  table  44.4  mgs.  glucose  and  72.8  mgs.  maltose  reduce 

44  4 
respectively  100  mgs.  CuO,  then  —  ^  =  0.610,  the  reducing  ratio  of  maltose  to 

7  £.G 

glucose. 

If  K,  however,  is  calculated  from  the  weights  of  sugars  as  determined 
by  the  solution  factor  3.86,  as  is  sometimes  done,  then  the  true  reducing 
ratio  is  not  found  unless  a  correction  be  applied  as  indicated  on  page  32. 

The  disaccharides,  lactose  and  maltose,  do  not  show  usually  the 
same  constancy  in  reducing  ratios  for  different  weights  of  copper  as  the 
monosaccharides.  This  is  due  to  the  partial  hydrolysis  of  the  disac- 
charides as  previously  explained;  the  reducing  ratio  is  usually  higher 
the  greater  the  amount  of  disaccharide.  The  copper-reducing  ratios  of 
lactose  and  maltose  are  approximately  as  follows  for  Allihn's  method: 

LactoJhydrate  =  °-66  to  °-71'  or  approximately  0.7. 
•jyF~TT-  ~  =  0-56  to  0.62,  or  approximately  0.6. 
*  J.  Chem.  Soc.  (1897),  96, 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     423 

If  the  copper-reducing  power  of  a  sugar  is  determined  (as  by  Allihn's 
method),  the  corresponding  glucose  value  of  Allihn's  table  divided  by 
the  reducing  ratio  of  the  sugar  to  glucose  will  give  the  weight  of  sugar 
in  the  25  c.c.  of  solution. 

Example.  —  25  c.c.  of  a  fructose  solution  gave  by  Allihn's  method  265.3 
mgs.  of  copper. 

The  amount  of  glucose  corresponding  to  265.3  mgs.  of  copper,  according 
to  Allihn's  table,  is  137.45  mgs.  137.45  -f-  0.915  (the  reducing  ratio  of  fructose 
to  glucose)  =  150.2  mgs.  of  fructose.  The  amount  of  fructose  corresponding  to 
265.3  mgs.  of  copper  according  to  Honig  and  Jesser  is  150  mgs. 

The  reducing  ratios  of  the  different  sugars,  have  an  important  bearing 
upon  the  analysis  of  sugar  mixtures,  as  described  in  Chapter  XVI. 

Special  copper-reduction  methods  and  tables,  similar  to  those  of 
Allihn,  have  been  established  for  other  reducing  sugars.  It  is  im- 
possible to  describe  all  of  these  in  detail  and  only  the  following  examples 
are  given  for  invert  sugar,  maltose  and  lactose.  The  methods  and 
tables  are  taken  from  Wein's  "Zuckertabellen." 

Meissl's  *  Method  for  Determining  Invert  Sugar.  —  The  Soxhlet 
formula  for  Fehling's  solution  is  used;  25  c.c.  of  the  copper-sulphate 
solution  and  25  c.c.  of  the  alkaline-tart  rate  solution  are  mixed  with  the 
sugar  solution,  which  should  not  contain  over  0.245  gm.  of  invert 
sugar.  Enough  water  is  added  to  make  the  whole  up  to  100  c.c.,  the 
liquid  is  heated  to  boiling  and  kept  at  ebullition  for  exactly  2  minutes. 
The  cuprous  oxide  is  then  filtered  on  asbestos  and  the  reduced  copper 
determined  by  any  of  the  usual  methods.  The  amounts  of  invert 
sugar  corresponding  to  different  weights  of  reduced  copper  are  given  in 
the  Appendix  in  Table  13,  which  was  calculated  by  Wein  from  Meissl's 
reduction  factors. 

Wein'sf  Method  for  Determining  Maltose.  —  The  Soxhlet  formula 
for  Fehling's  solution  is  used;  25  c.c.  of  the  copper-sulphate  solution 
and  25  c.c.  of  the  alkaline-tartrate  solution  are  mixed  and  heated  to 
boiling;  25  c.c.  of  the  sugar  solution,  which  should  not  contain  over 
0.25  gm.  of  maltose,  are  then  added  and  the  liquid  boiled  for  exactly 
4  minutes.  The  cuprous  oxide  is  filtered  on  asbestos  and  the  reduced 
copper  determined  by  any  of  the  usual  methods.  The  amounts  of 
maltose  corresponding  to  different  weights  of  reduced  copper  are  given 
in  the  Appendix  in  Table  14. 

According  to  Brown,  Morris  and  Millar,  J  whose  results  have  been 

*  Z.  Ver.  Deut.  Zuckerind.,  29,  1050. 

f  Wein's  "Tabellen."  %  J.  Chem.  Soc.,  Trans.,  71,  96. 


424  SUGAR  ANALYSIS 

confirmed  by  Ling  and  Baker,*  the  table  of  Wein  gives  results  which 
are  about  5  per  cent  too  low. 

Soxhlet'sj  Method  for  Determining  Lactose.  —  The  Soxhlet  formula 
for  Fehling's  solution  is  used;  25  c.c.  of  the  copper-sulphate  solution 
and  25  c.c.  of  the  alkaline-tartrate  solution  are  mixed  with  20  to 
100  c.c.  (according  to  concentration)  of  the  milk-sugar  solution,  which 
should  not  contain  over  0.300  gms.  of  lactose  hydrate.  If  less  than 
100  c.c.  of  milk-sugar  solution  is  taken  sufficient  water  is  added  to  make 
the  whole  up  to  150  c.c.  The  liquid  is  then  heated  to  boiling  and  kept 
at  ebullition  for  exactly  6  minutes.  The  cuprous  oxide  is  filtered  on 
asbestos  and  the  reduced  copper  determined  by  any  of  the  usual 
methods.  The  amounts  of  lactose  hydrate  corresponding  to  different 
weights  of  reduced  copper  are  given  in  the  Appendix  in  Table  15,  cal- 
culated by  Wein  from  Soxhlet's  reduction  factors. 

UNIFIED    COPPER-REDUCTION    METHODS    FOR    SEVERAL    SUGARS 

The  confusing  multiplicity  of  copper-reducing  tables  is  due  to  the 
fact  that  different  investigators  have  confined  their  work  to  one  single 
sugar  for  one  individual  set  of  conditions.  A  number  of  chemists,  how- 
ever, have  worked  with  the  purpose  of  establishing  one  uniform  method 
for  all  reducing  sugars.  Examples  of  such  unified  methods  are  those  of 
Kjeldahl  and  Woy,  Defren,  Munson  and  Walker,  and  Bertrand. 

Unified  Method  of  KjeldahlJ  and  Woy.§  —  In  Kjeldahl's  method, 
as  modified  by  Woy,  the  Fehling's  solution  is  prepared  for  each  analysis 
with  a  freshly  weighed  portion  of  Rochelle  salts.  The  following  solu- 
tions are  used: 

(A)  69.278  gms.  of  pure  CuS04.5  H20  are  dissolved  to  1000  c.c. 

(B)  130  gms.  of  pure  sodium   hydroxide   (the  amount   must   be 

established  by  titration)  are  dissolved  to  1000  c.c. 
According  to  the  richness  of  the  sugar  solution,  15  c.c.,  30  c.c.  or  50  c.c. 
of  mixed  reagent  are  made  up  in  an  Erlenmeyer  flask  holding  about 
150  c.c. 
For  15  c.c.  of  reagent  take  7.5  c.c.  of  A,  7.5  c.c.  of  B  and  2.6  gms. 

Rochelle  salts. 
For  30  c.c.  of  reagent  take  15.0  c.c.  of  A,  15.0  c.c.  of  B  and  5.2  gms. 

Rochelle  salts. 
For  50  c.c.  of  reagent  take  25.0  c.c.  of  A,  25.0  c.c.  of  B  and  8.65  gms. 

Rochelle  salts. 
The  sugar  solution  is  then  added,  the  total  volume  of  liquid  in  the 

*  J.  Chem.  Soc.,  Trans.,  71,  509.         I  Neue  Z.  Riibenzuckerind.,  37,  29. 
t  J.  prakt.  Chem.,  21,  266.  §  Chem.  Centralblatt.  97  [2],  986. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     425 

flask  being  always  brought  to  100  c.c.  The  flask  is  then  plunged  in  a 
boiling-water  bath  and  heated  for  exactly  20  minutes,  while  leading 
through  the  liquid  a  stream  of  hydrogen,  or  of  illuminating  gas  which 
has  been  freed  of  oxygen  by  passing  through  a  gas  washer  containing 
pyrogallic  acid  and  sodium  hydroxide  solution.  The  reoxidation  of  the 
cuprous  oxide  by  the  air  is  in  this  way  prevented.  At  the  end  of  the  20 
minutes  the  cuprous  oxide  is  filtered  on  asbestos,  washed,  ignited  and 
weighed  as  cupric  oxide.  The  amounts  of  glucose,  fructose,  invert  sugar, 
lactose  hydrate  or  maltose  corresponding  to  different  weights  of  cupric 
oxide  or  copper  are  given  in  the  Appendix  in  Table  16,  which  was  cal- 
culated by  Woy  for  the  15-c.c.,  30-c.c.  and  50-c.c.  volumes  of  reagent. 

The  Kjeldahl-Woy  method  is  one  of  great  exactness,  being  carried 
out  under  rigidly  defined  conditions.  The  rather  complicated  details 
in  preparing  the  copper  reagent  and  in  conducting  the  reduction  have 
prevented  the  process  from  coming  into  extensive  use. 

Unified  Method  of  Brown,  Morris  and  Millar.*  —  In  this  method, 
which  is  adapted  from  a  previous  process  by  O'Sullivan,  the  Fehling's 
solution  is  prepared  by  dissolving  34.6  gms.  crystallized  copper  sulphate, 
173  gms.  Rochelle  salts  and  65  gms.  anhydrous  sodium  hydroxide  to 
1000  c.c.;  50  c.c.  of  the  reagent  are  placed  in  a  beaker  of  about  250  c.c. 
capacity  and  of  7.5  cm.  diameter.  The  beaker  is  set  in  a  boiling-water 
bath,  and  when  the  solution  has  acquired  the  same  temperature,  the 
measured  volume  of  sugar  solution  is  added  and  the  whole  made  up 
to  100  c.c.  with  boiling  distilled  water.  The  beaker  is  covered  with  a 
clock  glass,  returned  to  the  bath  and  heated  exactly  12  minutes.  The 
cuprous  oxide  is  filtered  in  a  tube  and  weighed  as  metallic  copper  or 
cupric  oxide. 

The  table  of  Brown,  Morris  and  Millar  (Appendix,  Table  17)  gives 
the  weight  of  copper  and  cupric  oxide  which  correspond  to  the  same 
weight  of  glucose,  fructose  and  invert  sugar,  the  order  of  arrangement 
being  the  reverse  of  that  in  most  tables. 

Unified  Method  of  Defren.f  —  In  Defren's  method,  which  is 
adapted  from  O'Sullivan,  Soxhlet's  formula  for  Fehling's  solution  is 
used;  15  c.c.  of  the  copper-sulphate  solution  and  15  c.c.  of  the  alkaline- 
tartrate  solution  are  diluted  with  50  c.c.  of  water  in  a  300-c.c.  Erlen- 
meyer  flask.  The  latter  is  then  immersed  for  5  minutes  in  a  boiling- 
water  bath,  when  25  c.c.  of  the  sugar  solution  are  quickly  run  in  from  a 
burette.  The  flask  is  replaced  in  the  bath  and  heated  for  exactly  15 
minutes.  The  cuprous  oxide  is  then  filtered  on  asbestos,  washed, 

*  J.  Chem.  Soc.,  Trans.,  71,  281. 
t  J.  Am.  Chem.  Soc.,  18,  751. 


426  SUGAR  ANALYSIS 

ignited  and  weighed  as  cupric  oxide.  The  amounts  of  glucose,  maltose 
or  lactose  corresponding  to  different  weights  of  cupric  oxide  are  given 
in  the  Appendix  in  Table  18. 

Unified  Method  of  Munson  and  Walker.*  —  Transfer  25  c.c.  each 
of  the  copper  and  alkaline-tartrate  solutions  (Soxhlet's  formula)  to  a 
400-c.c.  Jena  or  Non-sol  beaker  and  add  50  c.c.  of  reducing  sugar- solu- 
tion, or,  if  a  smaller  volume  of  sugar  solution  be  used  add  water  to 
make  the  final  volume  100  c.c.  Heat  the  beaker  upon  an  asbestos  gauze 
over  a  Bunsen  burner;  so  regulate  the  flame  that  boiling  begins  in  4  min- 
utes, and  continue  the  boiling  for  exactly  2  minutes.  Keep  the  beaker 
covered  with  a  watch  glass  throughout  the  entire  time  of  heating. 
Without  diluting  filter  the  cuprous  oxide  at  once  on  an  asbestos  felt  in 
a  porcelain  Gooch  crucible,  using  suction.  Wash  the  cuprous  oxide 
thoroughly  with  water  at  a  temperature  of  about  60°  C.,  then  with 
10  c.c.  of  alcohol  and  finally  with  10  c.c.  of  ether.  Dry  for  30  minutes 
in  a  water  oven  at  100°  C.,  cool  in  a  desiccator  and  weigh  as  cuprous 
oxide.  The  amounts  of  glucose,  invert  sugar,  lactose  or  maltose  cor- 
responding to  different  weights  of  cuprous  oxide  or  copper  are  given  in 
the  Appendix  in  Table  19. 

Unified  Method  of  Bertrand.f  —  The  following  formula  is  used  in 
preparing  the  copper  reagents: 

(A)  40  gms.  of  pure  CuS04.5  H02  are  dissolved  to  1000  c.c., 

(B)  200  gms.  of  Rochelle  salts  and  150  gms.  of  sodium  hydroxide  in 

sticks  are  dissolved  to  1000  c.c.: 

20  c.c.  of  the  sugar  solution,  which  should  not  contain  over  0.100  gm. 
of  reducing  sugars,  are  transferred  to  a  150-c.c.  Erlenmeyer  flask,  and 
20  c.c.  each  of  solutions  A  and  B  added.  The  liquid  is  then  heated  to 
boiling  and  kept  at  gentle  ebullition  for  exactly  3  minutes.  The  solu- 
tion is  then  filtered  through  asbestos,  the  precipitate  of  cuprous  oxide 
washed  with  distilled  water  and  the  reduced  copper  determined  by 
the  volumetric  permanganate  method. 

The  table  of  Bertrand  (Appendix,  Table  20)  gives  the  different 
weights  of  reduced  copper  which  correspond  to  the  same  weight  of 
invert  sugar,  glucose,  galactose,  maltose  and  lactose,  the  order  of 
arrangement  being  the  same  as  in  the  table  of  Brown,  Morris  and 
Millar. 

METHODS  FOR  DETERMINING  REDUCING  SUGARS  IN  PRESENCE  OF  SUCROSE 

Reference  has  been  made  to  the  slight  hydrolytic  action  of  hot 
Fehling's  solution  upon  the  higher  saccharides.  While  this  action  in 

*  J.  Am.  Chem.  Soc.,  28,  663;  29,  541;  34,  202.         f  Bull,  soc.  chim.,  35,  1285. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     427 


case  of  sucrose  is  slight  it  is,  nevertheless,  sufficiently  pronounced  to 
cause  a  considerable  error  in  the  determination  of  reducing  sugars 
when  much  sucrose  is  present. 

Conditions  Affecting  the  Reducing  Action  of  Sucrose  upon  Fehl- 
ing's  Solution.  —  The  reducing  action  of  sucrose  upon  Fehling's 
solution  is  proportional  first,  to  the  concentration  of  the  sucrose  and, 
second,  to  the  amount  of  copper  left  unreduced.  If  enough  reducing 
sugars  are  present  to  precipitate  nearly  all  the  copper  from  the  Fehl- 
ing's  solution  the  inversion  of  the  sucrose  will  be  very  slight.  This  is 
shown  in  Table  LXXV,  which  gives  a  series  of  experiments  by  Browne.* 
Constant  quantities  of  sucrose,  and  varying  amounts  of  glucose,  were 
taken,  and  a  determination  of  the  latter  made  by  Allihn's  method. 

TABLE  LXXV 

Showing  Influence  of  Sucrose  Upon  the  Reducing  Action  of  Glucose 


A, 

Sucrose  taken 
in  25  c.c. 

B. 

Glucose  taken 
in  25  c.c. 

c. 

Glucose  found 
in  25  c.c. 

D. 

Error 

(C-B). 

E. 
Calculated  correc- 
tion, 
/     mgs.  sucrose     \ 

F. 

Corrected  glu- 
cose, 

(C-E). 

\rngs.  glucose  +  40/ 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

250 

50 

52.3 

2.3 

2.7 

49.6 

250 

100 

102.8 

2.8 

1.8 

101.0 

250 

150 

151.8 

1.8 

1.3 

150.5 

250 

200 

199.0 

-1.0 

1.0 

198.0 

500 

100 

104.5 

4.5 

3.5 

101.0 

500 

150 

153.2 

3.2 

2.6 

150.6 

500 

200 

203.2 

3.2 

2.1 

201.1 

500 

250 

251.3 

1.3 

1.7 

249.6 

1000 

50 

60.3 

10.3 

10.0 

50.3 

1000 

100 

108.2 

8.2 

6.8 

101.4 

1000 

200 

205.3 

5.3 

4.1 

201.2 

1000 

250 

252.0 

2.0 

3.4 

248.6 

2000 

50 

66.6 

16.6 

18.8 

47.8 

2000 

100 

113.7 

13.7 

13.0 

100.7 

2000 

200 

207.5 

7.5 

8.1 

199.4 

2000 

250 

255.5 

5.5 

6.8 

248.7 

The  error  in  the  glucose  determination,  when  sucrose  is  present,  is 
seen  to  be  considerable;  it  is  even  more  pronounced  in  such  reduction 
methods  as  those  of  Kjeldahl  or  Pfliiger,  which  employ  a  long  period  of 
heating. 

It  is  seen  from  Table  LXXV  that  the  error  in  the  glucose  determina- 
tion is  directly  proportional  to  the  amount  of  sucrose,  and  inversely 
proportional  to  the  amount  of  glucose.  Browne  has  proposed  the  use 

r  milligrams  sucrose  , 

of  an  empirical  formula,     .„.  .  Ar.>  as  a  means  of  correct- 

milligrams  glucose  r\-  40 

*  J.  Am.  Chem.  Soc.,  28,  451. 


428  SUGAR  ANALYSIS 

ing  for  the  reducing  action  of  sucrose,  when  using  Allihn's  method. 
Table  LXXV  gives  a  comparison  of  the  actual  errors  and  of  the  results 
corrected  by  means  of  such  a  formula. 

In  the  volumetric  methods  of  Soxhlet,  Violette,  etc.,  where  the  in- 
vert sugar  solution  is  added  to  the  point  of  complete  reduction,  no 
excess  of  copper  is  left  in  solution,  and  the  error  due  to  the  presence  of 
sucrose  is  practically  negligible. 

A  number  of  special  copper-reduction  methods  have  been  designed 
for  determining  invert  sugar  in  sugar-house  products.  The  methods 
are  classified  according  to  the  excess  of  sucrose  over  invert  sugar  in  the 
material  to  be  analyzed. 

Herzf eld's*  Method  for  Determining  Invert  Sugar  in  Raw  Sugars 
Containing  Less  than  1.5  per  cent  Invert  Sugar.  —  This  method  is 
designed  for  the  analysis  of  the  higher  grades  of  raw  sugar.  The  sugar 
solution,  which  should  contain  20  gms.  of  material  in  100  c.c.  and  be 
free  from  suspended  or  soluble  impurities,  is  conveniently  prepared  as 
follows : 

Dissolve  44  gms.  of  sugar  in  about  100  c.c.  of  water  in  a  200-c.c. 
graduated  flask.  A  little  normal  lead-acetate  solution,  just  sufficient 
for  clarification,  is  then  added  and  the  volume  completed  to  200  c.c. 
The  solution  is  shaken,  filtered  and  100  c.c.  of  the  filtrate  (22  gms. 
sugar)  measured  into  a  100-110  c.c.  flask.  Sufficient  carbonate,  or 
sulphate  of  sodium  is  then  added  to  precipitate  the  excess  of  lead  and 
the  volume  made  up  to  110  c.c.  The  solution  is  shaken,  filtered  and 
50  c.c.  of  the  filtrate  (10  gms.  of  sugar)  used  for  the  determination. 

Heat  25  c.c.  each  of  the  copper-sulphate  and  alkaline-tartrate  solu- 
tions (Soxhlet 's  formula)  to  boiling;  the  50  c.c.  of  clarified  sugar  solution 
are  then  added  and  the  whole  boiled  for  exactly  2  minutes.  The  cuprous 
oxide  is  filtered  on  asbestos,  washed  and  the  reduced  copper  determined 
by  any  of  the  usual  methods.  The  amounts  of  invert  sugar  corre- 
sponding to  different  weights  of  copper  are  given  in  the  Appendix,  in 
Table  21. 

In  case  the  percentage  of  invert  sugar  in  the  raw  sugar  exceeds 
1.5  per  cent,  Herzf eld's  method  is  no  longer  applicable. 

Meissl  and  Wein'st  Method  for  Determining  Invert  Sugar  in 
Mixtures  of  90  to  99  per  cent  Sucrose  with  10  to  i  per  cent  Invert 
Sugar.  —  This  method  is  designed  for  the  analysis  of  low-grade  raw 
sugars,  or  of  other  sugar-house  products  which  do  not  contain  a  large 

*  Z.  Ver.  Deut.  Zuckerind.  (1885),  985. 
t  Wein's  "Tabellen." 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     429 


excess  of  invert  sugar.  The  sugar  solution  is  prepared  as  in  the  previous 
method,  the  final  filtrate  being  diluted  if  necessary  so  as  not  to  contain 
more  than  0.2  to  0.245  gms.  of  invert  sugar  in  50  c.c. 

Mix  25  c.c.  each  of  the  copper-sulphate  and  alkaline- tartrate  solu- 
tions (Soxhlet's  formula)  with  the  50  c.c.  of  clarified  sugar  solution;  the 
liquid  is  then  heated  to  boiling  and  kept  at  gentle  ebullition  for  exactly 
2  minutes.  The  cuprous  oxide  is  then  filtered  on  asbestos,  washed  and 
the  reduced  copper  determined  by  any  of  the  usual  methods. 

For  determining  the  weights  of  invert  sugar  corresponding  to  differ- 
ent weights  of  reduced  copper,  for  percentages  of  sucrose  between  90 
and  99,  the  following  condensed  table  has  been  calculated  by  Wein. 
Intermediary  values  can  be  easily  calculated  by  interpolating. 

TABLE  LXXVI 

For  Determining  Invert  Sugar  in  Presence  of  Sucrose.     (Meissl  and  Wein.) 


In  mixtures  of  sucrose 
(S)  and  invert  sugar  (/) 
in  parts  per  hundred. 

Milligrams  of  invert  sugar. 

245 

225 

200 

175 

150 

125 

100 

75 

50 

Correspond  to  Milligrams  of  Copper. 

99  S  +    17 

417.3 
393.7 
385.7 
381.7 
379.3 
376.6 
374.6 
373.1 
372.0 
371.1 

370.8 
357.7 
350.6 
339.1 
337.0 
334.7 
332.3 
330.4 
328.8 
327.8 

323.6 
304.7 
298.4 
295.3 
293.4 
290.1 
287.8 
286.3 
285.1 
284.0 

277.5 
259.7 
253.8 
250.8 
249.0 
245.4 
242.9 
241.0 
239.4 
238.2 

230.0 
213.7 
207.9 
205.0 
203.3 
199.8 
197.3 
195.4 
193.9 
192.7 

182.0 
166.0 
158.3 
155.4 
153.6 
151.0 
149.2 
147.9 
146.8 
146.0 

131.5 
113.8 
107.9 
105.7 
103.2 
101.5 
100.2 
99.3 
98.6 
98.0 

98  S+  27.  .. 

97  S+  37.  .     . 

96  S  +  47  
95  S  +  57  
94  S  +  67  
93  S+  77  

439  '.7 

438.5 
437.6 
437.0 
436.5 
436.1 

420.1 
416.5 
413.9 
411.9 
410.3 
409.2 

52  iSf  +  87 

91  S+  9  7. 

90S+107  

The  employment  of  the  above  table  is  best  understood  from  an  ex- 
ample : 

A  sugar,  which  indicated  96.2  per  cent  sucrose  by  Clerget's  method,  was 
made  up  so  that  50  c.c.  of  the  clarified  and  deleaded  solution  contained 
10  gms.  of  sample.  The  amount  of  reduced  copper  obtained  by  MeissPs  method 
was  324  mgs.  Required  the  percentage  of  invert  sugar. 

The  invert  sugar  corresponding  to  324  mgs.  copper  according  to  Meissl's 
table  for  invert  sugar  alone  is  178  mgs.  or  1.78  per  cent  (uncorrected) .  The 
percentage  composition,  in  a  mixture  of  96.2  parts  sucrose  with  1.78  parts  in- 
vert sugar  is  approximately  98  per  cent  sucrose  and  2  per  cent  invert  sugar. 
Opposite  the  mixture  98  S  +  2  7  of  the  table  it  is  seen  that 

357.7  mgs.  of  copper  =  175  mgs.  invert  sugar, 
and  304.7  mgs.  of  copper  =  150  mgs.  invert  sugar, 


430  SUGAR  ANALYSIS 

then  for  the  intermediary  324.0  mgs.  of  copper 

324.0  -  304.7  Q  =  15Q  Q  mgg 


357.7  —  304.7 

of  invert  sugar  or  1.59  per  cent. 

Meissl  and  Wein's  method  is  not  applicable  to  products  which  con- 
tain more  than  10  parts  invert  sugar  in  100  parts  of  mixed  sugars.  For 
this  reason  the  method  has  largely  given  place  to  the  more  general 
process  of  Meissl  and  Hiller. 

Meissl  and  Killer's  *  Method  for  Determining  Invert  Sugar  in 
Mixtures  Containing  less  than  99  per  cent  Sucrose  and  more  than  i 
per  cent  Invert  Sugar.  —  This  method  is  designed  for  the  analysis  of 
all  sugar-house  products  except  the  highest  grades  of  raw  sugars.  The 
method  is  based  upon  the  principle  of  taking  such  a  quantity  of  material 
for  analysis  that  the  invert  sugar  will  reduce  nearly  all  the  copper, 
thus  reducing  the  error  due  to  presence  of  sucrose  to  a  minimum. 

The  sugar  solution  is  prepared  as  in  the  two  previous  methods  so 
that  100  c.c.,  after  clarification  and  deleading,  contain  20  gms.  of 
sample.  Prepare  a  series  of  solutions  in  large  test  tubes  by  adding 
1,  2,  3,  4  and  5  c.c.  of  this  solution  to  each  tube  successively.  Add 
5  c.c.  of  the  mixed  copper  reagent  (Soxhlet's  formula)  to  each,  heat 
to  boiling  2  minutes,  and  filter.  Note  the  volume  of  sugar  solution 
which  gives  the  filtrate  lightest  in  tint,  but  still  distinctly  blue.  Place 
20  times  this  volume  of  the  sugar  solution  in  a  100-c.c.  flask,  dilute  to 
the  mark  and  mix  well.  Use  50  c.c.  of  the  solution  for  the  determina- 
tion, which  is  conducted  as  in  the  method  of  Meissl  and  Wein.  The 
invert  sugar  is  then  calculated  -by  means  of  the  following  formulae. 

Let  Cu  =  the  weight  of  copper  obtained; 
P  =  the  polarization  of  the  sample; 
W  =  the  weight  of  sample  in  the  50  c.c.  of  solution  used  for 

determination; 

F  =  the  factor  obtained  from  the  table  for  conversion  of  cop- 
per to  invert  sugar; 

-rt-  =  approximate  weight  of  invert  sugar  =  A  ; 

100 
AX-yy  =  approximate  per  cent  of  invert  sugar  =  y, 

100  P 

p  ,      =  o,  approximate  per  cent  of  sucrose  in  mixture  of  sugars; 

100  —  S  =  /,  approximate  per  cent  of  invert  sugar; 
C\iF 
~w~  =  per  cent  of  invert  sugar. 

*  Z.  Ver.  Deut.  Zuckerind.  (1889),  735. 


REDUCTION  METHODS  .FOR  DETERMINING  SUGARS     431 


The  factor  F  for  calculating  copper  to  invert  sugar  is  then  found 
from  the  following  table: 

TABLE  LXXVII 

Meissl  and  Hitter7 s  Factors  for  Calculating  Copper  to  Invert  Sugar  for  Different  Ratio* 

of  Sucrose  to  Invert  Sugar 


Ratio  of 
sucrose  to  in- 
vert sugar 
=5:7. 

Approximate  weight  of  invert  sugar  =  A. 

200 
Mgs. 

175 
Mgs. 

150 
Mgs. 

125 
Mgs. 

100 
Mgs. 

75 

Mgs. 

50 
Mgs. 

0:100 

56.4 

55.4 

54.5 

53.8 

53.2 

53.0 

53.0 

10:90 

56.3 

55.3 

54.4 

53.8 

53.2 

52.9 

52.9 

20:80 

56.2 

55.2 

54.3 

53.7 

53.2 

52.7 

52.7 

30:70 

56.1 

55.1 

54.2 

53.7 

53.2 

52.6 

52.6 

40:  60 

55.9 

55.0 

54.1 

53.6 

53.1 

52.5 

52.4 

50:50 

55.7 

54.9 

54.0 

53.5 

53.1 

52.3 

52.2 

60  :  40 

55.6 

54.7 

53.8 

53.2 

52.8 

52.1 

51.9 

70:30 

55.5 

54.5 

53.5 

52.9 

52.5 

51.9 

51.6 

80:20 

55.4 

54.3 

53.3 

52.7 

52.2 

51.7 

51.3 

90:  10 

54.6 

53.6 

53.1 

52.6 

52.1 

51.6 

51.2 

91  :9 

54.1 

53.6 

52.6 

52.1 

51.6 

51.2 

50.7 

92:8 

53.6 

53.1 

52.1 

51.6 

51.2 

50.7 

50.3 

93:7 

53.6 

53.1 

52.1 

51.2 

50.7 

50.3 

49.8 

94:6 

53.1 

52.6 

51.6 

50.7 

50.3 

49.8 

48.9 

95:5 

52.6 

52.1 

51.2 

50.3 

49.4 

48.9 

48.5 

96:4 

52.1 

51.2 

50.7 

49.8 

48.9 

47.7 

46.9 

97:3 

50.7 

50.3 

49.8 

48.9 

47.7 

46.2 

45.1 

98:2 

49.9 

48.9 

48.5 

47.3 

45.8 

43.3 

40.0 

99:  1 

47.7 

47.3 

46.5 

45.1 

43.3 

41.2 

38.1 

The  use  of  Meissl  and  Hiller's  formulae  and  table  for  calculating 
invert  sugar  is  best  understood  from  an  example. 

The  polarization  of  a  sugar  was  86.4;  50  c.c.  of  a  solution  containing  3.256 
gms.  of  sample,  reduced  by  Meissl  and  Hiller's  method,  0.290  gms.  of  copper. 
Required  the  per  cent  of  invert  sugar. 
Cu  =  0.290 
2 


=  0.145  =  A. 


_0145 
-    0.145 


y- 


100  P 


8640 


--  95.1  =  S. 
I  =  4.9. 


P  +  y      86.4  +  4.45 
100  -  S  =  100  -  95.1  = 

S  :  I  =  95.1  :  4.9. 

By  consulting  the  table  it  is  seen  that  the  vertical  column  headed  150  is 
nearest  to  A,  145,  and  the  horizontal  column  having  the  ratio  95  :  5  is  nearest 
to  the  ratio  of  S  to  /,  95.1  :  4.9.  At  the  intersection  of  these  columns  is  found 

C\iF      0.290X51.2 


the  factor  51.2  which  enters  into  the  final  calculation 
per  cent  of  invert  sugar. 


W 


3.256 


=  4.56 


432  SUGAR  ANALYSIS 

Munson  and  Walker's  *  Method  for  Determining  Invert  Sugar  in 
Presence  of  Sucrose.  —  Munson  and  Walker  have  included  in  their 
unified  method  for  reducing  sugars  determinations  of  invert  sugar  in 
presence  of  variable  amounts  of  sucrose.  Their  table  (Appendix,  Table 
19)  gives  the  weight  of  invert  sugar  for  different  weights  of  cuprous  oxide 
or  copper,  when  the  total  weight  of  invert  sugar  and  sucrose  in  the 
solution  taken  is  0.4  gm.  and  2.0  gms.  The  0.4  gm.  amount  is  used 
preferably  for  sugar  products  containing  between  1  and  9  parts  of 
sucrose  to  1  part  of  invert  sugar  and  the  2.0  gms.  amount  for  sugar 
products  containing  over  9  parts  of  sucrose  to  1  part  of  invert  sugar. 
This  range  is  sufficient  to  include  all  the  products  of  the  sugar  factory. 

The  method  requires  a  preliminary  investigation  of  the  material  in 
order  to  determine  the  approximate  percentages  of  sucrose  and  invert 
sugar  for  use  in  making  up  the  solution. 

MISCELLANEOUS    COPPER-REDUCTION   METHODS 

The  large  amount  of  free  alkali  in  Fehling's  copper  solution  has 
proved  its  most  objectionable  feature,  owing  to  the  influence  which  it 
has  in  rendering  sucrose  and  other  substances  slightly  copper  reducing. 
Attempts  have  accordingly  been  made  to  devise  a  copper  reagent  for 
sugar  analysis  which  would  contain  no  caustic  alkali.  While  none  of 
the  solutions  thus  designed  has  shown  the  same  all  around  suitability 
as  that  of  Fehling,  a  few  of  them  have  found  a  certain  usefulness  in 
special  cases. 

Barfoed's  f  Copper-acetate  Method.  —  Barfoed's  copper-acetate 
solution  (p.  336),  which  is  not  reduced  by  the  disaccharides,  maltose  and 
lactose,  has  appealed  to  chemists  as  a  convenient  means  of  determining 
glucose,  fructose  and  other  monosaccharides  in  presence  of  the  higher  re- 
ducing sugars.  But  notwithstanding  its  value  for  qualitative  purposes, 
attempts  to  use  Barfoed's  reagent  for  the  quantitative  determination  of 
glucose  and  other  monosaccharides  have  always  given  unsatisfactory 
results. 

Soldaini's  J  Copper-bicarbonate  Method.  —  Soldaini's  copper-bi- 
carbonate solution  (p.  337)  has  also  appealed  to  chemists  as  a  means 
of  avoiding  certain  errors  resulting  from  tiie  use  of  Fehling's  solution. 
Soldaini's  method,  however,  has  usually  given  unreliable  results,  when 
used  for  quantitative  purposes,  the  principal  objections  being  the  de- 
position of  copper  hydroxide  and  the  precipitation  of  lime  and  other 
mineral  impurities  with  the  reduced  copper. 

*  J.  Am.  Chem.  Soc.,  28,  663. 

t  Z.  analyt.  Chem.,  12,  27.  $  Ber.,  9,  1126. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     433 


Ost's  *  Copper-bicarbonate  Method.  —  Ost  has  modified  Soldaini's 
reagent  in  order  to  eliminate  its  objectionable  features.  In  his  latest 
improvement  of  the  method  the  copper  reagent  is  prepared  as  follows: 
250  gms.  of  chemically-pure  potassium  carbonate  and  100  gms.  of  chemi- 
cally-pure potassium  bicarbonate  are  dissolved  in  water,  and  a  solution 
containing  17.5  gms.  of  chemically-pure  crystallized  copper  sulphate 
slowly  added.  The  volume  is  then  made  up  to  1000  c.c.  and  the  solu- 
tion filtered  through  asbestos,  the  first  runnings  of  the  filtrate  being 
rejected. 

In  making  the  determination  100  c.c.  of  the  copper  reagent  are 
treated  with  50  c.c.  of  the  sugar  solution  and  the  liquid  boiled  for  10 
minutes.  The  precipitate  is  then  filtered  upon  asbestos  and  the  re- 
duced copper  determined  by  any  of  the  usual  methods. 

Ost  has  unified  his  method  for  a  number  of  reducing  sugars;  a  few 
of  the  values  for  different  weights  of  reduced  copper  are  given  in  Table 
LXXVIII. 

TABLE  LXXVIII 
Showing  Reducing  Power  of  Different  Sugars  upon  Ost's  Copper  Solution 


Reduced  copper. 

Glucose. 

Fructose. 

Invert  sugar. 

Maltose. 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

100 

30.7 

29.0 

30.0 

57.9 

150 

45.4 

42.7 

44.4 

85.4 

200 

60.7 

57.0 

59  0 

112.9 

250 

76.5 

71.6 

74  3 

141.1 

300 

93.0 

87.5 

90.9 

170.3 

350 

112.8 

106.4 

109.8 

201.5 

400 

134.9. 

128.2 

131.0 

235.6 

The  method  has  not  been  found  to  give  good  results  with  lactose. 
Glucose,  by  Ost's  process,  reduces  about  60  per  cent  more  copper  than 
by  Allihn's  method. 

For  determining  small  amounts  of  reducing  sugars  Ost  recommends 
the  use  of  his  ^-normal  copper  solution  which  contains  250  gms.  chemi- 
cally-pure potassium  carbonate,  100  gms.  chemically-pure  potassium 
bicarbonate  and  3.6  gms.  chemically-pure  crystallized  copper  sulphate 
to  the  liter.  In  using  this  solution,  which  is  very  sensitive  towards 
small  amounts  of  reducing  sugars,  the  time  of  boiling  is  reduced  to  5 
minutes. 

Ost's  method  has  given  good  results  in  the  analysis  of  pure  sugar 
solutions,  but  has  proved  less  reliable  in  the  examination  of  low-grade 
products  owing  to  the  precipitation  of  lime  and  other  mineral  impurities. 

*  Chem.  Ztg.,  19,  1784,  1829. 


434 


SUGAR  ANALYSIS 


This  difficulty,  according  to  Ost,  may  be  obviated  by  precipitating  the 
lime  with  ammonium  oxalate  during  the  clarification.  The  method 
upon  the  whole  has  not  offered  sufficient  advantages  over  Fehling's 
solution  to  come  into  general  use. 

Bang's  Copper-bicarbonate  Method.  —  Bang  *  has  recently  em- 
ployed the  copper-bicarbonate  method  for  the  volumetric  determina- 
tion of  very  small  amounts  of  glucose.  In  this  method  the  excess  of 
copper,  which  remains  in  solution  after  reduction,  is  titrated  with  a 
standard  hydroxylamine-sulphate  solution  in  presence  of  potassium 
thiocyanate. 

TABLE  LXXIX 


Hydroxyl- 
amine. 

Glucose. 

Hydroxyl- 
amine. 

Glucose. 

Hydroxyl- 
amine. 

Glucose. 

Hydroxyl- 
amine. 

Glucose. 

c.c. 

Mgs. 

c.c. 

Mgs. 

c.c. 

Mgs. 

c.c. 

Mgs. 

43.85 

5 

29.60 

19 

17.75 

33 

7.65 

47 

42.75 

6 

28.65 

20 

16.95 

34 

7.05 

48 

41.65 

7 

27.75 

21 

16.15 

35 

6.50 

49 

40.60 

8 

26.85 

22 

15.35 

36 

5.90 

50 

39.50 

9 

26.00 

23 

14.60 

37 

5.35 

51 

38.40 

10 

25.10 

24 

13.80 

38 

4.75 

52 

37.40 

11 

24.20 

25 

13.05 

39 

4.20 

53 

36.40 

12 

23.40 

26 

12.30 

40 

3.60 

54 

35.40 

13 

22.60 

27 

11.50 

41 

3.05 

55 

34.40 

14 

21.75 

28 

10.90 

42 

2.60 

56 

33.40 

15 

21.00 

29 

10.20 

43 

2.15 

57 

32.45 

16 

20.15 

30 

9.50 

44 

1.65 

58 

31.50 

17 

19.35 

31 

8.80 

45 

1.20 

59 

30.55 

18 

18.55 

32 

8.20 

46 

0.75 

60 

The  unreduced  copper  and  hydroxylamine  react  as  follows: 
4  CuO  +  2  NH2OH  =  2  Cu20  +  N20  +  3  H2O. 

The  Cu20,  which  is  thus  formed,  is  immediately  precipitated  as  white 
cuprous  thiocyanate  Cu2(SCN)2.  The  hydroxylamine  solution  is  added 
until  the  blue  color,  due  to  the  excess  of  unreduced  copper,  just  dis- 
appears. The  following  solutions  are  employed: 

(A)  250  gms.  of  pure  potassium  carbonate,  50  gms.  of  pure  potas- 
sium bicarbonate  and  200  gms.  of  potassium  thiocyanate  are  dissolved 
by  warming  in'about  600  c.c.  of  water.     The  liquid  is  cooled  and  a  cold 
solution  of  12.5  gms.  crystallized  copper  sulphate  in  about  75  c.c.  of 
water  slowly  added.     The  solution  is  made  up  to  1000  c.c.  and,  after 
standing  24  hours,  filtered. 

(B)  6.55  gms.  of  pure  hydroxylamine  sulphate  and  200  gms.  of 
potassium  thiocyanate  are  dissolved  to  2000  c.c. 

One  cubic  centimeter  of  B  should  correspond  to  exactly  1  c.c.  of  A. 
*  Biochem.  Zeitschr.,  2,  271. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     435 

In  making  the  determination  10  c.c.  of  the  sugar  solution,  which 
should  not  contain  over  60  mgs.  of  glucose,  are  measured  into  a  200-c.c. 
flask  and  50  c.c.  of  solution  A  added.  The  liquid  is  heated  to  boiling 
and  kept  at  ebullition  for  exactly  3  minutes.  The  solution  in  then 
cooled  and  solution  B  added  from  a  burette  until  the  blue  color  just  dis- 
appears. Table  LXXIX  gives  the  milligrams  of  glucose  correspond- 
ing to  the  cubic  centimeters  of  hydroxylamine  solution  used. 

Kendall's  Alkaline-salicylate  Method.  —  Kendall*  has  recently 
devised  a  method  for  determining  reducing  sugars,  in  which  salicylic 
acid  and  potassium  bicarbonate  are  used  in  place  of  the  ordinary 
alkaline-tartrate  mixture  of  Fehling's  -solution.  The  advantages 
claimed  are  that  the  alkaline-salicylate  mixture  has  no  copper-re- 
ducing power  of  its  own  and  that  much  larger  amounts  of  copper  are 
reduced  by  a  given  weight  of  sugar  when  the  carbonates  of  the  alka- 
lies are  used  in  place  of  the  hydroxides. 

The  sugar  solution  is  measured  into  a  200-c.c.  Erlenmeyer  flask, 
and  the  volume  made  up  to  100  c.c.  with  distilled  water.  There  are 
then  added  in  succession  5  gins,  salicylic  acid,  15  c.c.  copper-sulphate 
solution,  containing  133.33  gms.  CuS04.5  H2O  per  liter,  and  25  c.c. 
potassium-carbonate  solution,  containing  600  gms.  K2C03  per  liter. 
The  flask  is  shaken  until  the  salicylic  acid  has  completely  dissolved, 
and  then  placed  in  a  boiling- water  bath  for  exactly  20  minutes;  the 
reduced  cuprous  oxide  is  then  filtered  upon  asbestos,  washed  with  hot 
water,  and  the  copper  determined  by  Kendall's  modified  iodide 
method  (p.  412).  From  the  milligrams  of  copper  thus  found  the 
corresponding  weights  of  glucose,  invert  sugar,  lactose  hydrate  and 
maltose  hydrate  are  determined  from  a  specially  calculated  table. 

VOLUMETRIC-REDUCTION  METHODS  BY  MEANS  OF  MERCURY  SOLUTIONS 
Of  other  metallic  salt  solutions  besides  copper  only  those  of  mercury 
have  been  used  to  any  great  extent  for  determining  reducing  sugars. 

Knapp'sf  Alkaline  Mercuric-cyanide  Method.  —  The  solution  used 
in  Knapp's  method  is  prepared  by  dissolving  10  gms.  of  pure  mercuric 
cyanide  and  100  c.c.  of  sodium-hydroxide  solution  of  1.145  sp.  gr.  to 
1000  c.c.  The  solution  contains  7.9363  gms.  of  metallic  mercury  per  liter. 
In  making  the  determination  a  measured  volume  of  the  reagent, 
previously  standardized  against  a  known  weight  of  the  pure  sugar,  is 
heated  to  boiling  and  the  sugar  solution  added  from  a  burette  until 
a  drop  of  the  filtered  solution  shows  upon  acidifying  with  acetic  acid 
no  coloration  with  ammonium-sulphide  solution.  The  calculation  of 


J,  Am,  Chem.  Soc.,  34,  317.  t  Z.  analyt.  Chem.,  9,  395. 


436  SUGAR  ANALYSIS 

sugar  is  made  in  the  same  manner  as  described  under  Soxhlet's  volu- 
metric method  with  Fehling's  solution. 

The  end  reaction  in  Knapp's  method  has  been  found  uncertain 
and  the  process  at  present  is  but  little  used. 

Sachsse's  *  Alkaline  Mercuric-iodide  Method.  —  The  solution  of 
Sachsse  is  prepared  as  follows:  18  gms.  of  pure  dry  mercuric  iodide 
(prepared  by  precipitating  mercuric-chloride  solution  with  potassium 
iodide,  and  washing  and  drying  at  100°  C.)  are  dissolved  in  a  solution 
containing  25  gms.  of  pure  potassium  iodide;  a  solution  containing  80 
gms.  of  potassium  hydroxide  is  then  added  and  the  volume  completed 
to  1000  c.c.  The  solution  contains  7.9323  gms.  of  metallic  mercury 
per  liter. 

An  alkaline  stannous-chloride  solution,  prepared  by  treating  a 
solution  of  stannous  chloride  with  an  excess  of  potassium  hydroxide,  is 
used  for  determining  the  end  point. 

In  making  the  determination  a  measured  volume  of  reagent  is 
heated  to  boiling,  and  the  sugar  solution  added  until  a  drop  of  the 
filtered  solution  shows  no  coloration  with  the  alkaline  tin  solution. 
The  comparative  reducing  power  of  several  sugars  upon  Sachsse's  solu- 
tion is  given  in  Table  LXXXII,  page  474. 

ESTIMATION  OF  HIGHER  SACCHARIDES  BY  DETERMINING  THE  COPPER- 
REDUCING   POWER  AFTER  HYDROLYSIS 

The  methods  previously  described  in  this  chapter  for  determining 
reducing  sugars  are  equally  applicable  to  the  analysis  of  the  higher  non- 
reducing  saccharides  provided  the  latter  first  undergo  a  quantitative 
hydrolysis  into  sugars  of  known  reducing  power. 

The  best  examples  of  such  applications  of  the  method  are  the  de- 
terminations of  sucrose,  starch,  dextrin  and  glycogen  by  means  of 
Fehling's  solution. 

DETERMINATION  OF  SUCROSE  BY  MEANS  OF  FEHLING'S  SOLUTION 

Sucrose  upon  treatment  with  invertase  or  acids  is  hydrolyzed  quan- 
titatively, 95  parts  of  sucrose  yielding  100  parts  of  invert  sugar. 
If  the  copper-reducing  power  of  an  inverted-sucrose  solution  be  deter- 
mined, the  equivalent  of  invert  sugar  multiplied  by  the  factor  0.95  will 
give  the  amount  of  sucrose  present. 

In  making  the  determination  care  must  be  taken  that  the  amount 
of  sugar  after  inversion  does  not  exceed  the  limit  of  the  tables,  which 
for  50  c.c.  of  mixed  Fehling's  solution  is  about  240  mgs.  of  invert  sugar, 

*  Z.  Ver.  Deut.  Zuckerind.,  26,  872. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     437 

or  the  equivalent  of  about  225  mgs.  of  sucrose.  The  chemist  should 
check  the  method  with  pure  sucrose,  in  which  case  the  following  pro- 
cedure may  be  followed. 

Dissolve  1.9  gms.  of  pure  sucrose  in  about  75  c.c.  of  water  in  a 
500-c.c.  graduated  flask  and  invert  the  solution  according  to  the  method 
of  Herzfeld,  or  any  of  the  processes  described  in  Chapter  X.  After 
cooling,  the  solution  is  nearly  neutralized  with  sodium  hydroxide 
(carefully  avoiding  any  excess)  and  the  volume  completed  to  500  c.c.; 
50  c.c.  of  this  solution  (containing  200  mgs.  invert  sugar  =  190  mgs. 
sucrose)  are  then  treated  according  to  any  of  the  copper-reduction 
methods  for  invert  sugar  and  the  weight  of  reduced  copper  determined. 
The  milligrams  of  invert  sugar,  corresponding  to  this  weight  of  cop- 
per, multiplied  by  the  factor  0.95  gives  the  milligrams  of  sucrose. 

In  applying  the  method  to  the  determination  of  sucrose  in  sugar- 
house  products,  and  other  substances,  which  contain  invert  sugar, 
the  difference  between  the  invert-sugar  equivalents  before  and  after 
inversion  is  multiplied  by  0.95.  The  same  methods  for  determining 
invert  sugar  should  be  employed  in  both  cases.  The  method  of  cal- 
culation is  best  illustrated  by  an  example: 

Four  grams  of  apple  must  were  made  up  to  100  c.c.  (solution  A).  Four  gms. 
of  the  same  must  were  inverted,  nearly  neutralized  and  made  up  to  100  c.c. 
(solution  B). 

50  c.c.  of  sol.  B  gave  by  MeissFs  method  407  mgs.  Cu  =  230  mgs.  invert  sugar 
50  c.c.  of  sol.  A  gave  by  Meissl's  method  235  mgs.  Cu  =  126  mgs.  invert  sugar 

Difference  =  172  mgs.  Cu       104  mgs.  invert  sugar. 

104  mgs.  invert  sugar  X  0.95  =  98.8  mgs.  or  4.94  per  cent  sucrose. 

The  mistake  is  sometimes  made  of  taking  the  difference  between 
the  weights  of  reduced  copper  before  and  after  inversion  and  calculat- 
ing the  invert  sugar  and  sucrose  from  this.  The  extent  of  this  error, 
which  is  due  to  the  variation  in  the  copper-reducing  power  for  different 
parts  of  the  table  (as  shown  in  Table  LXXI),  may  be  seen  from  the 
previous  example,  where  a  difference  of  172  mgs.  of  copper  was  found. 
172  mgs.  of  copper  according  to  Meissl's  table  correspond  to  90.8  mgs. 
of  invert  sugar.  90.8  X  0.95  =  86.2  mgs.  or  4.31  per  cent  of  sucrose, 
a  result  considerably  less  than  that  obtained  by  the  other  method. 

In  calculating  sucrose  by  any  of  the  chemical  methods,  the  reducing 
sugars  before  inversion  must  always  be  expressed  as  invert  sugar,  al- 
though it  may  actually  exist  as  glucose,  lactose,  maltose,  etc.,  or  a 
mixture  of  several  of  these.  This,  of  course,  applies  only  to  the  sucrose 
calculation  and  not  to  that  of  the  reducing  sugars. 


438  SUGAR  ANALYSIS 

Example.  —  5  gms.  of  a  sirup  containing  sucrose  and  maltose  were  made  up 
to  500  c.c.  (solution  A).  5  gms.  of  the  same  sirup  were  dissolved,  inverted, 
nearly  neutralized  and  made  up  to  500  c.c.  (solution  B). 


Maltose- 


Mgs.        Mgs.  Mga. 

50  c.c.  of  sol.  B  gave  by  Munson  and  Walker's  method  390  =  215.0 

50  c.c.  of  sol.  A  gave  by  Munson  and  Walker's  method  199  =  103.7  =  175.5 

Difference  191      111.3. 

111.3  X  0.95  =  105.7  mgs.  =  21.14  per  cent  sucrose  in  sirup. 
175.5  mgs.  =  35.10  per  cent  maltose  in  sirup. 

Calculating  the  sucrose  from  the  difference  in  copper,  as  is  sometimes 
wrongly  done,  would  give  the  following:  191  mgs.  Cu  =  99.3  mgs.  invert 
sugar  (by  Munson  and  Walker's  table),  99.  3X  0.95  =  94.3  mgs.  =  18.86  per 
cent  sucrose  in  sirup. 

The  unified  methods  and  tables  are  most  convenient  for  converting 
the  equivalents  of  any  reducing  sugar  into  that  of  invert  sugar.  The 
same  result,  however,  may  be  accomplished  by  means  of  the  copper- 
reducing  ratios  given  on  page  421. 

Example.  —  10  gms.  of  a  sirup  containing  sucrose  and  fructose  were  made 
up  to  500  c.c.  (solution  A).     10  gms.  of  the  same  sirup  were  dissolved,  inverted, 
nearly  neutralized  and  made  up  to  500  c.c.  (solution  B). 
25  c.c.  of  sol.  B  gave  by  Allihn's  method  414  mgs.  Cu  =  221  mgs.  glucose 
25  c.c.  of  sol.  A  gave  by  Allihn's  method  195  mgs.  Cu  =  100  mgs.  glucose 

Difference  =121  mgs.  glucose. 

The  reducing  ratio  of  invert  sugar  to  glucose  is  0.958  for  Allihn's  method. 
121  -r-  0.958  =  126.3  mgs.  invert  sugar.  126.3  X  0.95  =  120  mgs.  =  24.00  per 
cent  sucrose  in  sirup. 

The  reducing  ratio  of  fructose  to  glucose  is  0.915  for  Allihn's  method. 
100  -^  0.915  =  109.3  mgs.  =  21.86  per  cent  fructose  in  sirup. 

Owing  to  the  slight  variation  in  the  reducing  ratios  of  some  of  the 
sugars,  as  maltose  and  lactose,  it  is  more  accurate  to  determine  the 
equivalents  by  one  of  the  unified  methods. 

DETERMINATION  OF  STARCH  BY  MEANS  OF  FEHLING's  SOLUTION 

Starch  upon  heating  with  dilute  hydrochloric  acid  is  hydrolyzed  al- 
most quantitatively  according  to  the  equation  (C6Hi005)n  -f-  nH20  = 
nC6Hi206,  in  which  90  parts  of  starch  yield  100  parts  of  glucose.  The 
conversion  of  starch  into  glucose  may  be  accomplished  either  by  direct 
acid  hydrolysis,  as  in  Sachsse's  method,  or  by  first  converting  the  starch 
into  soluble  products,  as  with  diastase,  and  then  hydrolyzing  the  filtered 
solution  with  acid. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     439 

Method  of  Sachsse,  as  modified  by  the  Association  of  Official 
Agricultural  Chemists.*  —  Stir  a  convenient  quantity  of  the  sample 
(representing  from  2.5  to  3  gms.  of  the  dry  material)  in  a  beaker  with 
50  c.c.  of  cold  water  for  an  hour.  Transfer  to  a  filter  and  wash  with 
250  c.c.  of  cold  water.  Heat  the  insoluble  residue  for  two  and  a  half 
hours  with  200  c.c.  of  water  and  20  c.c.  of  hydrochloric  acid  (sp.  gr. 
1.125)  in  a  flask  provided  with  a  reflux  condenser.  Cool,  and  nearly 
neutralize  with  sodium  hydroxide;  complete  the  volume  to  250  c.c., 
filter  and  determine  the  glucose  in  an  aliquot  of  the  filtrate  by  any  of 
the  usual  methods  of  copper  reduction.  The  weight  of  glucose  multi- 
plied by  0.90  gives  the  weight  of  starch. 

Owing  to  the  fact  that  a  perfect  theoretical  yield  of  glucose  is  never 
obtained  from  starch  by  acid  hydrolysis,  Ost  f  recommends  the  use 
of  the  factor  0.925  for  converting  glucose  into  starch  by  Sachsse's 
method. 

Sachsse's  method  is  one  of  the  simplest  processes  for  estimating 
starch,  but  has  the  objection  of  converting  pentosans  and  other  hemi- 
celluloses  into  reducing  sugars.  The  method  for  this  reason  gives  too 
high  results  in  the  analysis  of  starchy  substances  which  contain  much 
cellular  tissue.  In  order  to  eliminate  this  error  the  starch  must  be 
dissolved  from  cellular  substances  before  hydrolyzing  with  acid;  solu- 
tion of  starch  may  be  effected  by  heating  under  pressure  or  by  the 
action  of  diastase. 

Method  of  Determining  Starch  by  Solution  under  Pressure.! — 
Three  grams  of  the  finely-ground  sample  are  extracted  with  cold  water, 
as  in  the  previous  method  in  order  to  remove  sugars,  dextrin,  gums,  etc. 
If  much  oil  or  fat  is  present  the  material  should  first  be  extracted  with 
ether.  The  residue  is  then  heated  in  a  covered  flask  or  metal  beaker, 
of  about  200-c.c.  capacity,  with  100  c.c.  of  water  in  an  autoclave,  a 
form  of  which  designed  by  Soxhlet  is  shown  in  Fig.  175.  The  heating 
is  continued  for  3  to  4  hours  at  3  atmospheres  pressure.  If  an  autoclave 
is  not  available,  Lintner  pressure  bottles  (Fig.  176)  may  be  used;  the 
bottles  are  immersed  in  a  glycerol  bath  and  heated  for.  8  hours  at 
108°  to  109°  C. 

When  the  digestion  is  finished  the  pressure  is  first  allowed  to  sub- 
side, when  the  autoclave,  or  pressure  flask,  is  opened  and  the  solution 
filtered  through  asbestos.  The  insoluble  residue  is  well  washed  with 
hot  water,  and  should  show  no  blue  reaction  with  iodine  when  ex- 

*  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  53. 

f  Chem.  Ztg.,  19,  1501. 

t  Konig's  "Untersuchung"  (1898),  p.  221. 


440 


SUGAR  ANALYSIS 


amined  under  the  microscope.     The  filtrate  is  made  up  to  200  c.c.  and 
then  heated  with  20  c.c.  of  hydrochloric  acid,  of  1.125  sp.  gr.,  for  3 


Fig.  175. — Soxhlet's  autoclave. 


Fig.  176.  — Lintner's  pressure  bottle. 


hours  in  a  boiling-water  bath,  the  flask,  which  holds  the  solution,  being 
connected  with  a  reflux  condenser.  The  solution,  after  cooling,  is  near- 
ly neutralized  with  sodium  hydroxide  and  made  up  to  500  c.c.  The 
copper-reducing  power  of  the  solution  is  then  determined;  the  glu- 
cose equivalent  of  the  copper  multiplied  by  0.9  gives  the  corresponding 
equivalent  of  starch. 

Method  of  Determining  Starch  by  Solution  with  Diastase.  - 
Marcker*  found  that  the  best  method  of  dissolving  starch  from  hemi- 
celluloses  was  by  means  of  diastase.     The  method  of  Marcker,  as  modi- 
fied by  the  Association  of  Official  Agricultural  Chemists,  is  as  follows: 

Preparation  of  Malt  Extract.  —  Digest    10   gms.  of   fresh,  finely- 
ground  malt  2  or  3  hours  at  ordinary  temperature  wi-th  200  c.c.  of 
*  "Handbuch  der  Spiritusfabrikation"  (1886),  94. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     441 

water  and  filter.  Determine y  the  amount  of  glucose  in  a  given  quantity 
of  the  filtrate  after  boiling  with  acid,  etc.,  as  in  the  starch  determina- 
tion, and  make  the  proper  correction  in  the  subsequent  determination. 

Determination.  —  Extract  a  convenient  quantity  of  the  substance 
(ground  to  an  impalpable  powder  and  representing  from  4  to  5  gms.  of 
the  dry  material)  on  a  hardened  filter  with  5  successive  portions  of 
10  c.c.  of  ether;  wash  with  150  c.c.  of  10  per  cent  alcohol  and  then 
with  a  little  strong  alcohol.  Place  the  residue  in  a  beaker  with  50  c.c. 
of  water,  immerse  the  beaker  in  a  boiling-water  bath  and  stir  constantly 
for  15  minutes  or  until  all  the  starch  is  gelatinized;  cool  to  55°  C.,  add 
20  c.c.  of  malt  extract  and  maintain  at  this  temperature  for  an  hour. 
Heat  again  to  boiling  for  a  few  minutes,  cool  to  55°  C.,  add  20  c.c.  of 
malt  extract  and  maintain  at  this  temperature  for  1  hour  or  until  a 
microscopic  examination  of  the  residue  with  iodine  shows  no  starch. 
Cool  and  make  up  directly  to  250  c.c.;  filter.  Place  200  c.c.  of  the 
filtrate  in  a  flask  with  20  c.c.  of  hydrochloric  acid  (sp.  gr.  1.125);  con- 
nect with  a  reflux  condenser  and  heat  in  a  boiling-water  bath  for  two 
and  one-half  hours.  Cool,  nearly  neutralize  with  sodium  hydroxide 
and  make  up  to  500  c.c.  Mix  the  solution  well,  pour  through  a  dry 
filter  and  determine  the  glucose  in  an  aliquot  of  the  filtrate  by  any  of 
the  usual  methods  of  copper  reduction.  The  weight  of  glucose  multi- 
plied by  0.90  gives  the  weight  of  starch. 

Wein  *  has  calculated  a  table  for  the  above  methods  which  gives 
the  milligrams  of  starch  or  dextrin  corresponding  to  milligrams  of  re- 
duced copper  as  obtained  by  Allihn's  method.  The  table  was  con- 
structed by  simply  multiplying  the  milligrams  of  glucose  in  Allihn's 
table  by  the  factor  0.9. 

Of  the  various  processes  for  determining  starch  the  diastase  method 
secures  the  most  perfect  solution  of  starch  with  the  least  solution  of 
accompanying  hemicelluloses.  In  cases,  however,  where  much  cellular 
matter  is  present  the  hot  water  and  malt  solution  may  dissolve  a  small 
amount  of  pentosans,  which,  by  being  afterwards  hydrolyzed  into  re- 
ducing pentose  sugars,  introduce  a  slight  error  in  the  determination. 

A  more  serious  error  than  the  above  consists  in  the  incomplete 
hydrolysis  of  starch  into  glucose.  Experiments  by  W.  A.  Noyes,f 
and  his  coworkers,  testing  the  action  of  2.5  per  cent  hydrochloric  acid 
upon  the  malt  conversion  of  starch,  show  a  hydrolysis,  into  glucose 
which  is  about  97  per  cent  of  the  theoretical.  A  diminished  yield  of 
glucose  necessitates  the  use  of  a  conversion  factor  somewhat  greater 
than  0.9. 

*  Wein's  "Tabellen."  t  J-  Am.  Chem.  Soc.,  26,  266. 


442  SUGAR  ANALYSIS 

Modification  of  Noyes*  for  Determining  Starch  by  the  Diastase 
Method.  —  In  the  modification  recommended  by  Noyes  the  filtrate 
from  the  malt  digestion  is  treated  with  one-tenth  its  volume  of  hydro- 
chloric acid  of  sp.  gr.  1.125.  "  After  heating  for  1  hour  in  a  flask 
immersed  in  a  boiling-water  bath,  making  allowance  for  the  time  re- 
quired for  the  solution  to  attain  the  temperature  of  the  bath,  the  solu- 
tion is  cooled,  enough  sodium  hydroxide  is  added  to  neutralize  90  per 
cent  of  the  hydrochloric  acid  used,  the  solution  made  up  to  a  definite 
volume,  filtered  on  a  dry  filter,  if  necessary,  and  the  reducing  power  de- 
termined by  Fehling's  solution;  100  parts  of  glucose  found  in  this 
manner  represent  93  parts  of  starch  in  the  original  material." 

Noyes  emphasizes  the  importance  of  each  chemist  determining  for 
himself  with  pure  glucose  the  ratio  between  glucose  and  copper  for  the 
particular  solutions  and  method  which  he  uses. 


DETERMINATION  OF  DEXTRIN  BY  MEANS  OF  FEHLING's  SOLUTION 

The  principle  of  the  method  is  the  same  as  that  described  for  starch. 
In  the  process  described  by  Konig  f  a  weighed  amount  of  the  dextrin  is 
dissolved  in  cold  water,  made  up  to  1000  c.c.  and  filtered.  Three 
portions  of  200  c.c.  each  of  the  filtrate  are  heated  in  a  boiling-water  bath 
with  20  c.c.  of  hydrochloric  acid  of  1.125  sp.  gr.  for  periods  of  1,  2  and 
3  hours.  The  solutions  are  cooled,  nearly  neutralized  with  sodium 
hydroxide  and  made  up  to  volume  so  that  the  solution  does  not  contain 
over  1  per  cent  glucose.  The  glucose  is  then  determined  by  any  of  the 
usual  methods,  and  the  highest  results  of  the  three  experiments  taken  as 
the  correct  value.  The  weight  of  glucose  multiplied  by  the  factor  0.9 
gives  the  equivalent  of  dextrin. 

If  sugars  are  also  present,  the  glucose  equivalent  of  these  must  be 
subtracted  from  the  glucose  equivalent  after  hydrolysis  and  the  differ- 
ence calculated  to  dextrin. 

The  hydrolysis  of  dextrin  by  dilute  hydrochloric  acid  was  found  by 
W.  A.  Noyes  t  and  his  co-workers  to,  be  a  little  less  than  95  per  cent 
complete  at  the  end  of  2  hours'  heating  and  the  results  seemed  to  indi- 
cate that  the  theoretical  yield  of  glucose  could  not  be  obtained  even  by 
prolonged  heating.  The  theoretical  factor  0.9  for  converting  glucose 
to  dextrin  is  no  doubt  considerably  too  low  for  the  method  of  acid 
hydrolysis. 

*  J.  Am.  Chem.  Soc.,  26,  266. 

t  Konig's  "Untereuchung"  (1898),  p.  215. 

j  J.  Am.  Chem.  Soc.,  26,  266. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     443 

DETERMINATION  OF  GLYCOGEN  BY  MEANS  OF  FEHLING's  SOLUTION 

Pfluger's*  Glycogen  Method.  —  The  method  is  based  upon  the 
hydrolysis  into  glucose  of  the  impure  glycogen  (C6Hio05)n,  which  has 
previously  been  precipitated  from  the  solution  of  animal  substance. 

One  hundred  grams  of  the  finely  divided  tissue  are  heated  with  100  c.c. 
of  60  per  cent  potassium-hydroxide  solution,  in  a  boiling-water  bath  for 
3  hours,  the  flask,  which  contains  the  solution,  being  shaken  at  frequent 
intervals.  The  cooled  solution  is  made  up  to  400  c.c.  and  treated  with 
800  c.c.  of  96  per  cent  alcohol.  After  standing  24  hours  the  clear  solu- 
tion is  decanted  through  a  filter,  the  precipitate  of  impure  glycogen 
stirred  with  an  excess  of  60  per  cent  alcohol  and  again  set  aside.  The 
settling  of  the  glycogen  in  the  numerous  treatments  may  be  hastened 
by  adding  a  few  drops  of  concentrated  salt  solution.  The  clear  liquid 
is  again  decanted  and  the  process  repeated  for  a  third  time.  The  puri- 
fication is  then  continued  in  the  same  way,  twice  with  96  per  cent  alco- 
hol, once  with  absolute  alcohol,  three  times  with  ether  and  once  again 
with  absolute  alcohol.  Any  material  adhering  to  the  filter  is  then 
removed  to  the  main  portion  of  precipitate,  and  the  raw  glycogen  dis- 
solved in  hot  water.  The  solution  is  then  neutralized  with  hydro- 
chloric acid  of  1.19  sp.  gr.,  and  transferred  to  a  500-c.c.  flask;  25  c.c.  of 
hydrochloric  acid  (sp.  gr.  1.19)  are  then  added  and  the  liquid  heated 
in  a  boiling-water  bath  for  3  hours.  The  solution  is  then  cooled,  neu- 
tralized, made  up  to  500  c.c.,  filtered  and  the  glucose  determined  in 
the  filtrate  by  Pfluger's  method.  The  amount  of  glucose  multiplied  by 
the  factor  0.927  gives  the  corresponding  amount  of  glycogen. 

EXTRACTION  OF  SUGARS  AND  PREPARATION  OF  SOLUTIONS  FOR  CHEMICAL 
METHODS  OF  ANALYSIS 

The  methods  and  precautions  previously  given  for  the  extraction  of 
sugars  and  preparation  of  solutions  for  polarimetric  examination  hold 
also  for  the  chemical  methods  of  analysis. 

Clarification  of  Solutions.  —  With  products  which  contain  but 
little  insoluble  matter,  such  as  sugars,  molasses,  sirups,  jellies,  honeys, 
etc.,  the  weighed  amount  of  material  is  dissolved  in  water,  clarified,  if 
necessary,  with  a  minimum  of  neutral  lead-acetate  solution,  made  up  to 
volume  and  filtered.  The  filtrate,  after  deleading  by  means  of  sodium 
carbonate,  sodium  sulphate,  potassium  oxalate  or  other  means,  as  de- 
scribed on  page  276,  is  then  ready  for  analysis. 

With  products  of  high  purity,  which  contain  but  little  mineral 
matter  or  organic  non-sugars,  the  use  of  lead  acetate  may  be  dispensed 

*  Pfluger's  Archiv,  114,  242. 


444 


SUGAR  ANALYSIS 


with,  and  a  few  cubic  centimeters  of  alumina  cream  be  used  for  clari- 
fication. 

Precipitation  of  Reducing  Sugars  by  Basic-lead  Salts.  —  Lead  sub- 
acetate,  or  other  basic  salts  of  lead,  which  are  employed  as  clarifying 
agents  in  the  polarimetric  determination  of  sucrose,  should  never  be 
used  upon  solutions  in  which  reducing  sugars  are  to  be  determined. 
The  action  of  such  compounds  in  causing  a  precipitation,  or  occlusion, 
of  reducing  sugars  in  the  lead  precipitate  has  already  been  mentioned. 
Bryan  *  found  that  basic-lead  salts,  in  presence  of  magnesium  sulphate 
and  ammonium  tartrate,  precipitated  in  case  of  glucose  from  3  per  cent 
to  17  per  cent,  and  in  case  of  fructose  from  8  per  cent  to  35  per  cent,  of 
the  total  amount  of  sugar  in  solution.  Neutral  lead  acetate  under  the 
same  conditions  caused  the  precipitation  of  only  0.9  per  cent  of  the  total 
glucose  and  0.0  per  cent  of  the  total  fructose..  (See  Table  XL,  p.  216.) 

In  a  series  of  independent  experiments  made  by  Bryan  and  Home  f 
upon  raw  cane  sugar  and  cane  molasses  the  following  results  were 

obtained. 

TABLE  LXXX 

Showing  Influence  of  Clarification  with  Lead  Subacetate  upon  Determination  of  Reduc- 
ing Sugars 


Clarifying  agent  and  analyst. 

Allihn's  method. 

Munson  and  Walker's  Method. 

Weigh- 
ing as 
Cu20. 

Weigh- 
ing as 
CuO. 

Titration 
of  Cu  by 
Low's 
Method. 

Weigh- 
ing as 
Cu20. 

Weigh- 
ing as 
CuO. 

Titration 
of  Cu  by 
Low's 
method. 

r 

'  No  Clarifying  Agent  — 
A.  H.  Bryan  
W.  D.  Home  

Average 

Percent 
6.45 

7.08 

Per  cent 
6.22 

7.05 

Per  cent 

5.88 
7.02 

Per  cent 
6.29 

6.43 

Per  cent 
5.98 
6.51 

Per  cent 

5.83 
6.37 

6.77 

6.63 

6.45 

6.36 

6.25 

6.10 

Lead-subacetate  Solution  — 
A.  H.  Bryan.    . 

6.14 
6.61 

5.67 
6.51 

5.67 
6.51 

5.76 
6.19 

5.51 
6.01 

5.30 
5.99 

W.  D.  Home  

L.             Average  . 

6.38 

6.09 

6.09 

5.98 

5.76 

5.65 

'  No  Clarifying  Agent  — 
A.  H.  Bryan  
W.  D.  Home  

19.77 
20.60 

19.37 
20.06 

19.45 
19.97 

19.20 
20.00 

18.34 
19.43 

18.43 
19.44 

Average  .  . 

20.19 

19.72 

19.71 

19.60 

18.89 

18.94 

Lead-subacetate  Solution  — 
A.  H.  Bryan 

17.51 
19.45 

16.47 
19.16 

16.29 
19.16 

17.27 
19.00 

16.26 
18.53 

15.97 
18.26 

W.  D.  Home 

Average 

18.48 

17.82 

17.73 

18.14 

17.39 

17.12 

*  Bull.  116,  U.  S.  Bur.  of  Chem.,  p.  73.      t  Bull.  116,  U.  S.  Bur.  of  Chem.,  pp.  72,  74. 


1 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     445 

Clarification  with  lead  subacetate  caused  a  loss  of  about  10  per 
cent  of  the  total  reducing  sugars  present.  The  variable  results,  due  to 
method  of  estimating  copper,  show  a  contamination  of  the  cuprous 
oxide  as  explained  on  page  416.  The  higher  results  by  Allihn's  method 
are  due  to  the  greater  inverting  action  of  the  more  strongly  alkaline 
Fehling's  solution. 


PREPARATION  OF  SUGAR  SOLUTIONS  FROM  PLANT  SUBSTANCES 

If  the  material  to  be  analyzed  contains  much  insoluble  matter,  as 
is  the  case  with  plant  substances  containing  cellular  tissue,  the  sugars 
must  first  be  extracted  by  means  of  water  or  alcohol.  In  the  case  of 
grains,  cattle-feeds,  etc.,  the  following  provisional  method  is  used  by 
the  Association  of  Official  Agricultural  Chemists.* 

Extraction  of  Sugars  with  Cold  Water.  —  Weigh  into  a  flask  or 
bottle,  suitable  for  stirring  or  shaking,  10  to  20  gms.  of  the  material, 
depending  upon  the  amount  of  soluble  carbohydrates  present.  Add 
250  c.c.  of  ice-cold  water,  less  the  volume  of  water  present  as  moisture 
in  the  material,  and  stir  or  shake  for  4  hours.  If  enzymatic  action  is 
feared  the  extraction  should  be  made  at  a  low  temperature,  preferably 
by  surrounding  the  extraction  flask  with  broken  ice;  or  extract  at  ordi- 
nary temperature  with  40  to  50  per  cent  alcohol.  If  there  is  present  in 
the  material  much  soluble  substance,  correction  should  also  be  made  for 
the  increase  in  volume  due  to  solution.  If  necessary  for  clear  filtration, 
add  from  5  to  10  c.c.  of  alumina  cream,  just  before  filtering.  The  volume 
of  alumina  cream  to  be  added  must  be  taken  into  account  in  determin- 
ing the  amount  of  water  used  for  the  extraction.  After  the  extraction 
filter  immediately,  pouring  back  upon  the  filter  the  first  portions  of 
cloudy  filtrate  until  the  filtrate  is  clear.  To  free  from  soluble  impuri- 
ties add  sufficient  normal  lead-acetate  solution  to  200  c.c.  of  the  filtrate 
to  precipitate  all  impurities,  make  up  to  250  c.c.  and  filter.  Remove 
the  excess  of  lead  by  means  of  anhydrous  sodium  carbonate  or  anhy- 
drous sodium  sulphate,  followed  in  the  latter  case  by  a  small  amount  of 
anhydrous  sodium  carbonate,  care  being  taken  not  to  use  an  excess. 
Filter  again  and  use  the  clear  filtrate  for  the  determination  of  reducing 
sugars. 

The  extraction  of  sugars  from  plant  substances  by  means  of  cold 
water  is  not  always  trustworthy  owing  to  the  action  of  enzymes  upon 
sucrose,  starch  and  other  higher  saccharides.  The  employment  of  hot 

*  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  57. 


446  SUGAR  ANALYSIS 

water  is  also  often  unreliable  on  account  of  the  solution  of  hemicellu- 
loses,  starch  and  gums. 

Extraction  of  Sugars  with  Dilute  Alcohol.  —  Bryan,  Given  and 
Straughn  *  have  recently  made  experiments  upon  the  extraction  of 
sugars  from  grains  and  similar  products,  using  as  solvents  50  per  cent 
alcohol  and  0.2  per  cent  sodium-carbonate  solution.  Both  of  these 
solvents  inhibit  the  action  of  enzymes  and  were  found  to  give  con- 
cordant results  upon  certain  classes  of  products.  In  many  cases,  how- 
ever, the  sodium-carbonate  extraction  gave  much  higher  amounts  of 
reducing  sugar  after  inversion  —  a  result,  perhaps,  of  the  solvent 
action  of  the  alkali  upon  pentosans  and  other  hemicelluloses.  Bryan, 
Given  and  Straughn  believe  that  extraction  with  50  per  cent  alcohol,  all 
points  considered,  is  the  most  reliable  method  for  general  sugar  work. 
The  method  outlined  by  them  is  as  follows: 

Method  of  Bryan,  Given  and  Straughn.  —  Place  12  gms.  of  the  finely 
ground  substance  in  a  300-c.c.  graduated  flask,  adding,  in  case  the 
material  is  acid,  from  1  to  3  gms.  of  precipitated  calcium  carbonate. 
Add  150  c.c.  of  neutral  alcohol  of  50  per  cent  volume  strength;  mix 
thoroughly  and  boil  on  a  hot-water  bath  for  1  hour,  placing  a  small 
funnel  in  the  neck  of  the  flask  to  condense  the  vapor.  Cool  and  make 
up  to  300  c.c.  with  neutral  95  per  cent  alcohol.  After  mixing  and  set- 
tling transfer  200  c.c.  of  the  clear  solution  to  a  distilling  flask  and  distil 
off  the  excess  of  alcohol,  which  is  thus  recovered  for  future  use.  The 
liquid  residue  is  evaporated  to  a  volume  of  20  to  30  c.c.  (but  not  to 
dryness),  and  then  washed  with  water  into  a  100-c.c.  graduated  flask. 
The  solution  is  clarified  with  the  necessary  amount  of  neutral  lead- 
acetate  solution,  and,  after  standing  15  minutes,  made  up  to  100  c.c. 
Pass  through  a  folded  filter,  carefully  saving  all  of  the  filtrate,  to  which 
add  enough  anhydrous  sodium  carbonate  to  precipitate  the  excess  of 
lead;  allow  to  stand  15  minutes  and  then  pour  through  an  ashl< 
filter.  Over  75  c.c.  of  filtrate  should  be  obtained;  25  c.c.  of  the  cl< 
filtrate  (equivalent  to  2  gms.  of  original  material)  are  diluted  with  25  c.c. 
of  water  and  used  for  the  determination  of  reducing  sugars;  50  c.c.  oi 
the  same  filtrate  are  transferred  to  a  100-c.c.  flask,  inverted  with  5  c.c. 
of  concentrated  hydrochloric  acid,  neutralized  and  made  up  to  100  c.c. 
Filter,  if  necessary,  and  take  50  c.c.  (equivalent  to  2  gms.  of  original 
material)  for  the  determination  of  reducing  sugars  after  inversion. 
The  percentages  of  invert  sugar  and  sucrose  are  calculated  in  the 
usual  way  and  the  results  multiplied  by  the  factor  0.97  to  correct  for 
the  volume  of  insoluble  matter. 

*  Circular  71,  U.  S.  Bur.  of  Chem. 


REDUCTION  METHODS  FOR  DETERMINING  SUGARS     447 


PREPARATION  OF  SUGAR  SOLUTIONS  FROM  ANIMAL  SUBSTANCES 

Clarification.  —  Liquids  of  animal  origin,  such  as  blood,  serum, 
urine,  milk,  secretions,  extracts,  etc.,  frequently  contain  large  amounts 
of  albuminoids  and  other  nitrogenous  substances  which  interfere  with 
the  determination  of  reducing  sugars  by  the  methods  of  copper  re- 
duction. The  clarifying  agent  which  is  most  used  for  such  liquids  is 
mercuric  nitrate. 

Mercuric-nitrate  Solution.  —  Treat  220  gms.  of  yellow  oxide  of  mer- 
cury with  300  to  400  c.c.  of  water;  then  add  nitric  acid  in  small  portions, 
with  warming  and  stirring,  until  the  precipitate  is  dissolved.  Dilute  to 
1000  c.c.  and  filter. 

The  liquid  to  be  clarified  is  treated  with  mercuric-nitrate  solution 
until  no  more  precipitate  forms;  the  solution  is  then  nearly  neutralized 
with  sodium-hydroxide  solution  of  1.3  sp.  gr.,  made  up  to  volume  and 
filtered.  A  measured  portion  of  the  slightly  acid  filtrate  is  then  freed 
from  excess  of  mercury  by  precipitating  with  hydrogen  sulphide;  the 
solution  is  filtered,  the  hydrogen  sulphide  removed  by  a  current  of  air 
and  the  reducing  sugars  determined  by  any  of  the  usual  methods. 

Clarification  of  Milk.  —  For  the  clarification  of  milk,  the  use  of 
copper  sulphate  and  potassium  hydroxide  will  be  found  more  con- 
venient. The  following  is  the  official  method  of  the  Association  of 
Agricultural  Chemists.* 

Dilute  25  c.c.  of  the  milk  with  400  c.c.  of  water  and  add  10  cc.  of  a 
solution  of  copper  sulphate  of  the  strength  given  for  Soxhlet's  modi- 
fication of  Fehling's  solution.  Add  about  7.5  c.c.  of  a  solution'  of 
potassium  hydroxide  of  such  strength  that  one  volume  of  it  is  just 
sufficient  to  completely  precipitate  the  copper  as  hydroxide  from  one 
volume  of  the  solution  of  copper  sulphate.  Instead  of  a  solution  of 
potassium  hydroxide  of  this  strength,  8.8  c.c.  of  a  half-normal  solution 
of  sodium  hydroxide  may  be  used.  After  the  addition  of  the  alkali 
solution  the  mixture  must  still  have  an  acid  reaction  and  contain 
copper  in  solution.  Fill  the  flask  to  the  500-c.c.  mark,  mix  and  filter 
through  a  dry  filter.  Determine  the  lactose  by  any  of  the  usual 
methods. 

In  determining  reducing  sugars  in  substances  of  animal  origin,  the 
precipitate  of  cuprous  oxide  is  often  badly  contaminated  with  mineral 
and  organic  impurities,  so  that  the  reduced  copper  should  be  deter- 
mined directly  and  not  by  weighing  as  suboxide  or  oxide. 
*  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  119. 


448  SUGAR  ANALYSIS 


CONCENTRATION    OF   SUGAR   SOLUTIONS 

In  working  with  very  dilute  solutions,  such  as  contain  only  a  few 
hundredths  of  a  per  cent  of  sugar,  it  is  often  necessary  to  concentrate 
the  liquid  to  one-half,  one-fifth  or  one-tenth  the  original  volume  be- 
fore a  satisfactory  determination  of  the  copper-reducing  power  can  be 
made.  It  is  exceedingly  important  in  evaporating  such  solutions  that 
the  liquid  be  kept  exactly  neutral,  otherwise  changes  may  result  in  the 
composition  of  the  sugars.  Traces  of  free  acid  may  become  sufficiently 
concentrated  towards  the  end  of  evaporation  to  hydrolyze  higher  saccha- 
rides,  and  traces  of  free  alkali  may  modify  or  destroy  reducing  sugars. 

The  evaporation  of  solutions  containing  reducing  sugars  must  be 
conducted  in  vessels  which  do  not  give  up  soluble  alkali;  the  concen- 
tration of  sugar  solutions  in  glass  vessels,  unless  of  perfect  resistant 
non-soluble  quality,  is  for  this  reason  to  be  avoided.  The  author  has 
found  flasks  and  basins  of  tinned  copper  to  be  very  suitable  for  con- 
centrating sugar  solutions,  there  being  no  change  in  reducing  power 
after  diluting  and  evaporating  to  the  original  volume. 

If  the  solution  to  be  concentrated  is  slightly  acid  an  excess  of  finely 
powdered  calcium  carbonate  (alkali  free)  will  prevent  the  hydrolysis  of 
higher  saccharides.  If  the  solution,  is  alkaline,  dilute  acetic  acid  is  first 
added  to  faint  acidity,  and  then  an  excess  of  calcium  carbonate.  When 
the  evaporation  is  completed,  the  residue  of  insoluble  matter  is  removed 
by  filtration. 


CHAPTER  XV 

SPECIAL   QUANTITATIVE  METHODS 

THE  determination  of  sugars  by  means  of  their  reducing  power  upon 
Fehling's  solution,  Sachsse's  solution  or  other  metallic  salt  combina- 
tions is  a  general  method,  and  has  no  value  for  the  selective  determi- 
nation of  particular  groups  of  reducing  sugars.  For  such  purposes 
more  special  processes  of  analysis  must  be  adopted.  The  present 
chapter  will  describe  a  number  of  the  best  known  of  such  special  quan- 
titative methods. 

DETERMINATION  OF  PENTOSES  AND  PENTOSANS 
Theory  of  Method.  —  The  methods  for  determining  pentoses  and 
pentosans  are  due  to  the  researches  of  Tollens,*  and  his  school;  they  all 
depend  upon  the  conversion  of  the  pentose  sugars  into  furfural  by  dis- 
tilling with  hydrochloric  acid,  according  to  the  principles  described  on 
p.  374.  The  amount  of  furfural,  which  distills  over,  is  determined  and 
calculated  to  pentoses.  The  yield  of  furfural  does  not  correspond  per- 
fectly to  the  equation, 

C5H1005  C5H402        +        3H20, 

100  parts  pentose  64  parts  furfural 

being  for  arabinose  about  75  per  cent  and  for  xylose  about  90  per  cent 
of  the  theoretical.  Yet  by  making  the  distillation  under  carefully  con- 
trolled conditions,  it  is  possible,  by  means  of  formulae  or  tables  which 
have  been  established  for  different  weights  of  pure  pentoses,  to  make 
a  determination  with  a  very  close  degree  of  approximation. 

Different  reagents  have  been  used  for  precipitating  the  furfural  in 
the  determination  of  pentoses.  Tollens  and  Stone  first  attempted  to 
determine  furfural  by  precipitating  with  ammonia  as  furfuramide. 
An  important  advance  was  then  made  by  Tollens,  in  company  with 
Giinther,  de  Chalmot,  Flint  and  Mann,  in  using  phenylhydrazine  for 
precipitating  the  furfural.  The  use  of  phenylhydrazine  was  attended, 
however,  with  certain  inconveniences  and  was  finally  abandoned  upon 
the  discovery  by  Councler  f  of  the  precipitating  action  of  phloroglucin. 

*  For  a  review  of  the  subject  see  papers  by  Tollens  with  bibliography  in  Abder- 
halden's  "Arbeitsmethoden,"  1909,  II,  130,  and  in  Papier-Zeitung,  1907,  Nos.  56,  60 
and  61  (Reprint). 

t  Chem.  Ztg.,  17,  1743;  18,  966. 

449 


450  SUGAR  ANALYSIS 

The  phloroglucin  method,  as  first  developed  by  Tollens  and  Kriiger,* 
was  further  improved  by  Tollens  and  Rimbach,  and  finally  established 
in  its  present  form  by  Tollens  and  Krober.f 

Description  of  the  Method.  —  The  necessary  apparatus  for  making 
the  determination  is  shown  in  Fig.  177.  From  2  to  5  gms.  of  substance, 
according  to  the  richness  of  the  material  in  pentoses  or  pentosans,  are 
placed  in  a  300-c.c.  distillation  flask  with  100  c.c.  of  hydrochloric  acid 


Fig.  177.  —  Apparatus  for  determining  pentoses  and  pentosans  by  distillation  with 

hydrochloric  acid. 

of  1.06  sp.  gr.  The  flask  is  closed  with  a  two-hole  rubber  stopper, 
one  opening  of  which  is  fitted  to  the  connecting  tube*  of  a  condenser 
and  the  other  to  a  small  separatory  funnel.  The  latter  is  preferably 
of  cylindrical  form  with  graduation  marks  at  30  c.c.  and  60  c.c.  The 
flask  is  then  placed  in  a  bath  of  Rose's  alloy  (1  pgh*t  lead,  1  part  tin 
and  2  parts  bismuth,  melting  near  100°  C.),  which,  after  Beating  just 
beyond  the  point  of  fusion,  is  brought  up  slightly  above  th6  level  of 
the  bottom  of  the  flask.  The  distillate  is  received  in  a  graduated 
cylinder;  when  30  c.c.  of  liquid  have  passed  over,  which  should  re- 
quire from  10  to  11  minutes,  30  c.c.  more  of  the  hydrochloric  acid  of 
1.06  sp.  gr.  are  added  from  the  separatory  funnel.  The  process  is  con- 
tinued in  this  way  until  fr  drop  of  the  distillate  shows  no  pink  colora- 

*  Z.  Ver.  Deut.  Zuckerind.,  46,  21,  195. 

t  Jour.  f.  Landwirtsch.  (1900),  355,  (1901),  7. 


SPECIAL  QUANTITATIVE  METHODS  451 

tion  with  aniline-acetate  paper  (see  p.  375).  From  9  to  12  portions  of 
30  c.c.  usually  require  to  be  distilled  over,  depending  upon  the  amount 
of  furfural.  The  distillation  is  then  suspended  and  the  furfural  de- 
termined by  precipitation  with  phloroglucin. 

Preparation  of  Phloroglucin.*  —  Dissolve  a  small  quantity  of  phlo- 
roglucin in  a  few  drops  of  acetic  anhydride,  heat  almost  to  boiling  and 
add  a.  few  drops  of  concentrated  sulphuric  acid.  A  violet  color  indi- 
cates the  presence  of  diresorcin.  A  phloroglucin  which  gives  more  than 
a  faint  coloration  may  be  purified  by  the  following  method: 

Heat  in  a  beaker  about  300  c.c.  of  hydrochloric  acid  (sp.  gr.,  1.06) 
and  11  gms.  of  phloroglucin,  added  in  small  quantities  at  a  time,  stirring 
constantly  until  it  has  almost  entirely  dissolved.  Some  impurities  may 
resist  solution,  but  it  is  unnecessary  to  dissolve  them.  Pour  the  hot 
solution  into  a  sufficient  quantity  of  the  same  hydrochloric  acid  (cold) 
to  make  the  volume  1500  c.c.  Allow  it  to  stand  at  least  over  night  — 
better  several  days  —  to  allow  the  diresorcin  to  crystallize  out,  and 
filter  immediately  before  using.  The  solution  may  turn  yellow,  but 
this  does  not  interfere  with  its  usefulness.  In  using  it,  add  the  volume 
containing  the  required  amount  to  the  distillate. 

Precipitation  of  Phloroglucide.  —  The  distillate  obtained  by  the 
method  previously  described  is  treated  in  a  500-c.c.  lipped  beaker  with 
a  measured  volume  of  phloroglucin  solution,  so  that  the  amount  of 
phloroglucin  is  about  double  that  of  the  furfural  expected.  The  solu- 
tion first  turns  yellow,  then  green  and  finally  becomes  almost  black 
when  the  amorphous  dark-green  precipitate  of  furfural  phloroglucide, 
CnH8O4,  begins  to  deposit.  The  liquid  is  then  made  up  to  400  c.c. 
with  the  12  per  cent  hydrochloric  acid  (1.06  sp.  gr.)  and  allowed  to 
stand  over  night.  The  solution,  after  testing  with  aniline-acetate 
paper  to  make  sure  that  all  furfural  has  been  precipitated,  is  filtered 
through  a  weighed  Gooch  crucible;  the  precipitate  of  phloroglucide  is 
brought  carefully  upon  the  asbestos  and  washed  with  150  c.c.  of  water 
in  such  a  way  that  the  water  is  not  entirely  removed  from  the  crucible 
until  the  y^ry  last.  The  crucible  is  then  placed  upon  a  support,  so 
that  the  bottom  is  free  to  the  air,  and  dried  for  4  hours  in  a  boiling- 
water  bath;  i|  is  then  placed  in  a  weighing  bottle,  cooled  in  a  desiccator 
and  weighed.  The  increase  in  weight  is  the  amount  of  furfural  phloro- 
glucide which  is  calculated  to  furfural,  pentose  or  pentosan  according  to 
the  table  of  Krober  (Appendix,  Table  22). 

The  weights  of  pentose  in  Krober's  table  are  the  averages  of  the 
corresponding  weights  of  xylose  and  arabinose.     The  weights  of  pen- 
*  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  54. 


452  SUGAR  ANALYSIS 

tosan  are  obtained  by  multiplying  the  corresponding  weights  of  pen- 
tose  by  the  factor  0.88,  which  represents  the  ratio  of  ?iC5Hi0O5  to 
(C5H8O4)n  or  ijj$.  The  table  of  Krober  has  a  range  for  weights  of 
phloroglucide  between  0.030  and  0.300  gms.  For  weights  of  phloro- 
glucide  outside  of  these  limits  Krober  gives  the  formulae: 

For  weight  of  phloroglucide  "a"  under  0.03  gm. 

Furfural  =  (a  +  0.0052)  X  0.5170  gm. 

Pentoses  =  (a  +  0.0052)  X  1.0170  gm. 

Pentosans  =  (a  +  0.0052)  X  0.8949  gm. 

For  weight  of  phloroglucide  "  a  "  over  0.300  gm. 

Furfural  =  (a  +  0.0052)  X  0.5180  gm. 

Pentoses  =  (a  +  0.0052)  X  1.0026  gm. 

Pentosans  =  (a  +  0.0052)  X  0.8824  gm. 

The  factor  0.0052  represents  the  weight  (5.2  mgs.)  of  phloroglucide, 
which  remains  dissolved  in  the  400  c.c.  of  acid  solution. 

For  weights  of  phloroglucide  which  exceed  0.5  gm.  it  may  be  found 
necessary  to  dry  for  a  longer  period  than  4  hours  in  order  to  attain 
constancy  in  weight.  It  is  always  better  in  making  the  determination 
to  regulate  the  weight  of  material  so  that  the  amount  of  phloroglucide 
falls  within  the  range  of  the  table. 

Precautions  and  Limitations.  —  In  making  the  determination  of 
pentosans  by  the  method  of  acid  distillation,  several  precautions  should 
be  noted.  It  is  important  first  that  the  heat  be  applied  to  the  flask  in 
such  a  way  that  charring  of  solids  upon  the  surface  of  the  glass  above 
the  liquid  be  avoided.  Such  charring  is  very  apt  to  occur  when  the 
flask  is  heated  over  the  open  flame  or  upon  wire  gauze;  the  use  of  the 
metal  bath  for  heating  is  for  this  reason  to  be  preferred.  It  is  also  im- 
portant that  the  distillate  be  perfectly  clear,  and  free  from  suspended 
impurities,  before  adding  the  solution  of  phloroglucin.  With  sub- 
stances which  contain  much  oil  or  wax,  fatty  decomposition  products 
are  sometimes  carried  over  into  the  distillate;  in  determining  pentoses 
in  the  urine  of  herbivorous  animals,  benzoic  acid  (a  decomposition  prod- 
uct of  hippuric  acid)  is  distilled  over  in  considerable  amount.  In  all 
such  cases  the  distillate  must  be  filtered  from  suspended  matter  before 
precipitating  the  furfural  with  phloroglucin. 

Two  important  limitations  of  the  distillation  method  for  determin- 
ing pentoses  should  be  mentioned.  1.  Furfural  is  formed  from  other 
substances  than  pentoses  (the  so-called  furfuroids).  2.  Other  sub- 
stances, which  form  a  precipitate  with  phloroglucin,  are  distilled  over 
besides  furfural  (the  so-called  furaloids). 


SPECIAL  QUANTITATIVE  METHODS  453 

"  Furfuroids."  —  The  formation  of  furfural  from  glucuronic  acid 
and  oxy cellulose  has  already  been  considered  (p.  375).  The  presence  of 
glucuronic  acid  in  urine,  or  of  oxycellulose  in  plant  substances,  will  in- 
troduce, therefore,  a  certain  error  in  the  determination  of  pentoses  in 
such  materials.  Cross  and  Bevan  *  for  this  reason  propose  that  the 
names  furfurose,  furfurosan  or  furfuroid  be  used  to  designate  the  fur- 
fural-yielding complex  of  plants.  The  researches  of  Tollens  show, 
however,  that  the  pentosans  are  by  far  the  most  important  of  the  fur- 
fural-yielding groups;  the  term  pentosans,  though  not  a  perfectly  correct 
expression,  seems  destined  to  remain  until  more  accurate  methods  are 
devised  for  determining  the  different  furfural-yielding  groups. 

The  distillates  obtained  by  boiling  cellulose,  starch,  sucrose,  fructose, 
glucose  and  other  hexose  carbohydrates  with  hydrochloric  acid  give 
with  phloroglucin  a  small  yield  of  phloroglucide  corresponding  to  0.5  to 
1.0  per  cent  pentosans.  Whether  the  reacting  substance  in  such  dis- 
tillates is  furfural,  oxymethylfurfural  or  mixtures  of  these  has  not 
been  definitely  determined.  A  slight  error  is,  nevertheless,  introduced 
into  the  pentose,  or  pentosan,  determination  by  the  phloroglucin 
method  and  the  chemist  should  always  bear  this  fact  in  mind  when  only 
small  amounts  of  phloroglucide  are  obtained. 

"Furaloids."  -  The  distillation  of  other  products,  which  give  pre- 
cipitates with  phloroglucin,  besides  furfural  has  also  been  long  recog- 
nized. Methylfurfural,  which  is  obtained  by  the  distillation  of  methyl- 
pentoses  with  hydrochloric  acid,  forms  for  example  a  red  precipitate 
with  phloroglucin,  which,  unless  removed  by  solution  in  alcohol,  as 
afterwards  described,  will  give  too  high  a  weight  of  furfural  phloro- 
glucide. In  the  same  way  oxymethylfurfural  (see  p.  620)  which  is 
formed  in  slight  amounts  by  the  action  of  hydrochloric  acid  upon 
fructose,  sucrose  and  other  hexose  carbohydrates,  forms  a  precipitate 
with  phloroglucin. 

Frapsf  has  estimated  that  the  amount  of  foreign  products  ("fur- 
aloid  ")  in  the  hydrochloric-acid  distillate  of  different  plant  substances 
may  vary  from  7  to  23  per  cent  of  the  crude  furfural.  The  "  furaloid  " 
is  decomposed  according  to  Fraps  by  redistilling  the  acid  distillates; 
the  pure  furfural  thus  obtained  is  precipitated  with  phloroglucin,  the 
weight  of  phloroglucide  corresponding  to  the  amount  of  furfural-yield- 
ing bodies  (pentosans  or  furfuroids);  the  difference  between  the 
weights  of  phloroglucide  for  distillate  and  redistilled  distillate  corre- 
sponds to  the  amount  of  furaloid-yielding  bodies,  the  exact  nature  of 

*  Gross  and  Bevan's  "Cellulose"  (1895),  p.  99. 
t  Am.  Chem.  Jour.,  25,  501. 


454  SUGAR  ANALYSIS 

which  Fraps  did  not  determine.  Furaloid  does  not  seem  to  be  formed 
from  the  pure  pentose  sugars. 

Precipitation  of  Furfural  by  Means  of  Barbituric  Acid.  —  Jager 
and  linger  *  have  suggested  barbituric  acid  for  precipitating  furfural 
in  presence  of  foreign  distillation  products.  Cellulose,  starch,  sucrose 
and  other  hexose  carbohydrates  give  hydrochloric-acid  distillates 
which,  though  reacting  with  phloroglucin,  form  no  precipitate  with 
barbituric  acid.  Jager  and  Unger  claim  that  the  reagent  offers,  there- 
fore, a  more  accurate  means  of  estimating  pentosans. 

In  making  the  precipitation  the  hydrochloric-acid  distillate  is  treated 
with  a  solution  of  pure  barbituric  acid  in  hydrochloric  acid  of  1.06  sp.  gr., 
using  8  parts  of  barbituric  acid  to  1  part  of  estimated  furfural.  The 
solution  is  stirred  and  after  standing  24  hours  the  yellow  granular  precip- 
itate filtered  into  a  Gooch  crucible,  washed  with  water  and  dried  for  4 
hours  at  105°  C.  The  weight  of  precipitate  is  increased  by  0.0049  gm. 
for  the  amount  of  substance  dissolved  in  the  400  c.c.  of  acid  solu- 
tion. 

The  reaction  between  furfural  and  barbituric  acid  proceeds  as  fol- 
lows: 

yCO-NHv  /CO-NHv 

C4H30  -  CHO+H2C  '  ;  CO  =C4H30  -  CH  •  C  (  ;  C0+H20. 

XCO-NHX  XCO-NHX 

Furfural  (96)  Barbituric  acid  (128)  Condensation  product  (206) . 

One  hundred  parts  of  condensation  product  thus  correspond  to  46.6  parts 
of  furfural. 

The  barbituric-acid  method  for  determining  pentosans  offers  several 
good  features,  but  the  process  has  not  been  tried  sufficiently  as  yet  by 
chemists  to  form  a  conclusion  as  to  its  reliability. 

Jolles's  Method  of  Determinating  Pentoses.  —  Jolles  f  has  recently 
proposed  a  method  for  determining  pentoses  which  differs  in  several 
particulars  from  that  of  Tollens.  The  substance  to  be  distilled  is 
placed  in  a  1500  c.c.  flask  with  200  c.c.  of  12  per  cent  hydrochloric  acid; 
the  flask  is  heated,  while  a  current  of  steam  is  passed  through  the 
liquid,  the  distillation  being  regulated  so  that  the  volume  of  solution 
does  not  fall  at  any  time  below  100  c.c.  By  distilling  the  furfural  with 
steam  the  formation  of  humus  substances  is  said  to  be  prevented  and  a 
quantitative  yield  of  furfural  obtained.  The  process  is  continued  until 
1  c.c.  of  the  distillate  shows  no  coloration  with  Bial's  orcin  reagent 
(p.  382);  100  c.c.  of  the  distillate  (usually  between  2  and  3  liters) 

*  Ber.,  35,  4440;  36,  1222. 

t  Sitzungsber.  Wiener  Akad.,  114  (II  b),  1191  (1905). 


SPECIAL  QUANTITATIVE  METHODS  455 

are  neutralized  with  sodium  hydroxide,  and  then  made  faintly  acid 
to  methyl  orange  with  a  few  drops  of  half-normal  hydrochloric  acid. 
A  measured  volume  of  TVnormal  sodium-bisulphite  solution  is  then 
added,  and  the  solution  allowed  to  stand  2  hours.  The  amount  of  bisul- 
phite, remaining  after  the  reaction  with  the  furfural,  is  then  titrated 
back  with  TVnormal  iodine  solution,  using  starch  solution  as  indicator. 
The  difference  between  the  volumes  of  bisulphite  and  iodine  solutions 
gives  the  amount  of  bisulphite  which  entered  into  combination  with 
the  furfural.  The  reaction  between  the  two  is  expressed  by  the  equa- 
tion : 

/OH 
C4H3O  •  CHO-{-NaHSO3  =  C4H3O  •  CH 

x  SO3Na 

The  titration  of  an  aliquot,  which  is  less  than  5  per  cent  of  the  total 
distillate,  involves  a  very  great  multiplication  of  any  experimental 
errors.  Jolles's  process  has  not  as  yet  demonstrated  its  superiority  over 
the  much  shorter  and  simpler  method  of  Tollens. 

The  method  of  Tollens  for  determining  pentoses  gives  good  results 
with  pure  arabinose  or  xylose  but,  as  has  been  shown,  yields  only 
rough  approximations  in  the  case  of  the  various  furfuroids.  Even  in 
the  case  of  pure  pentosans  the  calculation  of  furfural  to  a  mixture  of 
araban  or  xylan  in  equal  amounts,  when  perhaps  the  pentosan  itself 
may  consist  almost  entirely  of  one  substance,  may  involve  an  error  of 
several  per  cent  in  the  calculation.  In  certain  plant  exudations,  as 
cherry  gum,  the  pentosans  consist  almost  entirely  of  araban;  in  the 
hemicelluloses  of  certain  woods,  as  the  beech,  almost  entirely  of  xylan; 
in  the  encrusting  substances  of  most  cellular  tissues  of  variable  mix- 
tures of  araban  and  xylan.  Until  accurate  methods  are  available  for 
the  estimation  of  xylan  and  araban,  and  for  the  determination  of  oxy- 
cellulose  and  other  furfuroids,  the  calculation  of  furfural  to  a  mixture 
of  xylan  and  araban  in  equal  amounts  can  be  regarded  only  as  a  con- 
ventional approximation. 

Applications  of  Pentosan  Method.  —  The  determination  of  pen- 
tosans, notwithstanding  certain  limitations  of  the  method,  has  found 
numerous  applications  in  the  assay  of  plant  gums,  in  the  analysis  of 
feeding  materials,  in  the  examination  of  forestry  products  and  in  other 
ways.  A  single  example  of  such  application  is  given  in  the  analysis  of 
paper  stock.  Krober,*  for  example,  gives  the  following  determinations 
of  pentosans  in  different  raw  materials  used  in  paper  manufacture. 

*  Jour.  f.  Landwirtsch.  (1901),  1. 


456 


SUGAR  ANALYSIS 
TABLE  LXXXI 


Material. 

Pentosans 
calculated  to 
ash-free  dry 
substance. 

Mechanical  wood  pulp  

Per  cent. 
12  24 

Mechanical  wood  pulp  

11   93 

Cotton 

1  03 

Linen 

2  20 

Bleached  straw.  .                 ... 

26  76 

Bleached  raw  cellulose  (soda  process)  .... 

6  41 

Bleached  raw  cellulose  (sulphite  process)  

7.09 

An  application  of  the  above  results  to  a  special  problem,  which  may 
confront  the  paper  chemist,  is  taken  from  the  work  of  Tollens.* 

A  sample  of  newspaper  is  known  to  be  made  up  of  mechanical  wood  pulp 
and  sulphite  cellulose;  it  is  desired  to  know  the  percentages  of  each  which 
were  used.  The  sample  of  paper  upon  analysis  showed  10  per  cent  pentosans 
calculated  to  ash-free  dry  substance.  Calling  the  percentage  of  pentosans  in 
the  ash-free  dry  substance  of  mechanical  wood  pulp  12  per  cent  and  of  sulphite 
cellulose  7  per  cent,  then 

X  100  =  60  per  cent  mechanical  wood  pulp. 


12-7 
12-10 
12-7 


X  100  =  40  per  cent  sulphite  cellulose. 


For  other  applications  of  the  method  the  chemist  is  referred  to  the 
original  paper  by  Tollens. 

DETERMINATION  OF  METHYLPENTOSES  AND  METHYLPENTOSANS 
The  conversion  of  methylpentoses  into  methylfurfural  by  distilla- 
tion with  hydrochloric  acid  was  described  on  p.  377.  The  method  for 
determining  methylpentoses,  or  methylpentosans,  is  based  upon  de- 
termining the  amount  of  methylfurfural  which  is  thus  produced.  The 
details  of  the  method,  which  were  first  worked  out  by  Tollens  and 
Ellett,f  and  further  elaborated  by  Tollens  and  Mayer,  {  are  practically 
the  same  as  described  for  the  determination  of  the  pentoses.  The 
same  apparatus  (Fig.  177)  is  used  and  the  substance  is  distilled  with 
12  per  cent  hydrochloric  acid  (1.06  sp.  gr.)  until  a  drop  of  the  distillate 
gives  no  yellow  coloration  with  aniline-acetate  paper.  The  methyl- 
furfural  is  then  precipitated  with  phloroglucin  and  the  solution  allowed 
to  remain  over  night,  when  the  red  precipitate  of  methylfurfural 

*  Reprint  Papier-Zeitung  (1907),  p.  17. 

t  Ber.,  38,  492. 

t  Z.  Ver.  Deut.  Zuckerind.  (1907),  620;  Ber.,  40,  2441. 


SPECIAL  QUANTITATIVE   METHODS  457 

phloroglucide  is  filtered,  washed,  dried  and  weighed  in  exactly  the 
same  manner  as  described  for  furfural  phloroglucide. 

The  weight  of  methylfurfural  phloroglucide  is  then  calculated 
either  to  rhamnose  by  the  table  of  Ellett  and  Tollens  or  to  fucose  by 
the  table  of  Mayer  and  Tollens.  The  rhamnose,  CHaCaHgC^  •  H2O. 
is  calculated  to  rhamnosan  (CH3C5H704)n  by  multiplying  by  the 
factor  111  =  0.80;  and  the  fucose,  CHsCsHgOs,  to  fucosan  by  the 
factor  |||  =  0.89.  The  combined  table  giving  the  weights  of  rham- 
nose, rhamnosan,  fucose,  fucosan,  and  methylpentosan  (mixture  of 
equal  parts  rhamnosan  and  fucosan)  corresponding  to  different  weights 
of  methylfurfural  phloroglucid  is  given  in  the  Appendix  (Table  23) . 

Instead  of  the  tables  the  following  formulae  may  be  used  in  which 

Ph  is  the  weight  in  grams  of  methylfurfural  phloroglucide. 

Fucose  =  2.66  Ph  -  12.25  Ph2  +  0.0005. 

Rhamnose  =  1.65  Ph  -     1.84  Ph2  +  0.0100. 

Methylpentosan  =  1.85  Ph  -     6.25  Ph2  +  0.0040. 

Fucose  decomposes  slower  than  rhamnose  with  hydrochloric  acid, 
so  that  the  distillation  must  be  continued  longer.  More  decomposition 
products  of  methylfurfural  are  consequently  formed  in  distilling  fucose 
with  a  corresponding  less  yield  of  phloroglucide. 

Methylfurfural,  according  to  Fromherz,*  may  also  be  estimated  by 
precipitation  with  barbituric  acid  in  the  same  manner  as  described  for 
furfural.  The  reaction  takes  place  according  to  the  equation: 

/CO-NHX 

CH3C4H2O  -  CHO +H2C  CO 

XCO-NHX 

/CO-NH, 

=  CH3C4H20  •  CH  -  C  ;  ,  CO +H20. 

XCO-NHX 

Methylfurfural  (110)  Barbituric  acid  (128)  Condensation  product  (220) 

Two  parts  of  condensation  product  thus  correspond  to  exactly  one 
part  of  methylfurfural.  The  yellow  crystalline  precipitate  is  filtered 
in  a  Gooch  crucible,  washed  with  water  and  then  dried  for  5  hours  in  a 
steam  bath.  The  precipitate  is  then  weighed,  and  after  correcting  for 
its  slight  solubility  in  the  12  per  cent  hydrochloric  acid  (2.29  mgs.  in 
100  c.c.),  calculated  to  methylfurfural  by  dividing  by  2. 

According  to  Jolles  f  methylfurfural  may  also  be  determined  by  his 
method  of  steam  distillation  and  titration  with  bisulphite  and  iodine 
solutions.  The  reaction  between  bisulphite  and  metyhlfurfural  is 
similar  to  that  described  for  bisulphite  and  furfural,  and  the  details  of 
the  two  methods  are  exactly  alike. 

*  Z.  physiol.  Chem.,  60,  241. 

t  Ann.,  361,  41. 


458  SUGAR  ANALYSIS 

DETERMINATION  OF  PENTOSES  AND  METHYLPENTOSES  IN  MIXTURE 

Method  of  Tollens  and  Ellett.  —  The  method  of  determining 
pentoses  and  methylpentoses  in  mixture  was  first  worked  out  by 
Tollens  and  Ellett,*  and  is  based  upon  the  solubility  of  methylfurfural 
phloroglucide,  and  the  insolubility  of  furfural  phloroglucide  in  warm  95 
per  cent  alcohol. 

In  making  the  determination  the  material  is  distilled  with  12  per 
cent  hydrochloric  acid,  the  distillate  precipitated  with  phloroglucin, 
and  the  mixed  phloroglucides  of  furfural  and  methylfurfural  filtered  in  a 
Gooch  crucible,  dried  and  weighed  according  to  the  usual  process. 

The  crucible  containing  the  mixed  phloroglucides  is  then  placed  in  a 
smaller  beaker  with  95  per  cent  alcohol  which  is  heated  nearly  to  boil- 
ing. The  brown-colored  solution  is  then  sucked  off  through  the  cru- 
cible by  means  of  a  filter  pump,  and  the  extraction  with  hot  95  per 
cent  alcohol  repeated  twice  more  in  the  same  way.  The  crucible  con- 
taining the  insoluble  furfural  phloroglucide  is  then  dried  for  2  hours  in  a 
hot-water  bath  and  reweighed  in  a  weighing  bottle.  The  residual 
weight  of  furfural  phloroglucide  is  then  calculated  to  pentoses  or  pen- 
tosans  and  the  loss  in  weight,  due  to  methylfurfural  phloroglucide, 
calculated  to  methylpentoses,  or  methylpentosans,  by  means  of  the 
respective  tables  or  formulae. 

Trials  of  this  method  of  separation  upon  known  mixtures  of  pentoses 
with  methylpentoses  were  made  by  Ellett  and  Tollens,  and  by  Mayer 
and  Tollens  with  very  close  agreements. 

Modification  by  Hay  wood  of  the  Tollens-Ellett  Method.  —  Haywood,f 
who  has  recently  tested  the  method  of  Tollens  and  Ellett,  believes  that 
a  correction  should  be  made  for  the  slight  solubility  of  the  furfural 
phloroglucide  in  95  per  cent  alcohol.  Experiments  made  by  Hay  wood 
upon  the  phloroglucide  obtained  from  pure  arabinose  showed  that  for 
varying  weights  of  substance,  and  extracting  3  to  5  times  with  alcohol, 
a  very  uniform  weight  of  about  0.0037  gm.  was  always  dissolved.  Hay- 
wood  believes  the  substance  thus  dissolved  to  be  occluded  phloroglucin 
and  not  phloroglucide.  The  following  slight  modification  of  the  Tollens- 
Ellett  method  is  proposed  by  Hay  wood: 

Place  the  Gooch  crucible  containing  the  mixed  phloroglucides  in  a 
100-c.c.  beaker  and  pour  into  the  crucible  30  c.c.  of  95  per  cent  alcohol 
heated  to  60°  G.  Place  the  beaker  for  10  minutes  in  a  water  bath 
heated  to  60°  C.  Remove  the  beaker  and  crucible  and  suck  from  the 

*  Z.  Ver.  Deut.  Zuckerind.  (1905),  19. 
t  Bull.  105,  U.  S.  Bur.  of  Chem.,  p.  112. 


SPECIAL  QUANTITATIVE  METHODS  459 

latter  all  alcohol  remaining  tnerein  with  a  suction  pump.  Repeat  this 
alternate  extraction  and  sucking  dry  of  the  precipitate  3  to  5  times, 
according  to  the  color  of  the  nitrate  obtained.  After  the  final  ex- 
traction place  the  Gooch  crucible  in  a  water  oven  and  dry  four  hours, 
making  the  final  weighing  in  a  closely  stoppered  glass  weighing  bottle. 

The  difference  in  weight  between  the  furfural  phloroglucide  plus 
methylfurfural  phloroglucide  first  obtained  and  the  furfural  phloro- 
glucide remaining  after  extraction  with  alcohol,  minus  0.0037,  repre- 
sents the  amount  of  methylfurfural  phloroglucide  present,  from  which 
the  methylpentose  or  methylpentosan  is  calculated  by  the  tables  or 
formulae. 

To  obtain  the  weight  of  pentosans,  subtract  the  corrected  weight 
of  methylphloroglucide  from  the  weight  of  the  mixture  and  calculate 
according  to  Krober's  tables  or  formulae. 

DETERMINATION  OF  GALACTOSE  OR  GALACTAN 

Tollens  *  and  his  co-workers  have  developed  a  method  for  estimat- 
ing galactose,  and  its  higher  condensation  product  galactan  (C6Hi005)n, 
which  is  based  upon  a  determination  of  the  mucic  acid  formed  by  oxi- 
dation of  the  substance  with  nitric  acid.  The  oxidation  of  galactose  to 
mucic  acid  according  to  theory  proceeds  as  follows: 

C6Hi206      +      2HNO3      =      C6H10O8      +      2H20  +  2NO. 

Galactosg^lSO)  Mucic  acid  (210) 

100  part^of  gatactose  thus  equal  116.66  parts  of  mucic  acid.  In  actual 
experiment  only  about  75  per  cent  of  the  weight  of  galactose  is  obtained 
as  mucic  acid.  This  yield,  however,  is  fairly  constant  for  the  given 
conditions  of  analysis,  so  that  the  weight  of  mucic. acid  multiplied  by 
1J  gives  the  weight  of  galactose. 

The  method  of  Tollens  as  employed  by  the  Association  of  Official 
Agricultural  Chemists  f  is  as  follows: 

Extract  a  convenient  quantity  of  the  substance,  representing  from 
2.5  to  3  grams  of  the  dry  material,  on  a  hardened  filter  with  5  suc- 
cessive portions  of  10  c.c.  of  ether;  place  the  extracted  residue  in  a 
beaker  about  5.5  cm.  in  diameter  and  7  cm.  deep,  together  with  60  c.c. 
of  nitric  acid  of  1.15  sp.  gr.,  and  evaporate  the  solution  to  exactly  one- 
third  its  volume  in  a  water  bath  at  a  temperature  of  94°  to  96°  C. 
After  standing  24  hours,  add  10  c.c.  of  water  to  the  precipitate,  and 
allow  it  to  stand  another  24  hours.  The  mucic  acid  has  in  the  mean- 
time crystallized  but  it  is  mixed  with  considerable  material  only  par- 

*  Ann.,  227,  223;  232,  187. 

f  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  55. 


460  SUGAR  ANALYSIS 

tially  oxidized  by  the  nitric  acid.  Filter  the  solution,  therefore,  through 
filter  paper,  wash  with  30  c.c.  of  water  to  remove  as  much  of  the  nitric 
acid  as  possible,  and  replace  the  filter  and  contents  in  the  beaker. 
Add  30  c.c.  of  ammonium-carbonate  solution,  consisting  of  1  part 
ammonium  carbonate,  19  parts  of  water  and  1  part  strong  ammonium 
hydroxide,  and  heat  the  mixture  on  a  water  bath,  at  80°  C.,  for  15  min- 
utes, with  constant  stirring.  The  ammonium  carbonate  takes  up  the 
mucic  acid,  forming  the  soluble  mucate  of  ammonia.  Then  wash  the 
filter  paper  and  contents  several  times  with  hot  water  by  decant ati on, 
passing  the  washings  through  a  filter  paper,  to  which  finally  transfer 
the  material  and  thoroughly  wash.  Evaporate  the  filtrate  to  dry  ness 
over  a  water  bath,  avoiding  unnecessary  heating  which  causes  decom- 
position; add  5  c.c.  of  nitric  acid  of  1.15  sp.  gr.,  thoroughly  stir  the 
•mixture  and  allow  to  stand  for  30  minutes.  The  nitric  acid  decomposes 
the  ammonium  mucate,  precipitating  the  mucic  acid;  collect  this  on  a 
tared  filter  or  Gooch  crucible,  wash  with  from  10  to  15  c.c.  of  water, 
then  with  60  c.c.  of  alcohol  and  a  number  of  times  with  ether;  dry  at 
the  temperature  of  boiling  water  for  3  hours,  and  weigh.  Multiply 
mucic  acid  by  1.33,  which  gives  galactose  and  multiply  this  product  by 
0.9  which  gives  galactan. 

The  method  of  Tollens  has  been  used  considerably  by  Schulze  and 
Steiger  *  for  determining  galactan  groups  in  different  plants  of  the 
Leguminosse  and  also  by  Bauer  f  for  estimating  galactose  jf$  lactose 
in  the  urine.  *  ^ 

The  presence  of  large  amounts  of  foreign  organic  matter  hinders 
the  precipitation  of  mucic  acid,  and  in  case  of  only  small  amounts  of 
the  latter  may  prevent  its  separation  entirely.  The  tendency  of  the 
method  is,  therefore,  to  give  too  low  rather  than  too  high  results. 

FERMENTATION  METHODS  FOR  DETERMINING  SUGARS 

A  method  for  estimating  sugars  has  been  described  (p.  299)  which  is 
based  upon  the  change  in  polarization  which  the  solution  undergoes 
after  fermenting  with  yeast. 

The  fermentation  methods  for  determining  sugars  are  more  usually 
carried  out  by  weighing  or  measuring  the  carbon  dioxide  which  is 
evolved.  The  theoretical  yield  of  carbon  dioxide  from  glucose,  accord- 
ing to  the  equation  C6Hi2O6  =  2  C2H5OH  +  2  CO2,  is  48.88  per  cent. 
In  actual  experiments  only  about  45  per  cent  of  CO2  is  obtained,  this 
figure  varying,  however,  by  several  per  cent  according  to  the  variety 

*  Landw.  Vers.  Stat.,  36,  11;  36,  438,  465. 
t  Z.  physiol.  Chem.,  61,  159. 


SPECIAL  QUANTITATIVE  METHODS 


461 


of  yeast,  influence  of  non-sugars  and  other  conditions.  The  weight  of 
carbon  dioxide  obtained  during  a  normal  fermentation  multiplied  by 
the  factor  2.2  will  give  the  approximate  amount  of  fermentable  hexose 
sugars  present.  The  fermentation  method  is  employed  almost  en- 
tirely for  determining  small  percentages  of  sugar,-  and  has  found  its 
widest  application  in  the  determination  of  glucose  in  urine. 

Direct  Method  by  Weighing  Carbon  Dioxide.— The  most  accurate 
method  for  determining  the  yield  of  carbon  dioxide  upon  fermentation 


Fig.  178. — Apparatus  for  determining  sugars  from  weight  of  carbon  dioxide  given 

off  by  fermentation. 

is  shown  in  Fig.  178.  A  known  amount  of  the  solution  is  sterilized  in  a 
small  flask,  then  cooled  and  inoculated  with  a  pure  culture  of  yeast. 
The  flask  is  then  connected  by  means  of  a  condenser  with  a  train  of 
absorption  tubes,  or  bulbs.  Bulb  I  (Fig.  178)  contains  a  few  cubic 
centimeters  of  water,  the  U-tubes  II  and  III  contain  calcium  chloride 
for  removing  all  moisture  from  the  current  of  gas,  the  Liebig  potash 
bulb  IV,  which  has  been  previously  weighed,  serves  to  absorb  the 
carbon  dioxide,  and  the  safety  tube  V,  containing  calcium  chloride  and 
soda  lime,  prevents  back  absorption  of  water,  or  carbon  dioxide,  from 
the  outside  air.  The  fermentation  is  allowed  to  proceed  either  at  room 
temperature,  or,  if  desired,  at  30°  C.,  in  which  case  the  flask  is  immersed 
in  a  water  bath  carefully  maintained  at  this  temperature.  At  the  end  of 
1  to  2  days,  when  no  more  gas  passes  through  the  bulb  I,  the  tube  V  is 
connected  with  the  aspirator  bottle  B,  the  pinchcock  at  p,  which  is 
previously  closed,  opened  and  a  slow  current  of  air,  freed  from  carbon 
dioxide  by  passing  through  potassium  hydroxide  solution,  led  through 


462 


SUGAR  ANALYSIS 


the  apparatus.  At  the  end  of  an  hour  the  liquid  in  the  flask  is  heated 
nearly  to  boiling,  while  a  current  of  cold  water  circulates  through  the 
condenser;  in  this  manner  the  last  traces  of  dissolved  carbon  dioxide 
are  expelled  from  the  liquid.  The  aspiration  is  continued  for  another 
hour,  when  the  potash  bulb  IV  is  disconnected  and  reweighed.  The 
increase  in  weight  gives  the  amount  of  carbonic  acid. 

The  more  usual  process,  in  the  fermentation  method  of  estimating 
sugars,  is  to  estimate  the  carbon  dioxide  by  measuring  the  volume  of 
gas;  1  c.c.  of  evolved  carbon  dioxide  (at  0°  C.  and  760-mm.  atmospheric 
pressure)  corresponds  to  1.96  mgs.  carbon  dioxide  or  about  4  mgs.  of 
glucose.  For  determining  sugars  by  this  method  special  forms  of  appa- 
ratus known  as  fermentation  saccharometers  have  been  devised,  of  which 
the  two  forms  devised  by  Einhorn  and  by  Lohnstein  are  selected  as 
examples. 

Einhorn's  Fermentation  Saccharometer.*  —  This  apparatus,  which 
is  designed  for  the  estimation  of  small  amounts  of  glucose  in  diabetic 

urine,  is  shown  in  Fig.  179.  One 
gram  of  commercial  pressed  "yeast  is 
shaken  thoroughly  in  the  graduated 
test  tube  with  10  c.c.  of  the  urine. 
The  mixture  is  then  poured  into  the 
bulb  of  the  saccharometer,  the  ap- 
paratus being  inclined  so  that  the 
graduated  tube  is  completely  filled. 
The  saccharometer  is  then  set  aside 
for  20  to  24  hours  at  ordinary 
temperature.  If  the  urine  contains 
sugar,  fermentation  will  usually  be- 
gin in  about  30  minutes.  When  the 
fermentation  is  finished  the  volume 
of  gas  is  measured  in  the  graduated 
tube,  the  divisions  of  which  indicate 
cubic  centimeters  of  gas  and  also  the 
approximate  fractions  of  per  cent 
glucose.  If  the  urine  contains  more 
than  1  per  cent  glucose  it  must  first 
be  diluted  with  water,  the  reading  of  the  saccharometer  being  then 
multiplied  by  the  degree  of  dilution.  For  diabetic  urines  of  straw 
color  and  a  specific  gravity  of  1.018  to  1.022  it  is  recommended  to  dilute 
twice;  of  1.022  to  1.028  sp.  gr.  5  times,  and  1.028  to  1.038  sp.  gr.  10  times. 
*  Circular  of  information. 


Fig.  179.  —  Einhorn's  fermentation 
saccharometer. 


SPECIAL  QUANTITATIVE  METHODS 


463 


It  is  always  desirable  in  making  the  test  to  make  a  duplicate  de- 
termination upon  a  normal  urine.  The  latter  should  show  at  most 
only  a  small  bubble  of  gas  at  the  top  of  the  tube;  should  a  larger 
amount  of  carbon  dioxide  be  obtained  with  normal  sugar-free  urine,  the 
yeast  is  probably  impure  and  the  determination  should  be  repeated. 
If  the  suspected  urine  shows  no  more  gas  than  the  control  experiment 
the  absence  of  glucose  is  indicated. 

Lohnstein's  *  Fermentation  Saccharometer.  —  In  Lohnstein's  sac- 
charometer  (Fig.  180)  the  liquid  is  fermented  over  mercury  in  a  closed 
bulb;  the  carbon  dioxide,  which  is  evolved,  forces 
the  mercury  into  an  upright  tube,  the  amount  of 
displacement  indicating  the  per  cent  of  glucose 
present. 

In  making  a  determination  the  detachable  scale 
S  is  hung  in  position  over  the  open  end  of  the  tube 
T,  and  a  quantity  of  mercury  poured  into  the  bulb 
B  until  its  level  in  the  tube  is  just  opposite  the 
zero  mark  of  the  scale.  The  standard  weight  of 
mercury,  necessary  for  the  adjustment,  accompanies 
each  instrument. 

A  small  piece  of  pressed  yeast  is  rubbed  with  2  to 
3  times  its  volume  of  ordinary  water  to  a  thin  paste ; 
0.5  c.c.  of  the  urine,  or  other  liquid  to  be  tested,  is 
then  measured  with  a  special  pipette  into  the  bulb; 
the  pipette  is  rinsed  into  the  bulb  with  a  little  ordi- 
nary water  and  2  to  4  drops  of  the  yeast  water 
added.  The  glass  stopper,  which  should  be  evenly 
greased,  is  then  inserted,  and  turned  so  that  the 
small  opening  on  its  inner  surface  comes  directly 

opposite  a  similar  opening  in  the  stem  of  the  bulb.Fig-180--Lohnstein's 
»     .       ,  ,.         ,,  •          fermentation    sac- 

Any  pressure  of  air,  due  to  inserting  the  stopper,  is      charometer 

thus  released.  The  stopper  is  again  slightly  turned, 
so  as  to  seal  the  contents  of  the  bulb  hermetically,  and  then  securely 
fastened  by  the  weight  W.  The  apparatus  is  then  set  aside  until  fer- 
mentation is  finished,  which  is  indicated  by  the  stationary  position  of  the 
mercury  column.  The  length  of  time  necessary  for  completing  the  test 
will  depend  upon  the  temperature  but  does  not  ordinarily  exceed  1  day  at 
20°  C.;  if  an  incubator  is  available  the  time  may  be  shortened  con- 
siderably by  fermenting  at  35°  C.  When  fermentation  is  finished  the 
scale  division  opposite  the  top  of  the  mercury  column  indicates  the 
*  Miinchener  med.  Wochenschr.  (1899)-,  No.  50;  also  circular  of  information. 


464  SUGAR  ANALYSIS 

percentage  of  sugar;  for  percentages  of  sugar  below  2.0  the  scale  may 
be  read  to  0.01  per  cent  and  for  percentages  between  2.0  and  10.0 
to  0.05  per  cent.  The  scale  is  calibrated  upon  one  side  for  20°  C.  and 
upon  the  other  for  35°  C.;  if  the  readings  be  made  at  intermediary 
temperatures  the  percentage  of  sugar  is  calculated  by  interpolating. 
Thus: 

The  reading  of  the  mercury  column  at  25°  C.  was  4.0  on  the  20°  C. 
scale  and  3.6  on  the  35°  C.  scale.  The  corrected  percentage  of  sugar  is 

then  3.6  +  4'!?  ~  ^6  (35  -  25)  =  3.87  per  cent. 

oO  —  ZO 

Instead  of  finding  the  weight  or  volume  of  carbon  dioxide  the  per- 
centage of  fermentable  sugar  may  also  be  calculated  from  the  amount 
of  alcohol  which  is  found  by  the  action  of  yeast,  or  from  the  difference 
in  specific  gravity  of  the  solution  before  and  after  fermentation.  A 
valuable  check  upon  the  accuracy  of  the  results  obtained  by  the  fer- 
mentation methods  is  to  determine  the  loss  in  reducing  sugars  by 
means  of  Fehling's  solution. 

COLORIMETRIC  METHODS  FOR  DETERMINING  SUGARS 

A  number  of  colorimetric  methods  have  been  devised  for  determin- 
ing small  amounts  of  different  sugars  in  solution.  The  first  process  of 
this  kind  was  due  to  Dubrunfaut  who  determined  small  percentages  of 
glucose  by  comparing  the  color,  which  was  produced  by  heating  the 
solution  with  alkalies,  with  the  colors  of  solutions  containing  known 
amounts  of  pure  glucose,  which  had  been  similarly  treated. 

In  addition  to  the  alkalies  many  of  the  special  reagents,  used  in 
making  color  and  spectral  reactions,  such  as  a-naphthol,  resorcin,  etc., 
have  been  employed  for  the  colorimetric  estimation  of  sugars.  The 
principal  requirement  in  the  use  of  such  reagents  for  quantitative  pur- 
poses is  that  the  color  produced  must  be  perfectly  soluble  and  of  a 
fair  degree  of  stability.  The  insoluble,  or  evanescent,  colors,  which 
are  produced  in  many  of  the  reactions  for  sugars,  are  valueless  for 
colorimetry. 

For  making  accurate  comparisons  of  intensity  of  color,  a  special 
apparatus,  called  a  colorimeter,  must  be  used.  The  colorimeter  of 
Duboscq  is  one  of  the  best  known  and  is  selected  for  description. 

Duboscq's*  Colorimeter.  —  The  colorimeter  of  Duboscq,  as  mod- 
ified by  Pellin,  is  shown  in  Fig.  181.  The  apparatus  consists  of  an 
upright  case,  the  front  and  sides  of  which  are  in  one  piece  B,  and 
hinged  to  the  back.  At  the  bottom  of  the  case  is  a  shelf  S,  containing 

*  Circular  of  information. 


SPECIAL  QUANTITATIVE  METHODS 


465 


two  circular  openings,  above  which  rest  the  two  cylinders  C  and  C'. 
The  latter  are  very  carefully  constructed,  being  closed  at  the  bottom 
by  disks  of  glass  whose  upper  and  lower  surfaces  are  perfectly  plane 
parallel.  Two  immersion  rods  of  solid  glass,  T  and  T'  —  the  ends  of 


M 


Fig.  181. 


Fig.  182. 


Duboscq's  colorimeter. 


which  are  also  plane  parallel  —  are  attached  to  movable  slides  in  the 
back  of  the  case  and  can  be  raised  or  lowered  within  the  cylinders. 
The  height  of  the  lower  surface  of  each  rod  above  the  bottom  of  its 
cylinder  is  indicated  upon  a  scale,  which  by  means  of  a  vernier  can  be 
read  to  0.1  mm.  The  colorimeter  is  illuminated  by  light  from  the  re- 
flector M,  which  from  its  opposite  surfaces  gives  either  bright  or  diffused 
light  according  to  the  requirements  of  sensibility.  The  light,  as  shown 
in  Fig.  182,  passes  upward  through  each  cylinder  and  immersion  rod  to 


466  SUGAR  ANALYSIS 

the  prisms  P  and  P',  from  which  it  is  reflected  upwards  into  the  tele- 
scope A.  The  field,  when  the  telescope  is  focused,  consists  of  a  circle 
F,  divided  into  equal  parts,  exactly  resembling  the  double  field  of  a 
polariscope.  Daylight  is  to  be  preferred  for  illuminating  the  colorim- 
eter although  artificial  white,  or  monochromatic,  light  may  be  used 
according  to  requirement.  In  preparing  the  instrument  for  use,  the 
mirror  must  be  adjusted  so  that  both  halves  of  the  field  appear  of  ex- 
actly equal  intensity. 

The  sugar  solution  which  is  to  be  tested  is  placed  in  one  cylinder 
and  the  standard  solution,  containing  a  known  percentage  of  the  same 
sugar,  in  the  other,  both  solutions  having  been  previously  treated  under 
similar  conditions  with  alkali  or  other  color-producing  reagent.  The 
door  of  the  case  is  then  closed  and  the  rod  immersed  in  the  solution  to 
be  tested  to  some  convenient  scale  division,  as  100  mm.,  50  mm.,  etc., 
at  which  point  the  color  of  its  half  of  the  field  should  be  of  suitable  in- 
tensity for  comparison.  The  other  rod  is  then  immersed  in  the  cylinder 
of  standard  solution,  and  lowered  or  raised  until  the  two  halves  of  the 
field  are  of  equal  intensity.  The  heights  of  the  immersion  rods  above 
the  bottoms  of  the  cylinders  will  then  be  inversely  proportional  to  the 
depth  of  color  and  hence  to  the  amount  of  sugar  in  solution.  The  cal- 
culation is  made  as  follows: 

If  A  =  the  elevation  of  rod  in  standard  solution, 
B  =  the  elevation  of  rod  in  solution  to  be  tested, 
P  =  the  per  cent  of  sugar  in  standard  solution, 
X  =  the  per  cent  of  sugar  in  solution  to  be  tested, 
AXP 


then  X  = 


B 


Example.  —  50  gms.  of  a  glucose  solution  of  unknown  strength  were  made 
up  to  500  c.c.  with  water,  adding  5  c.c.  of  dilute  NaOH  solution  (solution  I). 

One  gram  of  pure  glucose  was  dissolved  in  water  and  the  solution  made  up 
to  500  c.c.  adding  also  5  c.c.  of  the  same  NaOH  solution  (solution  II). 

Both  solutions  were  heated  in  a  hot-water  bath  for  the  same  length  of  time 
and  after  cooling  compared  in  a  Duboscq  colorimeter. 

When  the  immersion  rod  in  solution  I  was  set  at  100  mm.,  the  immersion 
rod  in  solution  II  gave  equal  intensity  to  the  field  at  160.2  mm. 


1 

Then        VL       =  1-60  gms.  of  glucose  in  the  500  c.c.  of  solution  I,  or  3.2 
per  cent  in  the  original  sample. 

Johnson*  has  recommended  heating  with  alkaline  picric-acid  solu- 
tion for  the  colorimetric  determination  of  glucose.     Picric  acid  is  reduced 
*  Mon.  sclent.,  Ill,  13,  939. 


SPECIAL  QUANTITATIVE  METHODS  467 

by  glucose  and  other  sugars  in  alkaline  solution  to  picramic  acid, 
the  deep  red  color  of  which  is  sharply  developed  by  less  than  0.01  per 
cent  of  sugar.  As  stable  color  standards  Johnson  recommends  solu- 
tions of  ferric  acetate,  or  of  ferric  chloride  and  acetic  acid,  which  have 
been  prepared  so  as  to  match  the  color  produced  by  a  known  weight  of 
sugar  under  the  conditions  of  the  method. 

Many  of  the  color  reactions  of  sugars  are  affected  by  the  presence 
of  organic  or  mineral  impurities;  the  usefulness  of  colorimetric  methods 
in  estimating  sugars  is  for  this  reason  largely  curtailed. 

Ehrlich's  Colorimetric  Method  for  Estimating  Caramel.  —  Ehrlich* 
has  devised  a  colorimetric  method  for  estimating  caramel,  in  which  the 
standard  of  comparison  is  saccharan.  This  dark-colored  caramel  sub- 
stance is  produced  by  heating  sucrose  in  a  flask  immersed  in  oil  to 
about  200°  C.  under  vacuum.  The  residue,  after  extracting  with 
boiling  methyl  alcohol,  is  dissolved  in  water,  filtered  and  evaporated. 
The  saccharan,  Ci2Hi809,  is  obtained  as  a  dark-brown  residue  (about 
20  per  cent  of  the  weight  of  sucrose)  which  is  easily  pulverized  to  an 
amorphous  powder.  One  part  of  saccharan  in  10,000  of  water  colors 
the  solution  a  deep  brown,  which  is  intensified  by  the  addition  of 
alkalies.  Saccharan  is  not  precipitated  by  lead  sub-acetate  solution, 
so  if  the  latter  is  used  for  precipitating  other  coloring  substances  from 
solutions  of  sugars,  molasses,  etc.,  the  percentage  of  saccharan  in  the 
neutralized  filtrates  may  be  estimated  by  comparison  in  a  colorimeter 
with  a  solution  containing  a  known  weight  of  saccharan.  The  amount 
of  saccharan  multiplied  by  5  indicates  the  approximate  amount  of 
sucrose  destroyed  by  superheating  during  manufacture. 

Stammer's  Colorimeter.  —  Colorimeters  are  employed  in  technical 
sugar  analysis  for  grading  sirups,  for  estimating  the  decolorizing  power 
of  bone  black  or  other  clarifying  agent,  and  for  many  other  purposes 
in  which  degree  of  color,  and  not  determination  of  color-producing  sub- 
stance, is  desired.  For  determinations  of  this  kind  colored  plates,  or 
disks,  of  glass  are  usually  employed  as  a  standard  of  comparison,  the 
results  being  expressed  in  units  of  an  arbitrary  color  scale. 

A  colorimeter  which  is  used  extensively  in  the  sugar  industry  is 
that  of  Stammer  f  (Fig.  183).  The  general  principle  of  this  apparatus 
is  the  same  as  that  of  Duboscq.  The  liquid  to  be  tested  is  placed  in 
the  cylinder  a,  which  is  closed  by  a  glass  plate  at  the  bottom.  The 
measuring  tube  c,  also  closed  at  the  bottom  by  a  glass  plate,  fits 

*  Z.  Ver.  Deut.  Zuckerind.,  59,  746.  Proceedings,  Seventh  International  Con- 
gress of  Applied  Chem.,  Sect.,  V,  p.  92. 

t  Stammer's  "  Zuckerf  abrikation  "  (1887),  p.  747. 


468 


SUGAR  ANALYSIS 


loosely  into  a  and  can  be'  raised  or  lowered  to  any  desired  level.     The 
comparison  tube  b,  which  is  open  at  the  bottom,  is  joined  to  c,  the 

two  being  moved  in  conjunction  by  a 
slide  in  the  back  of  the  instrument. 
The  colorimeter  is  illuminated  by  a  re- 
flector at  the  bottom,  the  light  passing 
upward  through  b  and  c  into  the  prisms 
in  d  which  produce  the  same  double- 
field  effect  as  in  the  Duboscq  apparatus. 
In  operating  the  colorimeter  the 
standard  plate  of  colored  glass  is  placed 
upon  tube  6,  which  together  with  tube  c 
is  then  raised  or  lowered  until  the  in- 
tensity of  shade  for  solution  and  color 
plate  is  the  same  in  both  halves  of 
the  field.  A  millimeter  scale  upon  the 
back  of  the  instrument  marks  the  eleva- 
tion of  the  measuring  tube  above  the 
bottom  of  the  cylinder,  thus  indicating 
the  thickness  of  the  column  of  liquid. 

Stammer  gives  a  solution  which 
matches  the  standard  plate  for  a  scale 
reading  of  1  mm.,  a  color  value  of  100. 
The  color  value  of  any  liquid  is  found 
by  dividing  100  by  the  reading  of  the 
scale  in  millimeters. 

In  measuring  the  color  of  sugars, 
molasses,  etc.,  a  weighed  amount  of 
substance  is  dissolved  in  water,  made 
up  to  a  definite  volume  and,  if  the  solution  is  not  clear,  filtered. 
The  color  value  of  the  solution  is  then  calculated  either  to  the 
original  amount  of  substance,  or  to  a  polarization  of  100,  according 
to  requirement. 

Example.  —  20  gms.  of  a  sugar,  polarizing  92.4,  were  dissolved  to  100  c.c. 
and  filtered.  The  solution  gave  a  reading  of  15  mm.  upon  Stammer's  colorim- 
eter. Then  W  =  6.666  the  color  value  of  the  solution.  The  color  value 
calculated  to  100  parts  sugar  would  be  20  :  6.666  ::  100  :  x  =  33.33.  The 
latter  calculated  to  100  polarization  would  give  92.4  :  33.33  ::  100  :  x  =  36.07. 

For  determining  the  decolorization  produced  by  bone  black  the 
color  value  of  the  solution  is  taken  before  and  after  filtration.  If  the 


Fig.  183.  —  Stammer's  colorimeter. 


SPECIAL  QUANTITATIVE  METHODS  469 

original  solution  is  too  dark  for  reading  in  the  colorimeter,  it  is  diluted 
with  water,  in  which  case  the  filtered  solution  is  also  diluted  to  the  same 
density. 

Example.  —  An  unfiltered  sirup  diluted  to  10  degrees  Brix  gave  a  reading 
of  8  mm.,  or  l|a  =  12.5  color  units,  using  a  Stammer  colorimeter.  The  liquid, 
after  filtering  through  bone  black,  and  diluting  to  10  degrees  Brix  gave  a  read- 
ing of  40  mm.,  or  W  =  2.5  color  units.  The  amount  of  color  removed  by  the 

10  K  9  ^ 

bone  black  is  then  -  X  100  =  80  per  cent. 

12.5 

A  table  of  reciprocals  (Appendix,  Table  25)  will  be  found  convenient 
for  converting  the  scale  measurements  of  Stammer's  colorimeter  into 
color  units. 

DETERMINATION  OF  SUGARS  BY  WEIGHING  AS  HYDRAZONES  AND 

OSAZONES 

The  varying  solubility  of  the  different  hydrazones  and  osazones  of 
sugars  in  presence  of  impurities,  or  of  other  similar  derivatives,  has 
prevented  the  general  employment  for  quantitative  purposes  of  this 
means  of  separating  sugars.  In  certain  cases,  however,  where  the 
hydrazone,  or  osazone,  is  characterized  by  great  insolubility  a  fairly 
accurate  determination  of  several  of  the  sugars  has  been  found  possible. 

Determination  of  Arabinose  as  Diphenylhydrazone.  —  According 
to  Neuberg  *  arabinose  is  precipitated  quantitatively  by  treating  the 
sirupy  solution  of  sugar  with  a  slight  excess  of  diphenylhydrazine. 
Sufficient  alcohol  is  added  to  form  a  perfectly  clear  solution,  and  the 
mixture  heated  to  boiling  for  30  minutes  in  a  water  bath  in  a  flask  con- 
nected with  a  reflux  condenser.  The  solution  is  cooled,  allowed  to 
stand  for  several  hours  and  the  white  crystalline  hydrazone  filtered 
into  a  weighed  Gooch  crucible.  After  washing  with  a  few  cubic  centi- 
meters of  cold  alcohol,  the  crucible  is  dried  in  a  water  oven  and  weighed. 

The  weight  of  arabinose  diphenylhydrazone,  CsHioC^N  •  N(-C6H5)2, 
is  calculated  to  arabinose,  C5Hi005,  by  multiplying  by  M§  =  0.4747. 
This  method  of  analysis  has  been  used  by  Neuberg  for  estimating 
arabinose  in  the  urine  and  by  Maurenbrecher  and  Tollens  f  for  de- 
termining arabinose  in  cacao. 

Determination  of  Mannose  as  Phenylhydrazone.  —  The  property 
of  mannose  in  forming  with  phenylhydrazine  a  very  insoluble  hydra- 
zone,  discovered  by  Fischer  and  Hirschberger,t  has  been  used  for  the 
quantitative  estimation  of  mannose.  The  precipitation,  according  to 

*  Ber.,  36,  2243.  f  Ber.,  39,  3578.  |  Ber.,  21,  1805. 


470  SUGAR  ANALYSIS 

Bourquelot  and  Herissey,*  is  best  accomplished  by  treating  a  3  to  6 
per  cent  solution  of  the  sugar  with  an  excess  of  phenylhydrazine  acetate 
at  a  temperature  not  above  10°  C.  After  standing  24  hours,  the  white 
crystalline  hydrazone  is  filtered  upon  a  weighed  Gooch  crucible,  washed 
with  a  little  cold  water,  dried  in  a  water  oven  and  weighed.  The  solu- 
bility of  the  hydrazone  is  0.04  gm.  in  100  c.c.  of  solution,  and  the 
weight  of  precipitate  should  be  corrected  accordingly. 

The  weight  of  mannose  phenylhydrazone,  CeH^C^^HCeHs,  is  cal- . 
culated  to  mannose,  C6Hi2O6,  by  multiplying  by  |f§  =  f ,  or  0.6666. 
The  method  is  well  adapted  for  determining  mannose  in  presence  of 
other  sugars  and  has  been  employed  by  Pellet  f  for  estimating  small 
amounts  of  mannose  in  sugar-cane  molasses. 

Determination  of  Fructose  as  Methylphenylosazone.  —  According 
to  Neuberg  {  fructose  may  be  determined  with  a  fair  approximation 
by  precipitating  as  its  methylphenylosazone,  CeHioO^^CHsCeH^. 
About  10  c.c.  of  the  concentrated  sugar  solution  are  treated  with  a 
slight  excess  of  methylphenylhydrazine,  and  sufficient  alcohol  added 
to  give  a  clear  solution.  If  other  sugars  than  fructose  are  present  the 
solution  is  slightly  warmed  and  allowed  to  stand  24  hours  for  the  sepa- 
ration of  any  insoluble  hydrazones  of  mannose,  galactose,  etc.  After 
removing  any  precipitate  by  suction,  the  filtrate  is  treated  with  4  c.c. 
of  50  per  cent  acetic  acid,  heated  5  to  10  minutes  upon  the  water  bath, 
and  then  set  aside  in  the  cold  for  24  hours.  The  reddish-yellow  crys- 
tals of  the  osazone  are  filtered  in  a  weighed  Gooch  crucible  and  cal- 
culated to  fructose,  C6Hi206,  by  multiplying  by  J|J  =  0.4663.  The 
method  is  only  approximate  as  10  per  cent  or  more  of  the  osazone 
remains  in  solution.  By  using  a  very  cold  freezing  mixture  the  sepa- 
ration has  been  made  almost  quantitatively. 

SIEBEN'S  METHOD  FOR  ESTIMATING  FRUCTOSE 

Sieben  §  in  1884  proposed  a  method  for  determining  fructose  which 
is  based  upon  the  destruction  of  this  sugar  when  heated  with  dilute 
hydrochloric  acid.  The  method  was  designed  for  estimating  fructose 
in  honey,  sirups  and  other  products  which  contain  glucose.  The  latter 
sugar,  like  other  aldoses,  is  much  less  susceptible  to  the  destructive 
action  of  acids,  so  that  the  difference  in  the  reducing  power  of  a  solu- 

*  Compt.  rend.,  129,  339. 

t  Bull,  assoc.  chim.  sucr.  dist.,  16,  1181;   18,  758. 

t  Ber.,  35,  960. 

§  Z.  Ver.  Deut.  Zuckerind.  (1884),  837,  865. 


SPECIAL  QUANTITATIVE  METHODS  471 

tion  before  and  after  treatment  by  Sieben's  process  is  taken  as  the 
equivalent  of  the  fructose  present. 

In  making  the  determination  100  c.c.  of  the  solution,  which  should 
contain  about  2.5  gms.  of  total  reducing  sugars,  are  heated  in  a 
250-c.c.  graduated  flask  with  60  c.c  of  6-normal  hydrochloric  acid 
(36.47  X  6  =  218.8  gms.  HC1  per  liter)  for  3  hours  in  a  boiling-water 
bath.  A  funnel  is  placed  in  the  neck  of  the  flask  to  prevent  evapo- 
ration. The  solution  is  then  cooled  and  neutralized  with  6-normal 
sodium  hydroxide  (40  X  6  =  240  gms.  NaOH  per  liter),  of  which  from 
56  to  58  c.c.  are  usualty  required.  The  contents  of  the  flask  are  then 
made  up  to  250  c.c.,  filtered  and  the  reducing  sugars  determined  in  25  c.c. 
of  the  filtrate  by  Allihn's  method.  The  reducing  sugar  thus  found  is 
calculated  as  glucose,  and  the  difference  in  reducing  sugar  before  and 
after  the  acid  treatment  estimated  as  fructose. 

According  to  Sieben  only  about  1.5  per  cent  of  the  total  glucose  is 
destroyed  under  the  conditions  of  his  method.  Herzf eld  *  found,  how- 
ever, that  the  destruction  of  glucose  may  exceed  7  per  cent.  Wiech- 
mannf  also  showed  that  the  complete  destruction  of  the  fructose  is  not 
always  assured  so  that  "  the  results  obtained  by  this  method  must  be 
received  with  some  caution."  Dammullert  found  that  the  destructive 
power  of  the  acid  depended  largely  upon  the  ratio  of  glucose  to  fructose; 
with  mixtures  of  glucose  and  fructose  in  equal  proportions  only  1.28 
per  cent  of  glucose  was  destroyed,  with  pure  glucose  on  the  other  hand 
the  loss  exceeded  28  per  cent.  Attempts  to  modify  and  improve  the 
process  so  as  to  overcome  these  objections  have  not  been  wholly  suc- 
cessful. 

*  Z.  Ver.  Deut.  Zuckerind.,  35,  967. 
t  Wiechmann's  "Sugar  Analysis"  (1898),  p.  54. 
4  Z.  Ver.  Deut.  Zuckerind.,  38,  751. 


CHAPTER  XVI 

COMBINED  METHODS   AND  THE  ANALYSIS  OF  SUGAR  MIXTURES 

IN  previous  chapters  upon  polariscopic  and  chemical  methods 
several  instances  were  given  of  the  application  of  certain  processes  to 
the  analysis  of  sugar  mixtures.  In  the  present  chapter  the  problem  of 
determining  several  sugars  in  presence  of  one  another  will  be  taken  up 
in  somewhat  fuller  detail. 

If  the  sum  of  the  specific  rotations,  copper-reducing  powers  or 
other  properties  of  the  different  sugars  in  a  mixture  can  be  expressed 
by  a  sufficient  number  of  equations,  the  problem  of  determining  the 
percentage  of  each  sugar  in  the  mixture  may  be  solved  by  simple  alge- 
braic analysis.  By  thus  combining  the  results  of  several  distinct 
methods  it  is  possible  by  indirect  means  to  make  an  analysis  of  many 
sugar  mixtures  with  a  fair  degree  of  accuracy.  The  combinations  of 
methods,  which  have  been  proposed  for  this  purpose,  are  almost  number- 
less and  only  a  few  examples  will  be  chosen  to  illustrate  the  general 
principle.  The  methods  will  be  grouped  for  convenience  under 
(1)  Combined  polariscopic  methods;  (2)  Combined  reduction  methods; 
(3)  Combined  polariscopic  and  reduction  methods. 

COMBINED  POLARISCOPIC  METHODS 

If  two  sugars,  A  and  B,  exhibit  a  known  variation  in  specific  rota- 
tion under  different  conditions  of  polarization,  then  the  percentages,  x 
and  y,  of  the  two  sugars  may  be  determined  by  means  of  the  following 
equations: 

ax  +  by  =  lOOWz),  (1) 

a'x+b'y=lW[a]D',  (2) 

in  which  [oi\D  and  [U]D  are  the  specific  rotations  of  the  mixture  A  +  J5, 
a  and  a'  the  known  specific  rotations  of  sugar  A  and  b  and  bf  the  known 
specific  rotations  of  sugar  B,  under  the  respective  conditions  of  (1)  and  (2) . 
By  determining  [O\D  and  [O\D  ,  the  percentages  x  and  y  are  readily  cal- 
culated. 

As  an  example  of  this  method  of  analysis  the  determination  of 
glucose  and  fructose  by  polarization  at  20°  C.  and  87°  C.,  under  the 

472 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    473 

conditions  previously  described  (p.  296),  is  given.  If  the  [«]*>  and  [a]% 
of  glucose  are  +52.5  and  of  fructose  —92.5  and  —52.5  respectively,  then 
the  [«]g  and  [a]g  of  a  mixture  containing  x  per  cent  glucose  and  y  per 

cent  fructose  are 

52.5  x  -  92.5  y  =  100[a]£ 

52.5  x  -  52.5  y  =  100[a]g 

By  determining  the  [a]"  and  [«]^  of  the  mixture  the  percentages  of 
glucose  and  fructose  are  readily  calculated. 

Any  other  temperature,  at  which  the  [a]^  of  each  of  the  sugars  is 
known,  may  of  course  be  taken  instead  of  20°  C.  and  87°  C.  The  re- 
sults as  thus  calculated  are  of  course  only  approximate  and  require  to 
be  corrected  for  the  influence  of  concentration. 

In  addition  to  varying  the  temperature,  changes  of  condition  may 
be  accomplished  by  making  one  polarization  in  neutral  and  the  other 
in  acid  solution;  or  one  polarization  in  water,  and  the  other  in  some 
other  solvent;  or  one  polarization  in  the  absence  and  the  other  in  the 
presence  of  borax  or  other  substance;  in  all  of  which  changes  of  con- 
dition a  definite  known  alteration  in  the  polarizing  power  of  one  or 
both  sugars  must  be  produced.  Obviously  the  greater  the  degree  of 
this  change  in  polarizing  power,  the  less  will  be  the  influence  of  ex- 
perimental errors. 

COMBINED  REDUCTION  METHODS 

If  two  sugars,  A  and  B,  exhibit  a  known  variation  in  reducing 
power  under  different  conditions  of  analysis,  then  the  percentages  x 
and  y  of  the  two  sugars  may  be  determined  by  means  of  the  general 
equations : 

ax  +  by  =  100/2,  (1) 

a'x+b'y  =  lQOR',  (2) 

in  which  R  and  Rf  are  the  reducing  powers  of  the  mixture  A  +  B,  a  and 
a'  the  known  reducing  powers  of  sugar  A,  and  b  and  bf  the  known  re- 
ducing powers  of  sugar  B,  under  the  respective  conditions  of  (1)  and  (2). 
By  determining  R  and  R',  the  percentages  x  and  y  are  readily  calculated. 

A  good  example  of  the  application  of  the  above  formulae  is  given  by 
Soxhlet's  *  well-known  method  for  determining  two  sugars  in  mixture. 

A  comparison  of  the  reducing  powers  of  different  sugars  upon  Feh- 
ling's  copper  solution  (Soxhlet's  formula)  and  Sachsse's  mercury  solu- 
tion was  made  by  Soxhlet  with  the  following  results: 

*  J.  prakt.  Chem.  (1880),  21,  300;  Konig's  " Untersuchung "  (1898),  217. 


474 


SUGAR  ANALYSIS 


TABLE  LXXXII 
Showing  Relative  Reducing  Power  of  Fehling's  and  Sachsse's  Solutions 


Sugar. 

1  gm.  sugar  in  1  per  cent  solu- 
tion reduces 

Milligrams  of  sugar  in  1  per  cent 
solution  reduce 

Fehling's  solu- 
tion. 

Sachsse's  solu- 
tion. 

100  c.c. 

Fehling's  solu- 
tion. 

100  c.c. 
Sachsse's  solu- 
tion. 

Glucose  

c.c. 

210.4 
194.4 
202.4 
196.0 
148.0 
202.4 
128.4 

c.c. 

302.5 
449.5 
376.0 
226.0 
214.5 
257.7 
197.6 

Mgs. 
475.3 
514.4 
494.1 
510.2 
675.7 
494.1 
778.8 

Mgs. 

330.5 
222.5 
266.0 
442.0 
466.0 
388.0 
506.0 

Fructose 

Invert  sugar 

Galactose 

Milk  sugar  ... 

Milk  sugar  hydrolyzed  
Maltose 

The  results  show  that  the  various  sugars  differ  very  decidedly  in 
their  relative  reducing  powers  upon  the  two  reagents,  glucose,  for  ex- 
ample, reducing  more  Fehling's  but  less  Sachsse's  solution  than  fructose. 

The  combined  influences  of  two  sugars,  A  and  B,  in  their  reducing 
powers  upon  Fehling's  and  Sachsse's  solutions  may  be  expressed  as 
follows : 

Let  x  =  gms.  of  reducing  sugar  A  in  100  c.c.  of  the  1  per  cent  sugar 

solution. 
Let  y  =  gms.  of  reducing  sugar  B  in  100  c.c.  of  the  1  per  cent  sugar 

solution. 
Let  a  =  c.c.  of  Fehling's  solution  reduced  by  1  gm.  of  sugar  A  in  100 

c.c.  of  solution. 
Let  b  =  c.c.  of  Fehling's  solution  reduced  by  1  gm.  of  sugar  B  in  100 

c.c.  of  solution. 
Let  o!  =  c.c.  of  Sachsse's  solution  reduced  by  1  gm.  of  sugar  A  in 

100  c.c.  of  solution. 
Let  b'  =  c.c.  of  Sachsse's  solution  reduced  by  1  gm.  of  sugar  B  in 

100  c.c.  of  solution. 

Let  F  =  c.c.  of  Fehling's  solution  reduced  by  100  c.c.  of  sugar  solution. 
Let  S  =  c.c.  of  Sachsse's  solution  reduced  by  100  c.c.  of  sugar  solution. 
Then  ax  +  by  =  F, 

and  a'x  +  b'y  =  S. 

For  a  mixture  of  x  per  cent  glucose  and  y  per  cent  fructose,  and 
taking  Soxhlet's  values  in  Table  LXXXII  for  a,  6,  o!  and  b',  the  equa- 
tions would  be 

210.4  x  +  194.4  y  =  F 

302.5  x  +  449.5  y  =  S. 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    475 

By  determining  the  values  F  and  S  of  the  mixture  of  sugars,  the 
percentages  x  and  y  are  readily  calculated. 

In  using  the  above,  or  other  combined  reduction  methods,  the  con- 
stants a,  bj  a'  and  &'  should  be  determined  empirically  by  the  chemist 
for  the  particular  sugars  with  which  he  is  working. 

As  another  example  of  combined  reduction  methods  may  be  men- 
tioned Kjeldahl's*  process  of  determining  the  reducing  power  of  the 
mixture  of  two  sugars  in  both  dilute  and  more  concentrated  solution, 
using  respectively  15  c.c.  and  50  c.c.  of  mixed  Fehling's  solution  ac- 
cording to  the  details  of  his  reduction  method  (p.  424).  The  relative 
differences  in  the  copper-reducing  powers  under  the  two  conditions  of 
analysis  are  not  sufficiently  pronounced,  however,  to  afford  a  reliable 
basis  of  calculation  and  the  method  has  been  generally  condemned. 

The  use  of  combined  polariscopic,  or  of  combined  reduction,  methods 
alone  for  analyzing  sugar  mixtures  has  largely  given  place  to  the  more 
accurate  procedure  of  combining  these  two  distinct  physical  and  chem- 
ical methods  in  one. 

COMBINED  POLARISCOPIC  AND  REDUCTION  METHODS 
1.  ANALYSIS  OF  MIXTURES  CONTAINING  TWO  SUGARS 
The  calculation  of  the  percentages  of  two  sugars  in  mixture  by  com- 
bining the  results  of  polarization  and  copper  reduction  was  first  at- 
tempted by  Neubauerf  in  1877,  and  the  principle  of  his  indirect  method 
has  been  that  of  most  subsequent  modifications.  In  the  earlier  methods 
of  this  class  the  total  reducing  power  of  the  mixture  was  determined  as 
glucose,  fructose  or  invert  sugar,  the  percentage  thus  obtained  being 
taken  as  the  total  amount,  or  sum,  of  the  sugars  present.  In  the  case 
of  two  sugars,  A  and  B,  the  percentages  x  and  y  of  each  were  expressed 
by  the  formula 

x  +  y  =  R 

in  which  R  was  the  percentage  of  total  reducing  sugar  determined  as 
glucose,  fructose  or  invert  sugar.  The  results  calculated  by  such  a 
formula  have,  however,  only  an  approximate  value,  as  the  difference 
in  copper-reducing  power  of  the  two  sugars  A  and  B  has  not  been  taken 
into  account. 

The  error  last  mentioned  has  been  largely  obviated  in  the  later 
methods  of  this  class  through  the  use  of  reduction  factors  (p.  421)  by 
means  of  which  the  copper-reducing  power  of  a  sugar  can  be  con- 
verted into  the  equivalent  of  any  other  reducing  sugar  which  is  selected 
as  a  standard  of  comparison.  For  the  latter  purpose  glucose  is  usually 
*  Z.  analyt.  Chem.,  35,  345-347.  f  Ber.,  10,  827. 


476 


SUGAR  ANALYSIS 


selected,  this  being  the  most  common  of  the  reducing  sugars  and  the 
one  most  easily  obtained  in  a  pure  condition. 

It  was  shown  upon  p.  421  that  the  different  monosaccharides  bear 
a  constant  ratio  to  glucose  for  the  same  weight  of  reduced  copper. 
This  ratio  was  given  for  several  sugars  and  was  found  by  Allihn's  method 
to  be  0.915  for  fructose,  0.958  for  invert  sugar,  0.898  for  galactose, 
0.983  for  xylose  and  1.032  for  arabinose. 

For  a  solution  containing  a  mixture  of  monosaccharides,  the  sum  of 
the  glucose  equivalents  of  the  individual  sugars  should  equal  the  total 
reducing  sugars  estimated  as  glucose.  This  is  shown  in  the  following 
experiments  by  Browne,  *  who  mixed  known  weights  of  different  sugars 
and  compared  the  calculated  glucose  equivalents  with  the  amount  of 
glucose  corresponding  to  the  reduced  copper  obtained  by  Allihn's 

method. 

TABLE  LXXXIII 
Showing  Glucose  Equivalents  of  Mixed  Reducing  Sugars 


Sugars. 

Grams  sugar  in  25  c.c. 

Total 
weight 
of 
sugars. 

Glucose  equiv- 
alent. 

Error. 

1. 

2. 

3. 

Calcu- 
lated. 

Found. 

Glucos6  fructose 

0.0967 
0.0484 
0.0461 
0.0231 
0.0740 
0.1786 
0.0893 
0.0265 
0.0681 
0.0155 
0.1853 
0.0927 
0.2162 
0.1081 
0.1513 
0.0757 
0.0495 
0.0248 
0.1371 
0.0646 

0.0904 
0.0452 
0.1408 
0.0704 
0.0198 
0.0585 
0.0293 
0.0960 
0.0175 
0.1070 
0.0569 
0.0285 
0.0429 
0.0215 
0.0433 
0.0217 
0.1535 
0.0768 
0.0226 
0.0822 

Gram. 

0.1871 
0.0936 
0.1869 
0.0935 
0.0938 
0.2371 
0.1186 
0.1225 
0.0856 
0.1225 
0.2422 
0.1212 
0.2591 
0.1296 
0.1946 
0.0974 
0.2030 
0.1016 
0.2206 
0.2435 

Gram. 

0.1794 
0.0898 
0.1749 
0.0875 
0.0921 
0.2311 
0.1156 
0.1127 
0.0780 
0.1102 
0.2282 
0.1141 
0.2361 
0.1181 
0.1934 
0.0967 
0.2070 
0.1035 
0.2203 
0.2270 

Gram. 

0.1780 
0.0906 
0.1755 
0.0877 
0.0927 
0.2294 
0.1161 
0.1132 
0.0764 
0.1097 
0.2267 
0.1131 
0.2369 
0.1183 
0.1933 
0.0981 
0.2083 
0.1044 
0.2210 
0.2280 

+0.0014 

-0.0008 
-0.0006 
-0.0002 
-0.0006 
+0.0017 
-0.0005 
-0.0005 
+0.0016 
+0.0005 
+0.0015 
+0.0010 
-0.0008 
-0.0002 
+0.0001 
-0.0014 
-0.0013 
-0.0009 
-0.0007 
-0.0010 



galactose   .  . 

Fructose,  galactose  

arabinose 

«                  u 

Galactose,  xylose  

«                (f 

Xylose,  arabinose 

«               a 

((               (t 

0.0609 
0.0967 

tt               ti 

Glucose,  arabinose,  xylose  
Glucose,  galactose,  fructose].  . 

The  weights  in  columns  1,  2  and  3  are  given  in  the  order  of  the  respective 
sugars  as  named. 

The  calculated  glucose  equivalents  of  the  mixtures  were  found  by  multiplying 
the  weights  of  each  sugar  by  its  reducing  ratio  and  adding  together  the  products. 

The  greatest  difference  between  the  calculated  glucose  equivalents 
and  those  determined  by  experiment  is  0.0017  gm.,  which  is  within  the 
limits  of  experimental  error.     It  seems,  therefore,  safe  to  conclude  that 
*  J.  Am.  Chem.  Soc.,  28,  443. 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    477 

the  reducing  ratio  of  a  sugar  remains  the  same  whether  it  occurs  alone 
or  with  other  monosaccharides. 

General  Formulae  for  Analysis  of  Sugar  Mixtures.  —  If  the  re- 
ducing ratio  of  sugar  A  to  glucose  is  a,  and  of  sugar  B  to  glucose  &, 
then  in  a  mixture  of  x  per  cent  A  and  y  per  cent  B,  the  combined  in- 
fluence is  represented  by  the  equation: 

ax  +  by  =  R  (1) 

in  which  R  is  the  percentage  of  total  sugars  determined  as  glucose.       1 
If  the  relative  polarizing  power  of  sugar  A  be  expressed  by  a  and 
that  of  sugar  B  by  j8,  then  in  a  mixture  of  x  per  cent  A  and  y  per  cent 
B,  the  combined  influence  is  represented  by  the  equation: 

ax  +  (3y  =  P  (2) 

in  which  P  is  the  polarizing  power  of  the  mixture  of  sugars. 
By  combining  equations  (1)  and  (2)  we  obtain: 


~  ab-ap 
aR-  aP          R-  ax 

y=-«b^'or  •—•  <*> 

When  the  constants  a,  b,  a  and  0  are  known,  the  percentages  x  and 
y  of  any  two  monosaccharides  can  be  calculated  very  closely  from  the 
percentage  of  total  reducing  sugar,  determined  as  glucose,  and  from 
the  polarizing  power  of,  the  mixture. 

Applications  of  the  Method.*  —  In  the  following  applications  of 
the  preceding  formulae  to  special  problems  of  analysis,  the  polariza- 
tions were  made  upon  a  Ventzke-scale  saccharimeter  using  the  sucrose 
normal  weight.  The  relative  polarizing  power  of  a  sugar  under  these 
conditions  is  best  expressed  in  terms  of  sucrose'and  is  found  by  dividing 
its  specific  rotation  by  the  specific  rotation  of  sucrose,  or  +66.5. 

In  making  up  the  various  mixtures  the  sugars  were  weighed  in  a 
small  stoppered  flask.  After  adding  the  requisite  amount  of  water 
the  flask  was  reweighed  and  the  percentage  of  each  sugar  in  the  solu- 
tion calculated.  After  the  sugars  were  dissolved,  the  solutions  were 
allowed  to  stand  24  hours  before  beginning  the  analysis,  in  order  to 
remove  all  possibility  of  error  through  mutarotation. 

Analysis  of  Mixtures  of  Fructose  and  Glucose.  — 
Reducing  ratio  of  fructose  to  glucose  =  0.915  =  a. 
Reducing  ratio  of  glucose  to  glucose   =  1.000  =  b. 

*  The  applications  of  the  method  to  the  analysis  of  mixtures  containing  two 
sugars  are  taken  from  the  paper  by  Browne  upon  "The  Analysis  of  Sugar  Mixtures," 
J.  Am.  Chem.  Soc.,  28,  439. 


478 


SUGAR  ANALYSIS 


Polarizing  ratio  of  fructose  (20°  C.,  10  per  cent  solution)  to  sucrose 


-90.18 


Polarizing  ratio  of  glucose  (10  per  cent  solution)  to  sucrose 


By  substituting  the  values  for  a,  6,  a  and  /3  in  the  general  equations 
previously  given,  we  obtain: 

0  7Q3  7?  _  P 
Per  cent  fructose  (F)  =  -  -  =  0.381  #  -  0.481  P,  at  20°  C.  (1) 

Z.Uo 

Per  cent  glucose  =  R  -  0.915  F.  (2) 

Owing  to  the  great  susceptibility  of  fructose  to  variations  in  specific 
rotation  through  changes  of  temperature  and  concentration,  the  use  of 
a  fixed  polarization  factor  is  only  possible  when  the  analyses  are  made 
under  perfectly  similar  conditions.  The  values  of  the  polarization 
factor  of  fructose  for  different  temperatures  and  concentrations  are 
given  below: 


Tempera- 

Deg  C 

1  per  cent. 

2  per  cent. 

3  per  cent. 

4  per  cent. 

5  per  cent. 

10  per  cent. 

25  per  cent. 

15 

-1.384 

-1.385 

-1.387 

-1.389 

-1.390 

-1.398 

-1.422 

20 

-1.341 

-1.343 

-1.345 

-1.346 

-1.348 

-1.356 

-1.380 

25 

-1.299 

-1.301 

-1.303 

-1.304 

-1.306 

-1.314 

-1.338 

30 

-1.257 

-1.259 

-1.261 

-1.262 

-1.264 

-1.272 

-1.296 

The  above  figures  were  calculated  from  the  general  formula  of 
Jungfleisch  and  Grimbert,  [«]£  =  -  (101.38  -  0.56 1  +  0.108  (c  -  10)). 

The  variations  of  the  polarization  constant  due  to  concentration 
are  so  small  that  they  do  not  affect  the  accuracy  of  the  calculations  ap- 
preciably and  a  10  per  cent  concentration  was  taken  as  the  basis.  The 
influence  of  temperature,  however,  is  so  pronounced  that  it  cannot  be 
disregarded. 

For  other  temperatures  than  20°  C.  the  denominator  in  equation 
(1)  for  fructose  becomes  2.12  at  15°  C.,  2.04  at  25°  C.  and  2.00  at  30°  C. 

The  percentage  of  invert  sugar  in  mixtures  of  glucose  and  fructose 
is  easily  found  by  combining  the  smaller  percentage  with  an  equal 
amount  of  the  other  component.  Thus,  in  the  first  experiment  of  the 
following  series  there  would  be  1.96  per  cent  invert  sugar  and  1.13  per 
cent  glucose,  and  in  the  last  experiment  7.52  per  cent  invert  sugar  and 
7.47  per  cent  fructose. 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    479 


The  following  analyses  were  made  of  seven  mixtures  containing 
known  amounts  of  fructose  and  glucose: 


Taken. 

Found. 

Error. 

Temp. 

R 

P 

Fructose. 

Glucose. 

Fructose. 

Glucose. 

Fructose. 

Glucose. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

0.99 

2.06 

3.01 

+  0.35 

22° 

0.98 

2.11 

-0.01 

+0.05 

1.59 

5.92 

7.41 

+  2.65 

23° 

1.56 

5.98 

-0.03 

+0.06 

3.17 

11.83 

14.54 

-I-  5.30 

23° 

3  02 

11.78 

-0.15 

-0.05 

4.52 

4.84 

9.06 

-  2.15 

22° 

4.51 

4.83 

-0.01 

-0.01 

5.63 

1.85 

7.02 

-  6.00 

23° 

5.61 

1.89 

-0.02 

+0.04 

9.04 

9.67 

17.80 

-  4.30 

22° 

8.90 

9.66 

-0.14 

-0  01 

11.26 

3.69 

14.04 

-12.00 

23° 

11.23 

3.76 

-0.03 

+0.07 

Average  error  

-0.06 

±0.04 

Applications  of  the  Method.  —  The  formulae  for  calculating  the  per- 
centages of  glucose  and  fructose  in  mixture  admit  of  numerous  appli- 
cations. The  determinations  of  fructose  by  this  means  have  been 
found  by  the  author  to  show  usually  a  very  close  agreement  with  the 
results  obtained  by  the  method  of  high-temperature  polarization, 
when  other  copper-reducing  or  optically  active  substances  are  absent. 

In  the  determination  of  fructose  and  glucose  in  cider  vinegar, 
Mott*  has  shown  that  the  presence  of  copper-reducing  aldehydes  may 
introduce  a  considerable  error  in  the  calculation.  If  the  aldehydes, 
however,  are  first  volatilized  by  evaporating  the  vinegar  to  dryness 
in  a  platinum  dish,  dissolving  the  solids  in  water  and  again  evaporat- 
ing several  times,  the  true  copper-reducing  power  of  the  mixed  sugars 
is  obtained,  in  which  case  the  results  of  the  calculation  agree  closely 
with  those  obtained  by  the  method  of  high-temperature  polarization. 
The  following  table  by  Mott  gives  the  percentages  of  fructose  and 
glucose  in  the  dry  substance  of  several  cider  vinegars  as  calculated  by 
Browne's  formula  and  the  excess  of  fructose  over  glucose  as  thus 
found  and  as  determined  by  polarization  at  87°  C. 


Variety  of  Vinegar 

Computed  by  formulae  of  Browne 

Excess  of  fructose 
over     glucose     by 
polarizing  at  87°  C 

Fructose  in  solids 

Glucose  in  solids 

Excess  of  fructose 

Baldwin. 

Per  cent 

19.7 
18.7 
23.1 
16.0 
14.2 

Per  cent 

8.8 
7.4 
9.1 
8.6 
7.1 

Per  cent 
10.9 
11.3 
14.0 

7.4 

7.1 

Per  cent 

10.9 
11.8 
13.9 
7.2 
8.6 

King  .... 

Greening 

Russet  
Mixed,  pressing  

*  J.  Ind.  Eng  Chem.,  3,  747. 


480 


SUGAR  ANALYSIS 


Analysis  of  Mixtures  of  Glucose  and  Galactose.  — 

Reducing  ratio  of  glucose  to  glucose  =  1.000  =  a. 

Reducing  ratio  of  galactose  to  glucose  =  0.898  =  b. 

Polarizing  ratio  of  glucose  (10  per  cent  solution)  to  sucrose 

+  52.74 


Polarizing  ratio  of  galactose  (20°  C.,  10  per  cent  solution)  to  sucrose 

•  +80-49  -  1  21  -  B 
T66^~ 

By  substituting  the  values  for  a,  b,  a.  and  /?  in  the  general  equations, 
we  obtain: 

i  91   r>  _  f)  OQO  p 

Per  cent  glucose  G  =  A  ,no  =  2-43  R  -  1.803  P,  at  20°  C.  (3) 


Per  cent  galactose  = 


0.498 
R-G 


(4) 


0.898 

The  specific  rotation  of  galactose  varies  somewhat  with  tempera- 
ture and  concentration,  the  differences,  however,  being  much  less  than 
those  of  fructose.  The  following  values  for  the  polarization  factor  of 
galactose  at  different  temperatures  and  concentrations  were  calculated 
from  the  general  formula  of  Meissl. 


Temperature. 
Degrees.  C. 

10  per  cent. 

15  per  cent. 

20  per  cent. 

10 
20 

30 

1.242 
1.210 
1.179 

1.248 
1.216 
1.185 

1.254 
1.222 
1.191 

The  concentration  influence  of  galactose  upon  the  polarization 
factor  is  too  slight  to  influence  the  calculations  appreciably;  the  tem- 
perature influence,  however,  should  be  regarded  in  case  the  readings 
are  made  very  much  above  or  below  20°  C. 

The  following  analyses  were  made  of  four  mixtures  containing  known 
amounts  of  glucose  and  galactose.  The  polarizations  were  taken  at 

OCOO  1. 195  B-  0.898  P 

25   C.  at  which  temperature  the  per  cent  glucose  =  - 


Taken. 

R 

P 

Temp. 
°C. 

Found. 

Error. 

Glucose. 

Galactose. 

Glucose. 

Galactose. 

Glucose. 

Galactose. 
Per  cent. 

+0.21 
+0.16 
-0.01 
+0.34 

Per  cent. 
2.12 
4.24 
7.15 
14.29 

Per  cent. 
7.68 
15.35 
2.34 
4.68 

9.06 
18.16 
9.29 
18.35 

+11.0 
+21.9 
+  8.5 
+17.0 

25° 
25° 
25° 
25° 

Per  cent. 
1.97 
4.23 

7.20 
13.82 

Average  e 

Per  cent. 

7.89 
15.51 
2  33 
5.04 

jrror  

Per  cent. 

-0.15 
-0.01 
+0.05 
-0.47 

±0.17 

±0.18 

COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    481 


The  average  error  in  the  above  series  of  experiments  is  nearly  four 
times  that  found  in  the  separation  of  fructose  and  glucose.  This  was 
to  be  expected  since,  owing  to  the  small  difference  in  the  specific  rota- 
tions of  glucose  and  galactose,  the  errors  of  observation  are  doubled;  in 
the  analysis  of  the  fructose-glucose  mixtures  on  the  other  hand  the 
wide  range  in  the  specific  rotation  diminishes  the  experimental  errors 
one-half. 

Analysis  of  Mixtures  of  Fructose  and  Galactose.  — 

Reducing  ratio  of  fructose  to  glucose  =  0.915  =  a. 
Reducing  ratio  of  galactose  to  glucose  =  0.898  =  6. 
Polarizing  ratio  of  fructose  (20°  C.,  10  per  cent  solution)  to  sucrose 

-  90.18 


+  66.5 


-  1.356  =  a. 


Polarizing  ratio  of  galactose  (20°  C.,  10  per  cent  solution)  to  sucrose 


+  80.49 


1.21 


+  66.5 

By  substituting  the  above  values  for  a,  b,  a  and  0,  in  the  general 
equations  we  obtain: 

•I    o-j     r>   _   r\   OQO    p 

Per  cent  fructose  (F)  =  -  —  =0.521  fl-  0.386  P  (20°  C.).  (5) 


p  _  A  qi  c  J? 

Per  cent  galactose  =  -  -  =  1.114  R  -  1.019  F.  (6) 


The  susceptibility  of  the  specific  rotations  of  both  fructose  and 
galactose  to  temperature  variations  necessitates  a  considerable  cor- 
rection if  the  polarizations  are  made  much  above  or  below  20°  C.  By 
using  the  polarization  factors  for  fructose  and  galactose  previously 
given,  formula  (5)  can  be  corrected  for  any  desired  temperature.  Thus 

,     Qn0^  .,  1.179#  -0.898  P 

for  30   C.  per  cent  fructose  =  -      ~o~ooi~      — 

The  following  analyses  were  made  of  four  mixtures  containing  known 
amounts  of  glucose  and  galactose. 


Taken. 

R 

P 

Temp. 
°C. 

Found. 

Error. 

Fructose. 

Galactose. 

Fructose. 

Galactose. 

Fructose. 

Galactose. 

Per  cent. 

1.24 
2.47 
5.44 
10.89 

Per  cent. 
8.56 
17.12 

1.40 
2.80 

8.78 
17.78 
6.11 
12.31 

+  8.75 
+17.40 
-  5.35 
-10.50 

28° 
25° 
28° 
29° 

Per  cent. 
1.14 

2.46 
5.38 
10.76 

Average 

Per  cent. 
8.62 
17.29 
1.33 
2.74 

error  

Percent. 

+0.10 

-0.01 

-0.06 

-0.13 

Per  cent. 
+0.06 
+0.17 

-0.07 
-0.06 

±0.07 

±0.09 

482 


SUGAR  ANALYSIS 


Analysis  of  Mixtures  of  Fructose  and  Arabinose.  — 

Reducing  ratio  of  fructose  to  glucose  =  0.915  =  a. 
Reducing  ratio  of  arabinose  to  glucose  =  1.032  =  6. 
Polarizing  ratio  of  fructose  (20°  C.,  10  per  cent  solution)  to  sucrose 

-  90.18 


Polarizing  ratio  of  arabinose  to  sucrose 


+  66.5 
+  104.5 


=  -1.356  =a. 
=      1.571  =  j8. 


+    66.5 

By  substituting  the  above  values  for  a,  b}  a  and  /3,  in  the  general 
equations,  we  obtain: 


Per  cent  fructose  (F)  = 


Per  cent  arabinose 


1 


_  1  0*39  P 


R 


2.836 
0.915  F 


1.032 


=  0.554#-0.364P(20°C.).    (7) 
0.969  R-  0.887  F.  (8) 


Correction  for  changes  in  temperature  is  made  as  in  the  previous  cases. 
The  following   analyses  were   made   of  two   mixtures   containing 
known  amounts  of  fructose  and  arabinose. 


Taken. 

R 

P 

Temp. 
°C. 

Found. 

Error. 

Fructose. 

Arabinose. 

Fructose. 

Arabinose. 

Fructose. 

Arabinose. 

Per  cent. 
7.41 

14.82 

Per  cent. 

2.28 
4.55 

9.05 
18.14 

-6.1 
-12.3 

27° 
26° 

Per  cent. 

7.39 
14  80 

Average 

Per  cent. 

2.22 
4.46 

error  

Per  cent. 

-0.02 
-0.02 

Per  cent. 

-0.06 

-0.09 

-0.02 

-0.07 

In  the  estimation  of  fructose  and  arabinose  there  is  a  wider  range 
of  specific  rotations  than  with  any  other  mixture  of  two  sugars  and  a 
corresponding  reduction  in  the  experimental  sources  of  error. 
Analysis  of  Mixtures  of  Xylose  and  Arabinose.  — 

Reducing  ratio   of  xylose  to   glucose  =  0.983  =  a. 
Reducing  ratio  of  arabinose  to  glucose  =  1.032  =  b. 

+  18.79 


Polarizing  ratio  of  xylose  (10  per  cent  solution) 


+  66.5 


=  0.283  =  a. 


Polarizing  ratio  of  arabinose  =  -         '    =  1.517  =  0. 

~f~  OO.O 

By  substituting  the  above  values  for  a,  &,  a  and  /3,  in  the  general 
equations,  we  obtain: 

Per  cent  xylose  (X)  =  1>571      ~°32P  =  1.255  R  -  0.824  P.     (9) 


Per  cent  arabinose  = 


5 

_   A  QOO    V 


=  0.969  R  -  0.953  X. 


(10) 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    483 


The  following  analyses  were  made  of  four  mixtures  containing  known 
amounts  of  xylose  and  arabinose. 


Taken. 

R 

P 

Temp. 

c. 

Found. 

Error. 

Xylose. 

Arabinose. 

Xylose. 

Arabinose. 

Xylose. 

Arabinose 

Per  cent. 
1.98 

3.96 
6.05 
12.10 

Per  cent. 
6.14 
12.28 

1.73 
3.46 

8.35 
16.66 
7.85 
15.46 

+  10.2 
+20.3 
+  4.5 

+  8.8 

25° 
25° 
25° 

25° 

Per  cent. 
2.05 

4.17 
6.14 
12.14 

Average  e 

Per  cent. 

6.13 
12.17 
1.75 
3.42 

rror  

Per  cent. 
+0.07 

+0.21 
+0.09 
+0.04 

Per  cent. 

-0.01 
-0.11 
+0.02 
-0.04 

+0.10 

±0.05 

The  five  special  cases,  which  have  been  selected,  are  sufficient  to 
illustrate  the  principle  and  comparative  accuracy  of  the  combined 
polariscopic  and  reduction  methods  for  analyzing  mixtures  of  two  re- 
ducing sugars.  The  method  can  also  be  used  in  analyzing  mixtures 
which  contain  rhamnose,  fucose,  mannose,  sorbose,  etc.;  the  reducing 
factors  of  these  less  studied  sugars  have  not  as  yet  been  definitely 
established.  The  method  can  also  be  applied  to  the  analysis  of  mix- 
tures containing  the  disaccharides,  lactose  and  maltose,  although,  as 
previously  stated,  the  reducing  factors  of  the  higher  sugars  do  not 
have  the  same  constancy  as  those  of  the  monosaccharides.  A  reducing 
ratio  to  glucose  of  0.7  for  lactose  hydrate  and  of  0.6  for  maltose  may  be 
employed  for  Allihn's  method  with  a  fair  degree  of  approximation. 

The  reducing  factors  of  the  different  sugars  for  other  methods,  as 
those  of  Kjeldahl,  Defren,  Munson  and  Walker,  etc.,  differ  slightly 
from  those  found  by  Allihn's  process.  The  chemist,  so  far  as  possible, 
should  determine  his  own  factors  under  the  conditions  of  the  method 
which  he  is  using. 

The  degree  of  accuracy  obtainable  by  a  given  combination  of 
polariscopic  and  reduction  methods  is  greatest,  other  conditions  being 
equal,  where  there  is  the  greatest  difference  between  the  specific  rota- 
tions and  reducing  powers  of  the  two  sugars.  The  probable  errors  of 
the  method  are  always  indicated  by  the  magnitude  of  the  factors  for  R 
and  P  in  the  different  equations.  Thus  an  error  in  copper-reducing 
power  is  made  six  times  as  great  in  equation  (3)  as  in  equation  (1), 
and  an  error  in  polarization  five  times  as  great  in  equation  (3)  as  in 
equation  7.  In  mixtures  of  glucose  and  lactose,  whose  rotations  are 
nearly  alike,  experimental  errors  are  multiplied  more  than  in  the  cases 
noted.  Taking  the  polarizing  ratio  of  lactose  as  0.79  and  the  reducing 
ratio  as  0.7,  the  percentage  of  lactose  (L)  is  L  =  4.26  P  —  3.37  R. 


484  SUGAR  ANALYSIS 

II.    ANALYSIS  OF  MIXTURES  CONTAINING  THREE  SUGARS 

The  indirect  method  of  combining  polarization  and  reducing  power 
can  also  be  applied,  but  with  considerable  limitations,  to  the  analysis 
of  mixtures  containing  three  sugars. 

Methods  Based  upon  a  Determination  of  Total  Sugars,  Reducing 
Power,  and  Polarization. — The  calculation  of  three  sugars  in  a  mixture 
is  sometimes  made  (1)  from  a  determination  of  the  total  sugars,  as  by 
drying  or  by  densimetric  means,  (2)  from  the  reducing  power  and 
(3)  from  the  polarization. 

If  three  sugars  A ,  B  and  C  constitute  a  mixture,  and  no  other  sub- 
stances are  present,  the  percentages  x,  y  and  z  of  each  may  be  expressed 

as  follows: 

x  +  y  +  z  =  T  (total  solids).  (1) 

ax  +  by  +  gz  =  R  (reducing  sugars  as  glucose) .  (2) 

ax  -f  &y  +  72  =  P  (polarization).  (3) 

Having  determined  T,  R  and  P,  and  knowing  the  reducing  con- 
stants a,  b,  and  g  and  polarizing  constants  a,  /3,  and  7  of  the  three  sugars, 
the  percentages  x,  y  and  z  of  each  may  be  calculated  in  certain  cases 
with  a  fair  degree  of  approximation.  It  frequently  happens,  however, 
in  making  calculations  by  this  method  that  small  experimental  errors 
are  enormously  multiplied,  so  that  the  final  results,  even  with  mix- 
tures of  pure  sugars,  can  be  regarded  as  only  very  roughly  approximate. 
Analysis  of  a  Mixture  Containing  Glucose,  Galactose  and  Fructose.  — 
As  an  example  of  the  limitations  above  mentioned  the  problem  of 
analyzing  a  mixture  containing  x  per  cent  glucose,  y  per  cent  galactose 
and  z  per  cent  fructose  is  taken.  By  substituting  the  reducing  and 
polarizing  constants  previously  employed  for  these  three  sugars  in  the 
general  equations  (1),  (2)  and  (3)  we  obtain: 

x  +  y  +  z  =  T, 
x  +  0.898  y  +  0.915  z  =  R, 
0.793  x  +  1.21y-  1.356  z  =  P,  at  20°  C., 
whence, 

z  =  per  cent  fructose  =  1.957  T  -  1.638  R  -  0.401  P,  at  20°  C.      (1) 

y  =  per  cent  galactose  =  8.175  T  -  8.433  R  +  0.33  P,  at  20°  C.      (2) 

x  =  per  cent  glucose  =  T  —  y  —  z.  (3) 

It  is  seen  that  any  experimental  errors  in  determining  total  solids 

or  reducing  sugars  are  magnified  in  the  calculation  of  galactose  over 

eight  times. 

Example.  —  A  solution  containing  6.46  per  cent  glucose,  8.22  per  cent 
galactose  and  9.67  per  cent  fructose  gave  upon  analysis  the  following  results: 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    485 

Total  solids  (T)  by  drying  in  vacuo  24.20  per  cent;  reducing  sugars  (R)  as  glu- 
cose 22.80  per  cent;  polarization  (P  for  26  gms.  in  100  c.c.,  200-mra.  tube  at 
20°  C.)  +  1.95°  V.  Substituting  these  values  for  T,  R  and  P  in  the  previous 
equations  gives  fructose  9.23  per  cent;  galactose,  6.21  per  cent  and  glucose 
8.76  per  cent. 

The  relationships  between  experimental  errors  and  the  errors  in 
calculated  results  in  the  above  example  are  as  follows: 


Theoretical. 

Found. 

Error. 

Total  solids 

24  35 

24  20 

-0   15     ) 

Reducing  sugars  as  glucose  
Polarization         .  . 

22.70 
+1  96 

22.80 
+  1  95 

-1-010     >  Experi- 

±o.M  \  mentaL 

Glucose                 .                .  .         ... 

6  46 

8  76 

+2  30    ) 

Galactose.                            

8.22 

6  21 

9  ni      f  Calcu- 

Fructose  

9.67 

9.23 

-0.44    )  kted- 

It  is  seen  that  a  combination  of  very  slight  experimental  errors  in- 
troduces an  error  of  over  2  per  cent  in  the  calculation  of  glucose  and 
galactose. 

Analysis  of  a  Mixture  Containing  Glucose,  Fructose  and  Sucrose.  — 
When  one  of  the  three  sugars  in  a  mixture  is  non-reducing,  the  calcula- 
tion by  the  above  indirect  method  can  frequently  be  made  with  a  much 
greater  degree  of  accuracy.  Thus  for  a  mixture  containing  x  per  cent 
glucose,  y  per  cent  fructose  and  z  per  cent  sucrose,  the  three  general 
equations  would  give: 

x  +  y  +  z  =  T, 
x  +  0.915  y  =R, 

0.793  z  -  1.356  y  +  z  =  P,  at  20°  C., 
whence, 

y  =  per  cent  fructose  =  0.461  (T  -  P)  -  0.096  R,  at  20°  C.         (4) 

x  =  per  cent  glucose  =  R  —  0.915  y.  (5) 

z  =  per  cent  sucrose  =  T  —  x  —  y.  (6) 

It  is  seen  that  in  a  mixture  of  glucose,  fructose  and  sucrose  there 

is  a  division,  rather  than  a  multiplication,  of  experimental  errors  in  the 

calculation. 

Example.  —  A  solution  containing  5.43  per  cent  fructose,  10.02  per  cent 
glucose  and  16.16  per  cent  sucrose  gave  upon  analysis  the  following  results: 
Total  solids  (T)  by  drying  in  vacuo  31.50  per  cent;  reducing  sugars  (R)  as  glucose 
by  Allihn's  method,  15.24  per  cent;  polarization  (P,  26  gms.  in  100  c.c.,  200- 
mm.  tube  at  25°  C.)  -f-  17.05°  V.  Substituting  these  values  for  T,  R  and  P  in 
equations  (4),  (5)  and  (6)  gives  5.40  per  cent  fructose,  10.30  per  cent  glucose  and 
15.80  per  cent  sucrose. 


486 


SUGAR  ANALYSIS 


The  relationship  between  experimental  errors  and  the  errors  in  cal- 
culated results  in  the  above  example  are  as  follows: 


Theoretical. 

Found. 

Error. 

Total  solids  

31.61 

31.50 

-0.11     ) 

Reducing  sugar  as  glucose  .  .  . 
Polarization 

14.99 
+  16  75  (20°  C.) 

15.24 

+17.  05  (25°  C.) 

+0.25    > 
+0  30    ) 

Experi- 
mental. 

Fructose                        

5.43 

5.20 

-0  23    ) 

Glucose                

10.02 

10.48 

+0.46    > 

Calcu- 

Sucrose        

16.16 

15.82 

-0.34    ) 

It  is  seen  that  the  calculation  by  this  method  gives  a  very  good 
approximation,  notwithstanding  the  influence  of  rather  large  experi- 
mental errors  (due  to  polarizing  at  25°  C.  instead  of  20°  C.  and  to  the 
slight  reducing  action  of  sucrose). 

.Analysis  of  a  Mixture  Containing  Glucose,  Maltose  and  Dextrin.  — 
Several  indirect  methods,  based  upon  determinations  of  total  solids, 
reducing  power  and  polarization  have  been  proposed  for  the  analysis 
of  starch-conversion  products  which  contain  the  three  carbohydrates, 
glucose,  maltose  and  dextrin. 

In  the  method  proposed  by  Allen*  the  [O\D  of  glucose  is  taken  as 
+52.7,  of  maltose  as  +139.2  and  of  dextrin  as  +198.0.  The  copper- 
reducing  power  of  glucose  is  taken  as  1,  of  maltose  as  0.62,  and  of 
dextrin  as  0.  The  sum  of  the  glucose  (gr),  maltose  (m)  and  dextrin  (d) 
is  taken  as  the  total  organic  solids  (0),  and  is  found  by  subtracting  the 
percentage  of  ash  from  the  percentage  of  total  dry  substance.  The 
three  general  equations  used  by  Allen  are: 
g  +  m  +  d  =  0  (organic  solids). 

g  +  0.62m  =  K  (copper-reducing  power  by  O'Sullivan's  method). 
52.7  g  +  139.2m  +  198  d  =  100  S  (specific  rotation). 
By  substituting  the  first  equation  in  the  last  and  transposing  we  obtain: 

139.2  m  =  100  S  -  52.7  g  -  198  (O  -  g  -  m) ; 

by  substituting  K  —  0.62  m  for  g  in  the  preceding  equation  and  trans- 
posing, we  obtain: 

31.3m  =  100  S  -  52.7  tf  -  198  (0  -  K}\ 
dividing  the  above  by  100  we  obtain: 

52.7  #+  198  (O-K)' 


m  =    £>  — 


100 


-)  -r  0.313. 


g  =  K-  0.62m. 
d  =  O  —  a  —  m. 


(D 

(2) 
(3) 


Allen's  "Commercial  Organic  Analysis"  (1901),  Vol.  I,  365. 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    487 

Equation  (1)  of  Allen,  expressed  in  its  simplest  decimal  form,  be- 
comes 

m  =  3.195  S  +  4.642  K  -  6.326  0.  (4) 

If  the  sample  be  polarized  upon  a  saccharimeter,  where  the  ratio  of 
the  scale  reading  for  the  normal  weight  to  specific  rotation  will  be  as 
the  [O\D  of  sucrose  (+66.5)  is  to  100,  the  factor  for  the  saccharimeter  read- 
ing of  a  normal  weight  would  be  for  equation  (4) 
100:  66.5::  3.195  :x  =  2.125. 

Equation  (1)  of  Allen  modified  for  the  polarization  (P)  of  a  sucrose 
normal  weight  upon  a  saccharimeter  would  then  be: 
m  =  2.125  P  +  4.642  K  -  6.326  0. 

In  the  analysis  of  starch-conversion  products  the  total  solids  are 
frequently  calculated  by  means  of  the  solution  factor  3.86.  When  this 
is  done,  a  correction  must  be  introduced  for  the  variations  from  3.86 
in  the  solution  factors  of  the  different  ingredients.  The  solution  factor 
of  the  mineral  matter,  or  ash,  in  a  conversion  product  has  been  placed 
at  8;*  taking  as  the  solution  f  actors  f  of  glucose  (0),  maltose  (m)  and 
dextrin  (d),  the  values  3.83,  3.92  and  4.21  respectively  (p.  31),  then  the 
equation  for  total  solids  (T7)  as  calculated  from  the  specific  gravity  by 
the  solution  factor  3.86  (usually  written  T*.M)  would  be: 
3.86  .  3.86  .  3.86  ,  .  3.86 


Knowing  the  percentage  of  ash  (a),  the  equation  of  Allen  for  organic 
solids  would  be: 

3.86     ,  3.86       ,3.86,  _T          3.86 
3.83  g  +  3.92  m  ^4.21^  8 

If  the  reducing  power  be  expressed  in  percentage  of  the  solids  as 
calculated  by  the  factor  3.86  (written  K^e)  then 
3.86      .   3.86 


3*3         32 

In  the  same  way  if  the  [O\D  of  the  solids,  as  calculated  by  the  factor 

*  Allen's  "Commercial  Organic  Analysis"  (1901),  Vol.  I,  376. 

t  It  is  noted  that  the  solution  factors  of  glucose,  maltose  and  dextrin  increase  in  the 
order  of  their  specific  rotations.  From  this  relationship  Rolfe  (J.  Am.  Chem.  Soc., 
19,  698)  has  derived  a  general  equation  S  =  0.004023  -  0.000001329  (195  -  [«]#), 
for  calculating  the  specific  gravity  influence  "of  any  acid-hydrolyzed  starch  solution. 
when  the  value  for  [a]D  (obtained  by  the  factor  0.00386  between  the  densities  1.035 
and  1.045)  is  known.  The  value  for  S  multiplied  by  1000  will  give  of  course  the 
O'SuUivan  solution  factor. 


488  SUGAR  ANALYSIS 

3.86,  be  used  instead  of  the  [«]/>  of  the  moist  product,  then,  using  the 
values  of  Allen  for  the  [<*]/>  of  glucose,  maltose  and  dextrin 

52.7  g  +         139.2  m  +         198  d  =  100[a]fl 


,,, 

Several  other  methods  of  calculating  maltose,  glucose  and  dex- 
trin have  been  proposed.  These  are  similar  to  that  of  Allen,  except 
that  slightly  different  values  are  used  for  the  polarizing  and  reducing 
constants. 

It  is  seen  that  in  the  calculation  of  maltose  by  Allen's  method  any 
experimental  errors  in  determining  organic  solids,  reducing  power  or 
specific  rotation  are  greatly  multiplied.  The  value  of  the  method  in 
the  analysis  of  hydrolyzed  starch  products  is  still  further  diminished  by 
the  fact  that  no  account  is  taken  of  isomaltose  and  of  the  various  re- 
version products  which  are  always  present  in  materials  of  high  con- 
version. Any  reducing  power  and  rotation  due  to  other  substances 
than  glucose,  maltose  and  dextrin  affect  the  accuracy  of  the  method 
to  a  marked  degree.  Furthermore  the  dextrins  of  starch  conversion 
are  of  a  mixed  character  with  different  rotations  and  reducing  powers, 
so  that  the  selection  of  an  initial  dextrin  of  [O\D  +  198  and  negative  re- 
ducing power  is  largely  arbitrary.  The  percentages  of  glucose,  maltose 
and  dextrin  in  starch-conversion  products,  as  calculated  from  determina- 
tions of  organic  solids,  reducing  power  and  polarization  are,  therefore, 
largely  conventional  quantities;  the  latter,  when  properly  understood, 
may  serve,  however,  as  a  valuable  means  of  comparison. 

The  methods  of  estimating  three  sugars  in  mixture  which  depend 
upon  a  determination  of  total  sugars  become  largely  valueless  in  the 
case  of  such  products  as  molasses,  fruit  juices,  honeys,  etc.,  which  con- 
tain varying  amounts  of  organic  and  mineral  salts,  gums,  and  acids. 
With  such  materials  a  determination  of  dry  substance,  or  of  organic 
solids,  gives  too  high  a  percentage  of  total  sugars,  and  the  results  of  the 
calculation  may  even  lack  the  value  of  an  approximation.  It  is,  there- 
fore, always  the  best  plan  to  determine  as  many  of  the  sugars  as  pos- 
sible in  a  mixture  by  direct  means. 

Methods  of  Calculating  the  Percentages  of  Three  Sugars  from  the 
Combined  Reducing  Power  and  Polarization  and  the  Direct  De- 
termination of  One  Sugar.  —  If  in  a  mixture  of  three  sugars  contain- 
ing x  per  cent  A,  y  per  cent  B  and  z  per  cent  C,  the  percentage  z  of  C 
be  determined  by  direct  means,  then  x  and  y  can  be  calculated  by 
means  of  the  following  equations  : 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    489 

ax  +  by  -f  gz  =  R  (total  reducing  sugars  as  glucose) , 
ax  +  fiy  +  yz  =  P  (polarization) , 

z  =  Z  (direct  determination), 
whence  ax  -f  by  =  R  —  gZ, 

ax  +  (3y  =  P-  yZ. 

Having  determined  R,  P  and  Z  and  knowing  the  reducing  and  polar- 
izing constants  of  the  three  sugars,  the  percentages  x  and  y  can  be 
calculated  as  described  on  page  477,  for  mixtures  of  two  sugars. 
Several  applications  of  the  method  will  be  described. 
Analysis  of  a  Mixture  Containing  Glucose,  Fructose  and  Sucrose.  — 
The  sucrose  is  best  determined  by  the  methods  of  inversion,  using 
either  the  process  of  double  polarization  or  that  of  copper  reduction. 
If  the  polariscopic  method  be  used,  the  inversion  is  best  accomplished 
by  means  of  invertase  in  order  to  eliminate  the  influence  of  the  acid 
upon  the  rotation  of  fructose. 

Knowing  the  percentage  (S)  of  sucrose  in  a  mixture  containing  x 
per  cent  glucose  and  y  per  cent  fructose,  and  no  other  optically  active 
or  reducing  substances,  the  percentages  x  and  y  can  be  calculated  by 
means  of  the  two  equations : 

x  +  0.915 y  —  R  (reducing  sugars  as  glucose), 

0.793  x  -  1.356  y  +  S  =  P,  20°  C.  (Polari^ion  of  a  sucrose  normal) 

V     weight  on  a  saccharimeter       / 

,f  0.793  R  +  S-P      ,  OAOr,  /1A 

whence,    y  =  per  cent  fructose  =  -      — =-^ —    —  ,  at  20  C.  (1) 

Z.Oo 

x  =  per  cent  glucose  =  R  —  0.915  y.  (2) 

The  determination  of  R  will  be  a  little  too  high,  unless  a  correction 
is  made  for  the  slight  reducing  action  of  sucrose  upon  Fehling's  solu- 
tion. This  correction  can  be  made  by  using  an  empirical  formula, 
such  as  proposed  by  Browne  for  Allihn's  method  (p.  427),  or  by  using 
the  special  methods  and  tables  for  determining  reducing  sugars  in 
presence  of  sucrose. 

Example.  —  The  solution  employed  in  the  previous  example  (p.  485)  gave 
by  the  method  of  inversion  16.27  per  cent  of  sucrose  (S} ;  substituting  this  and 
the  previous  values,  R  =  15.24,  and  P  =  +  17.05  at  25°  C.,  in  equation  (1)  we 
obtain: 

Fructose  _  0.793  (15.24) +  16.27 -17.05  _  ^  pef  cent 

Z.Oo 

Glucose  =  15.24  -  0.915(5.43)  =  10.27  per  cent. 

These  percentages  agree  more  closely  than  in  the  previous  example  with 
the  actual  amounts  of  sugars  taken,  viz.:  5.43  per  cent  fructose,  10.02  per  cent 
glucose  and  16.16  per  cent  sucrose. 


490  SUGAR  ANALYSIS 

Analysis  of  a  Mixture  Containing  Glucose,  Maltose  and  Dextrin.  — 
In  addition  to  the  method  of  Allen  previously  described,  several  proc- 
esses have  been  devised  for  determining  glucose,  maltose  and  dextrin 
in  starch-conversion  products,  which  are  based  upon  a  direct  deter- 
mination of  the  dextrin. 

Determination  of  Dextrin.  —  Several  methods  have  been  proposed 
for  the  direct  estimation  of  dextrin  in  presence  of  other  carbo- 
hydrates, but  none  of  these  has  been  found  to  give  perfectly  reliable 
results. 

The  dextrin  is  sometimes  precipitated  from  the  sirupy  solution  by 
adding  a  large  excess  of  hot  95  per  cent  alcohol,  and  stirring,  after 
which  the  precipitate  of  dextrin  is  allowed  to  subside.  The  clear 
solution  when  deposition  is  complete  is  decanted  through  a  filter,  the 
dextrin  dissolved  in  a  little  water  and  again  precipitated  by  adding 
alcohol  as  before.  The  process  is  repeated  for  a  third  time,  after  which 
the  precipitate  is  washed  into  a  platinum  evaporating  dish,  and  dried 
and  weighed.  The  residue  is  then  ignited  and  the  weight  of  ash  de- 
ducted from  the  weight  of  dried  alcohol  precipitate;  the  difference  is 
estimated  as  dextrin.  The  difficulty  with  this  method  of  estimation  is 
to  precipitate  all  of  the  dextrin  without  occluding  any  of  the  glucose 
or  maltose.  The  dextrin  after  repeated  precipitations  with  alcohol 
still  reduces  Fehling's  solution;  this  may  be  due,  however,  to  the 
presence  of  reducing  maltodextrins  as  well  as  to  the  occlusion  of 
sugars. 

Methods  based  upon  a  destruction  of  reducing  sugars  by  fermenta- 
tion or  oxidation,  and  then  calculating  the  residual  polarizing  power  to 
dextrin  have  already  been  referred  to  (p.  301).  The  principal  objec- 
tion to  the  fermentation  method  is  that  most  yeasts  ferment  or  modify 
dextrin  to  a  greater  or  less  degree  so  that  the  residual  polarizing  power 
does  not  represent  that  of  the  dextrins  originally  present.  In  Wiley's 
method  (p.  306)  of  destroying  reducing  sugars  by  oxidation  with  alka- 
line mercuric  cyanide,  it  has  been  found  that  the  polarizing  power  of 
maltose  is  not  completely  destroyed  and  that  the  dextrins  themselves 
undergo  partial  oxidation  to  dextrinic  acid. 

Owing  to  the  limitations  of  the  methods  just  described  it  is  evident 
that  the  percentages  of  dextrin  thus  determined  have  only  a  nominal 
value. 

Assuming  that  the  residual  polarizing  power  (P'),  after  destroying 
maltose  and  glucose,  is  due  to  an  unchanged  dextrin  of  [a]D  +  193,  and 
calling  the  [a]D  of  glucose  (0)  +  53  and  of  maltose  (ra)  +  138,  and  sup- 
posing the  relative  reducing  powers  of  glucose  and  maltose  to  be  100 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    491 

and  62*  respectively,  the  calculation  of  the  percentages  g,  m  and  d  in  a 
starch-conversion  product  is  made  by  Wiley f  as  follows: 

g  +  0.62m  =  R  (total  reducing  sugars  as  glucose).  (1) 

53  g  +  138 m  +  193  d  =  100  P,  (P  =  [a]D  of  product).  (2) 

193  d  =  100  P',  (P'  =  [a]D  after  destroying  g  and  m).  (3) 
Subtracting  (3)  from  (2)  gives 

53  g  +  138  m  =  100  (P  -  P').  (4) 

Multiplying  (1)  by  53  and  subtracting  from  (4)  gives 

105.14m  =  100  (P  -  P'}  -  53  #,  (5) 

whence 

1  C\C\  (  T^  .--L--.    ~pf\          £\Q  7? 

m  =  -          105  14~       -  =  0.951  (P-P')- 0.504/2.   (G) 
g  =  R  -0.62m.  (7) 

d  =  ^f'  (8) 

Example.  —  A  sample  of  midzu  ame  (Japanese  glucose)  was  analyzed  by 
Wiley  with  the  following  results: 

[a\D  before  fermentation  =  +  132.6  =  P. 
[a  D  after  fermentation  =  +  59.2  =  P'. 
Total  reducing  sugars  as  glucose  =  33.33  per  cent  =  R. 
Substituting  these  values  in  equations  (6),  (7)  and  (8)  gives: 

Maltose  =  0.951(132.6  -  59.2)  -  0.504(33.33)  =  53.01  per  cent, 
Glucose  =  33.33  -  0.62(53.01)  =  0.47  per  cent, 

Dextrin  =  10Q  (59'2)  =  30.67  per  cent. 

.L  i/o 

If  the  sample  be  polarized  upon  a  saccharimeter  the  factor  for  the 
scale  readings,  P  and  P'  of  a  sucrose  normal  weight  would  be  for  equa- 
tion (6) 

100:66.5::  0.951  :  x  =  0.632. 

Equation  (6)  of  Wiley  modified  for  the  polarizations  of  a  sucrose  nor- 
mal weight  upon  a  saccharimeter  would  then  be 

m  =  0.632  (P  -  P')  -  0.504  R. 

Equation  (8)  of  Wiley  modified  for  calculating  dextrin  from  the  sac- 
charimeter reading  (P')  of  a  sucrose  normal  weight  would  be 
193  P' 

&Md  =  P''  whenced  =  ^902' 

The  criticisms  on  page  488  of  the  indirect  method  of  estimating  glu- 
cose, maltose  and   dextrin  from   organic   solids,  polarization  and  re- 
ducing power  apply  also  to  the  method  of  calculation  just  described. 
*  The  ratio  62,  or  in  decimal  form  0.62,  is  strictly  true  only  for  O'Sullivan's 
method.     The  factor  is  less  than  this  for  other  processes  of  copper  reduction, 
t  Wiley's  "Agricultural  Analysis"  (1897),  Vol.  Ill,  288. 


492  SUGAR  ANALYSIS 

Owing  to  the  mixed  character  of  the  dextrins  in  starch  conversion 
products,  the  selection  of  a  dextrin  of  [O\D  =  +  193,  or  of  any  other 
fixed  value,  as  a  basis  of  calculation  is  largely  conventional.  The 
presence  of  the  unfermentable  reducing  sugar  isomaltose  and  of  opti- 
cally-active reversion  products  also  affects  the  accuracy  of  the  method. 
Owing  to  these  reasons,  as  well  as  to  the  general  unreliability  of  the 
methods  for  estimating  dextrin,  the  results  of  such  calculations  have 
frequently  no  absolute  scientific  value. 

Applications  of  the  Method  to  Other  Sugar  Mixtures.  —  The 
general  principle  of  combining  the  results  of  polariscopic  and  reduction 
methods  with  those  of  a  direct  determination  in  analyzing  mixtures  of 
three  sugars  has  been  sufficiently  indicated,  and  additional  examples 
need  not  be  given.  Such  schemes  of  analysis  obviously  admit  of  un- 
limited extension.  If  one  of  the  three  sugars  is  a  pentose  or  methyl- 
pentose,  its  percentage  may  be  determined  from  the  yield  of  furfural-  or 
methylf urf ural-phloroglucide ;  mannose  may  be  determined  from  the 
yield  of  phenylhydrazone;  lactose  or  galactose  from  the  yield  of  mucic 
acid;  raffinose  by  the  method  of  inversion;  etc.  In  combining  the 
results  of  such  direct  determinations  with  those  of  polarization  and 
reducing  power,  the  chemist  must  consider  in  each  case  the  limitations 
of  the  methods  used  and  the  extent  to  which  experimental  errors  are 
multiplied  in  the  calculation. 

The  final  test  of  accuracy  consists  in  applying  the  method  to  the 
analysis  of  mixtures  containing  known  amounts  of  the  several  sugars, 
and  this  verification  should  be  made  whenever  possible. 

III.     ANALYSIS  OF  MIXTURES  CONTAINING  FOUR  SUGARS 

Schemes  of  analysis  have  also  been  proposed  for  the  analysis  of 
mixtures  containing  four  sugars,  in  which  case,  however,  two  of  the  mem- 
bers present  must  usually  be  determined  by  direct  means. 

As  a  single  illustration  of  such  methods  the  following  scheme  is 
given  for  analyzing  a  mixture  containing  g  per  cent  glucose,  /  per  cent 
fructose,  s  per  cent  sucrose  and  x  per  cent  xylose. 

0.793S  -  1.356/  +  .  + 0.283*  =  P  (Polariftion  of  a  sucrose  normalN 

\  weight  upon  a  sacchanmeter  / 

g  +  0.915/  +  0.983  x  =  R  (total  reducing  sugars  as  glucose).  (2) 
s  =  S  (sucrose  determined  by  method  of  inversion) .  (3) 

x  =  X  (xylose  determined  from  yield  of  furfural  phloroglucide).    (4) 
Substituting  the  known  values  of  S  and  X  in  (1)  and  (2)  gives: 

0.793  0-1.356/  =  P-S-  0.283  X.  (5) 

fl-  0.983  X  (6) 


COMBINED  METHODS  AND  ANALYSIS  OF  SUGAR  MIXTURES    493 

Multiplying  (6)  by  0.793  and  combining  with  (5)  gives: 

S  +  0.793  R-P-QA97X 
f  =  per  cent  fructose  =  "2082  ~ ' 

g  =  per  cent  glucose  =  R  -  0.915  /  -  0.983  X. 

The  application  of  such  formulae  as  the  above  to  the  analysis  of 
complicated  mixtures  of  sugars  usually  involves,  however,  such  a  com- 
bination and  multiplication  of  experimental  errors,  that  a  scheme  of 
calculation,  perfectly  correct  in  theory,  is  shown  in  practice  to  be 
almost  valueless. 

It  is  scarcely  necessary  to  remark  that  in  working  with  unknown 
mixtures  of  sugars,  each  of  the  constituents  present  must  be  identified 
by  careful  qualitative  tests  before  beginning  the  analysis. 

For  a  description  of  other  methods  and  schemes  which  have  been 
proposed  for  analyzing  different  mixtures  of  sugars,  the  chemist  is 
referred  to  Lipmann.* 

*  "Chemie  der  Zuckerarten,"  Vol.  I,  616-623;  894-899. 

See  also  Wiechmann's  "Sugar  Analysis"  (1898),  and  the  papers  by  Halenke 
and  Moslinger  (Z.  analyt.  Chem.,  34,  263)  and  by  Geelmuyden  (Z.  analyt.  Chem., 
48, 137)  for  other  examples  of  calculation. 


CHAPTER  XVII 

MISCELLANEOUS   APPLICATIONS 

THE  present  chapter  will  give  several  practical  applications  of  the 
principles  and  methods  previously  described  to  a  few  selected  prob- 
lems of  technical  sugar  analysis.  A  large  number  of  such  applications 
have  already  been  considered  and  a  description  of  these  will  be  passed 
over.  The  methods  will  be  grouped  under  three  main  divisions  of  prod- 
ucts: (1)  Sugar-factory  products;  (2)  Starch-conversion  products;  (3) 
Food  products. 

SUGAR-FACTORY  PRODUCTS 

In  addition  to  the  analytical  methods,  previously  considered,  a  few 
definitions  of  common  terms  and  several  descriptions  of  illustrative 
commercial  methods  will  be  given.  For  the  application  of  methods  to 
sugar-factory  control,  the  technical  works  of  Geerligs,  Mittelstaedt, 
Morse,  Spencer,  Pellet  and  Metillon  and  others  should  be  consulted. 

Coefficient  of  Purity.  —  The  coefficient  of  purity  of  a  juice,  sirup, 
molasses,  sugar,  etc.,  is  the  percentage  of  sucrose  in  the  total  solid 
matter  of  the  product.'  The  term,  which  is  also  called  "  quotient  of 
purity,"  "degree  of  purity,"  "purity"  or  "exponent,"  has  been  vari- 
ously interpreted,  and  the  chemist  must  distinguish  carefully  between 
the  true  and  the  apparent  coefficient  of  purity. 

The  true  coefficient  of  purity  is  the  percentage  of  actual  sucrose  in  , 
the  total  solid  matter  as  determined  by  the  method  of  drying. 

The  apparent  coefficient  of  purity  is  usually  taken  as  the  ratio  of  the 
direct  polarization  to  100  parts  of  apparent  solids  as  calculated  from 
the  degrees  Brix,  or  by  other  indirect  means. 

Example.  —  A  sugar-cane  molasses  gave  upon  analysis  the  following  result  : 
Total  solids  by  actual  drying  ...................  75.10  per  cent 

Total  solids  by  degrees  Brix  ....................  77.10  per  cent 

Total  solids  by  refractometer  ...................  74.20  per  cent 

Direct  polarization  ............................  42.20 

Sucrose  by  method  of  inversion  ..................  45.70  per  cent 

True  coefficient  of  purity  =      ^  x  10n  =  60.85. 


- 
Apparent  coefficient  of  purity  =  ^~  X  100  =  54.73.  (1) 

494 


MISCELLANEOUS  APPLICATIONS  495 


Apparent  coefficient  of  purity  =  X  100  =  56.87.  (2) 


Sometimes  the  true  percentage  of  sucrose  is  used  in  calculating  apparent 
purity  in  which  case 

Apparent  coefficient  of  purity  =      '      =  59.27.  (3) 

Apparent  coefficient  of  purity  =      '      =  61.59.  (4) 

The  coefficient  of  purity  of  sugar-cane  or  sugar-beet  juices  is  often 
loosely  applied  to  the  entire  cane  or  beet. 

Numerous  tables  and  formulae  have  been  calculated  for  converting 
apparent  into  true  purities,  but  these  can  only  be  used  upon  the  special 
classes  of  products  for  which  they  were  designed. 

Determination  of  Ash.  —  The  determination  of  ash  is  of  great  im- 
portance in  the  technical  analysis  of  sugar  products.  Several  methods 
of  the  Association  of  Official  Agricultural  Chemists  *  are  given. 

Direct  Incineration.  —  Heat  from  5  to  10  gms.  of  sugar,  molasses, 
etc.,  in  a  platinum  dish  of  from  50-  to  100-c.c.  capacity  at  100°  C.  until 
the  water  is  expelled,  and  then  slowly  over  a  flame  until  intumescence 
ceases.  Then  place  the  dish  in  a  muffle  and  heat  at  low  redness  until  a 
white  ash  is  obtained. 

Soluble  and  Insoluble  Ash.  —  Add  water  to  the  ash  in  the  platinum 
dish  after  weighing  the  total  ash  in  the  previous  method,  heat  nearly 
to  boiling,  filter  through  ash-free  filter  paper  and  wash  with  hot  water 
until  the  filtrate  and  washings  amount  to  about  60  c.c.  Return  the 
filter  paper  and  contents  to  the  platinum  dish,  carefully  ignite  and 
weigh.  The  residue  is  the  weight  of  insoluble  ash.  The  difference 
between  insoluble  and  total  ash  gives  the  soluble  ash. 

Owing  to  the  difficulty  of  obtaining  a  perfectly  carbon-free  ash  and 
to  the  danger  of  expelling  volatile  salts  during  ignition  Scheiblerf  has 
recommended  burning  the  sample  in  presence  of  sulphuric  acid. 

Ignition  with  Sulphuric  Acid.  —  Saturate  the  sample  with  sulphuric 
acid,  dry,  ignite  gently,  then  burn  in  a  muffle  at  low  redness.  Deduct 
one-tenth  of  the  weight  of  the  ash,  then  calculate  the  per  cent. 

Instead  of  deducting  one-tenth,  to  correct  for  the  weight  of  com- 
bined sulphuric  acid,  Girard  and  Violette  propose  the  deduction  of 
one-fifth. 

Preparation  of  Ash  for  Quantitative  Examination.  —  When  it  is  de- 
sired to  obtain  a  pure  carbon-free  ash  for  quantitative  examination  the 
following  method  should  be  used  :  *  Carbonize  the  mass  at  a  low  heat, 

*  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  pp.  67  and  68. 
f  Stammer's  Jahresbericht,  4,  221;  7,  267. 


496  SUGAR  ANALYSIS 

dissolve  the  soluble  salts  with  hot  water,  burn  the  residual  mass  to 
whiteness,  add  the  solution  of  soluble  salts,  and  evaporate  to  dryness 
at  100  °C.,  ignite  gently,  cool  in  a  desiccator  and  weigh. 

Determination  of  Organic  Matter.  —  The  percentage  of  ash  de- 
ducted from  the  percentage  of  total  solids  gives  the  percentage  of 
organic  matter. 

Determination  of  Non-sugar. — The  percentage  of  sucrose  deducted 
from  the  percentage  of  total  solids  gives  the  percentage  of  non-sugars. 

Determination  of  Organic  Non-sugar.  —  The  percentage  of  ash  de- 
ducted from  the  percentage  of  non-sugar  gives  the  organic  non-sugar. 

Saline  Quotient.  —  This  coefficient  is  found  by  dividing  the  per- 
centage of  sucrose  by  the  percentage  of  ash. 

Glucose  Ratio.  —  The  glucose  ratio,  or  coefficient,  represents  the 
parts  of  glucose  per  100  of  sucrose.  It  is  found  by  multiplying  the  per- 
centage of  reducing  sugars  by  100  and  dividing  by  the  percentage  of 
sucrose. 

The  determination  of  the  glucose  ratio  is  of  great  importance  in 
sugar-house  control.  Any  increase  in  this  coefficient  during  clarifica- 
tion or  evaporation  indicates  a  partial  inversion  of  sucrose. 

Determination  of  Extraction.  —  The  term  extraction  has  been 
given  several  meanings  in  consequence  of  which  occasional  confusions 
and  misunderstandings  have  arisen. 

In  Louisiana  and  Cuba,  extraction  indicates  the  percentage  of  un- 
diluted juice  which  is  obtained  from  a  given  weight  of  cane.  Thus,  if 
2000  Ibs.  of  cane  give  1500  Ibs.  of  undiluted  juice  the  extraction  is 
M££  X  100  =  75  per  cent.  If  the  juice  has  been  diluted  owing  to 
saturation  (i.e.,  spraying  the  ground  cane  with  water  before  regrinding), 
its  equivalent  in  undiluted  juice  must  first  be  determined  before  mak- 
ing the  calculation. 

In  the  Hawaiian  Islands,  extraction  means  the  percentage  of  sucrose 
in  the  cane  that  is  obtained  in  the  mixed  juices  and  is  calculated  by  the 

-         ,    percent  sucrose  in  mixed  juice  X  weight  of  mixed  juice       1An 

lormuia  — : —  — -. — r— — ^ —  X  luu. 

per  cent  sucrose  in  cane  X  weight  of  cane 

Example.  —  2000  Ibs.  of  cane  containing  15  per  cent  sucrose  gave  2300  Ibs. 
of  mixed  diluted  juice  which  polarized  12.4.  Then 

1  o  A   v  9*300 

i  g  s/oTWT  X  10°  =  95-07  Per  cent  extraction, 
lo  X  ^UUU 

Determination    of    Acidity    and    Alkalinity    of    Sugar    Products. 

Herzfeld's  Method.  —  The  determination  of  the  acidity  and  alka- 
linity of  sugar  products  is  at  times  a  matter  of  considerable  impor- 
tance. The  Herzfeld  or  German  official  method  for  determining  the 


MISCELLANEOUS  APPLICATIONS  497 

acidity  and  alkalinity  of  raw  sugars  is  selected  for  description.     The 
following  solutions  are  used: 

(1)  Phenolphthalein.  —  One  part  of  phenolphthalein  is  dissolved 
in  30  parts  of  neutral  90  per  cent  alcohol. 

(2)  Neutral  Water.  —  -  Ten  liters  of  freshly  boiled  distilled  water 
are  treated  with  5  c.c.  of  the  phenolphthalein  solution  and  sufficient 
dilute  alkali  (see  under  4)  added  to  produce  a  permanent  pink  tinge. 
The  water  should  be  prepared  several  hours  before  use,  but  should 
not  be  used  after  one  or  two  days  as  the  indicator  loses  its  sensi- 
bility. 

(3)  Standard   Sulphuric  Acid.  —  A  n/280  sulphuric  acid  solution 
is  prepared,  1  c.c.  of  which  is  equivalent  to  0.0001  gm.  CaO. 

(4)  Standard    Sodium    Hydroxide.  —  A  n/280    sodium-hydroxide 
solution  is  prepared,  1  c.c.  of  which  exactly  neutralizes  1  c.c.  of  the 
standard  acid. 

Ten  grams  of  the  sugar  are  dissolved  in  100  c.c.  of  the  neutral 
water  *  in  a  porcelain  evaporating  dish.  If  the  pink  tinge  of  the 
neutral  water  is  discharged  the  sugar  is  acid  and  the  acidity  is  meas- 
ured by  noting  the  volume  of  standard  alkali  necessary  to  restore  the 
original  color.  If  the  pink  tinge  of  the  neutral  water  is  reddened  the 
sugar  is  alkaline  and  the  alkalinity  is  measured  by  noting  the  volume 
of  standard  acid  necessary  to  bring  back  the  original  tint.  If  the 
end-point  of  the  titration  is  over-run,  the  solution  is  titrated  back 
with  acid  or  alkali  as  the  case  may  be.  The  acidity  or  alkalinity  of 
the  sugar  is  then  expressed  in  the  equivalent  percentage  of  CaO. 
Thus  10  gms.  of  a  sugar  requiring  30  c.c.  of  standard  acid  for  neu- 
tralization would  have  an  alkalinity  of  0.03  per  cent  CaO. 

Normal  Juice.  —  The  true  normal  juice  is  the  mixed  juice  as  it 
actually  exists  in  the  tissues  of  the  cane  or  beet.  It  is  impossible  to 
obtain  this  true  normal  juice  by  any  method  of  pressing  or  milling  for 
reasons  explained  on  page  232,  so  that  its  composition  and  percentage 
must  be  calculated  by  indirect  means.  In  cane-sugar  factories  it  is 
often  customary  to  call  the  undiluted  juice  of  the  first  mill  the  normal 
juice  and  to  make  all  calculations  upon  this  basis.  A  more  correct 
practice  is  to  determine  the  degrees  Brix  and  polarizations  of  the  differ- 
ent mill  juices  and  then  by  means  of  empirical  factors,  established  for 
the  conditions  of  each  factory,  to  calculate  the  approximate  percentage 
and  composition  of  the  normal  juice. 

*  With  dark  sugars  a  larger  volume  of  the  neutral  water  must  be  taken.  Cross 
(Int.  Sugar  J.  13,  305),  in  a  modification  of  Herzf eld's  method,  employs  200  c.c.  of 
neutral  water. 


498  SUGAR  ANALYSIS 

Dutch  Standard.  —  The  Dutch  standard  consists  of  a  series  of 
samples  of  cane  sugar  ranging  in  color  from  a  very  dark  No.  7  to"  an 
almost  white  No.  25.  These  samples  are  put  up  each  year  in  sealed 
bottles  by  two  firms  in  Holland,  under  the  direction  of  the  Netherlands 
Trading  Society,  and  are  sent  to  different  parts  of  the  world  as  color 
standards  for  classifying  sugars  in  the  assessment  of  duty.  The  rela- 
tion between  color  and  composition  is  such  a  loose  one  that  the  Dutch 
standard  has  purely  an  arbitrary  value. 

Calculation  of  Rendement.*  -  -  The  rendement  is  the  yield  of  pure 
crystallized  sucrose  which  can  be  obtained  from  a  raw  product.  The 
various  formulae,  employed  in  its  calculation,  subtract  from  the  polariza- 
tion, or  sucrose  content,  of  the  product  a  certain  quantity  which  is 
taken  to  represent  the  melassigenic  influence  of  the  ash  or  other  non- 
sugars.  One  of  the  most  common  methods  of  calculation  is  that  first 
proposed  by  Monnier  in  France  in  1863;  Monnier  assumed  that  1  part 
of  mineral  impurities  prevented  the  crystallization  of  5  parts  of  sucrose, 
and  so  calculated  the  yield  of  crystallizable  sugar  by  subtracting  5 
times  the  percentage  of  ash  from  the  polarization  of  the  raw  product. 
This  method  of  calculation  is  very  largely  used  in  the  valuation  of  raw 
beet  sugars.  For  cane  sugars  the  following  formula  is  often  used: 
Rendement  =  Polarization  —  (5  X  per  cent  ash  +  per  cent  invert  sugar) . 

Monnier's  formula  for  calculating  rendement  is  used,  however, 
more  in  other  countries  than  in  France  itself.  The  method  most  used 
in  France  at  present  is  to  subtract  from  the  polarization  4  times  the 
percentage  of  ash  and  twice  the  percentage  of  invert  sugar;  from  this 
remainder  1.5  per  cent  additional  is  then  deducted  as  the  loss  in  refin- 
ing. In  1893  the  German  Refiners'  Association  introduced  a  method 
for  calculating  rendement  which  consisted  in  multiplying  the  percentage 
of  total  non-sugars  by  2J  and  subtracting  the  product  from  the  polari- 
zation. This  "  non-sugar  yield  "  was  found,  however,  to  be  less  sat- 
isfactory than  the  "  ash  yield  "  and  a  return  was  made  to  the  old 
method  of  Monnier.  The  number  of  methods  used  by  different  asso- 
ciations and  factories  for  calculating  rendement  is  almost  unlimited. 

Determination  of  Crystal  Content.  —  The  calculation  of  rendement 
by  formula  is  unsatisfactory  for  the  reason  that  the  variations  in 
melassigenic  influence  of  the  non-sugars  are  not  considered.  A  direct 
determination  of  the  sucrose  crystals  in  a  raw  sugar  has,  therefore, 
been  proposed  as  a  better  means  of  determining  the  refining  yield. 

*  For  a  very  full  discussion  of  methods  for  calculating  the  refining  value,  "  net 
analysis,"  or  rendement  of  raw  sugars  see  Mittelstaedt's  "Technical  Calculations 
for  Sugar  Works." 


I 


MISCELLANEOUS  APPLICATIONS  499 

^Method  of  Payen.  —  The  different  methods  for  determining  sugar 
content  are  all  modifications  of  the  early  process  of  Payen,*  which  con- 
sisted in  washing  the  adhering  sirup  from  the  crystals  of  raw  sugar 
by  means  of  88  per  cent  alcohol,  saturated  with  sugar  and  containing 
50  c.c.  of  strong  acetic  acid  per  liter.  The  object  of  the  acid  was  to 
break  up  saccharates  and  promote  the  solution  of  calcium  carbonate 
and  other  mineral  matter.  The  method  of  Payen  was  displaced  in 
1871  by  the  following  modification  of  Scheibler.f 

Scheibler's  Method  for  Determining  Crystal  Content.  —  The  four  wash- 
ing liquids  used  in  Scheibler's  method  have  the  following  composition: 

(1)  85  per  cent  alcohol  containing  50  c.c.  of  strong  acetic  acid  per 
liter  is  saturated  by  shaking  with  an  excess  of  powdered  sucrose. 

(2)  92  per  cent  alcohol  saturated  with  sucrose  as  (1). 

(3)  96  per  cent  alcohol  saturated  with  sucrose  as  (1). 

(4)  A  mixture  containing  2  volumes  of  absolute  alcohol  and  1  vol- 
ume of  ether. 

Stock  solutions  (1),  (2)  and  (3)  are  preserved  in  large  double-neck 
bottles  (Fig.  184),  which  are  filled,  as  is  also  the  siphon  tube  $,  with 
lumps  of  loaf  sugar.  The  tube  T  contains  calcium  chloride  for  pre- 
venting absorption  of  moisture  from  the  air.  The  solutions  should 
not  be  exposed  to  wide  changes  in  temperature. 

In  making  the  determination  a  half-normal  weight  of  the  ground 
sample  of  sugar  is  placed  in  a  50-c.c.  graduated  flask  F,  which  is  closed 
with  a  two-hole  stopper.  One  hole  of  the  latter  is  fitted  with  the  inlet 
tube  7,  through  which  the  washing  liquids  are  added,  and  the  other  with 
the  outlet  tube  0,  through  which  they  are  withdrawn.  The  tube  0  ex- 
tends to  the  bottom  of  the  flask  and  at  its  lower  enlarged  end  is  fitted 
with  a  filtering  plug  of  felt.  The  large  bottle  B,  which  receives  the  spent 
washing  liquids,  is  connected  by  the  opening  of  its  stopper  to  the  outlet 
tube  0  of  the  sugar  flask  and  by  the  side  opening  to  a  suction  pump. 

The  alcohol-ether  solution  (4)  is  first  run  into  the  flask  F,  using 
about  2  volumes  to  1  volume  of  sugar.  After  standing  10  minutes, 
with  occasional  shaking,  the  liquid  is  sucked  off  into  B.  The  alcohol- 
ether  removes  moisture  from  the  sugar  and  at  the  same  time  precipi- 
tates sucrose  from  the  film  of  sirup  adhering  to  the  crystals.  The 
sugar  is  then  treated  in  exactly  the  same  way  with  solutions  (3)  and  (2) ; 
the  latter  remove  the  traces  of  alcohol  and  ether  left  from  (4)  and  pre- 
pare the  sugar  for  the  action  of  solution  (1)  which  accomplishes  the 

*  Dingier 's  Poly  tech.  Journal  (1846),  100,  127. 

t  Full  descriptions  of  Scheibler's  experiments  are  given  in  Stammer's  Jahres- 
bericht,  Vols.  12  and  13  (1872  and  1873). 


500 


SUGAR  ANALYSIS 


chief  part  of  the  washing.  Solution  (1)  is  next  added,  using  the  same 
proportions  as  before.  After  shaking  10  to  15  minutes  the  spent  liquor 
is  withdrawn,  and  a  second  portion  of  (1)  added;  the  process  is  con- 
tinued with  (1)  until  the  washings  become  colorless.  The  sugar  is 

T 


Fig.  184.  —  Scheibler's  apparatus  for  determining  crystal  content  of  raw  sugars. 

then  treated  with  solutions  (2),  (3)  and  (4)  in  the  order  named.  After 
removing  as  much  of  (4)  as  possible,  the  flask  F  is  gently  warmed, 
while  a  strong  current  of  air  is  drawn  through  to  remove  the  last  traces 
of  alcohol  and  ether.  The  connections  are  then  removed  from  F,  any 
particles  of  sugar  adhering  to  the  tube  0,  or  plug  of  felt,  washed  into 
the  flask,  and  sufficient  water  added  to  dissolve  the  contents.  A  few 


MISCELLANEOUS  APPLICATIONS  501 

drops  of  lead  reagent  are  added,  and  the  volume  completed  to  50  c.c. 
The  solution  is  then  filtered  and  polarized;  the  saccharimeter  reading 
gives  the  percentage  of  sucrose  crystals  in  the  sugar. 

The  method  of  Scheibler  for  determining  crystal  content  has  not 
given  satisfactory  results  and  is  at  present  but  little  used.  It  has  been 
found  that  a  considerable  precipitation  of  sucrose  may  take  place  from 
adhering  wash  liquors  especially  upon  contact  with  the  alcohol-ether. 
The  precipitation  of  sucrose  from  the  molasses  in  the  sugar  is  also 
objectionable,  especially  when  it  is  desired  to  calculate  the  composition 
and  amount  of  such  molasses. 

Koydl's  Method  for  Determining  Crystal  Content.  —  In  order  to  re- 
duce the  above-named  errors  and  simplify  the  manipulation,  Koydl* 
has  recently  modified  the  Payen-Scheibler  method  as  follows : 

The  following  five  washing  liquids  are  used: 

(1)  82  per  cent  (by  weight)  alcohol  containing  50  c.c.  concentrated 
acetic  acid  per  liter. 

(2)  86  per  cent  (by  weight)  alcohol  containing  25  c.c.  concentrated 
acetic  acid  per  liter. 

(3)  91  per  cent  (by  weight)  alcohol. 

(4)  96  per  cent  (by  weight)  alcohol. 

All  of  the  above  solutions  are  saturated  with  sucrose  in  the  cold, 
and  kept  over  lump  sugar  in  stock  bottles. 

(5)  Common  absolute  alcohol. 

In  making  the  determination  50  gms.  of  sugar  are  weighed  into  a 
beaker  of  ordinary  form,  18  cm.  high;  250  c.c.  of  solution  (1)  are  meas- 
ured into  a  wash  bottle  from  which  a  sufficient  quantity  is  added  to 
the  beaker  until  the  sugar  is  covered  about  1  cm.  deep.  After  well 
mixing,  the  solution  is  poured  through  a  weighed  filter  paper  (16  cm. 
diameter)  in  a  covered  funnel.  The  process  is  repeated  several  times, 
the  sugar  being  finally  transferred  to  the  filter  and  washed  with  solution 
(1)  until  the  250  c.c.  are  used.  When  the  filter  has  drained  completely, 
50  c.c.  of  solutions  (2),  (3)  and  (4)  are  poured  in  successive  portions 
upon  the  sugar,  each  liquid  being  allowed  to  filter  off  before  adding  the 
one  following.  The  sugar  is  then  washed  with  100  c.c.  of  (5)  taking 
care  to  wash  well  the  edges  of  the  paper.  When  the  alcohol  has  filtered 
completely,  the  paper  and  its  contents  are  dried  in  an  oven  and  then 
weighed.  The  weight  of  product  multiplied  by  two  gives  the  crystal 
content  of  the  sugar. 

Koydl's  method  has  been  found  to  give  results  which  are  approxi- 
mately quantitative,  when  the  requirements  of  uniform  temperature, 
*  Oester.  Ungar.  Z.  Zuckerind.,  (1906),  277.' 


502 


SUGAR  ANALYSIS 


saturation  of  solutions  and  other  details  are  carefully  maintained. 
With  variations  from  these  requirements  a  considerable  error  may  re- 
sult from  solution  or  precipitation  of  sucrose.  A  certain  amount  of 
gum  and  mineral  matter  is  always  precipitated  from  the  adhering 
molasses  by  the  alcoholic  solutions;  the  final  crystals  when  dried 
polarize  from  99.4  to  99.8  and  contain  about  0.2  per  cent  organic  non- 
sugar  and  0.15  per  cent  ash. 

Results  of  analyses  of  several  beet  sugars  giving  the  composition, 
rendement  (polarization  less  5  times  ash)  and  crystal  content  by  Koydl's 
method  are  given  in  Table  LXXXIV  which  is  taken  from  results  by 
Ehrlich.* 

TABLE  LXXXIV 


No. 

Polariza- 
tion. 

Moisture. 

Ash. 

Organic 
non-sugar. 

Rendement. 

Crystals  (Koydl's 
method). 

Molasses 
(100  less 
per  cent 

I. 

II. 

crystals). 

1 

96.30 

Per  cent. 
1.49 

Per  cent 
0.81 

Per  cent. 
1.40 

92.25 

Per  cent. 

93.32 

Per  cent. 

93.14 

Per  cent. 
6.77 

2 

95.85 

1.24 

1.17 

1.74 

90.00 

92.04 

92.28 

7.84 

3 

95.10 

2.04 

1.13 

1.73 

89.45 

90.83 

90.87 

9.15 

4 

94.50 

1.63 

1.41 

2.46 

87.45 

91.20 

91.17 

8.82 

5 

94.40 

1.84 

1.37 

2.39 

87.55 

89.87 

90.10 

10.02 

It  is  seen  that  no  strict  proportionality  exists  between  polarization, 
rendement  and  crystal  content.     Sugars  4  and  5  have  practically  the 


Fig.  185.  —  Laboratory  hand  centrifugals. 

same  polarization  and  rendement,  but  sugar  4  contains  over  1  per 
cent  more  crystals  and  over  1  per  cent  less  molasses  than  sugar  5,  and 
is,  therefore,  more  valuable  for  refining  purposes. 

*  Z.  Ver.  Deut.  Zuckerind.,  59,  548,  995. 


MISCELLANEOUS  APPLICATIONS 


503 


There  are  other  modifications  of  Payen's  method  for  determining 
crystal  content,  but  none  equal  in  practicability  to  those  of  Scheibler 
and  Koydl.*  Such  methods  have  found  their  chief  value  not  in  the 
work  of  routine  but  in  providing  a  control  upon  other  processes. 

In  many  European  refineries  the  crystal  content  of  raw  sugars, 
massecuites,  etc.,  is  determined  by  washing  a  large  sample  of  the 
product  in  a  laboratory  centrifugal  (Fig.  185)  with  a  saturated  sugar 
sirup.  The  results  obtained  by  a  practical  test  of  this  kind  are  often 
found  to  have  more  value  than  those  obtained  by  any  modification  of 
the  Payen  method. 

Method  of  Herzfeld  and  Zimmermann.  —  In  order  to  avoid  the 
error  due  to  the  use  of  alcoholic  washing  fluids,  Herzfeld  and  Zim- 
mermann f  have  recently  devised  a  method  for  determining  crystal 
content,  by  which  the  raw  sugar  is  simply  shaken  and  washed  with  a 
saturated  aqueous  sucrose  solution.  The  latter  is  always  prepared 
just  before  use  by  weighing  out  500  to  600  gms.  of  water  in  a  strong 
glass-stoppered  flask  and  adding  the  exact  amount  of  sucrose  to  pro- 
duce saturation  at  the  laboratory  temperature,  which  should  be  as 
near  20°  C.  as  possible.  The  grams  of  sucrose  necessary  for  satu- 
rating 100  gms.  of  water  at  temperatures  between  15°  and  35°  C.  are 
given  in  the  following  table: 


Laboratory 
temperature. 

Grams  sucrose  per 
100  gms.  water. 

Ratio  of  water 
to  sugar  sirup. 

Laboratory 
temperature. 

Grams  sucrose 
per  100  gms. 
water. 

Ratio  of  water 
to  sugar  sirup. 

Deg.  C. 

Deg.  C. 

15 

194.3 

2.943 

25 

208.3 

3.083 

16 

195.6 

2.956 

26 

209.8 

3.098 

17 

196.9 

2.969 

27 

211.3 

3.113 

18 

198.3 

2.983 

28 

212.9 

3.129 

19 

199.6 

2.996 

29 

214.5 

3.145 

20 

201.0 

3.010 

30 

216.1 

3.161 

21 

202.4 

3.024 

31 

217.7 

3.177 

22 

203.8 

3.038 

32 

219.3 

3.193 

23 

205.3 

3.053 

33 

221.0 

3.210 

24 

206.8 

3.068 

34 

222.8 

3.228 

The  stoppered  flask  containing  the  sugar  and  water  is  warmed 
until  the  sugar  has  dissolved  and  then  cooled  to  the  required  tem- 
perature. The  solution  is  then  placed  in  a  bottle  provided  with  a 
thermometer  and  delivery  tube  as  shown  by  F  in  Fig.  186. 

Fifty  grams  of  the  raw  sugar  are  weighed  into  the  pear-shaped 
glass  vessel  A,  which  has  a  capacity  of  about  500  c.c.  and  is  closed  at 

*  For  a  complete  review  of  Koydl's  method,  with  abstract  of  favorable  and  un- 
favorable reports,  see  Stammer's  Jahresbericht  for  1906,  1907  and  1908. 
t  Z.  Ver.  Deut.  Zuckerind.,  62,  166. 


504 


SUGAR  ANALYSIS 


its  lower  end  by  the  rubber  plug  Sf; 
200  c.c.  of  the  saturated  sucrose 
solution  are  then  added,  the  rub- 
ber stopper  S  is  inserted  and  the 
whole  shaken  vigorously  until  all 
molasses  adhering  to  the  sugar 
crystals  has  been  dissolved.  The 
vessel  A  should  not  be  handled 
with  the  bare  hands,  which  might 
warm  the  solution  and  dissolve 
some  of  the  crystals. 

The  vessel  A  is  then  attached 
by  the  rubber   stopper  B,   after 
removing  the  plug  $',  to  the  filter- 
ing cup  C.     The  open  bottom  of 
the  latter  is  closed  with  a  filter 
plate  h}  upon  which  rests  a  thin 
pad  of  felt  /,  and  above  the  latter 
a  disk  of  wire  gauze  g.      The  felt 
and  gauze  are  pre- 
viously    cleaned, 
dried  and  weighed. 
The  cup  C  is  then 
attached  to  the  fil- 
ter-flask D and  the 
stopper  S  replaced 
by  a  stopper  con- 
taining  a   small 
capillary  tube. 
Suction   is   then 
applied    and    the 
contents  of  A  are 
gently  discharged 
into  C.    The  inner 
surface    of    A    is 
then  washed  with 
a  little  sugar  solu- 
tion from  F  until 
all     crystals     are  Fig.  186.  — Herzfeld  and  Zimmermann's  apparatus  for  deter- 
removed;      about  mining  crystal  content  of  raw  sugars. 

50  c.c.  of  sugar  solution  are  sufficient.      The  cup,  without  sucking  off 


MISCELLANEOUS  APPLICATIONS 


505 


all  the  sirup,  is  then  placed  in  a  small  centrifugal  and  whirled  for  5 
minutes,  in  the  first  minute  at  2000,  in  the  second  minute  at  2500, 
and  for  the  remaining  time  at  2700  revolutions  per  minute.  The 
cup  is  then  removed  and  its  contents  are  discharged  into  a  weighing 
bottle  by  inverting  and  gently  pushing  the  bottom  plate  with  a  rod, 
any  crystals  left  adhering  to  the  walls  of  the  cup  being  also  carefully 
removed.  The  sugar,  felt  and  gauze  are  weighed,  and  then 
dried  in  vacuum  at  a  final  temperature  of  105°  to  110°  C.  After 
deducting  the  weight  of  felt  and  gauze  the  loss  by  drying  is  calcu- 
lated to  sugar-sirup  by  multiplying  by  the  ratio  of  water  to  sirup  for 
the  temperature  of  saturation.  The  weight  of  sirup  deducted  from 
the  weight  of  sugar  after  centrifuging  gives  the  weight  of  crystals. 
The  method  of  calculation  is  illustrated  by  the  following  example: 

A  saturated  sugar  solution  was  prepared  for  a  laboratory  temperature  of 
21°  C.;  the  ratio  of  water  to  sirup  for  this  temperature  is  1  :  3.024. 

Weight  of  raw  sugar  taken  =  50.00  gins. 

Weight  of  sugar  after  centrifuging    =  48.62  gms. 
Weight  of  sugar  after  drying  =  48.01  gms. 

Difference  due  to  water  of  sirup  =    0.61  gms. 

Adhering  sirup  =  0.61  X  3.024  =    1.84  gms. 

Weight  of  crystals  =  48.62  -  1.84  =  46.78  gms. 

Crystal  content  of  sugar  =  93.56  per  cent. 

Results  of  analyses  of  several  samples  of  raw  beet  sugar  by  the 
above  method  are  quoted  from  the  work  of  Herzfeld  and  Zimmer- 
mann. 


Rende- 

Color 

Calcu- 

Num- 
ber. 

Product. 

Direct 
polari- 
zation. 

Organic 
non- 
sugar. 

Ash. 

Mois- 
ture. 

ment; 
polari- 
zation 
less 

degrees 
(Stammer) 
for  100 
polariza- 

Crystal 
content. 

purity 
of  mo- 
lasses in 

5Xash. 

tion. 

sugar. 

1 

Raw  sugar  

91.80 

3.35 

2.05 

2.80 

81.55 

68 

82.52 

63.7 

Crystals 

99  90 

0  11 

3.1 

2 

Raw  sugar  

89.90 

4.04 

2.86 

3.20 

75.60 

114 

80.60 

62.4 

Crystals 

99  00 

0  70 

10.4 

3 

Raw  sugar  

91.20 

3.26 

2.44 

3.10 

79.00 

84 

82.10 

63.7 

Crystals  

99.60 

0.37 



7.4 





4 

Raw  sugar  

92.00 

3.41 

2.19 

2.40 

81.05 

145 

81.96 

64.9 

Crystals 

99  85 

0  18 

5.1 

It  is  seen  that  the  final  crystals  obtained  from  the  above  sugars 
contained  from  0.10  to  1.00  per  cent   ash  and  organic   impurities. 


506  SUGAR  ANALYSIS 

The  Herzfeld-Zimmermann  method  has  not  as  yet  been  generally 
tested,  but  deserves  recognition  from  its  simplicity.  The  process 
should  be  subjected  to  a  careful  control  according  to  individual 
technical  requirements. 

Calculation  of  Composition  and  Purity  of  Molasses  in  Raw 
Sugars.  —  A  knowledge  of  the  composition  and  purity  of  the  molasses 
contained  in  raw  sugars  is  often  desired.  The  determination  is  made 
indirectly  by  subtracting  the  sucrose  of  the  crystals  from  that  of  the 
raw  sugar  and  calculating  the  remaining  ingredients  as  due  to  molasses. 
The  purity  of  the  molasses  in  sugar  Number  2  of  the  previous  table 
would  be  calculated  as  follows: 

Per  cent. 

Dry  substance  of  raw  sugar  =  100.00  -  3.20  =  96.80 

Crystal  content  of  raw  sugar  =80.60 

Difference  =  Dry  substance  of  molasses  in  raw  sugar         =  16.20 
Polarization  of  raw  sugar  =  89.90 

Polarization  due  to  crystals  in  raw  sugar  =  80.60  X  0.99  =  79.79 
Difference  =  Polarization  due  to  molasses  in  raw  sugar      =  10.11 

Apparent  purity  of  molasses  in  raw  sugar  =  1A'on  X  100  =  62.4 

lo.zu 

STARCH  PRODUCTS 

Polariscopic  Methods  for  Determining  Starch.  —  Several  methods 
have  been  devised  for  estimating  starch  from  the  specific  rotation, 
after  conversion  into  the  soluble  form.  The  following  methods*  have 
been  used. 

Solution  of  Starch  by  Heating  Under  Pressure.  —  From  2  to  3  gms. 
of  material  are  heated  in  a  100-c.c.  flask  with  80  to  90  c.c.  of  water 
until  a  uniform  gelatinization  of  the  starch  has  been  obtained.  The 
flask  is  then  placed  in  an  autoclave  (Fig.  175)  and  heated  3  to  5  hours 
at  2  to  3  atmospheres'  pressure.  After  cooling,  the  clear  solution  is 
made  up  to  100  c.c.,  filtered  and  polarized.  The  soluble  starch  thus 
obtained  is  without  action  upon  Fehling's  solution;  its  rotation  is 
[<*]D  =  +196.5  to  +197.  Using  the  value  +196.5,  the  weight  of 
starch  in  the  100  c.c.  of  solution  is  calculated  from  the  angular  rotation 

a  in  the  200-mm.  tube  by  means  of  the  formula  [O\D  =  — rrj »  whence 

c  X  ' 

100  a 
grams  starch 


2  (+  196.5) 

Solution  of  Starch  by  Means  of  Hydrochloric  Acid.  —  Five  grams  of 
the  starch-containing  material  are  rubbed  with  20  c.c.  of  concentrated 
*  Wiley's  "  Agricultural  Analysis  "  (1897),  Vol.  Ill,  205. 


MISCELLANEOUS  APPLICATIONS 


507 


hydrochloric  acid  of  1.17  sp.  gr.  for  about  10  minutes.  When  the  solution 
has  cleared,  the  volume  is  completed  to  200  c.c.,  and  the  liquid  filtered 
and  polarized.  The  soluble  starch  as  thus  prepared  has  a  rotation  of 
[a]o  =  +  196.3  to  +196.7.  Using  the  mean  value  of  +196.5,  the  grams 
of  starch  in  100  c.c.  of  solution  are  calculated  as  in  the  previous  method. 

With  impure  starch-containing  materials,  neither  of  the  above 
polariscopic  methods  has  the  accuracy  of  the  diastase  method  de- 
scribed on  page  440. 

Calculating  the  Apparent  Composition  of  Starch-conversion  Prod- 
ucts from  the  Specific  Rotation.  —  Brown,  Morris  and  Millar  *  have 


100 


s  •" 

in 

>,co 


a 
& 
£20 

£.« 


3.0° 

MD 


190 


170 


150  130  110 

Specific  Rotation  [aj 


100 


Fig.  187.  —  Showing  relation  of  specific  rotation  to  composition  of  acid-hydrolyzed 

starch  products. 

shown  that  in  starch  products  of  diastase  conversion  a  constant  rela- 
tion exists  between  the  specific  rotation  and  copper-reducing  power  of 
the  total  solids.  Rolfe  and  Defrenf  have  also  shown  that  in  starch 
products  of  acid  conversion  the  solids  of  same  specific  rotation  have 
always  the  same  reducing  power  "  irrespective  of  the  source  of  the 
.starch,  the  nature  or  amount  of  the  hydrolyzing  acid,  or  the  tempera- 
ture conditions,  these  influencing  the  rate  of  hydrolysis  only."  It  is, 
therefore,  possible  to  express  by  means  of  a  curve  the  relationship  be- 
tween specific  rotation  and  copper-reducing  power,  or  between  either 
of  these  constants  and  the  apparent  percentages  of  glucose,  maltose 
and  dextrin,  calculated  by  means  of  such  formulae  as  are  used  in  Allen's 
method  (p.  486).  Upon  this  principle  Rolfe  has  prepared  the  diagram 
shown  in  Fig.  187,  which  gives  the  percentages  of  dextrose,  maltose 
and  dextrin  in  the  dry  substance  of  starch-conversion  products  cor- 

*  J.  Chem.  Soc.,  71,  115. 

t  J.  Am.  Chem.  Soc.,  18,  869;  Rolfe,  "  The  Polariscope  "  (1905),  p.  197. 


508  SUGAR  ANALYSIS 

responding  to  the  values  of  [a]D  for  dry  substance  (as  determined 
by  the  solution  factor  3.86)  between  +195  for  dextrin  and  +53  for 
glucose. 

A  value,  for  example,  of  [a]D  =  +  100  for  the  dry  substance  (cal- 
culated from  the  density  of  an  approximately  10  per  cent  solution  at 
15.5°  C.  by  the  solution  factor  3.86)  of  an  acid-conversion  product 
would  correspond  to  an  apparent  composition  of  dry  substance  of 
10  per  cent  dextrin,  40  per  cent  maltose  and  50  per  cent  glucose. 

The  apparent  percentages  as  thus  determined  are  useful  for  pur- 
poses of  comparison  and  valuation  but  must  not  be  mistaken  for 
absolute  percentages  for  reasons  already  given.  As  Rolfe  is  careful  to 
state  "  there  are  comparatively  few  commercial  products  pure  enough 
to  permit  of  their  constitution  being  determined  in  this  simple  manner." 

Analysis  of  Commercial  Dextrins.  —  The  following  method  has 
been  used  by  the  United  States  Bureau  of  Chemistry  in  testing  dextrins 
for  the  National  Bureau  of  Printing  and  Engraving.  The  method  is  a 
modification  by  Browne  and  Bryan  *  of  a  scheme  of  analysis  proposed  by 
F.  Lippmann.f 

Specific  Rotation.  —  Transfer  10  gms.  of  the  finely  divided  sample 
to  a  100-c.c.  flask,  and  after  solution  in  about  50  c.c.  of  cold  water  add 
5  c.c.  of  alumina  cream  and  make  up  the  contents  to  100  c.c.,  thoroughly 
shake  and  filter.  Polarize  the  filtrate  in  a  200-mm.  tube,  using  any 
form  of  polariscope  or  saccharimeter.  It  is  important  that  a  6  per 
cent  solution  of  bichromate  of  potash  in  a  3-mm.  tube  be  used  as  a 
light  filter.  In  using  a  Ventzke-scale  saccharimeter,  the  specific  rota- 

OA  ao  vx  TT 

tion  is  found  by  the  formula  [«]/>  =  -  —~^ »  in  which  V  =  Ventzke 

reading. 

Viscosity.  —  Dissolve  100  gms.  of  dextrin  in  200  c.c.  of  cold  water 
by  rubbing  up  in  a  mortar  or  porcelain  dish,  and  determine  the  vis- 
cosity of  the  solution  by  any  of  the  standard  forms  of  viscosimeter. 
Comparative  results  should  always  be  made  by  the  same  instrument 
and  under  similar  conditions  of  temperature ;  a  uniform  length  of  time 
should  also  elapse  after  making  up  the  solution  before  taking  the  vis- 
cosity. The  viscosity  should  be  determined  again  on  the  same  solu- 
tion after  standing  24  hours,  and  also  after  48  hours. 

Moisture.  —  Determine  by  drying  from  2  to  5  gms.  of  sample  for 
4  hours  at  a  temperature  of  105°  C.  Absolute  constancy  in  weight  can- 
not be  attained  on  account  of  the  slow  decomposition  of  the  dextrin. 

*  Proc.,  Sec.  V,  "  Seventh  Int.  Cong.  App.  Chem.,"  London,  1909,  p.  337. 
t  Z.  Spiritusind.,  25,  304,  307,  316,  317. 


II 


MISCELLANEOUS  APPLICATIONS  509 

Ash.  —  Five  to  10  gins,  of  the  sample  are  weighed  in  a  tared  pla- 
tinum dish  and  burned  over  a  flame  at  a  low  heat.  The  ash  should  not 
be  heated  to  fusion,  otherwise  loss  from  volatilization  will  occur. 

Soluble  Starch.  —  If  a  filtered  hot-water  solution  of  the  dextrin 
gives  a  blue  reaction  with  iodine  solution,  soluble  starch  is  indicated. 
Weigh  two  lots  of  dextrin,  10  gms.  each,  into  100-c.c.  flasks,  add  50  c.c. 
of  cold  water  to  each  and  after  all  soluble  matter  is  dissolved  make  up 
the  contents  of  the  one  flask  with  cold  water  at  100  c.c.,  shake  and 
filter.  Evaporate  20  c.c.  of  the  solution  (2  gms.)  to  dryness  and  dry 
for  4  hours  at  105°,  as  under  determination  of  moisture.  Weight 
of  residue,  less  ash  on  incineration,  equals  cold-water  soluble  organic 
matter.  Heat  the  contents  of  the  second  flask  to  boiling,  and  then 
after  cooling  make  up  to  100  c.c.,  shake  and  filter.  The  weight  of  hot- 
water  soluble  organic  matter  in  20  c.c.  of  solution  is  determined  as  be- 
fore. Hot- water  soluble  organic  less  cold-water  soluble  organic  gives 
the  soluble  starch. 

Unconverted  Starch.  —  If  the  residue  insoluble  in  hot  water  shows 
under  the  microscope  grains,  which  are  colored  blue  with  iodine, 
unconverted  starch  is  present.  To  determine  the  percentage,  collect 
the  residue  insoluble  in  hot  water  on  a  filter,  wash  until  free  from  solu- 
ble matter,  and  determine  the  starch  by  the  usual  methods. 

Reducing  Sugars.  —  Determine  in  an  aliquot  of  the  cold-water 
soluble  by  the  method  of  Allihn,  the  results  being  expressed  as  glucose. 

Dextrin.  —  Subtract  the  specific  rotation  of  the  dextrin  due  to  re- 

,     .  (52.5  X  per  cent  reducing  sugar  as  glucose)    , 

ducmg  sugars  A  &  -  from  the 

JLUU 

original  specific  rotation  of  the  sample.  Multiply  the  remainder  by 
100  and  divide  by  186  ([a]n  of  dextrin  *)  to  obtain  the  calculated  per- 
centage of  dextrin  in  the  sample. 

Undertermined  Solubles.  —  The  per  cent  of  cold-water  soluble  organic 
matter  less  calculated  percentage  of  dextrin  gives  the  percentage  of 
undetermined  solubles. 

In  Table  LXXXV  eight  analyses  of  commercial  dextrins  by  the 
above  method  are  given. 

It  is  noted  that  with  a  decrease  in  specific  rotation  there  is  a  uni- 
form decrease  in  viscosity  and  in  the  calculated  percentage  of  dextrin, 

*  The  [<x]D  +  186  of  dextrin  is  given  by  Schultze  (J.  prakt.  Chem.,  28,  327). 
This  is  considerably  lower  than  the  figures  +195  to  +205,  which  have  been  re- 
ported by  other  authorities  for  carefully  purified  dextrins.  The  value  +186  is 
used  only  as  a  commercial  standard  of  comparison,  and  the  percentages  of  dextrin 
thus  calculated  have  no  strict  scientific  value. 


510 


SUGAR  ANALYSIS 


and  a  uniform  increase  in  reducing  sugars  and  undetermined  matter. 
A  large  percentage  of  reducing  sugars  indicates  over-dextrinization,  and 
accompanying  this  there  is  always  a  formation  of  other  decomposition 
products. 

TABLE  LXXXV 
Giving  Analyses  of  Commercial  Dextrins 


Viscosity  at  20°  C. 

1  to  2  solution. 

Chemical  analysis. 

Water  =100. 

1    Cold 

Hot- 

No. 

Wi> 

water 
solution. 

water 
solution. 

Mois- 
ture 

A  oh 

Reduc- 
ing 

Cold- 
water 
insol- 

Dextrin. 

Un- 
deter- 

mined 

Acidity 
n/10 

Im- 
me- 
diate 

After 
24 
hours 

Im- 
me- 
diate 

After 
24 
hours 

at 
105°C 

AMI* 

sugars 
as  glu- 
cose. 

uble  or- 
ganic 
matter. 

By  dif- 
ference. 

From 
polariz- 
ation. 

soluble 
matter. 

per  10 
gms. 

Per 

Per 

Per 

Per 

Per 

Per 

Per 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

c.c. 

1 

+175.2 

844 

1332 

396 

428 

2.92 

0.09 

1.80 

0.24 

94.95 

93.74 

1.21 

2.2 

2 

+174.1 

620 

980 

396 

430 

3.96 

0.08 

1.77 

0.34 

93.85 

93.15 

0.70 

2.0 

3 

+172.7 

596 

860 

480 

480 

2.88 

0.14 

1.56 

0.45 

94.97 

92.46 

2.51 

2.6 

4 

+167.5 

480 

692 

242 

256 

4.46 

0.16 

2.44 

1.95 

90.99 

89.43 

1.56 

2.3 

5 

+163.7 

420 

636 

324 

330 

6.07 

0.09 

2.20 

0.31 

91.33 

87.45 

3.88 

2.5 

6 

+162.2 

384 

448 

348 

370 

4.76 

0.13 

2.03 

3.37 

89.71 

86.69 

3.02 

2.0 

7 

+159.2 

344 

392 

240 

260 

2.39 

0.14 

5.59 

3.27 

88.61 

84.16 

4.45 

4.0 

8 

+149.8 

300 

332 

184 

186 

4.42 

0.13 

5.78 

2.48 

87.19 

79.07 

8.12 

5.3 

The  viscosity  determination  is  of  paramount  value  as  a  physical 
test  in  examining  the  qualities  of  dextrins,  likewise  the  change  in  vis- 
cosity of  the  cold-water  solution  after  24  hours'  and  48  hours'  standing. 
In  the  technical  application  of  dextrins  such  an  increase  in  viscosity,  if 
large,  will  overtax  the  machines  or  impair  the  results  of  the  work. 
The  figures  in  the  table  corroborate  the  views  of  Lippmann  that  the 
cold-water  solution  only  should  be  used  for  the  viscosity  test,  since  the 
individual  differences  between  dextrins  are  thus  rendered  more  dis- 
tinguishable than  where  the  solutions  are  made  in  hot  water. 

Analysis  of  Malt  Extracts.  —  Malt  extracts  are  employed  by 
brewers  and  also  by  bakers,  who  use  them  extensively  for  the  improve- 
ment of  bread.  The  extracts  are  prepared  by  evaporating  the  filtered 
wort  from  mashed  malt  to  a  sirup.  Malt  extracts  are  in  many  cases 
valued  for  their  diastatic  power,  and  in  preparing  such  extracts  the 
evaporation  must  be  conducted  in  a  vacuum  apparatus  at  low  tempera- 
ture. Extracts  prepared  by  mashing  malt  with  cold  water  have  the 
highest  diastatic  activity;  in  such  extracts  the  percentage  of  sugars 
preexisting  in  the  malt,  as  sucrose  and  invert  sugar,  will  be  high  and 
the  percentage  of  maltose  low.  If  the  malt  be  mashed  at  60°  C.,  then 
the  extract  will  contain  a  large  excess  of  maltose  due  to  the  conversion 


MISCELLANEOUS  APPLICATIONS 


511 


of  the  starch  by  the  diastase.  The  following  analyses  by  Jago  *  show 
the  marked  difference  in  composition  between  extracts  made  by  cold- 
water  and  warm-water  mashing. 

TABLE  LXXXVI 


Constituent. 

Cold-water  mash. 

Warm-water  mash,  60°  C. 

Extract, 
unevaporated. 

Extract, 
evaporated. 

Extract,    "" 
unevaporated. 

Extract, 
evaporated. 

Water                              .     . 

95.17 
0.32 
0.80 
0.60 
0.45 
0.21 
2.45 

22.90 
4.80 
12.71 
13.66 
4.79 
2.69 
38.45 

86.70 

0.24 
0.86 
1.32 
0.43 
9.04 
1.41 

14.70 
1.70 
5.27 
10.82 
0.00 
60.97 
6.54 

Ash 

Proteids                  

Dextrin      

Sucrose  
Maltose  

Glucose  and  fructose  

100.00 

100.00 

100.00 

100.00 

In  the  analysis  of  such  a  complicated  mixture  of  sugars  and  car- 
bohydrates, as  occurs  in  malt  extracts,  the  chemist  must  employ  in- 
direct methods,  the  use  of  which  involves  a  considerable  multiplication 
of  experimental  errors  as  previously  explained  (p.  488).  The  sucrose 
can  be  determined  by  the  method  of  inversion,  the  dextrin  by  precipi- 
tation with  alcohol  (correcting  for  occluded  ash  and  proteids),  the 
fructose  by  high  temperature  polarization;  knowing  these  the  maltose 
and  glucose  may  be  calculated  indirectly  from  the  combined  copper-re- 
ducing power  and  polarization.  The  results  thus  determined  have 
only  an  approximate  value.  The  extracts  require  to  be  clarified  care- 
fully in  order  to  eliminate  the  influence  of  soluble  proteids. 

DETERMINATION    OF   DIASTATIC    POWER  f 

Malts  and  malt  extracts  are  frequently  purchased  upon  the  sole 
basis  of  diastatic  power  and  a  description  of  several  methods  for  de- 
termining this  factor  is  introduced  in  this  connection.  The  methods 
given  apply  also  to  the  valuation  of  commercial  amylases,  such  as 
diastase,  takadiastase,  pancreatin,  etc.,  which  find  a  medicinal  use  for 
certain  forms  of  indigestion. 

Determination  of  Diastatic  Power  of  Malt  and  Malt  Extracts, 
Lintner's  Method.  —  The  diastatic  power  of  malts  and  malt  extracts 
is  usually  determined  by  Lintner's  t  method,  the  results  of  which 

*  "  The  Technology  of  Bread  Making  "  (1911),  p.  512. 

f  For  a  fuller  description  of  methods  for  determining  diastatic  power  see 
Sherman's  "  Methods  of  Organic  Analysis,"  2nd  Ed.,  Chapter  V. 

t  J.  prakt.  Chem.  [2],  34,  378. 


512  SUGAR  ANALYSIS 

expressed  as  degrees  Lintner,  represent  the  copper-reducing  power 
produced  by  the  action  of  a  measured  volume  of  the  extract  upon  a 
solution  of  soluble  starch  at  21°  C.  for  1  hour. 

Soluble-starch  Solution.  —  A  solution  is  made  containing  2  gms.  of 
soluble  starch  (prepared  as  described  on  page  577)  in  100  c.c. 

Procedure.  —  In  determining  the  diastatic  power  of  malt,  or  flour, 
25  gms.  of  the  finely  ground  material  are  digested  with  500  c.c.  of 
water  at  room  temperature  for  5  hours.  The  solution  is  then  filtered 
until  perfectly  clear. 

Ten  test  tubes  are  placed  in  a  metal  rack  and  10  c.c.  of  the  soluble- 
starch  solution  added  to  each.  To  the  first  tube  0.1  c.c.  of  the  filtered 
malt  solution  is  added,  to  the  second  tube  0.2  c.c.,  and  so  on,  the  tenth 
tube  receiving  1.0  c.c.  The  tubes  are  shaken  and  then  placed  for  1 
hour  in  a  water  bath  kept  at  21°  C.,  5  c.c.  of  mixed  Fehling's  solution 
are  then  added  to  each  tube  and  the  .rack  is  placed  in  a  boiling-water 
bath  for  10  minutes.  The  rack  is  then  removed  and,  after  the  precipitates 
of  cuprous  oxide  have  settled,  the  two  tubes  are  selected  in  which  the 
copper  is  all  reduced  and  in  which  some  of  it  still  remains  in  solution, 
as  is  shown  by  the  absence  or  presence  of  blue  color,  or  by  means  of  the 
ferrocyanide  test.  The  amount  of  malt  solution  just  necessary  to  re- 
duce the  5  c.c.  of  Fehling's  solution  is  between  the  amounts  added  to 
these  two  tubes;  the  corrected  amount  is  then  assumed  to  be  midway 
between  these  limits,  or  the  value  of  the  second  decimal  estimated 
from  the  depth  of  blue  color  in  the  tube  where  reduction  is  incomplete. 

A  malt  is  given  a  diastatic  value  of  100  on  Lintner 's  scale  when 
0.1  c.c.  of  the  filtered  5  per  cent  extract  just  reduces  5  c.c.  of  Fehling's 
solution  under  the  above  conditions.  If  0.25  c.c.  of  malt  solution  were 
required  to  reduce  the  5  c.c.  of  Fehling's  solution  then  the  diastatic 

0  1  X  100 

power  of  the  malt  would  be    '         —  =  40  degrees  Lintner.     A  slight 

(J.dd 

correction  remains  to  be  made  for  the  reducing  sugars  in  the  malt  solu- 
tion and  for  any  reducing  power  of  the  soluble  starch.  This  correction 
is  found  by  taking  5  c.c.  of  Fehling's  solution,  10  c.c.  of  starch  solution 
and  10  c.c.  of  water  and  heating  to  boiling.  The  malt  solution  is  then 
added  from  a  burette  until  the  blue  color  is  just  discharged.  If  7  c.c. 
of  malt  solution  were  used  then  there  would  be  a  correction  of 

— = =  1.4  degrees  Lintner  to  be  subtracted  from  the  value  pre- 
viously found. 

In  the  case  of  evaporated  malt  extracts  of  high  diastatic  power  a 
1  per  cent  or  0.5  per  cent  solution  of  the  extract  is  used,  the  values  thus 


MISCELLANEOUS  APPLICATIONS  513 

obtained  being  multiplied  by  5  or  10  to  obtain  the  true  degrees  Lintner 
for  a  5  per  cent  solution. 

Lintner 's  Method  as  Applied  to  Diastases.  —  In  determining  the 
activity  of  diastase  preparations  Lintner*  uses  the  method  described 
for  malt,  the  only  difference  being  that  the  results  are  expressed  in 
terms  of  a  diastase  of  which  0.12  mg.  produces  sufficient  sugar  to  re- 
duce the  5  c.c.  of  Fehling's  solution.  In  making  the  test,  from  50  to 
100  mgs.  of  the  diastase  to  be  tested  are  dissolved  in  4  to  5  c.c.  of  water 
and  then  made  up  to  100  c.c.  or  200  c.c.  according  to  the  supposed 
strength  of  the  enzyme.  If  under  the  conditions  described  for  the 
malt  method  0.2  mg.  of  a  diastase  was  required  to  produce  sufficient 
sugar  to  reduce  the  5  c.c.  of  Fehling's  solution,  then  its  diastatic  power 

0  12  X  100 
would  be — =  60  degrees  Lintner  (diastase  scale) . 

It  should  be  noted  that  100  degrees  diastase  are  over  40  times 
( 0^2 —  J  as  powerful  as  100  degrees  malt  upon  Lintner's  scale. 

Sykes  and  Mitchell's  Gravimetric  Modification  of  Lintner's 
Method.  —  In  the  method  of  Sykes  and  Mitchell  f  100  c.c.  of  2  per 
cent  soluble-starch  solution  are  treated  with  1  c.c.  of  the  5  per  cent 
malt  extract  (prepared  as  in  Lintner's  method)  at  21°  C.  for  1  hour; 
50  c.c.  of  Fehling's  solution  are  then  added  and  the  liquid  heated 
quickly  to  98°  C.,  when  it  is  placed  in  a  boiling- water  bath  for  7  minutes. 
The  reduced  copper  is  then  determined,  the  weight  of  which  divided 
by  0.438  (the  grams  of  copper  in  50  c.c.  Fehling's  solution)  and  multi- 
plied by  100  gives  the  diastatic  power  in  degrees  of  the  Lintner  scale. 
The  results  are  said  to  compare  well  with  those  obtained  by  Lintner's 
method. 

A  gravimetric  method  for  determining  diastatic  power  permits  a 
closer  degree  of  estimation  than  is  possible  by  the  original  Lintner 
process.  Slight  errors  of  estimation  by  the  volumetric  method  cause 
considerable  differences  in  the  final  results,  when  only  small  volumes 
of  diastase  solution  are  taken.  Thus  between  0.1  c.c.  and  0.15  c.c.  the 
degrees  Lintner  (malt)  will  vary  between  100  and  66.6. 

Determination  of  Diastatic  Power  of  Commercial  Amylases, 
Method  of  Sherman,  Kendall  and  ClarkJ  —  In  studying  methods 
for  determining  the  diastatic  power  of  commercial  pancreatin,  Sherman, 
Kendall  and  Clark  found  that  the  conditions  of  temperature  and 

*  J.  prakt.  Chem.  [2],  34,  378;  36,  481. 

t  Analyst,  21,  122. 

J  J.  Am.  Chem.  Soc.,  32,  107a 


514  SUGAR  ANALYSIS 

activation  under  which  an  amylase  normally  works  should  be  incor- 
porated in  the  method.  These  authorities  also  showed  that  the 
amount  of  reduced  copper  does  not  stand  in  simple  proportion  to  diastatic 
power,  different  diastatic  values  being  obtained  when  different  weights 
of  enzyme  were  taken.  These  differences  are  due  to  the  influence  of 
variations  in  the  concentration  of  starch  upon  the  rate  of  conversion; 
if  the  velocity  of  the  reaction  be  considered,  however,  the  same  diastatic 
power  is  derived  from  the  weight  of  reduced  copper  for  any  weight  of 
enzyme.  The  following  gravimetric  method  was  used. 

Enzyme.  —  The  enzyme  may  be  dissolved  in  pure  water  if  its  power 
is  to  be  tested  immediately.  If  it  is  to  stand,  it  should  be  dissolved  in 
water  containing  4  c.c.  of  fiftieth-molar  disodium  phosphate  per  100  c.c. 
The  test  should  be  made  within  an  hour  in  any  case.  The  amount  of 
enzyme  to  be  weighed  out  will  depend  entirely  on  its  strength. 

Activating  Agents.  —  These  will  doubtless  differ  with  the  different 
amylases.  For  pancreatic  amylase  acting  on  2  per  cent  starch,  add 
300  mgs.  sodium  chloride  and  7  c.c.  of  fiftieth-molar  disodium  phosphate 
per  100  c.c.  (final  volume)  of  reaction  mixture. 

Procedure.  —  Prepare  400  c.c.  of  2  per  cent  soluble-starch  solution 
and  the  enzyme  solution  of  such  a  strength  that  1  c.c.  will  contain  from 
0.4  to  1.0  mg.  of  enzyme.  By  means  of  a  1  c.c.  Mohr's  pipette,  accu- 
rately calibrated  in  hundredths,  measure  into  four  200  c.c.  Erlenmeyer 
flasks  such  volumes  of  the  solution  as  will  contain  0.2,  0.5,  0.8  and  1.0 
mg.  of  enzyme,  respectively.  Now  100  c.c.  of  the  starch  solution,  pre- 
viously warmed  to  40°  C.  is  poured  into  each  flask  and  the  digestion 
allowed  to  proceed  for  30  minutes,  the  temperature  being  accurately 
maintained  at  40°  C.  At  the  expiration  of  the  30  minutes,  stop  the  re- 
action quickly  by  mixing  at  once  with  50  c.c.  of  Fehling's  solution  and 
immerse  the  flask  in  a  large  bath  of  boiling  water  for  15  minutes.  See 
that  the  water  of  the  bath  is  kept  boiling  and  that  it  stands  above  the 
level  of  the  contents  of  any  of  the  flasks.  At  the  end  of  this  heating 
filter  quickly  and  determine  the  reduced  copper  by  any  accurate 
method. 

Correct  the  weight  of  reduced  copper  or  cuprous  oxide  found  for 
the  reducing  power  of  the  soluble  starch  by  subtracting  from  it  the 
weight  obtained  in  a  "  blank  "  test  in  which  the  starch  solution  is 
treated  directly  with  the  Fehling  reagent.  Of  the  four  determinations 
thus  corrected,  select  the  highest  weight  of  cuprous  oxide  which  does 
not  exceed  300  mgs.  and  find  the  corresponding  value  of  K  in  the  follow- 
ing table.  This  value  of  K  divided  by  the  milligrams  of  substance 
gives  the  diastatic  power  of  the  enzyme  upon  Sherman's  scale. 


MISCELLANEOUS  APPLICATIONS 


515 


Values  for  K  from  Cuprous  Oxide  Found 


Cuprous 
oxide. 

K. 

Cuprous 
oxide. 

K. 

Cuprous 
oxide. 

K. 

Cuprous 
oxide. 

K. 

Mgs. 

Mgs. 

Mgs. 

Mgs. 

30 

9.1 

100 

31.2 

170 

54.1 

240 

78.3    , 

40 

12.2 

110 

34.4 

180 

57.5 

250 

81.8 

50 

15.3 

120 

37.6 

190 

60.9 

260 

85.4 

60 

18.4 

130 

40.9 

200 

64.3 

270 

89.0    J 

70 

21.6 

140 

44.2 

210 

67.8 

280 

92.6 

80 

24.8 

150 

47.5 

220 

71.3 

290 

96.3 

90 

28.0 

160 

50.8 

230 

74.8 

300 

100.0 

Example.  —  A  sample  of  soluble  starch  which  had  been  treated  with  1.5 
mgs.  of  enzyme  gave  295.5  mgs.  of  cuprous  oxide;  the  blank  test  for  the  soluble 
starch  gave  60.5  mgs.  The  corrected  weight  of  cuprous  oxide  is  295.5  —  60.5 


=  235  mgs.  which  corresponds  to  a  value  for  K  of  76.6.    —  -^-  =  51,  the  diastatic 

1.5 

power  of  the  enzyme  by  Sherman's  scale. 

The  values  for  K  in  the  above  table  represent  the  rate  of  diastatic 
conversion  and  were  determined  by  means  of  a  velocity  curve  which 
was  plotted  with  different  periods  of  time  as  abscissae  and  different 
yields  of  cuprous  oxide  as  ordinates  (see  p.  695). 

Iodine  Method  for  Determining  Diastatic  Power.  —  A  number  of 
methods  have  been  devised  for  determining  diastatic  power  colori- 
metrically  by  means  of  iodine.  In  Wohlgemuth's*  method  several 
5  c.c.  portions  of  a  1  per  cent  solution  of  soluble  starch  are  treated  with 
different  amounts  of  diastase  at  40°  C.  for  30  minutes.  The  solutions 
after  diluting  to  a  measured  volume  are  then  treated  with  1  drop  of 
tt/10  solution  of  iodine  and;  after  shaking,  the  tube  selected  in  which 
the  deep  blue  and  violet  of  soluble  starch  have  given  place  to  the  red 
or  orange  red  of  erythrodextrin.  The  amount  of  enzyme  added  to  this 
tube  is  noted  and  its  diastatic  power  calculated  as  the  number  of  cubic 
centimeters  of  1  per  cent  soluble-starch  solution  which  would  be  con- 
verted by  1  c.c.  or  1  gm.  of  substance.  Thus  if  0.02  c.c.  of  saliva  con- 
verts 5  c.c.  of  1  per  cent  soluble-starch  solution  in  30  minutes  at  40°  C. 
1  c.c.  will  digest  250  c.c.  The  diastatic  power  of  the  saliva  is  then  ex- 
pressed as  Dy  =  250  (Wohlgemuth's  scale). 

The  diastatic  values  obtained  by  the  iodine  method  represent  the 
dextrinizing  rather  than  the  saccharifying  power  of  an  amylase.  For 
certain  physiological  purposes  the  results  of  the  iodine  method  may 
have  a  greater  value  although  the  difficulty  of  securing  a  satisfactory 
end  point  interferes  at  times  with  the  accuracy  of  the  method. 

*  Biochem.  Zeitschrt,  9,  1-9. 


516  SUGAR  ANALYSIS 

MISCELLANEOUS  FOOD  PRODUCTS 

The  detection  and  estimation  of  sugars  in  food  products  are  made 
according  to  the  physical  and  chemical  methods  previously  described. 
Such  methods  are  often  valueless,  however,  for  many  purposes  of  the 
food  chemist,  who  frequently  desires  to  know  more  about  the  origin  of 
the  sugars  in  his  product  than  about  their  nature  or  exact  amount.  A 
polarization  of  maple  sugar,  for  example,  will  not  determine  whether 
its  sucrose  was  derived  from  the  maple  or  sugar  cane.  Neither  does  an 
estimation  of  the  invert  sugar  and  dextrin  in  a  honey  determine  whether 
these  have  been  gathered  by  the  bee  or  have  been  added  as  an  adulter- 
ation. In  the  solution  of  such  problems  as  these  the  food  chemist 
must  base  his  decision  upon  reactions  and  estimations  of  other  ingredi- 
ents than  sugar,  such,  for  example,  as  the  amount  of  matter  precipitated 
by  lead  subacetate  or  by  alcohol,  the  composition  of  the  ash  and 
organic  non-sugars,  miscroscopical  examination,  etc.  Such  determina- 
tions lie  strictly  outside  the  province  of  sugar  analysis  and  only  a  few 
typical  applications  of  such  methods  will  be  considered.  For  a  fuller 
description  of  such  processes  the  chemist  is  referred  to  the  special 
works  upon  food  analysis  by  Leach,  Wiley,  Allen,  Blythe,  Konig  and 
others. 

DETERMINATION   OF   LEAD-SUBACETATE   PRECIPITATE 

The  determination  of  the  amount  of  lead-subacetate  precipitate  is 
frequently  used  as  a  means  of  distinguishing  pure  maple  sugars  and 
sirups  from  those  which  are  adulterated  with  cane  sugar.  The  method 
is  based  upon  the  presence  in  maple  products,  and  the  absence  in  cane 
sugars,  of  salts  of  malic  acid  which  gives  a  copious  precipitate  with  lead 
subacetate. 

Hortvet's*  Method  for  Measuring  the  Volume  of  Lead  Precipi- 
tate. —  Apparatus.  —  The  apparatus  consists  of  a  glass  tube  and 
holder  as  shown  in  Fig.  188.  The  tube  and  holder  weigh  about  50  gms., 
and  should  be  so  constructed  that  when  fitted  together  the  bottom  of 
the  tube  will  be  exactly  even  with  the  lower  surface  of  the  holder.  In 
a  set,  each  couple,  tube  and  holder  should  be  made  to  balance  one  an- 
other. When  placed  in  the  centrifuge  there  should  be  as  nearly  as 
possible  a  balanced  load  carried  at  the  circumference  of  the  wheel. 

Determination.  —  Introduce  into  the  tube  5  c.c.  of  sirup  or  5  gms. 
of  sugar,  add  10  c.c.  of  water  and  dissolve.  Add  0.5  c.c.  (10  drops)  of 
alumina  cream  (prepared  as  directed  on  page  223)  and  1.5  c.c.  of  lead  sub- 
*  J.  Anthem.  Soc.,  26,  1523. 


MISCELLANEOUS  APPLICATIONS 


517 


acetate  and  shake  thoroughly.  Allow 
the  mixture  to  stand  from  45  to  60 
minutes,  occasionally  giving  the  tube 
a  twisting  motion  to  facilitate  the 
settling  of  the  precipitate.  Place  the 
tube  with  its  holder  in  the  centrif- 
ugal machine  and  run  6  minutes 
under  the  conditions  given  below. 
If  any  material  adheres  to  the  sides 
of  the  wider  portion,  remove  it  by 
means  of  a  small  wire  provided  with 
a  loop  at  the  end.  Return  the  tube 
to  the  centrifuge  and  run  6  minutes 
longer  at  the  same  rate.  Note  the 
volume  of  the  precipitate,  estimating 
to  0.01  c.c.  as  closely  as  possible. 
Run  a  blank,  using  water  and  the  re- 
agents named  above,  and  correct  for 
same.  In  the  case  of  a  sirup  the  re- 
sult is  reduced  to  the  5-gm.  basis  by 
dividing  by  the  specific  gravity  of  the 
sample. 

The  centrifuge  used  in  this  method  has  a  radius  of  18.5  cm.  and  is 
run  at  a  speed  of  1,600  revolutions  per  minute.  The  velocity  at  the 
circumference  of  the  wheel  is  computed  in  centimeters  per  second. 

Mv2 

Calling  M  (mass)  unity  in  the  formula  F  =  -  —  >  the  numerical  expres- 
sion for  F,  the  centrifugal  force,  becomes  519,363. 

By  measuring  the  radius  (r)  for  any  given  machine  and  substituting 
for  F,  the  numerical  constant  determination  above,  the  velocity  for  a 
given  machine  may  be  determined  by  the  following  formula,  v  =  VFr. 
Given  the  velocity  in  centimeters  per  second,  the  required  number  of 
revolutions  per  second  or  per  minute  can  be  computed. 

The  volume  of  lead  precipitate,  as  determined  above,  was  found  by 
Hortvet  to  vary  from  0.94  c.c.  to  1.82  c.c.  for  pure  maple  sirups,  and 
from  1.18  c.c.  to  4.41  c.c.  for  pure  maple  sugars.  Adulterated  maple 
sirups  gave  from  0.23  c.c.  to  0.95  c.c.  and  adulterated  maple  sugars  from 
0.10  c.c.  to  1.40  c.c. 

Winton's*    Method   for   Determining  Precipitated   Lead    (Lead 
Number).  —  Weigh  25  gms.  of  the  material  (or  26  gms.  if  a  portion  of 
*  J.  Am.  Chem.  Soc.,  28,  1204. 


Fig.  188.  —  Hortvet's  apparatus  for 
measuring  volume  of  lead  precipi- 
tate. 


518 


SUGAR  ANALYSIS 


the  filtrate  is  to  be  used  for  polarization)  and  transfer  by  means  of 
boiled  water  into  a  100-c.c.  flask.  Add  25  c.c.  of  standard  lead-sub- 
acetate  solution,  fill  to  the  mark,  shake,  allow  to  stand  at  least  3  hours 
and  filter  through  a  dry  filter.  From  the  clear  filtrate  pipette  off 
10  c.c.,  dilute  to  50  c.c.,  add  a  moderate  excess  of  sulphuric  acid  and 
100  c.c.  of  95  per  cent  alcohol.  Let  stand  over  night,  filter  on  a  Gooch 
crucible,  wash  with  95  per  cent  alcohol,  dry  at  a  moderate  heat,  ignite 
at  low  redness  for  3  minutes,  taking  care  to  avoid  the  reducing  cone  of 
the  flame,  cool  and  weigh.  Calculate  the  amount  of  lead  in  the  precipi- 
tate using  the  factor  0.6831,  subtract  this  from  the  amount  of  lead  in 
2.5  c.c.  of  the  standard  solution,  multiply  the  remainder  by  100  and 
divide  by  2.5,  thus  obtaining  the  lead  number. 

The  standard  lead-subacetate  is  prepared  by  diluting  a  measured 
volume  of  lead-subacetate  reagent  of  1.25  sp.  gr.  with  4  volumes  of 
water,  and  filtering  if  not  perfectly  clear. 

The  lead  number,  as  determined  above,  was  found  by  Winton  and 
Kreider  to  vary  from  1.19  to  1.66  for  pure  maple  sirups,  and  from  1.83 
to  2,48  for  pure  maple  sugar.  Adulterated  maple  sirups  gave  lead  num- 
bers ranging  from  0.02  to  0.92. 

Limitations  of  the  Lead-precipitate  Methods.  —  Raw  cane  sugars 
(especially  such  as  are  made  without  clarification  and  hence  contain  all 
the  organic  salts  of  the  juice)  may  give  amounts  of  lead  precipitate 
which  are  as  great  as  those  obtained  with  pure  maple  products.  Doo- 
little  and  Seeker  *  give,  for  example,  the  following  comparison  between 
a  Venezuelan  muscovado  sugar  ("  Melada  ")  and  a  pure  Vermont 
maple  sugar. 

TABLE  LXXXVII 


Determination. 

Muscovado 
sugar. 

Vermont  maple 
sugar. 

Moisture  (per  cent) 

7  50 

2  80 

Ash  (per  cent)    

1.30 

1  10 

Polarization,  direct  at  room  temperature  (°  V.)  

+82.4 

+84  0 

Polarization,  invert  at  room  temperature  (°  V.)  
Invert  polarization  at  86°  (°  V.). 

-26.8 
±00 

-29.6 
±00 

Sucrose  (Clerget)  (per  cent) 

83  1 

85  6 

Winton  lead  number  

2.12 

2  26 

It  is  seen  from  the  above  that  the  polarization  and  lead  number  are 
not  always  sufficient  to  distinguish  between  cane  and  maple  sugar. 
The  results  of  the  lead-precipitate  method  should  always  be  confirmed 
by  other  means. 

*  Bull.,  122,  U.  S.  Bur.  of  Chem.,  p.  196. 


MISCELLANEOUS  APPLICATIONS 


519 


ANALYSIS  OF  ASH  AS  A  MEANS  OF  DETERMINING  THE  ORIGIN  OF  SUGARS 

One  of  the  most  valuable  methods  of  ascertaining  the  source  of  a 
sugar  is  to  determine  the  composition  of  its  ash.  The  mineral  con- 
stituents of  the  juice  of  the  maple,  sugar  beet  and  sugar  cane  show 
very  pronounced  differences,  and,  notwithstanding  the  influences  of 
clarification  and  crystallization,  certain  of  these  constituents  find  their 
way  into  the  raw  sugar  in  sufficient  quantities  to  afford  a  valuable 
basis  of  opinion.  Sugar-beet  juice,  for  example,  in  distinction  from 
that  of  the  cane  and  maple,  contains  considerable  potassium  nitrate 
and  perceptible  quantities  of  the  latter  are  usually  present  in  raw  beet 
sugar.  Even  the  higher  grades  of  beet  sugar  will  frequently  respond  to 
delicate  tests  for  nitrates  and  this  has  been  used  as  one  means  of  dis- 
tinguishing beet  from  cane  sugar. 

As  an  example  of  the  application  of  the  ash-analysis  method  the 
following  results  by  Doolittle  and  Seeker*  upon  the  muscovado  and 
maple  sugar  of  Table  LXXXVII  are  given.  Average  determinations 
made  by  Jones  f  upon  the  ash  of  pure  maple  sugars  are  also  added  for 
comparison. 

TABLE  LXXXVIII 
Analysis  of  the  Ash  of  Muscovado  and  Maple  Sugar 


Determination. 

Muscovado 
sugar. 

Vermont 
maple  sugar. 

Average 
maple 
sugar  ash, 
by  Jones. 

Insoluble  in  boiling  nitric  acid  (1  :  3)  
Potassium  oxide 

Per  cent. 
3.41 

49  89 

Per  cent. 
8.9 

23  6 

Per  cent. 
26  49 

Sodium  oxide   

2  32 

1  6 

Calcium  oxide  

5  66 

35  9 

24.98 

Magnesium  oxide  

2  63 

3.0 

Ferric  oxide  

0.26 

|  Slight) 

Chlorine  

1.34 

(  trace) 
Trace 

Sulphur  trioxide  

23.21 

None 

1.82 

Phosphoric  acid 

3  68 

0.45 

Undetermined 

7.60 

26.55 

Water-soluble  ash  (per  cent)          .               .       .... 

1.23 

0.50 

0.53 

Water-insoluble  ash  (per  cent)  

0.17 

0.64 

0.48 

P     .      water-soluble  ash 

7  7 

0  8 

1  l 

water-insoluble  ash 
Alkalinity  of  water-soluble  ash  (c.c.  tenth-normal 
acid  per  ash  of  1  gm   of  sample) 

0.11 

0.49 

0.68 

Alkalinity  of  water-insoluble  ash  (c.c.  tenth-normal 
acid  per  ash  of  1  gm.  of  sample)     

0.03 

-1.47 

1.01 

*  Bull.,  122,  U.  S.  Bur.  of  Chem.,  p.  196. 

t  Eighteenth  Annual  Report,  Vermont  Agr.  Exp.  Sta.  (1905),  p.  331. 


520  SUGAR  ANALYSIS 

It  is  seen  that  in  certain  constituents,  as  potassium  oxide,  calcium 
oxide,  and  sulphur  trioxide,  the  ashes  of  the  muscovado  and  maple  sugars 
show  very  pronounced  differences.  The  determinations  of  water- 
soluble  and  water-insoluble  ash  and  of  the  alkalinities  of  the  latter 
are  valuable  aids  in  forming  an  opinion  as  to  the  origin  of  a  sugar. 
The  ash  for  such  determinations  should  be  prepared  according  to  the 
method  described  for  quantitative  examination  (page  495) . 

DETERMINATION    OF    ALCOHOL    PRECIPITATE 

The  determination  of  the  amount  of  substance  precipitated  by  strong 
alcohol  is  frequently  used  in  examining  sugar-containing  products. 
The  materials  which  are  precipitated  by  alcohol  may  consist  of  mineral 
or  organic  salts,  pectin,  dextrin,  dextran  and  other  gums.  In  many 
cases  a  qualitative  examination  of  the  alcohol  precipitate  throws  con- 
siderable light  upon  the  origin  of  the  product. 

Determination  of  Alcoholic  Precipitate  in  Fruit  Products.  Method 
of  the  Association  of  Official  Agricultural  Chemists*  —  Evaporate  100 
c.c.  of  a  20  per  cent  solution  of  the  fruit  product  to  20  c.c.;  add  slowly 
and  with  constant  stirring  200  c.c.  of  95  per  cent  alcohol  and  allow  the 
mixture  to  stand  over  night.  Filter  and  wash  with  80  per  cent  alcohol 
by  volume.  Wash  this  precipitate  off  the  filter  paper  with  hot  water 
into  a  platinum  dish,  evaporate  to  dryness,  dry  at  100°  C.  for  several 
hours  and  weigh;  then  burn  off  the  organic  matter  and  weigh  the 
residue  as  ash.  The  loss  in  weight  upon  ignition  is  called  alcohol 
precipitate. 

The  ash  should  be  largely  lime  and  not  more  than  5  per  cent  of  the 
total  weight  of  the  alcohol  precipitate.  If  it  is  larger  than  this  some 
of  the  salts  of  the  organic  acids  have  been  brought  down.  Titrate  the 
water-soluble  portion  of  this  ash  with  tenth-normal  acid,  as  any  potas- 
sium bitartrate  precipitated  by  the  alcohol  can  thus  be  estimated. 

The  general  appearance  of  the  alcohol  precipitate  is  one  of  the  best 
indications  as  to  the  presence  of  glucose  and  dextrin.  Upon  the  ad- 
dition of  alcohol  to  a  pure  fruit  product  a  flocculent  precipitate  is 
formed  with  no  turbidity,  while  in  the  presence  of  glucose  a  white  tur- 
bidity appears  at  once  upon  adding  the  alcohol,  and  a  thick  gummy 
precipitate  forms. 

When  the  quantity  of  gum  or  dextrin  is  large,  a  considerable  amount 
of  sugar  is  sometimes  occluded  in  the  alcohol  precipitate.     This  is  es- 
pecially the  case  with  honey,  for  determining  the  dextrin  in  which 
Browne  has  modified  the  alcohol  precipitate  method  as  follows. 
*  Bull.  107  (revised),  U.  S.  Bur.  of  Chem.,  p.  80. 


MISCELLANEOUS  APPLICATIONS  521 

Determination  of  Alcohol  Precipitate  in  Honey.  Browne's  * 
Method.  —  Eight  grams  of  honey  are  transferred  to  a  100-c.c.  flask 
with  4  c.c.  of  water  and  sufficient  absolute  alcohol  to  complete  to  the 
mark.  A  little  care  is  required  to  effect  the  complete  removal  of  the 
honey  from  the  weighing  dish  without  using  more  than  4  c.c.  of  water. 
The  transference  is  best  made  by  decanting  as  much  as  possible  of  the 
liquefied  honey  into  the  flask,  then  adding  2  c.c.  of  water  to  the  dish 
to  take  up  any  adhering  honey  and  again  decanting.  By  using  1  c.c. 
more  of  the  water  in  two  successive  washings  and  adding  a  few  cubic 
centimeters  of  the  absolute  alcohol  each  time  before  decanting,  the 
honey  can  be  completely  transferred  without  the  necessity  of  using 
more  water  than  the  4  c.c.  Absolute  alcohol  is  used  finally  to  rinse 
out  the  dish  and  is  then  added  to  the  flask  with  continual  agitation 
until  the  volume  is  completed  to  100  c.c.  After  shaking  thoroughly 
the  flask  is  allowed  to  stand  until  the  dextrin  has  settled  out  upon  the 
sides  and  bottom  and  the  supernatant  liquid  has  become  perfectly  clear 
(usually  in  24  hours). 

The  clear  solution  is  then  decanted  through  a  filter  and  the  pre- 
cipitated residue  washed  with  10  c.c.  of  cold  95  per  cent  alcohol  to  re- 
move adhering  liquid,  the  washings  being  also  poured  through  the 
filter.  The  residue  adhering  to  the  flask  and  the  particles  which  may 
have  been  caught  upon  the  filter  are  dissolved  in  a  little  boiling  dis- 
tilled water  and  washed  into  a  weighed  platinum  dish.  The  contents 
of  the  latter  are  then  evaporated  and  dried  in  a  water  oven  to  con- 
stancy in  weight.  Should  the  amount  of  precipitate  be  considerable, 
it  is  necessary  to  dry  upon  sand  in  vacuo  at  70°  C. 

After  determining  the  weight  of  the  dried  alcohol  precipitate  the 
latter  is  redissolved  in  water  and  made  to  a  definite  volume.  The 
following  dilutions  are  employed  in  making  up  the  solutions: 

Weight  of  precipitate 

in  grams 0.0-0.5    0.5-1.0    1.0-1.5     1.5-2,0    2.0-2.5    2.5-3.0 

Volume  of  solution 

in  cubic  centimeters 50          100          150  200          250          300 

The  sugars  are  then  determined  in  aliquots  from  the  filtered  solu- 
tion of  alcohol  precipitate  both  before  and  after  inversion.  The  total 
precipitate  less  invert  sugar  and  sucrose  gives  the  per  cent  of  dextrin. f 

While  this  method  of  estimating  dextrin  in  honeys  gives  much 
more  accurate  results  than  the  direct  weighing  of  the  alcohol  pre- 

*  Bull.  110,  U.  S.  Bur.  of  Chem.,  p.  19. 

t  With  honeydew  honey,  which  gives  a  large  amount  of  alcohol  precipitate,  it 
is  found  best  to  take  only  4  gms.  of  honey  for  analysis;  in  other  respects  the 
method  of  procedure  is  the  same. 


522 


SUGAR  ANALYSIS 


cipitate,  it  can  not  be  said  in  any  way  to  give  the  true  dextrin  content 
of  the  honey,  although  it  is  believed  that  the  figures  obtained  are  a 
close  approximation.  A  small  amount  of  dextrin  always  escapes  pre- 
cipitation with  alcohol;  furthermore  no  account  is  taken  of  those 
ingredients  which  may  be  occluded  in  the  alcohol  precipitate  other 
than  the  sugars,  and  no  correction  is  made  for  the  copper-reducing 
power  of  the  honey  dextrin  itself.  This  latter  factor,  though  ap- 
parently very  small,  might  prove  to  be  of  some  importance  if  much 
dextrin  were  present.  Notwithstanding  these  limitations,  however, 
the  percentage  of  dextrin  as  determined  by  the  method  described  has 
been  found  to  have  a  decided  value,  especially  when  it  is  wished  to 
compare  honeys  of  different  origins. 

The  percentages  of  dextrin  in  different  American  honeys,  as  deter- 
mined by  the  above  method,  is  given  in  the  following  table  of  com- 
position, which  is  taken  from  the  work  of  Browne.  The  honeys  are 
arranged  in  order  of  their  dextrin  content. 

TABLE  LXXXIX 
Giving  Composition  of  American  Honeys.    BuU.  110,  U.  S.  Bur.  of  Chem. 


Kind  of  honey. 

Num- 
ber of 
samples 

Polariza- 
tion 20°  C. 

Water. 

Invert 
sugar. 

Sucrose 

Ash. 

Dex- 
trin. 

Unde- 
ter- 
mined. 

Alfalfa  

8 

Deg.  V. 

-15.10 

Per  cent 

16.56 

Per  cent 

76.90 

Per  cent 

4.42 

Per  cent 
0.07 

Per  cent 

0  34 

Per  cent 
1   71 

Apple  

2 

-  8.55 

15.67 

73.16 

3.69 

0.08 

0.39 

7.01 

Orange 

1 

—  15  50 

16  99 

77  57 

0  60 

0  08 

0  45 

4  31 

Sweet  clover 

4 

-17  61 

17  49 

76  20 

2  24 

0  12 

0  45 

3  50 

Raspberry  

2 

-18  85 

18  08 

74.52 

1.42 

0  05 

0  56 

5  37 

Mangrove  
White  clover  
Cotton 

2 
15 
2 

-22.80 
-13.01 
-17  50 

19.18 
17.64 
18  35 

76.49 
74.92 
75  43 

1.73 
1.77 
1  38 

0.20 
0.07 
0  21 

0.56 
0.82 
1  10 

1.84 
4.78 
3  53 

Buckwheat 

2 

—  16  80 

18  54 

76  85 

0  03 

0  09 

1  22 

3  27 

Dandelion   . 

2 

—  12  40 

14  54 

76  84 

3  12 

0  16 

1  23 

4  11 

Tupelo  

2 

—24  00 

17  34 

72  24 

3  01 

0  07 

2  08 

5  26 

Golden  rod  
Willow  
Basswood  

3 
1 
6 

-12.33 

-12.80 
-  8.90 

19.88 
19.11 
17.42 

72.02 
71.47 
75.14 

1.68 
0.95 
0.72 

0.16 
0.35 
0.20 

2.18 
2.75 
3.07 

4.08 
5.37 
3.45 

Sumac 

3 

—  10  47 

18  85 

71  11 

0  92 

0  44 

3  57 

5  11 

Yellow  wood  . 

1 

-  7  00 

18  12 

71  51 

0  19 

0  39 

4  10 

5  69 

White  wood  

1 

-  4  90 

17  47 

69.02 

2.72 

0.51 

5  59 

4  69 

Poplar  
White  oak 

1 
1 

+  3.60 
+11  00 

17.02 
13  56 

65.80 
65  87 

3.10 
4  31 

0.76 
0  79 

10.19 
10  49 

3.13 
4  98 

Hickory. 

1 

+  7  80 

16  05 

65  89 

2  76 

0  78 

12  95 

1  57 

The  dextrins  of  honey  are  derived  largely  from  honeydew  (the 
gummy  exudation  from  leaves,  buds,  etc.)  and  not  from  floral  nectar. 
Honeydew  contains  considerable  mineral  matter,  and  its  presence  in 
honey  causes  a  marked  increase  in  the  ash  content.  Honey  dextrin  is 


'MISCELLANEOUS  APPLICATIONS  523 

strongly  dextrorotatory  ([«]/>  varies  from  about  +115  to  +160)  and 
the  presence  of  much  honey  dew  may 'cause  honey  to  polarize  to  the 
right. 

If  commercial  glucose  is  suspected,  honeydew  dextrins  may  be  dis- 
tinguished from  those  of  starch  conversion  by  dissolving  the  alcohol 
precipitate  in  a  little  water  and  adding  a  few  cubic  centimeters  of 
iodine  solution;  a  red  color,  due  to  erythrodextrin,  indicates  the  pres- 
ence of  commercial  glucose. 


PAET    II 

THE  OCCURRENCE,  METHODS  OF  PREPARATION, 

PROPERTIES  AND  PRINCIPAL  REACTIONS 

OF  THE  SUGARS  AND  ALLIED 

DERIVATIVES 


CHAPTER  XVIII 

CLASSIFICATION  OF  THE  SUGARS  AND  THEIR  FORMATION  IN  NATURE 

THE  sugars,  of  which  some  thirty  or  more  have  been  isolated  from 
plant  and  animal  substances,  are  among  the  most  widely  distributed, 
organic  compounds  in  nature. 

The  sugars  proper,  including  the  monosaccharides,  disaccharides, 
trisaccharides  and  tetrasaccharides,  are  colorless,  odorless,  crystalline 
substances,  usually  of  sweet  taste,  and  for  the  most  part  easily  soluble 
in  water.  The  more  complex  anhydride  condensation  products  of  the 
sugars,  the  polysaccharides,  are  usually  amorphous  compounds  of 
little  or  no  solubility  in  water.  The  entire  group  of  saccharides,  the 
so-called  carbohydrates,  constitute  approximately  three-fourths  of  the 
dry  matter  of  the  plant  world. 

The  Simple  Sugars.  —  A  simple  sugar,  or  monosaccharide,  may 
be  defined  as  an  aldehyde  or  ketone  alcohol  of  the  aliphatic  series,  the 
molecule  of  which  contains  one  carbonyl  and  one  or  more  alcohol 
groups,  one  of  the  latter  being  always  adjacent  to  the  carbonyl  group. 

H-C-O-H 

All  sugars  contain,  therefore,          |  as  a  characteristic  group 

C  =O 


upon  the  presence  of  which  nearly  all  of  the  chemical  properties  of  the 
sugars  depend.     The  simplest  possible  sugar  according  to  the  above  is 

H 

glycol  aldehyde.  H-C-O-H. 

H-C=O 
Sugars  containing  the  aldehyde  group  are  termed  aldoses 

I 
-C-O-H    characteristic  aldose  group 


(H-C-O-H 
H-C  =  0 


and  those  containing  the  ketone  group  ketoses 

H-C-O-H 

characteristic  ketose  group 


C=0 


-i- 


527 


528  SUGAR  ANALYSIS 

According  to  the  number  of  their  carbon  atoms  the  monosaccharides 
are  divided  into  dioses  (C2H402),  trioses  (C3H603),  tetroses  (C4H804), 
pentoses  (C5Hi005),  hexoses  (C6Hi2O6),  heptoses  (C7Hi407),  octoses 
(C8Hi6O6)  and  nonoses  (C9Hi8O9).  There  are  also  substituted  mono- 
saccharides in  which  one  or  more  hydrogen  atoms  of  a  diose,  triose, 
tetrose,  etc.,  are  replaced  by  a  methyl  group,  as,  for  example,  methyl- 
diose  (CH3C2H3O2),  dimethyldiose  (CH3C2H202CH3),  methyltriose 
(CH3C3H503),  methyltetrose  (CH3C4H704),  methylpentose  (CH3C5H905), 
methylhexose  (CH3C6Hn06),  methylheptose  (CH3C7Hi3O7),  etc. 

The  Compound  Sugars.  —  By  the  condensation  of  2,  3  or  4  mole- 
cules of  the  monosaccharides,  the  disaccharides,  trisaccharides  and 
tetrasaccharides  are  formed.  In  such  condensations  one  molecule  less 
of  water  is  eliminated  than  the  number  of  reacting  sugars,  thus : 

2C6Hi206  -     H2O  =  CtfH^On  (disaccharide). 
3C6Hi2O6  -  2H2O  =  Ci8H32Oi6  (trisaccharide). 
4C6Hi206  -  3H2O  =  C24H4202i  (tetrasaccharide). 
The   Polysaccharides.  —  By  the   condensation   of   an   indefinite 
number  of  molecules  of  the  monosaccharides  the  polysaccharides  are 
formed.     In  such  condensations  one  molecule  less  of  water  is  probably 
eliminated  than  the  total  number  of  reacting  sugar  molecules,  as,  for 
example : 

nC5H10O5  -  (n  -  1)  H2O  =  (C5H8O4)nH20. 

Pentose  Pentosan. 

nC6H1206  -  (n  -  1)  H2O  =  (C6H10O5)nH2O. 

Hexose  Hexosan. 

The  quantity  n  is  usually  so  large,  however,  that  the  formulae  of  the 
polysaccharides  may  be  taken  as  simply  (C5H8O4)n,  (C6Hi0O5)n,  etc., 
without  sensible  error. 

Carbohydrates.  —  The  term  carbohydrate  is  a  general  one  which 
is  frequently  applied  to  the  entire  group  of  saccharides.  In  its  original 
sense  it  was  applied  only  to  such  saccharide  substances  as  contain  six,  or 
a  multiple  of  six,  carbon  atoms  and  have  their  hydrogen  and  oxygen  in 
the  proportion  to  form  water.  Such  substances  were  regarded  loosely 
as  simple  compounds  of  carbon  and  water,  and  hence  the  name  carbo- 
hydrate. Thus : 

Glucose,  C6H1206  =  6  C  +  6  H2O. 
Sucrose,  Ci2H22On  =  12  C  +  11  H2O. 
Raffinose,  Ci8H32O16  =  18  C  +  16  H20. 
Cellulose,  (C6H10O5)n  =  n  (6  C  +  5  H,O). 

This  original  meaning  of  -carbohydrate  is  still  retained  by  some 
writers,  although  it  was  proved  long  ago  that  the  term  can  no  longer  be 


CLASSIFICATION  OF  SUGARS  AND  FORMATION  IN  NATURE     529 


taken  in  its  former  literal  sense.  A  large  number  of  sugars  contain  less 
than  six,  or  a  fractional  multiple  of  six,  carbon  atoms,  and  there  are 
also  many  sugars  whose  hydrogen  and  oxygen  atoms  have  a  different 
ratio  than  in  water,  such,  for  example,  as  the  methylpentoses,  C6Hi205. 
Alcohol  and  Acid  Derivatives  of  Sugars.  —  The  term  carbohy- 
drate is  very  often  extended  to  include  the  alcohol  and  acid  derivatives 
of  the  simple  sugars.  While  this  extension  of  meaning  is  not  approved 
of  by  all  chemists,  a  knowledge  of  these  compounds  so  closely  allied  to 
the  sugars  is  indispensable.  The  monosaccharides,  as  aldehydes,  stand 
midway  between  the  alcohols  and  acids.  They  are  easily  reduced  to 
the  former  on  the  one  hand  and  readily  oxidized  to  the  latter  on  the 
other.  Such  reactions  take  place  continually  in  the  chemical  pro- 
cesses of  plant  and  animal  life,  and  also  occur  in  the  industrial  opera- 
tions of  sugar  factories,  distilleries,  etc.  A  proper  understanding  of 
this  relationship  is,  therefore,  of  great  importance.  The  following  table, 
which  gives  a  classification  of  the  alcohols,  sugars  and  acids  of  differ- 
ent monosaccharides,  will  make  the  mutual  relationship  of  these  more 
clear.  The  members,  which  are  found  in  nature  either  free  or  in  a 
polysaccharide  form,  are  printed  in  heavy  type. 

TABLE  XC 
Showing  Group  Relationships  of  Alcohols,  Sugars  and  Acids 


Group. 

Alcohol. 

Sugar. 

Monobasic  acid. 

Dibasic  acid. 

Diose  (aldose) 

Glycol 
H-C-OH 

H-C-OH 
H 

Glycolose 
H 
H-C-OH 

H-C=O 

Glycollic 
H-C-OH 
HO-C=O 

Oxalic 

HO-C=O 

HO-C=O 

Methyldiose 
(aldose) 

Methylglycol 
CH3-C2H502 

Methylglycolose 
CH3-C2H3O2 

Lactic 
CHs-GjHsOs 

Dimethyldiose 
(ketose) 

Dimethylglycol 
CH3-C2H402-CH3 

Dimethylglycolose 
CH3-C2H202-CH3 

Triose  (aldose) 

Glycerol 

C3H803 

Glycerose 
C3H803 

Glyceric 
C3H6O4 

Tartronic 
C3H405 

Tetrose  (aldose) 

Erythrite 
C4H,o04 

Ervthrose 
C4H804 

Erythronic 
C4H806 

Tartaric 

C.HeO, 

Pentose  (aldose) 

Arabite 
Xylite 

Adonite 
C5H,205 

Arabinose 
Xylose 

Ribose 
CsHioOs 

Arabonic 
Xylonic 

Ribonic 
C5HioO« 

Trioxyglutaric 
Xylotrioxyglu- 
taric 
Ribotrioxyglu- 
taric 
C6H807 

Methylpentose 
(aldose) 

Rhamnite 
Fucite 
Rhodeite 
CeHuOs 

Rhamnose 
Fucose 
Rhodeose. 
C6H1206 

Rhamnonic 
Fuconic 
Rhodeonic 
CeHizOo 

530 


SUGAR  ANALYSIS 


TABLE  XC  (Continued) 
Showing  Group  Relationships  of  Alcohols,  Sugars  and  Acids 


Group. 

Alcohol. 

Sugar. 

Monobasic  acid. 

Dibasic  acid. 

Hexose  (aldose) 

Sorbite 
Mannite 
Dulcite 
CeHuOs 

Glucose 

Mannose 
Galactose 

CeHizOs 

Gluconic 
Mannonic 
Galactonic 
C6H12O7 

Saccharic 
Mannosaccharic 
Mucic 
C6H1008 

Hexose  (ketose) 

Sorbite+Mannite 
Sorbite+Idite 
C6Hi406 

Fructose 
Sorbose 

CeHizOe 

Heptose 

Perseite 
Volemite 
C7H1607 

Mannobeptose 
Volemose 
C7H1407 

Mannoheptonic 
C7H1408 

Pentoxypimelic 
C7H120, 

The  Asymmetric  Carbon  Atom  and  the  Optical  Activity  of  Sugars.  — 

As  first  pointed  out  by  Van't  Hoff  *  and  Le  Bel  f  the  optical  activity  of 
sugars,  as  of  other  organic  substances,  is  associated  with  the  presence 
of  an  asymmetric  carbon  atom,  by  which  is  meant  a  carbon  atom  united 
to  four  dissimilar  atoms  or  groups.  Upon  inspecting  the  structural  for- 
mula of  glycolose  in  the  preceding  table  it  is  seen  that  two  valences  of 
one  C  atom  are  united  alike  to  two  H  atoms,  and  that  two  valences 
of  the  other  C  atom  are  united  alike  to  an  0  atom.  Glycolose  contains 
no  asymmetric  carbon  atom  and  must,  therefore,  be  optically  inactive. 
In  the  sugar  glycerose,  on  the  other  hand,  the  central  C  atom  is 
united  with  the  four  dissimilar  atoms  or  groups,  CH2OH,  H,  OH  and 


CH2OH 


HO 


OH 


OHO 


CHQ 


Fig.  189.  —  Models  illustrating  antipodal  forms  of  glycerose. 

CHO;  glycerose  must,  therefore,  exist  in  an  optically  active  form.  If 
the  four  groups  connected  with  the  asymmetric  C  atom  of  glycerose  be 
placed  at  the  points  of  a  tetrahedral  model,  as  in  Fig.  189,  it  will  be 
found  that  two  structural  combinations  alone  are  possible.  These 
two  forms,  which  bear  the  relationship  of  mirror  images  to  each  other, 
cannot  by  any  manner  of  turning  be  superimposed.  They  constitute  a 
pair  of  optical  isomers,  or  antipodes,  one  of  which  is  dextrorotatory  and 
the  other  levorotatory  to  exactly  the  same  degree. 

*  Van't  Hoff' s  "  La  Chimie  dans  1'Espace  "  (1875). 
t  Bull.  soc.  chim.  (1874),  p.  337. 


CLASSIFICATION  OF  SUGARS  AND  FORMATION  IN  NATURE     531 

Optical  Inactivity  of  Sugars.  External  Compensation.  —  Van't 
Hoff*  called  attention  to  the  important  fact  that  when  a  compound 
with  an  asymmetric  carbon  atom  is  produced  in  the  vegetable  or  animal 
organism  it  is  found  in  most  cases  to  possess  optical  activity.  When, 
however,  such  a  compound  is  formed  synthetically,  from  an  inactive 
substance,  optical  activity  is  wanting.  Van't  Hoff  showed  that  in  the 
latter  case  inactivity  was  due  to  the  two  opposite  isomers  being  pro- 
duced in  exactly  equal  amounts,  whereas  in  nature  only  one  of  these 
isomers  is  formed.  Thus  the  fructose  produced  in  nature  is  levoro- 
tatory;  the  fructose  made  synthetically  from  acrolein  dibromide  is 
optically  inactive,  and  consists  of  equal  proportions  of  left-rotating  and 
right-rotating  sugar.  If  the  synthetic  fructose  be  fermented,  however, 
the  left-rotating  sugar  is  destroyed,  when  the  unfermented  isomer  will 
polarize  to  the  right. 

Internal  Compensation.  —  In  addition  to  the  above  case  of  external 
compensation  between  two  asymmetric  carbon  compounds,  there  is  also 
the  case  of  optical  inactivity  through  internal  compensation  between 
two  opposite  symmetrical  halves  of  the  molecule.  Thus  mesotartaric 
acid  can  be  given  either  of  the  following  configurations: 

COOH  COOH 

HOCH           HCOH 
I I 

HOCH  HCOH 

COOH  COOH. 

These  apparently  opposite  forms  are  identical,  however,  for  one  con- 
figuration can  be  brought  into  coincidence  with  the  other  by  rotating 
through  an  angle  of  180°.  The  two  C  atoms  printed  in  heavy  type 
are  each  asymmetric,  yet  the  compound  is  inactive,  since  the  optical 
effect  of  the  one  is  counterbalanced  by  that  of  the  other.  In  such 
cases  of  internal  compensation  the  molecule  can  be  divided  by  a  plane 
of  symmetry  (indicated  above  by  the  dotted  line)  into  two  opposite 
halves,  which  are  mirror  images  of  each  other. 

Optical  inactivity  through  internal  compensation  cannot  exist  with 
the  sugars  or  their  monobasic  acids;  it  is  common,  however,  with  the 
sugar  alcohols  and  dibasic  acids.  Mesoerythrite,  adonite,  xylite,  dul- 
cite,  mucic  and  allomucic  acids,  ribo-  and  xylotrioxyglutaric  acids  are 
other  examples. 

Nomenclature  of  Optically  Opposite  Isomers.  —  Since  every  opti- 
cally active  substance  has  an  antipode,  or  isomer,  of  equal  but  exactly 
opposite  rotation,  the  nomenclature  of  such  isomers  is  of  considerable 
*  "  Chemistry  in  Space,"  Oxford  (1891),  p.  38. 


532  SUGAR  ANALYSIS 

importance.  In  only  a  few  cases,  as  with  fucose  and  rhodeose,  where 
the  compounds  were  named  before  their  antipodal  nature  was  dis- 
covered, have  wholly  distinct  names  been  given  to  the  members  of  an 
opposite  pair.  The  optical  antipodes  of  known  sugars  were  first  syn- 
thesized by  Fischer*  who  adopted  the  plan  of  distinguishing  such 
compounds  by  means  of  the  letters  d  and  1.  These  symbols,  which 
primarily  refer  to  the  character  of  rotation  (d  =  dexter,  right ;  /  =  Icevus, 
left) ,  were  used  by  Fischer  to  indicate  synthetic  relationships  rather  than 
directions  of  rotation.  Fischer,  starting  with  the  common  dextrorota- 
tory sugars,  glucose  and  galactose,  gave  them  the  symbols  d-,  and  their 
opposite  isomers  the  symbols  1-.  All  sugars  which  could  be  derived 
from  these  sugars  synthetically  were  grouped  in  the  corresponding  d- 
and  1-  class.  Ordinary  fructose,  or  levulose,  which  though  levorotatory 
can  be  synthesized  from  d-glucose,  was,  therefore,  named  d-fructose. 
Ordinary  xylose  is  dextrorotatory  but  was  called  1-xylose  by  Fischer,f 
because  its  first  discovered  synthetic  relationship  connected  it  with 
1-glucose.  Salkowski  and  Neuberg  afterwards  found  that  ordinary 
xylose  could  be  derived  from  d-glucose  through  d-glucuronic  acid. 
As  Fischer  remarks,  had  this  latter  relationship  been  discovered  first, 
he  would  have  named  the  sugar  d-xylose.  Such  a  nomenclature  has 
obviously  more  historic  than  scientific  value,  and  various  improvements 
have  been  proposed  by  Maquenne,J  Rosanoff,§  and  others.  The  origi- 
nal system  of  Fischer,  however,  is  still  the  one  most  used  and  is  retained 
without  change  in  the  present  volume. 

Racemic  mixtures,  i.e.,  mixtures  of  optical  antipodes  in  equal  pro- 
portions, are  necessarily  inactive.  The  combined  symbol  d,  1-,  intro- 
duced by  Fischer,  expresses  the  nature  of  such  a  combination  more 
clearly  than  the  symbol  i-,  which  has  also  been  used.  The  letter  i-, 
however,  is  sometimes  employed  to  designate  iso-,  and  sometimes  to 
specify  a  compound  which  is  inactive  through  internal  compensation, 
the  latter  use  being  the  one  followed  in  the  present  work. 

The  Formation  of  Carbohydrates  ||  in  Nature.  — The  carbohydrates 
are  formed  primarily  only  in  the  plant  world,  the  proximate  constituents 
of  their  formation  being  carbon  dioxide  and  water.  The  combination  of 
these  —  a  process  called  assimilation  —  is  effected  only  in  the  green 
chlorophyll-bearing  tissue  of  the  leaves.  The  carbon  dioxide  (3  vol- 

*  Ber.,  23,  370;  40,  102.  J  Maquenne's  "  Les  Sucres." 

t  Ber.,  40,  102.  §  J.  Am.  Chem.  Soc.,  28,  114. 

II  For  a  very  complete  treatment  of  the  subject  of  assimilation  and  of  the  origin 

of  carbohydrates  in  plants  the  reader  is  referred  to  Czapek's  "  Biochemie  der 

Pflanzen,"  Jena,  1905,  Vol.  I,  pp.  188-583. 


CLASSIFICATION  OF  SUGARS  AND  FORMATION  IN  NATURE     533 

umes  of  which  occur  in  10,000  volumes  of  air)  enters  the  leaf  through 
the  breathing  pores  and  there  unites  with  the  water  which  has  been 
drawn  up  through  the  roots  from  the  soil.  The  combination  takes 
place  with  the  liberation  of  one  volume  of  oxygen  for  each  volume  of 
carbon  dioxide  assimilated.  The  process  is  thus  the  opposite  of  respira- 
tion and  combustion,  as  is  illustrated  by  the  following  equations: 
Respiration  and  Combustion  ........  C6Hi2O6  +  6  O2  =  6  C02  +  6  H20. 

Sugar        +  oxygen  =     <»a      +  water. 


Assimilation  ......................  6  CO2  +  6  H2O  =  C6Hi2O6  +  6  02. 

dioxide    +    water  *          sugar       +  oxygen. 

Assimilation  in  building  up  sugar  thus  plays  an  important  part  in 
purifying  the  atmosphere  and  in  keeping  a  balance  in  the  economy  of 
nature. 

Photosynthesis.  Assimilation  takes  place  only  by  daylight  and  is  most 
active  in  the  bright  sunshine.  The  chlorophyll  grains  constitute  the 
mechanism  by  which  the  energy  of  the  light  waves  is  transformed  into 
chemical  work;*  it  has  been  observed  that  light  in  passing  through  the 
green  coloring  matter  of  chlorophyll  is  changed  from  shorter  into  longer 
wave  length,  and  this  phenomenon  plays,  no  doubt,  an  important  part 
in  the  process  of  assimilation. 

The  many  intermediate  steps  in  the  process  of  assimilation  are  still 
hidden  in  obscurity.     The  most  widely  accepted  view,  that  of  Baeyer,f 
is  that  formaldehyde  is  the  first  product  formed, 
C02+  H20  =  CH20  +  02. 

The  fact  that  formaldehyde  is  found  in  green  leaves  only  in  the  smallest 
traces  is  explained  by  assuming  that  it  immediately  undergoes  a  con- 
densation to  form  a  hexose  carbohydrate, 

6  CH2O  =  C6H1206. 

The  condensation  by  Loew  of  formaldehyde  to  a  mixture  of  hexose 
sugars  has  been  advanced  as  an  argument  in  support  of  this  theory. 

Opinions  differ  widely  as  to  the  nature  of  the  carbohydrate  which 
is  first  formed  in  assimilation.  Many  plant-physiologists  and  chemists 
consider  the  first  product  to  be  glucose,  from  which  all  the  other  car- 
bohydrates are  .  afterwards  derived.  Others  believe  starch  to  be  the 

*  The  fact  that  the  light  from  the  sky  is  more  or  less  polarized  has  given  rise  to 
the  hypothesis  that  the  energy  of  such  polarized  sunlight  produces  the  optical 
activity  of  the  sugars  which  are  formed  by  assimilation.  The  hypothesis  has  found 
no  scientific  support. 

t  Ber.,  3,  63  (1870). 


534  SUGAR  ANALYSIS 

first  carbohydrate  formed  and  others  sucrose.  Glucose,  fructose, 
sucrose,  maltose,  and  starch  have  all  been  detected  in  the  leaves  of 
plants,  but  the  ease  with  which  the  different  sugars  in  nature  pass  into 
one  another  by  condensation  or  hydrolysis  makes  it  difficult  to  say 
whether  this  or  that  sugar  is  of  primary  or  secondary  origin. 

It  is  well  established  that  the  starch  of  the  leaf  is  one  of  the  products 
of  photosynthesis.  If  the  leaves  of  plants  gathered  by  daylight  be  ex- 
tracted with  alcohol  to  remove  the  chlorophyll,  a  distinct  blue  colora- 
tion is  produced  upon  dipping  them  in  iodine  solution.  This  reaction 
for  starch  is  not  obtained,  however,  with  leaves  which  are  plucked  be- 
fore daylight;  which  proves  that  light  energy  is  necessary  for  the  for- 
mation of  starch  in  the  leaf  and  that  the  starch  which  is  thus  formed  is 
afterwards  hydrolyzed  into  sugar. 

Transportation  and  Metabolism  of  Sugars  in  Plants.  —  The  sugar, 
which  is  produced  in  the  leaf  is  afterwards  transported  to  various 
parts  of  the  plant,  where  it  is  either  transformed  into  cellulose,  hemi- 
cellulose,  and  other  substances  of  the  mechanical  tissue,  or  else  stored 
up  as  reserve  material  in  the  form  of  sucrose,  starch,  inulin,  and  other 
carbohydrates. 

The  intensity  of  assimilation  has  been  measured  for  many  different 
plants.  The  results  are  usually  expressed  in  grams  of  starch  or  sugar 
which  are  formed  per  square  meter  of  leaf  surface  in  an  hour.  The  de- 
terminations show  differences  for  different  plants  and  for  different  con- 
ditions of  temperature  and  sunlight,  the  results  varying  from  traces  up 
to  two  grams  or  more  of  carbohydrates  per  square  meter  of  leaf  area  per 
hour.  Measurements  of  sunshine,  temperature,  and  leaf  area  are  used 
in  fact  as  a  means  of  forecasting  the  probable  production  of  sugar  by  a 
beet  crop. 


CHAPTER  XIX 

THE  MONOSACCHARIDES 

DlOSES 

C2Hd02 

Glycolose.  —  Glycolaldehyde. 

CH2OH 

CHO 

Glycolose  has  not  been  found  as  yet  free  in  nature.    It  has  been  pre- 
pared synthetically  by  oxidation  *  of  its  alcohol  glycol  with  nitric  acid 
and  by  electrolysis  f  from  glyceric  acid. 
CH2OH 


|  CH2OH 

COOH 


HOH  =  +  C02  +  H2 

CHO 


Glyceric  acid  Glycolose 

Glycolose  is  also  obtained  by  the  condensation  of  two  molecules  of 
formaldehyde  and  in  many  other  ways. 

Properties.  —  Glycolose  crystallizes  in  colorless  plates,  melting  at 
95°  to  97°  C.,  is  easily  soluble  in  water  and  alcohol  and  has  a  sweet 
taste.  It  is  optically  inactive  and  unfermentable.  It  yields  upon 
oxidation  first  monobasic  glycollic  acid,  and  then  dibasic  oxalic  acid. 

Tests.  —  Glycolose  gives  all  the  ordinary  sugar  reactions.  a-Naphthol 
and  sulphuric  acid  give  a  bluish  violet  coloration  {  with  total  absorption 
of  the  red  and  violet  parts  of  the  spectrum  and  a  band  between  the  D  and 
E  lines.  It  forms  a  number  of  osazones  of  which  the  p-nitrophenyl- 
osazone  is  especially  characteristic ;  the  compound  is  very  insoluble  in 
the  ordinary  solvents  but  can  be  crystallized  from  pyridine;  its  melting 

point  is  311°  C. 

METHYLDIOSES 
CHS  •  C2H302 

Methylglycolose.  —  Lactic  aldehyde. 

CH3 

CHOH 

CHO 

*  Fischer  and  Tafel.,  Ber.,  20, 1091 ;  22,  96.      t  Neuberg,  Biochem.  Zeitschr.,  7,  527. 
t  Neuberg,  Z.  Ver.  Deut.  Zuckerind.,  61,  271. 
635 


536  SUGAR  ANALYSIS 

This,  the  simplest  of  methyl  sugars,  was  prepared  by  Wohl  and 
Lange*  by  saponifying  its  acetal  derivative  with  dilute  sulphuric  acid. 

CH3 

CH3 
CHOH 

+  H20  =  CHOH  +  2  C2H5OH 

/  OC2H6 

HC  CHO 

\OC2HS 

Lactic  diethylacetal  Lactic  aldehyde  Alcohol 

The  sugar  as  thus  split  off  is  obtained  in  a  polymerized  bimolecular 
form  (C3H602)2  consisting  of  large  needles  melting  at  101°  C.;  upon 
heating  this  polymerized  compound  the  simple  monomolecular  sugar  is 
obtained. 

Properties  and  Tests.  —  Methylglycolose  consists  of  a  colorless  liquid 
with  slightly  rancid  odor.  It  is  colored  brown  by  alkalies,  reduces 
Fehling's  solution,  and  gives  the  other  reactions  of  a  simple  reducing 
sugar.  Its  phenylhydrazone  forms  colorless  leaflets  melting  at  92°  C.; 
its  nitrophenylhydrazone  consists  of  bright  yellow  prisms  melting  at 
129°  C.  Its  osazone  is  identical  with  that  of  acetol  and  methyl- 
glyoxal. 

While  methylglycolose  has  not  thus  far  been  found  free  in  nature 
its  monobasic  acid  derivative  lactic  acid,  CH3CHOHCOOH,  is  very 
widely  distributed. 

Acetol.  —  Acetylcarbinol. 

CH3 

i-o 

CH2OH 

This,  the  simplest  of  ketose  sugars,  can  be  prepared  in  a  number 
of  ways.     It  is  formed  by  oxidizing  a-propylene  glycol  with  bromine 
water,  or  by  the  action  of  Bacterium  xylinum.] 
CH3  CH3 

CHOH        +    O     =  CO  -f  H2O 

CH2OH  CH2OH 

o-Propylene  glycol  Acetol 

Acetol  is  also  formed  in  large  amounts  by  distilling  glucose  with  very 
concentrated  potassium  hydroxide  solution. 

Properties.  —  Acetol  consists  of  a  colorless,  sweet-smelling  liquid 
with  a  nutty  flavor,  which  boils  in  vacuum  at  105  °C.  and  in  air  at 

*  Ber.,  41,  3612. 

t  Kling,  Compt.  rend.,  128,  244;  129,  219,  1252;  133,  231. 


THE   MONOSACCHARIDES  537 

147°  C.  with  decomposition.     It  is  easily  soluble  in  water,  alcohol  and 
ether  and  reduces  Fehling's  solution  strongly  in  the  cold. 

Reactions.  —  Acetol  gives  the  oxime,  hydrazone,  osazone  and 
other  reactions  common  to  reducing  sugars.  The  phenylosazone, 
Ci5Hi6N4,  is  formed  by  heating  acetol  with  phenylhydrazine  and 
consists  of  yellow  needles  melting  between  145°  and  148°  C.;  the  com- 
pound is  identical  with  the  osazone  of  lactic  aldehyde  and  methyl- 
glyoxal  (CH3CO  •  COH).  Acetol-phenylosazone  is  also  formed  * 
upon  heating  glucose  with  phenylhydrazine  in  alkaline  solution,  the 
acetol  being  first  formed  as  a  decomposition  product  of  the  glucose 
and  then  reacting  with  the  phenylhydrazine. 

DlMETHYLDIOSES 

(CH3)2C2H202 

Dimethylglycolose.  —  Dimethylketol.      Acetylmethylcarbinol. 

CH3 

CHOH 

Ao 

CH3 

Occurrence.  —  Dimethylglycolose  is  formed  in  small  amounts  in 
many  aerobic  fermentations  of  sugars.  It  is  a  common  constituent  of 
cider  vinegar  f  and  is  a  frequent  by-product  in  the  acetic  fermentation. 

Synthesis. — Dimethylglycolose  was  prepared  synthetically  by  Pech- 
mannj  by  reducing  diacetyl  with  zinc  and  sulphuric  acid. 

CH3  CH3 

CO  CHOH 

CO  ~CO 

CH3  CH3 

Diacetyl  Dimethylglycolose 

Properties.  —  Dimethylglycolose  is  a  colorless  liquid  boiling  at  141° 
to  142°  C.,  and  is  easily  soluble  in  water  and  alcohol.  Similar  to  other 
sugars  of  the  diose  group  it  is  easily  polymerized. 

Tests.  —  Dimethylglycolose  reduces  Fehling's  solution  even  in  the 
cold.  It  is  best  recognized  by  means  of  its  yellow  finely  crystalline 
phenylosazone,  Ci6Hi8N4,  which  is  very  insoluble  in  water,  alcohol,  and 
ether;  the  compound  is  also  distinguished  by  its  high  melting  point, 

*  Pinkus,  Ber.,  31,  31. 

t  Browne,  J.  Am.  Chem.  Soc.,  26,  31. 

J  Ber.,  21,  2754;  22,  2214;  23,  2421. 


538  SUGAR  ANALYSIS 

245°  C.,  which  seems  to  be  the  highest  of  any  phenylosazone  thus  far 

prepared. 

TRIOSES 

C3H604 

ALDOTRIOSES 

d,  1-Glycerose.  —  Glyceric  aldehyde. 

CH2OH 


HOH 

CHO 

Glycerose  has  not  been  found  free  in  nature,  but  has  been  prepared 
synthetically  by  oxidation  *  of  its  alcohol  glycerol,  by  action  of  water 
upon  acrolein  dibromide,  and  in  other  ways. 

Properties.  —  d,l-Glycerose  crystallizes  from  methyl  alcohol  in  the 
form  of  colorless  needles  melting  at  138°  C.  The  compound  shows  a 
great  tendency  to  polymerize.  It  is  optically  inactive.  The  fermen- 
tation of  glycerose  sirup  by  yeast,  observed  by  Fischer  and  Tafel,  is 
probably  due  to  the  formation  of  a  fermentable  condensation  product. 
Pure  glycerose  according  to  Wohl  f  and  Emmerling  {  is  not  fermentable. 

Tests.  —  Glycerose  reduces  Fehling's  solution  and  exhibits  all  the 
other  reactions  common  to  sugars.  Heating  with  concentrated  hydro- 
chloric acid  and  a  little  orcin  produces  a  bluish  green  color  §  which  soon 
separates  as  a  flocculent  precipitate;  solution  of  the  latter  in  amyl  alcohol 
gives  a  characteristic  absorption  band  between  the  C  and  D  lines  of  the 
spectrum.  Phloroglucin  II  in  presence  of  a  little  sulphuric  acid  gives  a 
flocculent  precipitate  with  dilute  glycerose  solutions  upon  warming. 

d,  1-Glycerose  gives  glycerol  upon  reduction,  and  upon  oxidation 
first  monobasic  d,  1-glyceric  acid  and  then  dibasic  tartronic  acid.  The 
sugar  has  not  been  resolved  as  yet  into  d-  and  1-glycerose;  although 
d,  1-glyceric  acid  has  been  separated  by  Frankland  and  Frew  If  by  fer- 
menting calcium  d,  1-glycerate  with  Bacillus  ethaceticus  which  attacks 
only  the  1-component. 

KETOTRIOSES 

Dioxyacetone.  — 

CH2OH 


i-o 

i 


H2OH 

*  Fischer  and  Tafel,  Ber.,  20,  3384.      §  Neuberg,  Z.  Ver.  Deut.  Zuckerind.,  61,  271, 
t  Ber.,  31,  1796,  2394.  ||  Wohl  and  Neuberg,  Ber.,  33,  3095. 

*  Ber.,  32,  544.  ^  J.  Chem.  Soc.,  69,  96;  63,  296. 


THE   MONOSACCHARIDES  539 

Dioxyacetone  is  formed  as  a  by-product  in  a  number  of  different 
fermentations.  It  has  been  prepared  synthetically  in  several  ways, 
but  the  best  method  is  that  of  Bertrand*  which  consists  in  fermenting 
a  5  or  6  per  cent  glycerol  solution  with  Bacterium  xylinum.  When  the 
reducing  power  of  the  solution  has  reached  its  maximum,  fermentation 
is  interrupted;  the  solution  is  evaporated  in  vacuum,  the  sirup  ex- 
tracted with  5  to  6  parts  alcohol  and  2  parts  ether,  and  the  dioxy- 
acetone  crystallized  from  the  alcohol-ether  extract. 

Properties.  —  Dioxyacetone  is  a  white  crystalline  compound  soluble 
in  cold  water  and  boiling  alcohol.  It  has  a  sweet  taste  and  melts  be- 
tween 68°  and  75°  C.  under  polymerization.  Its  concentrated  water 
solutions  also  polymerize  readily  yielding  a  crystalline  compound  of 
melting  point  155°  C.  It  is  optically  inactive  and  not  fermented  by 
yeast. 

Tests.  —  Dioxyacetone  reduces  Fehling's  solution  even  in  the  cold. 
Similar  to  all  ketoses  it  gives  the  characteristic  reaction  with  resorcinf 
and  an  osazone  with  methylphenylhydrazine.  This  osazonef  has  the 
formula  Ci7H2oN4O  and  melts  at  127°  to  130°  C.  Distillation  of  di- 
oxyacetone  with  20  per  cent  sulphuric  acid  gives  methylglyoxal,  § 
CH3  •  COCHO.  Reduction  with  sodium  amalgam  gives  glycerol  ||  quan- 
titatively. Dioxyacetone  does  not  give  the  reaction  with  phloroglucin 
characteristic  of  the  isomeric  glycerose. 

METHYLTRIOSES 
CH3  •  C3H503 

Methylglycerose.  — 


CH3 
HOH 
HOH 
HO 


This  compound  has  been  prepared  synthetically  by  Wohllf  and 
Frank  from  crotonaldehyde.  It  forms  a  colorless  sirup  easily  soluble 
in  water  and  alcohol  and  reduces  Fehling's  solution  about  half  as  strong 
as  glucose. 

*  Compt.  rend.,  126,  842,  984. 

t  Neuberg,  Z.  Ver.  Deut.  Zuckerind.,  61,  271. 

j  Neuberg,  Ber.,  36,  964. 

§  Pinkus,  Ber.,  31,  31. 

II  Piloty,  Ber.,  30,  1656,  3161. 

H  Ber.,  35,  1904. 


540  SUGAR  ANALYSIS 

TRIMETHYLTRIOSES 

(CH3)3C3H303 
Trimethyltriose.  — 

CH3CH3 
\  / 
COH 

CHOH 

i-o 

CH3 

This  compound,  which  belongs  to  the  ketoses,  has  been  made 
synthetically  by  Harries  and  Pappos  *  from  mesityl  oxide.  It  consists 
of  a  bright  yellow  sirup  of  caramel-like  odor,  easily  soluble  in  water, 
alcohol  and  ether. 

TETROSES 
C4H804 


ALDOTETROSES 


d-Erythrose.  — 


CH2OH 
HOCH 
HOCH 

CHO 

This  sugar  has  been  prepared  synthetically  from  d-arabonic  acid  by 
Wohl  t  through  decomposition  of  the  nitrile  with  ammoniacal  silver 
solution.  Rufff  has  also  prepared  the  sugar  by  oxidation  of  calcium 
d-arabonate  with  hydrogen  peroxide  in  presence  of  ferric  acetate.  In 
this  reaction  the  COOH  group  of  the  acid  is  split  off  with  evolution 

of  C02. 

CH2OH  CH2OH 

HOCH  HOCH 

HOCH  +  O  =  HOCH         +  CO2  +  H2O 
HCOH  CHO 

COOH 

d-Arabonic  acid  d-Erythrose 

The  configuration  of  d-erythrose  is  established  by  means  of  these 
reactions. 

Properties.  —  d-Erythrose  consists  of  a  colorless  sirup  which  solidi- 
fies to  a  white  mass  when  dried  over  phosphorus  pentoxide.  It  is 
*  Ber.,  34,  2979.  f  Ber.,  26,  743.  J  Ber.,  32,  3672. 


THE   MONOSACCHARIDES 


541 


easily  soluble  in  water  and  alcohol.  The  sugar  is  optically  active  and 
exhibits  mutarotation;  [O\D  —  —  14.5  (+  1.0  in  fresh  aqueous  solution). 
d-Erythrose  is  not  fermented  by  yeast. 

Tests.  —  d-Erythrose  reduces  Fehling's  solution  and  gives  all  other 
reactions  common  to  reducing  sugars.  Reduction  with  sodium  amalgam 
gives  optically  inactive  mesoerythrite,  which  is  widely  distributed  in 
nature  in  different  algae  and  lichens.  Oxidation  of  d-erythrose  pro- 
duces first  monobasic  d-erythronic  acid  and  then  dibasic  mesotartaric 
acid. 


1-Erythrose.  — 


CH2OH 
HCOH 
HCOH 


This  sugar  has  been  prepared  synthetically  from  1-arabonic  acid 
according  to  the  methods  of  Wohl*  and  Rufff  described  under  d-ery- 
throse. Neuberg  J  has  also  prepared  the  sugar  from  1-arabonic  acid  by 
his  method  of  electrolysis. 

Properties.  —  1-Erythrose  consists  of  a  colorless  sweet  sirup  which 
has  not  as  yet  been  obtained  crystalline.  The  sugar  is  dextrorotatory, 
[O\D  =  +  32.7  (Wohl) ;  Ruff  and  Meusser  §  found  [a]D  =  +  21.5  constant 
and  in  fresh  solution  +2.4.  The  differences  noted  are  probably  due  to 
the  fact  that  the  sugar  has  not  yet  been  isolated  in  the  pure  condition. 
1-Erythrose  is  not  fermentable. 

Tests. — 1-Erythrose  gives  all  the  ordinary  reactions  of  reducing 
sugars.  Reduction  with  sodium  amalgam  gives  inactive  mesoerythrite 
the  same  as  d-erythrose;  oxidation  produces  first  monobasic  1-erythronic 
acid  and  then  dibasic  mesotartaric  acid. 


d,  1-Erythrose.  —  Racemic  erythrose  is  formed  by  the  oxidation  ||  of 
natural  mesoerythrite. 

CH2OH  CHO  CH2OH 

HCOH  HCOH  HCOH 

2      |  +02=      |  +|  +  2H20 

HCOH  HCOH  HCOH 

CH2OH  CH2OH  CHO 

Mesoerythrite  d,l-Erythrose 


Ber.,  32,  3666.  f  Ber.,  34,  1366.  J  Biochem.  Zeitschr.,  7,  527. 

§  Ber.,  34,  1366.  II  Fischer  and  Tafel,  Ber.,  20,  1090. 


542  SUGAR  ANALYSIS 

The  sugar  is  of  course  inactive.     Oxidation  produces  first  d,  1 
erythronic  acid  and  then  mesotartaric  acid. 

1-Threose.  — 

CH2OH 

HOCH 
HCOH 


This  tetrose  sugar  has  been  formed  synthetically  by  oxidation  *  of 
calcium  1-xylonate  with  hydrogen  peroxide  and  ferric  acetate. 

CH2OH 

CH2OH 
HOCH 

HOCH 
HCOH   +  O  =         +  CO2  +  H2O 

|  HCOH 

HOCH 

|  CHO 

COOH 

l-Xylonic  acid  1-Threose 

The  configuration  of  1-threose  is  established  by  this  reaction. 

Properties.  —  1-Threose  has  only  been  obtained  in  a  sirupy  con- 
dition, all  attempts  to  promote  crystallization  having  failed. 

Tests.  —  1-Threose  upon  reduction  gives  1-erythrite  ([«]z>  in  water  = 
+4.25).  Oxidation  gives  first  1-threonic  acid  and  then  1-tartaric  acid. 

d-Threose.  —  The  optical  antipode  of  1-threose  has  not  as  yet 
been  prepared.  Its  alcohol  d-erythrite,  however,  has  been  obtained 
([O\D  in  water  =  —  4.40)  by  reduction  of  d-erythrulose. 

KETOTETROSES 

d-Erythrulose.  — 

CH2OH 

HCOH 


CH2OH 

This  sugar  is  best  prepared  by  oxidation  of  natural  mesoerythrite 
by  means  of  Bacterium  xylinum  according  to  Bertrand's  f  method. 

Properties.  —  d-Erythrulose  has  been  obtained  only  as  a  sirup ;  it  is 
very  soluble  in  water  and  alcohol,  and  is  dextrorotatory,  the  rotation 
increasing  after  solution.  The  sugar  is  unfermentable. 

Tests.  —  d-Erythrulose  gives  the  ordinary  ketose  reactions,  produc 

*  Ruff  and  Kohn,  Ber.,  34,  1370.         t  Compt.  rend.,  130,  1330. 


THE  MONOSACCHARIDES  543 

ing  a  coloration  with  resorcin  and  hydrochloric  acid  and  resisting  oxida- 
tion with  bromine  water.  Reduction  with  sodium  amalgam  gives  both 
meso-  and  d-erythrite. 

CH2OH  CH2OH  CH2OH 

HCOH  HCOH  HCOH 

21  +2H2=      |  +         | 

C=O  HCOH          HOCH 

CH2OH  CH2OH  CH2OH 

d-ErythruIose  Mesoerythrite         d-Erythrite 

This  property  of  yielding  two  different  alcohols  upon  reduction  is 
a  characteristic  of  the  ketose  sugars. 

d,  1-Erythrulose  is  formed  according  to  Neuberg*  during  the  oxi- 
dation of  mesoerythrite  by  hydrogen  peroxide  in  presence  of  ferrous  sul- 
phate (Fenton'sf  synthesis). 

The  sugar  has  been  obtained  only  as  a  sirup  and  has  not  been  re- 
solved as  yet  into  its  d-  and  1-  components. 

METHYLTETROSES 

CH3  •  C4H7O4 
Methyltetrose.  — 

CH3 

CHOH 
HCOH 


HO 


in 

CH( 


This  sugar  has  been  prepared  synthetically  by  Fischer  |  from  rham- 
nonic-acid  nitrile  by  Wohl's  method. 

Properties.  —  Methyltetrose  has  not  been  obtained  in  a  pure  crys- 
talline form,  but  only  as  a  yellowish  sweet  sirup  easily  soluble  in  water 
and  alcohol  with  levorotation,  [a]o  =  —  5M°  (in  water). 

Tests.  —  Methyltetrose  gives  the  ordinary  reactions  of  an  aldose 
sugar.  Reduction  with  sodium  amalgam  gives  methylerythrite.  Ox- 
idation with  bromine  gives  methyltetronic  acid,  whose  lactone  gives  [a]D 
=  -  47.5.  Oxidation  with  nitric  acid  splits  off  the  CH3  group  with  for- 
mation of  d-tartaric  acid. 

DlMETHYLTETROSES 

(CH3)2C4H6O4 

Digitoxose.  —  This  sugar  which  has  the  composition  of  a  dimethyl 
tetrose,  C6Hi204,  has  been  obtained  by  Kiliani  §  by  hydrolysis  of  digi- 
*  Ber.,  35,  2627.  t  Ber.,  29,  1377. 

f  J,  Chem.  Soc.,  71,  375  (1897).         §  Ber.,  31,  2454;  34,  3561. 


544  SUGAR  ANALYSIS 

toxin,   a  glucoside  found  in  different  plants  of  the  digitalis  family. 
The  formation  of  digitoxose  is  supposed  to  proceed  as  follows: 


C34H54On  +  H20  =  CaH»04  +  2  C6H1204. 

Digitoxin  Digitoxigenin  Digitoxose 

Digitoxose  has  been  obtained  as  prismatic  crystals  melting  at  101°  C., 
soluble  in  water  and  alcohol,  and  having  a  specific  rotation  of 
kb=+46°. 

Tests.  —  Oxidation  with  silver  oxide  gives  among  other  products 
considerable  acetic  acid.  Heated  with  concentrated  sulphuric  acid  and 
1  per  cent  ferrous  sulphate,  digitoxose  solutions  are  colored,  after  30 
minutes,  a  deep  blue,  which  changes  in  an  hour  or  two  to  bluish  green. 

OXYMETHYLTETROSES 

CH2OH  •  C4H704 

Apiose  —  /3-Ox"ymethyltetrose. 

CH2OH 

HOC-CH2OH 
CHOH 
CHO 

This  sugar,  which  has  the  same  empirical  formula  C5Hio05  as  a 
pentose,  has  been  found  by  Vongerichten  *  as  a  constituent  of  the  glu- 
coside, apiin,  which  occurs  in  the  parsley  plant.  Apiin  upon  treat- 
ment with  strong  acids  is  hydrolyzed  as  follows: 

C26H28014  +  2H20  =  C5H1005  +  C6H1206  +  C15H1005. 

Apiin  Apiose  d-Glucose  Apigenin. 

Apiose  has  been  obtained  only  as  an  optically  inactive,  unferment- 
able  sirup. 

Tests.  —  Apiose  is  distinguished  from  the  pentose  sugars  by  not 
giving  furfural  upon  heating  with  hydrochloric  acid.  Reduction  with 
hydriodic  acid  and  phosphorus  gives  iso valeric  acid, 

CH3 

HC-CH3 
HCH 
COOH, 

which  confirms  the  branched  structure  of  the  carbon  chain  assigned  to 
apiose. 

*  Ann.,  318,  121;  321,  71. 


THE   MONOSACCHARIDES  545 

PENTOSES 


ALDOPENTOSES 

d-Arabinose.  — 

CH2OH 

HOCH 


HOCH 


i 


OH 
HO 


This  sugar,  which  has  been  found  in  nature  only  as  a  constituent  of 
d,l-arabinose  in  abnormal  urines,  has  been  prepared  synthetically  by 
WohPs*  method  from  the  nitrile  of  d-gluconic  acid  and  by  Ruff's  f 
method  from  the  calcium  salt  of  d-gluconic  acid.  The  oxidation  of 
d-gluconic  acid  to  d-arabinose  proceeds  as  follows: 

CH2OH 

CH2OH 
HOCH 

HOCH 
HOCH 

+  O  =  HOCH    +  CO2  +  H2O 
HCOH 

HC01 


>H 
HOCH 

CHO 
COOH 

d-Gluconic  acid  d-Arabinose 


The  configuration  of  d-arabinose  is  established  by  means  of  this 
reaction. 

Properties.  —  d-Arabinose  consists  of  beautiful  prismatic  needles 
melting  at  160°  C.  and  easily  soluble  in  water,  but  insoluble  in  absolute 
alcohol.  The  sugar  shows  in  aqueous  solution  (c  =  9.45)  [a]D  =  —  105° 
(constant);  mutarotation  is  present;  d-arabinose  is  not  fermentable. 

Tests. — d-Arabinose  reduces  Fehling's  solution,  yields  furfural  upon 
distillation  with  hydrochloric  acid  and  gives  the  other  reactions  charac- 
teristic of  an  aldopentose  sugar.  Reduction  with  sodium  amalgam  gives 
d-arabite,  C5Hi2O5,  for  which  [a]n  =  +  7.7  (in  saturated  borax  solution). 
Oxidation  with  bromine  gives  d-arabonic  acid,  whose  lactone  C5H805 
gives  [d\D  =  +  73.73.  Oxidation  with  strong  nitric  acid  gives  d-trioxy- 
glutaric  acid,  [O\D  =  +  22.8.  Especially  characteristic  of  d-arabinose  is 
the  very  difficultly  soluble  1-menthylhydrazone  J  which  separates  in 

*  Ber.,  26,  730. 

t  Ber.,  31,  1573;  32,  550;  33,  1799;  36,  2360. 

J  Neuberg,  Ber.,  36,  1194. 


546  SUGAR  ANALYSIS 

colorless  crystals  melting  at  131°  C.  and  from  which  d-arabinose  can 
be  isolated  by  decomposition  with  formaldehyde. 

L-ARABINOSE.  — 

CH2OH 


HCOH 
HC01 


)H 
HOCH 
CHO 

Occurrence.  —  Ordinary  or  1-arabinose  has  not  been  found  free  in 
nature  except  as  a  constituent  of  d,  1-arabinose  in  abnormal  urines; 
parent  substances,  from  which  1-arabinose  may  be  derived  by  hydroly- 
sis, are,  however,  very  widely  distributed  in  nature.  Chief  of  these 
parent  substances  is  the  pentosan  araban  (C5H8O4)n  which  occurs  as 
a  constituent  of  many  plant  gums  (cherry  gum,  peach  gum,  gum 
arabic,  gum  tragacanth,  etc.),  of  the  hemicellulose  tissues  of  vegetable 
cells  (sugar  beet,  maize  stalks,  elder  pith,  sugar  cane,  bran,  etc.),  and 
of  many  plant  mucilages  (such  as  quince)  and  pectins.  1-Arabinose  has 
also  been  found  in  several  glucosides. 

The  Arabans.  —  Araban  itself  (C5H804)n  occurs  in  nature  not  so 
much  in  the  free  condition  as  in  a  combined  or  associated  form.  The 
chemistry  of  this  group  of  substances  is  exceedingly  complex  and  a 
satisfactory  classification  is  impossible.  Among  the  arabans,  or  sub- 
stances which  yield  1-arabinose  upon  hydrolysis,  are  metaraban,  gluco- 
araban,  galactoaraban,  arabinic  acid,  pectose,  pectin,  parapectin, 
metapectin,  parapectic  and  metapectic  acids,  and  many  other  ill-de- 
fined substances.  The  early  investigators  in  this  field  were  hampered 
by  a  lack  of  satisfactory  methods  and  many  of  the  substances,  to  which 
they  gave  separate  names,  would,  if  purified,  no  doubt  prove  to  be 
identical. 

A  comparatively  pure  araban  has  been  prepared  by  digesting  sugar- 
beet  pulp,*  and  other  hemicelluloses,f  with  dilute  alkalies.  The  clear 
filtrate  is  precipitated  with  weak  acids  in  presence  of  alcohol.  The 
precipitate,  after  washing  with  strong  alcohol,  is  purified  by  dissolving 
in  water,  and  reprecipitating  with  alcohol.  The  product,  after  drying, 
consists  of  a  white  amorphous  mass,  soluble  in  water  to  a  neutral  solu- 
tion, does  not  reduce  Fehling's  solution  and  is  strongly  levorotatory 
([<*]D  given  by  different  authorities  varies  from  —84  to  —123;  these 

*  Ullik,  Oest.  Ungar.  Z.  Zuckerind.,  23,  268. 
t  Schulze,  Z.  physiol.  Chem.,  16,  386. 


THE   MONOSACCHARIDES  547 

variations  are  probably  due  to  differences  in  the  purity  of  the  product). 
Upon  heating  with  1  per  cent  sulphuric  acid  araban  is  quickly  hydro- 
lyzed  to  1-arabinose. 

(C5H804)n  +  n  H20  =  n  C5H1005. 

Araban  1-Arabinose 

Metaraban*  is  found  in  the  bran  of  rye,  wheat  and  other  cereal 
grains.  The  bran,  after  removing  the  starch,  is  heated  3  hours  with 
1  per  cent  ammonia,  and  then  filtered  and  washed  with  water.  The 
residue  is  then  cooked  under  pressure  with  dilute  sodium  hydroxide  which 
dissolves  the  metaraban.  The  latter  is  precipitated  from  the  filtered 
solution  by  means  of  dilute  hydrochloric  acid  and  alcohol.  The  precipi- 
tate, after  washing  with  alcohol  and  drying,  forms  a  white  amorphous 
substance,  which  swells  up  in  water  and  finally  gives  a  mucilaginous, 
slightly  levorotatory  solution.  Hydrolysis  with  acids  gives  1-arabinose. 

Arabinic  Acid"\  (arabin,  metapectic  acid)  occurs  in  combination  with 
potassium,  calcium  and  magnesium  as  the  principal  constituent  of  gum 
arabic  and  the  gum  of  the  cherry,  peach,  plum  and  many  other  trees. 
It  is  also  produced  by  the  action  of  alkalies  upon  pectose  and  other 
pectin  substances.  Arabinic  acid  can  be  prepared  by  dissolving  gum 
arabic  t  in  10  parts  of  water,  acidifying  with  acetic  acid  to  break  up 
mineral  combinations  and  then  dialyzing,  or  washing,  in  acetic-acid 
solution  to  remove  soluble  salts  and  other  impurities.  The  product 
is  purified  by  dissolving  in  water  and  precipitating  with  alcohol;  it  is 
then  dried  over  sulphuric  acid  at  a  low  temperature,  preferably  in  a 
vacuum. 

Arabinic  acid  can  also  be  prepared,  but  in  a  less  pure  condition,  by 
the  action  of  alkalies  upon  beet  pulp.§  The  latter,  after  extraction 
with  water  and  cold  85  per  cent  alcohol,  is  boiled  in  water  until  all 
alcohol  is  expelled  and  then  cooked  with  an  excess  of  caustic  lime. 
The  solution  of  lime  arabinate  is  filtered  and  the  lime  precipitated  by 
means  of  carbon  dioxide,  or  oxalic  acid.  The  solution  is  again  filtered 
and  the  arabinic  acid  precipitated  by  adding  an  excess  of  strong  alcohol. 
The  crude  acid  is  purified  and  dried  as  previously  described. 

Arabinic  acid  is  a  white  vitreous  amorphous  substance.  Before 
being  dried  it  is  easily  soluble  in  water  to  an  acid  solution;  but  the  dry 
product  swells  up  with  water  to  a  mass  of  almost  neutral  reaction  —  a 
change  which  is  attributed  to  a  conversion  of  the  acid  into  its  lactone. 

*  Steiger  and  Schulze,  Ber.,  23,  3110. 

t  Neubauer,  J.  prakt.  chem.,  62,  193  (1854),  Scheibler,  Ber.,  1,  58;  6,  612. 

t  O'Sullivan,  J.  Chem.  Soc.,  45,  I,  41,  Proc.  Chem.  Soc.,  17,  156. 

§  Scheibler,  Z.  Ver.  Deut.  Zuckerind.,  23,  288. 


548 


SUGAR  ANALYSIS 


The  [a]o  of  arabinic  acid  of  different  origins  varies  from  over  —80  to 
over  +80.  Distillation  with  hydrochloric  acid  gives  large  amounts  of 
furfural  and  oxidation  with  nitric  acid  considerable  mucic  acid.  Herz- 
feld*  obtained  from  a  levorotatory  arabinic  acid  15.3  per  cent  furfural 
and  11.5  per  cent  mucic  acid  and  from  a  dextrorotatory  arabinic  acid 
5.9  per  cent  furfural  and  41.7  per  cent  mucic  acid.  It  is  thus  seen  that 
arabinic  acid  is  a  galactoaraban  of  varying  composition.  Hydrolysis 
of  both  levorotatory  and  dextrorotatory  arabinic  acid  gives  a  dextro- 
rotatory mixture  of  1-arabinose  and  d-galactose.  Neubauer  assigned 
the  formula  (Ci2H220ii)n  to  arabinic  acid;  0 'Sullivan  has  given  the 

formula  C9iHi42O74.  Such  differ- 
ences necessarily  follow  from  the 
variable  character  of  the  substance. 
Metarabin  is  obtained  by  heating 
arabinic  acid  to  slightly  above 
100°  C.,  at  which  temperature  water 
is  given  off.  It  is  insoluble  in  water, 
yielding  only  a  swollen  gelatinous 
mass.  The  formula  has  been  given 
as  (Ci2H20Oio)n. 

Other  mixed  arabans,  as  arabo- 
galactan  and  the  pectin  substances, 
are  described  under  d-galactose. 

Preparation  of  1-Arabinose.  — 
1-Arabinose  can  be  prepared  by  the 
hydrolysis  of  araban,  metaraban  or 
arabinic  acid;  it  is  more  convenient, 
however,  to  prepare  the  sugar  by 
the  direct  hydrolysis  of  certain 
gums.  Cherry  gum  is  one  of  the 
purest  sources  of  supply,  and  as  the 
preparation  of  arabinose  from  this 
substance  is  typical  of  other  hy- 
drolytic  processes,  the  following 


Fig.  190.  —  Tollens's  apparatus  for  hy- 
drolyzing  plant  and  animal  substances. 


method  of  Tollensf  will  be  described  in  fuller  detail. 

Hydrolysis  of  Cherry  Gum.  —  Treat  1000  gms.  of  pulverized  cherry 
gum  in  a  large  porcelain  pot  with  7000  c.c.  of  water  and  280  gms.  of  con- 
centrated sulphuric  acid,  thus  making  a  mixture  of  about  4  per  cent 
acid.  The  pot  is  immersed  in  a  boiling-water  bath,  as  shown  in  Fig. 

*  Z.  Ver.  Deut.  Zuckerind.,  41,  667. 

t  "  Handbuch  der  Biochemischen  Arbeitsmethoden  "  (1902),  Vol.  II,  65. 


THE   MONOSACCHARIDES 


549 


190,  and  the  mixture  stirred  until  the  gum  has  dissolved.  The  pot  is 
then  covered  and  the  heating  continued  for  5  hours.  The  liquid, 
which  smells  strongly  of  furfural,  is  then  poured  into  a  large  evaporat- 
ing dish,  and  while  still  hot  neutralized  with  an  excess  (300  to  320 
gms.)  of  precipitated  calcium  carbonate,  which  must  be  free  from 


Fig.  191. — Tollens's  apparatus  for  evaporating  sugar  solutions  under  reduced  pressure. 

magnesium  carbonate  (the  magnesium  sulphate  which  is  formed  interfer- 
ing with  the  crystallization  of  the  sugar).  The  liquid  after  cooling  is 
filtered  through  a  heavy  linen  bag,  and  the  precipitate  of  gypsum,  etc., 
squeezed  out  in  a  press  (Fig.  131)  to  remove  as  much  as  possible  of  the 
liquid.  The  hydrolyzed  solution  reduces  Fehling's  solution  strongly,  and 
contains  in  addition  to  arabinose  more  or  less  galactose  and  glucose.  In 
order  to  remove  the  latter,  the  solution  is  poured  into  a  large  bottle  and 
fermented  in  a  warm  place  with  a  little  pure  pressed  yeast.  When 
fermentation  is  complete  (3  to  4  days  at  most),  the  solution  is  filtered 
and  evaporated  under  diminished  pressure  to  a  sirup. 

Evaporation  Under  Reduced  Pressure.  —  In  conducting  the  evapora- 
tion of  sugar  solutions  a  small  laboratory  vacuum  pan  may  be  used  to 
advantage.  In  place  of  such  a  pan  the  arrangement  of  Tollens  shown 
in  Fig.  191  may  be  used  to  equal  advantage.  The  liquid  is  placed  in 


550  SUGAR  ANALYSIS 

the  large  balloon  flask  F  of  heavy  glass,  which  rests  in  an  inclined 
position  upon  the  hot-water  bath  W.  The  flask  is  closed  with  a  two- 
hole  rubber  stopper,  which  receives  through  one  opening  the  tube  t; 
the  latter,  drawn  out  to  a  fine  point,  reaches  nearly  to  the  bottom  of 
the  flask  and  is  fitted  at  the  outer  end  with  a  rubber  tube  and  pinch 
cock  c'.  The  flask  is  connected  by  the  bent  tube  c  to  a  vertical  con- 
denser, which  fits  into  a  large  Woulf  bottle  B.  The  latter  is  connected 
upon  one  side  with  a  closed  outlet  tube  G  and  upon  the  other  side  with  a 
safety  bottle  S  to  which  the  suction  pump  is  attached. 

In  making  an  evaporation  the  pump  is  started  and  a  gentle  current 
of  air  drawn  through  the  liquid  while  the  bath  is  being  heated.  By 
diminishing  the  air,  the  pressure  is  reduced  so  that  the  solution  soon 
begins  to  boil.  The  current  of  air  is  always  maintained  slightly  so  as 
to  keep  the  liquid  in  motion  and  prevent  bumping.  When  it  is  desired 
to  empty  the  receiver  the  pinch  cock  c'  is  opened  and  the  distillate 
siphoned  off  at  the  outlet  G. 

Purification  of  Sirups.  —  When  the  liquid  in  the  flask  has  been  con- 
centrated to  a  sirup,  the  latter  is  poured  out  and  a  fresh  quantity  of 
solution  evaporated.  The  concentrated  sirups  are  then  united  and 
shaken  with  4  to  5  volumes  of  hot  96  per  cent  alcohol.  After  the  de- 
posit of  gums  and  mineral  matter  has  settled,  the  alcoholic  solution  is 
filtered  and  evaporated  under  reduced  pressure  to  a  second  sirup.  If 
the  latter  be  very  dark  in  color,  it  may  be  further  purified  by  shaking 
out  again  with  warm  alcohol  to  which  a  little  ether  may  be  added  to 
increase  the  precipitation  of  gum.  An  excess  of  ether  must  be  avoided 
as  it  precipitates  part  of  the  sugar.  The  final  sirup,  which  should  be 
light  colored,  is  set  aside  in  a  cool  place. 

Crystallization.  —  The  crystallization  of  arabinose  from  sirups  pre- 
pared from  cherry  gum  is  usually  rapid;  it  may  be  hastened  by  prim- 
ing the  sirup  with  a  minute  crystal  of  sugar  from  a  stock  preparation. 
When  crystallization  is  complete,  the  crystals  of  sugar  are  sucked  off 
upon  a  filter,  washed  with  a  little  alcohol  and  ether,  and  air  dried.  If 
the  sugar  is  not  perfectly  white,  it  may  be  purified  by  recrystallizing 
from  hot  alcohol  after  filtering  through  bone  black.  The  yield  of 
1-arabinose  from  cherry  gum  by  the  above  process  is  about  20  per  cent. 

Properties.  —  1- Arabinose  crystallizes  in  beautiful  prismatic  needles 
melting  at  160°  C.,  easily  soluble  in  water  but  insoluble  in  absolute 
alcohol  and  ether.  The  sugar  shows  strong  mutarotation ;  [O\D  =  + 104.5 
(constant  in  aqueous  solution). 

1- Arabinose  is  not  fermented  by  yeast;  many  bacteria,  however,  are 
able  to  set  up  destructive  changes  with  formation  of  lactic,  acetic, 


THE  MONOSACCHARIDES  551 

formic,  succinic,  oxalic  and  other  acids.  Bacterium  xylinum  oxidizes 
the  sugar  to  1-arabonic  acid. 

Tests.  —  1-Arabinose  gives  all  the  general  reactions  described  for 
reducing  sugars  and  the  furfural,  color  and  other  special  reactions  de- 
scribed for  pentoses.  The  best  method  for  detecting  1-arabinose  in 
presence  of  other  sugars  (as  in  hydrolyzed  plant  materials)  is  by 
means  of  the  hydrazone  reaction  with  different  substituted  hydrazines, 
such  as  bromophenylhydrazine,*  methylphenylhydrazine,|  benzyl- 
phenylhydrazine  %  and  diphenylhydrazine.§  The  latter  reagent  is 
considered  to  be  the  best  and  produces  in  alcoholic  solution  in  the  cold, 
even  with  small  amounts  of  1-arabinose,  a  difficultly  soluble  hydrazone, 
Ci7H2oN204,  consisting  of  white  needles  and  melting  at  204°  to  205°  C.  || 

The  hydrazones  of  1-arabinose  yield,  upon  decomposition  with  for- 
maldehyde (p.  348),  the  free  sugar  which  may  then  be  crystallized  and 
further  identified  by  determining  its  specific  rotation. 

Sodium  amalgam  reduces  1-arabinose  to  1-arabite  C5Hi2O5,  for 
which  [O\D  =  —  5.31f  (in  saturated  borax  solution),  and  —42  **  (in  acid 
ammonium  molybdate).  Oxidation  of  1-arabinose  with  bromine  gives 
1-arabonic  acid,  whose  crystalline  lactone  C5H8O5  gives  [O\D  =  —  73.9. 
Oxidation  of  the  sugar  with  strong  nitric  acid  gives  1-trioxyglutaric 
acid,  [a]D  =  -  22.7. 

d,  1-Arabinose.  —  This  sugar,  which  is  a  racemic  mixture  of  d-  and 
1-arabinose,  has  been  found  as  a  constituent  ft  °f  abnormal  urines.  The 
sugar  may  also  be  prepared  by  dissolving  equal  parts  of  d-  and  1-ara- 
binose in  hot  alcohol  and  allowing  the  solution  to  crystallize. 

Properties.  —  d,l-Arabinose  forms  colorless  prismatic  crystals  of 
higher  melting  point  (164°  C.)  and  lower  solubility  than  either  of  its 
components.  The  sugar  is  optically  inactive  and  is  not  fermented  by 
yeast. 

Tests.  —  Reduction  of  d,  1-arabinose  with  sodium  amalgam  gives 
d, 1-arabite;  oxidation  with  bromine  gives  d,  1-arabonic  acid  and  with 
nitric  acid  d, 1-trioxyglutaric  acid.  Neuberg  J  J  has  resolved  the  sugar  into 
its  components  by  means  of  1-menthylhydrazine,  which  forms  a  very 
difficultly  soluble  hydrazone  with  d-arabinose,  but  not  with  1-arabinose 
(see  pages  362  and  545). 

*  Fischer,  Ber.,  24,  4214;  27,  2490.  H  Fischer,  Ber.,  24,  1836. 

t  Ruff  and  Ollendorff,  Ber.,  32,  3234.  **  Gernez,  Compt.  rend.,  112,  1360. 

t  Ruff  and  Ollendorff,  Ber.,  32,  3234.  ft  Neuberg,  Ber.,  33,  2243. 

§  Neuberg,  Ber.,  33,  2254;  37,  4616.  tt  Ber.,  36,  1194. 

II  Muther  and  Tollens,  Ber.,  37,  312. 


552  SUGAR  ANALYSIS 

d-Xylose.  — 

CH2OH 

HCOH 
HOCH 
HCOH 
CHO 

This  sugar  has  not  thus  far  been  found  in  nature  either  in  the  free 
or  combined  form.     It  has  been  made  synthetically  by  Fischer  and 
Ruff*  from  d-gulonic  acid  by  oxidation  of  the  calcium  salt  with  hydrogen 
peroxide  in  presence  of  ferric  acetate  (Ruff's  method). 
CH2OH 


+  C02  +  H2O 


1 

CH2OH 

HCOH 

1 

HOCH 
I            +0  = 
HCOH 

HCOH 

HCOH 
HOCH 

HCOH 

I 

I 

CHO 

COOH 

d-Gulonic  acid 

d-Xylose 

This  reaction  establishes  the  configuration  of  d-xylose. 

Properties.  —  d-Xylose  crystallizes  in  white  needles  melting  at  141.5° 
to  143°  C.  and  giving  a  constant  specific  rotation  [a]|J  =  —  18.6.  In 
all  other  respects,  except  rotation,  the  sugar  resembles  its  antipode, 
ordinary  1-xylose. 

Tests.  —  d-Xylose  gives  the  general  reactions  of  reducing  sugars 
and  all  the  special  tests  described  for  pentoses.  Oxidation  with  bromine 
gives  d-xylonic  acid  whose  cadmium  double  salt  (CsH^Oe^  Cd  +  CdBr2 
+  2  H2O  is  especially  characteristic.  This  salt  resembles  the  similar 
compound  of  1-xylonic  acid  which  is  described  under  1-xylose. 

L-XYLOSE.  —  Wood  sugar. 

CH2OH 

HOCH 

HCOH 
HOCH 
CHO 

Occurrence.  —  Ordinary,  or  1-xylose  has  not  been  found  free  in 
nature  except  perhaps  in  rare  cases  in  the  urine.  The  parent  substances, 

*  Ber.,  33,  2142. 


THE   MONOSACCHARIDES  553 

from  which  1-xylose  may  be  derived  by  hydrolysis,  are,  however,  among 
the  most  widely  distributed  substances  in  the  vegetable  world.  Chief 
of  these  parent  substances  is  the  pentosan  xylan  (CsHgOJn  or  wood 
gum,  which  occurs  as  a  constituent  of  the  incrusting  or  hemicellular 
materials  which  are  found  in  nearly  all  vegetable  cells.  Xylan  with  a 
little  araban  makes  up  from  25  to  30  per  cent  of  the  dry  matter  of 
cereal  straws  and  grasses,  about  15  to  25  per  cent  of  the  dry  matter  of 
the  wood  of  deciduous  trees  and  from  5  to  15  per  cent  of  the  dry 
matter  of  the  wood  of  coniferous  trees.  It  is  also  found  in  large 
quantities  in  bark,  roots,  bran  of  seeds  and  grains,  mosses,  fungi  and 
associated  with  araban  as  a  constituent  of  many  vegetable  gums. 
Xylan  is,  next  to  cellulose,  the  most  abundant  of  plant  constituents. 

Preparation  of  Xylan.  —  One  of  the  best  sources  for  preparing 
xylan  is  beech-wood  sawdust,  although  maize  stalks,  straw  and  other 
plant  materials  may  be  used.  According  to  the  method  of  Wheeler 
and  Tollens*  1  kg.  of  fine  beech-wood  sawdust  is  first  treated  in  the 
cold  for  24  hours  with  1  to  2  per  cent  ammonia  to  dissolve  albuminoids, 
etc. ;  the  ammoniacal  solution  is  then  pressed  out  and  the  process  re- 
peated for  a  second  or  third  time.  The  material  after  washing  with 
water  is  then  treated  in  a  warm  place  with  5  per  cent  sodium  hydroxide 
solution,  the  latter  being  added  in  sufficient  quantity  to  form  a  thick 
mush.  After  24  hours  the  extract  is  pressed  out  and  the  digestion  re- 
peated for  another  24  hours  using  less  sodium  hydroxide  solution.  The 
extracts  are  mixed  and  allowed  to  stand  in  a  flask  for  deposition  of  sus- 
pended impurities.  The  clear  brown  colored  solution  is  then  siphoned 
off  and  mixed  with  an  equal  volume  of  96  per  cent  alcohol  which  pre- 
cipitates the  xylan  as  a  sodium-gum  compound.  The  latter  is  filtered 
off  upon  cloth,  washed  with  alcohol  till  the  washings  are  colorless  and 
then  treated  in  presence  of  alcohol  with  hydrochloric  or  acetic  acid 
until  the  reaction  is  slightly  acid.  The  free  xylan,  which  is  thus  lib- 
erated, is  washed  first  with  alcohol  upon  cloth,  or  parchmentized  paper, 
using  suction,  until  all  acid  is  removed,  then  washed  with  a  little  ether, 
and  finally  dried  over  concentrated  sulphuric  acid.  The  product  thus 
prepared  consists  of  a  grayish  white  amorphous  powder,  which  is  almost 
insoluble  in  water.  In  alkaline  solution  it  is  levorotatory,  [O\D  =  —  70 
to  —  90  according  to  the  purity  and  origin  of  the  gum.  Xylan  upon 
heating  with  dilute  hydrochloric  or  sulphuric  acid  is  quickly  hydrolyzed 
to  1-xylose. 

(C5H804)n  +  n  H20  =  n  C5Hi005. 

Xylan  l-Xylose 

*  Z.  Ver.  Deut.  Zuckerind.,  39,  848,  863. 


554  SUGAR  ANALYSIS 

The  Xylo-proteids. — 1-Xylose  has  also  been  found  widely  distributed 
in  the  animal  world  as  a  constituent  of  many  nucleo-proteids.  The 
latter  are  complex  compounds  of  variable  composition  and  are  resolved 
by  hydrolysis  into  a  mixture  of  substances,  among  which  the  nitrog- 
enous bases  (adenine,  guanine,  xanthine  and  hypoxanthine),  phosphoric 
acid  and  various  sugars  have  been  identified.  1-Xylose  seems  to  be 
the  most  abundant  of  the  sugars  entering  into  the  composition  of 
the  nucleo-proteids  although  other  pentose  and  hexose  sugars  have 
been  identified.  The  amount  of  pentose  sugar  in  different  organs  has 
been  found  by  Grund  *  to  be  0.021  per  cent  in  muscle,  0.090  per  cent 
in  the  brain,  0.081  per  cent  in  the  spleen,  0.084  per  cent  in  the  kidney, 
0.110  per  cent  in  the  liver,  and  0.447  per  cent  in  the  pancreas;  it  is 
especially  in  the  pancreas  that  the  occurrence  of  1-xylose  in  the  animal 
body  is  localized.  The  origin  of  1-xylose  in  the  animal  organism  is  not 
absolutely  known  although  Neuberg  and  Salkowski  f  regard  d-glu- 
curonic  acid  as  the  parent  substance  from  which  it  is  derived.  The 
nucleo-proteids  are  also  widely  distributed  in  the  vegetable  kingdom 
and  give  the  same  products  upon  hydrolysis. 

Preparation  of  1-Xylose. — 1-Xylose  may  be  prepared  by  hydrolysis 
of  xylan  obtained  as  described  above  or  by  direct  hydrolysis  of  plant 
materials.  Xylan  may  be  hydrolyzed  with  sulphuric  acid  in  the  same 
way  as  described  for  cherry  gum  or  with  hydrochloric  acid  according 
to  Councler's  {  method.  For  the  latter  process  15  gms.  of  xylan  are 
heated  on  the  water  bath  with  200  c.c.  water  and  70  c.c.  hydrochloric 
acid  (1.19  sp.  gr.)  for  3  hours.  The  solution  is  then  treated  with  pure 
lead  carbonate,  until  Congo-red  test  paper  shows  no  free  acid,  and 
filtered.  The  filtrate  is  evaporated  to  a  thin  sirup  in  presence  of  a 
little  lead  carbonate  and  then  treated  with  strong  alcohol  to  precipi- 
tate gums,  lead  chloride  and  other  impurities.  The  alcohol  solution 
is  treated  with  hydrogen  sulphide  to  precipitate  any  remaining  lead, 
filtered  and  evaporated  to  a  sirup  in  presence  of  a  little  calcium  car- 
bonate. The  bright  straw-colored  sirup  thus  obtained  is  set  aside  in 
a  cool  place  when  crystallization  of  xylose  will  proceed  rapidly.  The 
crystals  are  purified  by  recrystallizing  from  alcohol  using  a  little  animal 
charcoal. 

1-Xylose  can  also  be  prepared  directly  from  wheat  straw,  maize 
stalks,  etc.,  by  the  process  of  Schulze  and  Tollens.§  The  material  is 
first  purified  by  digesting  with  2  per  cent  ammonia  and  water  (as  de- 
scribed under  preparation  of  xylan),  and  then,  after  pressing  as  dry  as 

*  Z.  physiol.  Chem.,  36,  111.  J  Chem.  Ztg.  (1892),  1719. 

t  Z.  physiol.  Chem.,  36,  261;  37,  464.  §  Ann.,  271,  40. 


THE  MONOSACCHARIDES  555 

possible,  heated  on  the  water  bath  4  hours  with  2  to  3  per  cent  sul- 
phuric acid.  The  acid  extract  is  pressed  out,  neutralized  with  pow- 
dered calcium  carbonate,  filtered  and  evaporated  (as  described  under 
preparation  of  1-arabinose)  to  a  sirup.  The  latter,  after  shaking  out 
several  times  with  hot  96  per  cent  alcohol  to  precipitate  gums,  yields 
upon  evaporation  3  to  5  per  cent  of  the  weight  of  straw  in  crystallized 
xylose. 

Properties  of  1-Xylose.  — 1-Xylose  crystallizes  in  white  needles  of 
a  sweetish  taste,  which  are  easily  soluble  in  water  and  hot  alcohol,  but 
insoluble  in  ether.  The  sugar  melts  at  about  145°  C.,  although  differ- 
ent authorities  vary  10°  C.  above  or  below  this  figure  owing  no  doubt 
to  variations  in  method.  1-Xylose  shows  stronger  mutarotation  than 
any  other  sugar;  [a]n  5  minutes  after  solution  =  +  85.68  (Wheeler  andv 
Tollens  *) ;  [a]o  constant  =  +  18.5.  The  sugar  is  not  fermented  by 
yeast;  many  bacteria  and  moulds,  however,  are  able  to  produce  de- 
structive changes  with  formation  of  lactic,  succinic,  acetic  and  1-xylonic 
acids. 

Tests.  —  1-Xylose  gives  all  the  general  reactions  described  for  re- 
ducing sugars  and  the  furfural  and  other  special  reactions  described 
for  the  pentoses.  One  of  the  best  methods  for  detecting  xylose  in 
presence  of  other  sugars  is  Bertrand's  f  reaction  by  means  of  bromine 
and  cadmium  carbonate.  The  bromine  oxidizes  the  xylose  to  xylonic 
acid  according  to  the  following  reaction: 

CH2OH  CH2OH 

(CHOH)3  +  H2O  +  Br2  =  (CHOH)3  +  2  HBr 

CHO  COOH 

Xylose  Xylonic  acid  Hydrobromic  acid 

The  xylonic  and  hydrobromic  acid  react  with  the  cadmium  carbonate 
forming  cadmium  xylonate  and  bromide,  the  solution  of  which  on 
evaporation  deposits  characteristic  boat-shaped  crystals  of  the  double 
bromide  and  xylonate  of  cadmium  (C5H9O6)2Cd  +  CdBr2  +  2  H2O.  The 
salt  can  be  purified  by  recrystallizing  and  should  show  upon  analysis 
29.86  per  cent  Cd  and  21.32  per  cent  Br. 

Bertrand's  reaction,  according  to  Tollens  and  Widtsoe,t  is  carried 
out  as  follows.  For  each  0.2  gm.  sugar  or  double  the  amount  of  sirup 
to  be  tested,  1  c.c.  of  water,  0.25  gm.  bromine  (7  to  8  drops)  and  0.5  gm. 
cadmium  carbonate  are  mixed  together  in  a  test  tube  with  gentle  warming 

*  Ber.,  22,  1046. 

t  Bull.  soc.  chim.,  [3],*  6,  546. 

J  Ber.,  33,  132. 


556  SUGAR  ANALYSIS 

and  then,  after  corking  loosely,  set  aside  for  24  hours.  The  solution  is 
then  evaporated  in  a  dish  almost  to  dryness,  taken  up  with  a  little  water, 
filtered  and  again  evaporated  almost  to  dryness.  If  xylose  is  present 
addition  of  a  little  alcohol  will  soon  cause  crystals  of  the  double  cad- 
mium salt  to  deposit.  Presence  of  impurities  may  delay  the  crystalliza- 
tion somewhat.  Too  much  bromine  must  be  avoided  in  making  the  test, 
and  an  excess  of  cadmium  carbonate  must  always  be  present.  The  first 
crop  of  crystals  frequently  appear  amorphous,  but  the  characteristic 
boat-shaped  needles  are  always  obtained  upon  recrystallizing. 

A  second  method  which  has  been  employed  for  the  detection  of 
1-xylose  in  impure  mixtures  is  by  means  of  the  diformal  *  compound, 
which  separates  in  crystalline  form  upon  boiling  xylose  solutions  with 
^paraformaldehyde  (trioxy methyl ene).  1-Xylose-diformal  has  the  for- 
mula C5H605(CH2)2  and  consists  of  white  crystals  melting  at  56°  C.;  it 
can  be  sublimed  without  decomposition  and  shows  in  methyl  alcohol 
H>=+25.7. 

1-Xylose  upon  reduction  with  sodium  amalgam  is  converted  into  the 
optically  inactive  pentite  alcohol,  xylite.  Oxidation  with  bromine  gives 
1-xylonic  acid  and  with  nitric  acid  inactive  xylotrioxyglutaric  acid. 
1-Xylose  has  been  synthetized  from  1-gulonic  acid  by  Fischer  and  Ruff  f 
employing  the  same  method  described  for  d-xylose. 

d,  1-Xylose.  —  Racemic  xylose  has  been  prepared  by  Fischer  and 
Rufft  by  crystallizing  a  mixture  of  equal  parts  of  d-  and  1-xylose 
out  of  96  per  cent  alcohol.  The  sugar  consists  of  small  prismatic 
crystals  melting  at  129°  to  131°  C.  Its  phenylosazone  melts  at 
210°  to  215°  C.,  whereas  the  phenylosazone  of  1-xylose  melts  at  only 
160°  C. 

d,  1-Xylose  is  also  formed  by  the  oxidation  of  inactive  xylite  by 
means  of  bromine. 

CH2OH        CHO      CH2OH 
HOCH         HOCH     HOCH 
2  HCOH  +  02  =  HCOH   +  HCOH   +  2  HZ0 
HOCH         HOCH     HOCH 
CH2OH         CH2OH     CHO 

Xylite  d-Xylose  1-Xylose 

*  Lobry  de  Bruyn  and  van  Ekenstein,  Rec.  trav.  Pays-  Has,  22,  159. 
t  Ber.,  33,  2142. 
t  Ber.,  33,  2145. 


THE  MONOSACCHARIDES  557 

d-1  Xylose  has  not  been  resolved  as  yet  into  its  optically  active 
components. 

d-Lyxose.  — 

CH2OH 

HOCH 


C 


HCOH 


HC< 


d-Lyxose  has  not  been  identified  with  certainty  in  any  natural  product, 
although  Haiser  and  Wenzel*  believe  to  have  obtained  it  in  the 
hydrolysis  of  inosinic  acid  (a  nucleic  acid  found  in  meat  extract).  The 
sugar  has  been  made  synthetically  in  a  variety  of  ways;  by  reduction 
of  d-lyxonic  lactone,  by  degradation  of  d-galactonic  nitrile  (Wohl'sf 
method)  and  by  oxidation  of  calcium  d-galactonate  by  hydrogen  per- 
oxide in  presence  of  ferric  acetate  (Ruffst  method). 


C02  +  H20 


CH2OH 

HOCH 

HCOH 

1            +° 
HCOH 

HOCH 

CH2OH 
HOCH 
=     HCOH 

HCOH 
T 

T 

CHO 

COOH 

d-Galactonic  acid 

d-Lyxose 

The  configuration  of  d-lyxose  is  established  by  this  reaction. 

Properties.  —  d-Lyxose  consists  of  large  monoclinic  crystals  melt- 
ing at  101°  C.;  the  sugar  is  sweet,  strongly  hygroscopic  and  readily 
soluble  in  water  and  alcohol.  [a]D  constant  =  —  13.&:  (4  minutes  after 
solution  [a]D  =  —  3.1).  d-Lyxose  is  not  fermented  by  yeast. 

Tests.  —  d-Lyxose  gives  the  general  reactions  of  reducing  sugars 
and  the  furfural  and  other  special  reactions  described  for  the  pentoses. 
Oxidation  with  bromine  gives  d-lyxonic  acid  ([a]D  of  lactone  =  +82.4), 
which,  by  heating  with  pyridine  to  135°  C.,  is  partially  changed  to 
1-xylonic  acid  (see  p.  775).  Reduction  of  d-lyxose  with  sodium  amal- 
gam gives  a  pentite  alcohol  which  is  identical  with  d-arabite. 

*  Monatshefte,  30,  377;  see,  however,  under  d-ribose,  the  contrary  opinion  of 
Levene  and  Jacobs. 
t  Ber.,  30,  3105. 
t  Ber.,  32,  552;  33,  1798. 


558 


SUGAR  ANALYSIS 


1-Lyxose  and  d,  1-lyxose  have  not  as  yet  been  prepared. 

d-Ribose.  — 

CH2OH 

HOCH 
HOCH 
HOCH 
CHO 

This  sugar  is  regarded  by  Levene  and  Jacobs  *  as  a  constituent  of  many 
nucleic  acids  in  the  animal  and  vegetable  kingdom.  Inosinic  acid 
according  to  these  authorities  has  the  configuration. 

N-C-N 

OH  CH 

/  H    H    H    H 

O  =  P-O-CH2-C-C-C-C  -  N-C-CH 


\ 


OH 


Phosphoric 
acid  radical 


d-Ribose 
radical 


OC-NH 

Hypoxanthine 
radical 


Hydrolysis  of  the  above  at  nearly  neutral  point  produces  free  phos- 
phoric acid  and  the  d-ribose-hypoxanthine  base;  the  latter  upon 
further  hydrolysis  is  decomposed  into  free  d-ribose  and  free  hypoxan- 
thine.  Levene  and  Jacobs  f  have  also  obtained  d-ribose  from  guanylic 
acid  and  yeast  nucleic  acid. 

Properties.  —  d-Ribose  as  prepared  by  Levene  and  Jacobs  forms 
colorless  crystals  melting  at  85°  C.  and  giving  [«]£  =-19.25°.  The 
bromophenylhydrazone  forms  white  needles  melting  at  170°  C. 

1-Ribose.  — 

CH2OH 

HCOH 

HCOH 

HCOH 

CHO 

This  sugar  has  not  been  found  as  yet  in  any  natural  product;  it 
has  been  prepared  J  synthetically  by  reducing  the  lactone  of  1-ribonic 

*  J.  Am.  Chem.  Soc.,  32,  231;    Ber.,  42,  1198.    This  view  of  Levene  and 
Jacobs  is  contested,  however,  by  Neuberg,  Ber.,  42,  2806. 
t  Ber.,  42,  2474. 
j  Fischer  and  Piloty,  Ber.,  24,  4214. 


THE  MONOSACCHARIDES  559 

acid  which  can  be  prepared  from  1-arabonic  acid  by  heating  with 
pyridine  (p.  775).  From  the  sirupy  mixture  obtained  by  this  reduction 
1-ribose  can  be  precipitated  as  the  phenylhydrazone  or  bromophenyl- 
hydrazone.  By  decomposition  of  the  latter  with  benzaldehyde  van 
Ekenstein  and  Blanksma*  were  able  to  isolate  the  sugar  in  the  pure 
crystalline  form. 

Properties.  —  1-Ribose  consists  of  white  needles  melting  at  87°  C., 
easily  soluble  in  water  and  alcohol,  and  showing  in  aqueous  solution 
[a]D  =+18.8  (c  =  1.5,  no  mutarotation  observable  at  this  dilution). 

Tests.  —  1-Ribose  gives  the  ordinary  reactions  of  the  pentose  sugars. 
Reduction  with  sodium  amalgam  gives  the  inactive  pentite  alcohol 
adonite,  which  has  been  found  in  nature  in  the  juice  of  the  plant  Adonis 
vernalis.]  Oxidation  of  1-ribose  with  bromine  gives  1-ribonic  acid  ([a]D 
1-ribonic  lactone  =  — 18.0)  and  with  nitric  acid  inactive  ribotrioxy- 
glutaric  acid. 

The  most  characteristic  hydrazine  derivative  is  1-ribose-bromo- 
phenylhydrazone  which  consists  of  colorless  crystals  melting  at  164°  to 
165°  C. 

1-Ribose-phenylosazone  is  identical  with  that  of  1-arabinose,  as  fol- 
lows from  their  configuration. 

d,  1-Ribose.  —  Racemic  ribose  is  formed  by  the  oxidation  of 
natural  adonite  by  means  of  bromine. 

CH2OH        CHO     CH2OH 

HCOH        HCOH    HCOH 
2  HCOH  +  02  =  HCOH   +  HCOH  +  2  H2O 
HCOH        HCOH    HCOH 
CH2OH       CH2OH    CHO 

Adonite  d-Ribose  1-Ribose 


The  sugar  is  also  formed  by  molecular  rearrangement  from  d,  1- 
arabinose  by  means  of  dilute  alkalies. 

d,  1-Ribose  has  not  as  yet  been  resolved  into  its  optically  active 
constituents. 

Pentose  Sugars  of  Unknown  Character  and  Constitution.  —  In 
addition  to  the  pentose  sugars  just  described  different  investigators 
have  reported  from  time  to  time  a  number  of  other  pentose  sugars,  the 

*  Chem.  Centralbl.  (1908),  II,  1584;   (1909),  II,  14. 
t  Podwyssotzki,  Archiv  Pharm.  (1889),  141. 


560  SUGAR  ANALYSIS 

isolation  and  identification  of  which  still  remain  a  matter  of  doubt. 
Among  such  pentoses*  may  be  mentioned: 

Cerasinose,  found  by  Martin  in  the  hydrolytic  products  of  cherry 

gum. 

Prunose,  found  by  Garros  in  the  hydrolytic  products  of  plum  gum. 
Traganthose,  found  by  O'Sullivan  in  the  hydrolytic  products  of 

gum  tragacanth. 
Cyclamose,  found  by  Michaud  in  the  hydrolytic  products  of  cyclamen 

bulbs. 

It  can  be  shown  upon  purely  theoretical  grounds  that  no  other  aldo- 
pentose  sugars  can  exist  than  the  eight  forms  already  described,  viz., 
d-  and  1-arabinose,  d-  and  1-xylose,  d-  and  1-lyxose  and  d-  and  1-ribose. 
This  may  be  seen  from  the  following  classification: 

d-arabinose  d-xylose  d-lyxose  d-ribose 

CH2OH  CH2OH  CH2OH  CH2OH 

HOCH  HCOH  frOCH  HOCH 

HOCH  HOCH  HCOH  HOCH 

HCOH  HCOH  HCOH  HOCH 

CHO  CHO  CHO  CHO 

l-arabinose  l-xylose  l-lyxose  l-ribose 

CH2OH  CH2OH  CH2OH  CH2OH 

HCOH  HOCH           HCOH  HCOH 

HCOH  HCOH  HOCH  HCOH 

HOCH  HOCH  HOCH  HCOH 

CHO  CHO           CHO  CHO 

The  possibilities  of  stereo-isomerism  in  the  aldopentoses  are  ex- 
hausted by  the  above  eight  forms,  and  the  existence  of  new  undiscovered 
sugars  in  this  class  is,  therefore,  precluded.  The  sugars  of  unknown 
character  just  mentioned  either  belong  to  some  one  of  the  known  pen- 
toses or  else  fall  in  another  class. 

KETOPENTOSES 

None  of  the  ketose  sugars  belonging  to  the  pentose  group  has  as  yet 
been  isolated  although  several  of  them  have  been  prepared  in  an  im- 
pure form.  The  number  of  normal  ketopentose  sugars  theoretically 

*  See  Lippmann's  "  Chemie  der  Zuckerarten,"  p.  154,  for  a  fuller  account  of 
these  doubtful  sugars. 


THE  MONOSACCHARIDES  561 

possible  is  only  four;  in  the  ketose  class  the  HCOH  group  adjoining  the 
aldehyde  CHO  is  replaced  by  a  ketone  CO  group,  while  the  CHO  is 
itself  replaced  by  a  CH2OH  group.  It  can  be  seen,  therefore,  from 
the  preceding  classification  that  d-araboketose  is  the  ketone  derivative 
of  d-arabinose  and  d-ribose;  1-araboketose  is  the  ketone  derivative 
of  1-arabinose  and  1-ribose;  d-xyloketose  is  the  ketone  derivative  of 
d-xylose  and  1-lyxose;  1-xyloketose  is  the  ketone  derivative  of  1-xylose 
and  d-lyxose. 

d-Arabbketose.  — 

CH2OH 

HOCH 
HOCH 

U 

CH2OH 

This  sugar  has  been  detected  together  with  d-arabinose  in  the 
urine  of  rabbits  fed  upon  d-arabite.*  It  has  also  been  prepared  syn- 
thetically by  oxidation  of  d-arabite  f  with  hydrogen  peroxide  in  presence 
of  ferrous  sulphate. 

Tests.  —  d-Araboketose  gives  not  only  the  furfural  reaction  of  the 
pentoses  but  also  the  reactions  characteristic  of  the  ketoses.  It 
forms  an  osazone  with  methylphenylhydrazine,  melting  at  173°  C., 
thus  differing  from  the  aldose  d-arabinose.  With  phenylhydrazine  it 
forms  an  osazone  which  is  identical  with  those  of  d-arabinose  and  d- 
ribose  (as  is  necessary  from  their  configuration). 

1-Araboketose.  — 

CH2OH 


HC( 


COH 
C  =  0 


H 


This  sugar  has  been  detected  by  Neuberg  t  in  the  oxidation  products 
of  1-arabite. 

Tests.  —  1-Araboketose  gives  the  furfural  reaction  of  the  pentoses 
and  the  resorcin  and  other  reactions  characteristic  of  the  ketoses.  Its 
phenylosazone  is  identical  with  those  of  1-arabinose  and  1-ribose  (as  is 
necessary  from  their  configuration). 

*  Neuberg  and  Wohlgemuth,  Ber.,  34,  1745.         t  Neuberg,  Ber.,  35,  962. 
J  Z.  physiol.  Chem.,  31,  564. 


562  SUGAR  ANALYSIS 

d,  1-Xyloketose.  - 


CH2OH 

CH2OH 

HCOH 

HOCH 

HOCH 

HCOH 

C=0 

cU 

CH2OH 

CH2OH 

d-Xyloketose 

l-Xyloketose 

This  sugar  has  been  prepared  in  an  impure  condition  by  Neuberg  * 
in  the  oxidation  of  xylite  by  means  of  lead  peroxide  (Pb02). 

Tests.  —  d,  1-Xyloketose  gives  the  ordinary  reactions  of  a  keto- 
pentose.  Its  methylphenylosazone  (typical  ketose  reaction)  forms 
yellow  needles  melting  at  173°  C.  Its  phenylosazone  is  identical  with 
those  of  d,  1-xylose  and  d,  1-lyxose  (as  follows  from  their  configuration). 

Several  ketopentoses  are  described  in  the  literature  under  what  is 
apparently  a  wrong  designation. 

Bertrand  t  by  the  action  of  Bacterium  xylinum  upon  1-arabite 
obtained  a  ketose  sugar  which  has  been  termed  1-araboketose.  The 
oxidation  of  1-arabite  by  Bacterium  xylinum  must  proceed,  as  is  shown 

on  p.  771,  as  follows: 

CH2OH  CH2OH 

HCOH          CO 
HCOH   +  O  =  HCOH   +  H20 
HOCH        HOCH 
CH2OH        CH2OH 

l-Arabite  d-Xyloketose 

To  produce  1-araboketose  oxidation  would  have  to  take^  place  in  a 
position  not  open  to  attack  by  Bacterium  xylinum. 

Neuberg  J  by  oxidation  of  adonite  with  lead  peroxide  obtained  a 
ketopentose  which  has   been   designated   d,l-riboketose.     The   oxida- 
tion of  adonite  to  form  a  d,  1-ketose  must  proceed  as  follows: 
CH2OH  CH2OH         CH2OH 

HCOH         CO     HCOH 
2  HCOH   +  O2  =  HCOH   +  HCOH   +  2  H2O 
HCOH        HCOH      CO 
CH2OH        CH2OH    CH2OH 

Adonite  d-Arabo-  1-Arabo- 

ketose  ketose 

*  Ber.,  36,  2628.  f  Compt.  rend.,  126,  762.  J  Ber.,  36,  2629. 


THE   MONOSACCHARIDES  563 

A  riboketose  must  from  its  configuration  necessarily  fall  in  the 
araboketose  class. 

METHYLPENTOSES 


RHAMNOSE.  —  Isodulcite.     Rhamnodulcite. 

CH3 

CHOH 
HCOH 
HOCH 


HOCH 
C 


HO 

Occurrence.  —  This  sugar  occurs  widely  distributed  in  nature  as  a 
component  of  many  vegetable  glucosides.  The  latter  are  condensation 
products  of  sugars  with  alcohols,  aldehydes,  phenols,  acids,  oils,  resins, 
alkaloids  and  other  substances;  the  glucosides  are  hydrolyzed  by  acids, 
and  also  in  most  cases  by  specific  enzymes,  with  liberation  of  the 
sugar  and  other  constituents  of  the  glucoside  molecule.  The  follow- 
ing glucosides  are  named  out  of  a  large  number  -which  yield  rhamnose 
upon  hydrolysis: 

Quercitrin*  a  dyestuff  obtained  from  the  bark  of  Quercus  citrina. 
The  rhamnose,  or  isodulcite,  sold  on  the  market  is  nearly  all  made 
from  this  source. 

C2l!l220i2     +      H2O       =       CeH^Os  *  H20        -f-      CisHioOy. 

Quercitrin  Rhamnose  hydrate  Quercetin. 

Frangulin^  a  dyestuff  from  the  bark  of  Rhamnus  frangula. 
C2iH2009      +      2H2O    =    C6H1205-H2O    +    Ci6HiqO5. 

Frangulin  Rhamnose  hydrate  Emodin. 

In  many  cases  a  second  sugar  is  associated  with  rhamnose  as  a  con- 
stituent of  the  glucoside,  as 

Sophorin,^  a  glucoside  from  Chinese  yellow  berries. 
C27H30016    +  3H20  =    C6H1205-H20   +   C6H1206    +    C15H10O7. 

Sophorin  Rhamnose  hydrate  d-Glucose  Sophoretin. 

Hesperidin,§  a  glucoside  found  in  many  plants  of  the  Aurantiacece. 


27    +    3H20    = 

Hesperidin  Rhamnose  hydrate  d-Glucose  Hesperetin. 

In  the  case  of  glucosides  which  are  hydrolyzed  into  several  sugars,  the 
latter  probably  exist  in  the  original  compound  as  a  higher  saccharide; 

*  Rigaud,  Ann.,  90,  283.  J  Forster,  Ber.,  16,  215. 

t  Schwabe,  Chem.  Ztg.,  12,  229.  §  Will,  Ber.,  20,  1186. 


564  SUGAR  ANALYSIS 

in  several  cases  this  higher  saccharide  has  in  fact  been  isolated.  Thus 
xanthorhamnin,  C34H42O2o,  a  glucoside  obtained  from  Rhamnus  sagrada 
and  other  plants,  when  hydrolyzed  by  the  enzyme  rhamninase,  gives  a 
crystalline  trisaccharide  sugar  rhamninose;*  the  latter  upon  heating 
with  dilute  acids  is  hydrolyzed  into  2  molecules  of  rhamnose  and  1  mole- 
cule of  galactose  (see  page  731). 

C18H32014     +      4H20      =      2C6H1205-H20  .  +     C6H1206. 

Rhamninose  Rhamnose  hydrate  d-Galactose 

Preparation.  —  The  best  material  for  the  preparation  of  rhamnose 
is  the  commercial  quercitrin  or  xanthorhamnin.  The  material  is  hydro- 
lyzed with  dilute  sulphuric  acid  in  the  same  manner  as  described  for 
1-xylose  and  1-arabinose.  The  acid  solution  is  then  neutralized  by  means 
of  barium  carbonate  and  the  filtrate  evaporated  to  a  sirup  under  dimin- 
ished pressure.  The  sirup  thus  obtained  will  deposit  crystals  of  rham- 
nose hydrate;  the  yield  may  be  increased  by  precipitating  gums  and 
other  impurities  from  the  sirup  by  means  of  alcohol.  The  sugar  is 
purified  by  recrystallization. 

Properties. — Rhamnose  exists  in  two  forms;  as  rhamnose  hydrate 
C6Hi2O5  •  H2O  and  as  rhamnose  anhydride  CeH^Os. 

Rhamnose  Hydrate.  —  The  common  crystalline  form  of  rhamnose 
consists  of  large  beautiful  crystals  having  a  sweetish  taste  but  leaving 
an  after-sensation  of  bitterness.  The  melting  point  of  this  form  of 
rhamnose  is  given  by  different  observers  from  70°  C.  to  110°  C,  a  cir- 
cumstance due  to  the  disturbances  produced  by  the  evolution  of  the 
water  of  crystallization.  The  constant  specific  rotation  of  rhamnose 
hydrate  is  [a]^  =+8.5;  the  value  decreasing  somewhat  with  increase 
in  temperature  (see  p.  179).  The  [a]|j  2  minutes  after  solution  is 
—  5°;  this  value  diminishes  and  after  about  10  minutes  [a]D=  0;  the 
rotation  then  becomes  dextrorotatory  attaining  the  constant  value 
+8.5  in  about  one  hour. 

Rhamnose  Anhydride. — Rhamnose  hydrate  begins  to  give  up  its  water 
of  crystallization  at  70°  C. ;  the  water  is  completely  removed  by  drying 
the  sugar  in  a  thin  layer  at  100°  to  105°  C.,  when  rhamnose  anhydride 
is  obtained  as  an  amorphous  vitreous  mass.  By  pulverizing  the  latter 
and  dissolving  it  in  hot  water-free  acetone,  Fischer  f  obtained  the  anhy- 
dride in  the  form  of  white  needles  melting  at  122°  to  126°  C.  The  con- 
stant specific  rotation  of  rhamnose  anhydride  is  [a]*J  =+9.4,  which 
corresponds  to  the  [<x]|j  of  the  hydrate  corrected  for  its  water  of  crys- 
tallization. The  value  for  [a]D  of  rhamnose  anhydride  one  minute  aftei 
solution  is  +31.5  (Fischer  J). 

*  Tanret,  Compt.  rend.,  129,  752.      f  Fischer,  Ber.,  28,  1162.      J  Ber.,  29,  325. 


THE   MONOSACCHARIDES  565 

A  peculiarity  observed  in  the  case  of  rhamnose  is  that  its  alcoholic 
solution  is  levorotatory;  [a]D  constant  in  ethyl  alcohol  =  —9.0. 

Tanret  *  has  explained  the  peculiar  mutarotation  of  rhamnose  hy- 
drate and  anhydride  by  the  existence  of  several  isomeric  forms. 

Rhamnose  is  not  fermented  by  yeast;  certain  bacteria,  however, 
bring  about  destructive  changes  with  production  of  acetic,  lactic  and 
other  acids. 

Tests.  —  Rhamnose  reduces  Fehling's  solution  and  gives  all  the 
other  general  reactions  characteristic  of  the  reducing  sugars.  It  also 
gives  the  group  reactions  of  the  methylpentoses,  giving  methylfur- 
fural  upon  distillation  with  hydrochloric  acid.  Reduction  of  rhamnose 
with  sodium  amalgam  produces  the  methylpentite  rhamnite,  C6Hi405, 
for  which  [a]D=  -f  10.7.  Oxidation  of  rhamnose  with  bromine  produces 
rhamnonic  acid,  whose  lactone,  C6Hi005,  shows  [a]D  of  about  —39. 

FUCOSE.  — 

CH3 

CHOH 
HOCH 
HOCH 


HC( 


,'OH  © 

CHO 

Occurrence.  —  Fucose  has  not  been  found  free  in  nature,  but  its 
mother  substance,  a  methylpentosan  (fucosan),  is  widely  distributed 
in  the  vegetable  kingdom. 

Fucosan  has  been  found  by  Tollens  and  Widtsoe  f  in  seaweed  (vari- 
eties of  Fucus,  whence  the  name  fucose),  Irish  moss,  many  vegetable 
gums  and  other  plant  materials.  It  has  also  been  found  by  Tollens 
and  Oshima  %  in  "Nori,"  a  Japanese  food  product  prepared  from  the 
purple  laver  (Porphyra  laciniata),  and  seems  to  be  almost  universally 
distributed  as  a  constituent  of  the  marine  algae.  Fucosan  upon  hy- 
drolysis with  dilute  acids  is  converted  into  fucose 

(CH3  -  C5H704)n  +  n  H2O  =  n  CH3  •  C5H905. 

Fucosan  Fucose 

Preparation.  —  Fucose  is  best  prepared  according  to  the  method  of 
Tollens.  §  One  kilo  of  dried  seaweed  (washed  as  free  as  possible  from 
sand,  etc.)  is  cut  into  fine  pieces  and  then  treated  in  the  cold  for  24  hours 
with  2  per  cent  sulphuric  acid  in  order  to  dissolve  mineral  salts  and 
other  impurities.  The  seaweed  is  then  pressed,  washed  several  times 
with  cold  water  and  then  hydrolyzed  with  6  liters  of  5  per  cent  sulphuric 
*  Compt.  rend.,  122,  86.  t  Ber.,  33,  132.  %  Ber.,  34,  1422.  §  Ber.,  33,  132. 


566  SUGAR  ANALYSIS 

acid  for  8  hours  in  a  boiling-water  bath.  The  hot  acid  extract  is  then 
pressed  out,  neutralized  with  calcium  carbonate  and  filtered.  The 
filtrate  is  then  evaporated  to  a  sirup  in  presence  of  a  little  calcium 
carbonate.  The  sirup  is  purified  by  precipitating  gums,  etc.,  with 
alcohol  and  the  alcoholic  solution  evaporated  to  a  second  sirup.  The 
process  of  purification  by  means  of  strong  alcohol  is  again  repeated; 
the  final  sirup  obtained  from  these  purifications  is  then  treated  in  the 
cold  with  phenylhydrazine.  After  24  hours  the  fucose-phenyl'hydra- 
zone,  which  has  crystallized  out,  is  filtered  off,  and  recrystallized 
from  dilute  alcohol.  The  final  product  should  be  nearly  white  and 
should  melt  at  about  170°  C. 

The  fucose-hydrazone  is  then  decomposed  with  benzaldehyde  (p.  348) 
by  heating  5  parts  hydrazone,  5  parts  benzaldehyde,  5  parts  alcohol  and 
4  parts  water  for  one-half  to  1  hour  upon  the  water  bath  in  a  flask  con- 
nected with  a  reflux  condenser.  After  cooling,  the  solution  is  filtered 
from  benzaldehyde-hydrazone,  shaken  out  with  ether,  clarified  with 
animal  charcoal  and  evaporated  to  a  sirup.  The  latter  is  set  aside  in  a 
cool  place  to  crystallize;  crystallization  can  be  hastened  greatly  by 
priming  the  sirup  with  a  minute  crystal  of  fucose  from  a  stock  prepa- 
ration. After  crystallization  is  complete  the  sugar  is  filtered  off  (or 
dried  upon  an  unglazed  plate)  and  recrystallized.  The  yield  of  fucose 
by  this  procS  is  3  to  8  grams  from  1  kg.  of  seaweed. 

Properties.  —  Fucose  consists  of  microscopic  needle-shaped  crystals 
of  an  agreeable  sweet  taste,  and  easily  soluble  in  water.  The  sugar 
shows  in  aqueous  solution  a  constant  rotation  of  about  [a]D=—75.5. 
The  rotation  immediately  after  solution  exceeds  —124. 

Tests.  —  Fucose  gives  all  the  reactions  characteristic  of  the  methyl- 
pentoses,  such  as  production  of  methylfurfural  upon  distillation  with 
hydrochloric  acid  and  the  color  and  spectral  reactions  described  on  p. 
384.  Of  its  hydrazine  derivatives  the  phenylhydrazone  melting  at 
171°  C.,  the  p-bromophenylhydrazone  melting  at  181°  to  183°  C.,  and 
the  diphenylhydrazone  melting  at  198°  C.  are  among  the  most  char- 
acteristic. Oxidation  of  fucose  with  bromine  gives  fuconic  acid, 
the  lactone  of  which,  C6HioO5,  gives  a  rotation  of  [a]D  =  +  78.3. 

RHODEOSE.  -  Cu3 


HCOH 
HCOH 
HOCH 

mo 


THE  MONOSACCHARIDES  567 

Occurrence.  —  Rhodeose,  the  antipode  of  fucose,  has  not  been  found 
free  in  nature;  it  occurs,  however,  the  same  ft  its  isomer,  rhamnose,  as 
a  constituent  of  certain  vegetable  glucosides.  The  best-known  glucoside 
in  which  rhodeose  has  been  found  is  convolvulin,*  the  purgative 
principle  of  jalap  (Convolvulus  purga).  Convolvulin  upon  hydrolysis 
yields  convolvulinic  acid  and  a  mixture  of  sugars  consisting  of  glu- 
cose, rhodeose  and  isorhodeose;  it  is  supposed  that  these  sugars  are 
united  in  the  glucoside  to  form  a  complex  saccharide. 
v  Preparation.  —  Rhodeose  is  best  prepared  from  the  commercial 
convolvulin;  50  gms.  of  convolvulin  are  dissolved  in  375  c.c.  of  barium- 
hydrate  solution  (saturated  at  room  temperature).  The  excess  of  ba- 
rium is  precipitated  by  carbon  dioxide  and  sulphuric  acid,  and  the  filtrate, 
which  should  contain  exactly  0.5  per  cent  free  sulphuric  acid,  heated 
to  100°  C.  for  40  hours.  The  filtered  solution  is  then  neutralized  with 
barium  carbonate  and  clarified  with  5  c.c.  of  saturated  lead-subacetate 
solution.  The  filtrate  is  freed  from  lead  by  means  of  hydrogen  sulphide, 
and  the  filtered  solution  evaporated  under  reduced  pressure  to  a  sirup, 
which  contains  the  sugars  in  the  proportion  of  2  parts  of  rhodeose  to  1 
part  of  glucose.  The  glucose  is  removed  from  the  sirup  by  fermentation 
with  yeast;  the  rhodeose  is  then  precipitated  by  means  of  methylphen- 
ylhydrazine  as  an  insoluble  hydrazone.  The  latter  after  recrystallizing 
is  decomposed  by  warming  several  times  with  benzaldehyde  and  the 
filtered  solution  after  shaking  out  with  ether  evaporated  to  a  sirup, 
which  is  then  set  aside  in  a  cool  place  for  crystallization.  Priming  the 
sirup  with  a  minute  crystal  of  rhodeose  from  a  previous  preparation 
will  hasten  crystallization. 

Properties.  —  Rhodeose  consists  of  small  needle-shaped  crystals 
having  a  sweet  taste  and  easily  soluble  in  water.  The  sugar  shows  in 
aqueous  solution  a  constant  rotation  of  [a]D  =  +75.5  (+86.5  after  solu- 
tion). 

Tests.  —  Rhodeose  gives  all  the  reactions  characteristic  of  the  meth- 
ylpentoses.  As  the  optical  antipode  of  fucose  it  resembles  the  latter 
in  its  behavior  with  many  reagents.  The  diphenylhydrazone  of 
rhodeose  melts  at  199°  C.  (that  of  fucose  at  198°  C.);  the  p-bromo- 
phenylhydrazone  of  rhodeose  melts  at  184°  C.  (that  of  fucose  at 
183°  C.);  the  methylphenylhydrazone  of  rhodeose  melts  at  174°  C.  (that 
of  fucose  at  177°  C.),  etc.  Upon  oxidation  with  bromine  rhodeose  gives 
rhodeonic  acid,  the  salts  of  which  have  the  same  composition  as  those  of 
fuconic  acid.  The  lactone  of  rhodeonic  acid  melts  at  105.5°  C.  (that 
of  fuconic  acid  at  106  to  107°  C.);  in  their  rotatory  power,  however,  the 
*  Taverne,  Chem.  Centralbl.  (1895),  I,  56;  Votocek,  Ber.,  37,  3859;  43,  469. 


568  SUGAR  ANALYSIS 

two  lactones  show  their  antipodal  character,  [a]D  rhodeonic  acid  lactone 
=  -76.3  (lactone  of  fuconic  acid  =  +78.3). 

Racemic  Sugar  from  Rhodeose  and  Fucose.  —  This  racemic  com- 
bination was  prepared  by  Votocek  *  by  evaporating  a  solution  contain- 
ing rhodeose  and  fucose  in  equal  amounts.  The  sugar  was  obtained  as 
minute  crystals  melting  at  161°  C.  and  optically  inactive;  it  is  much 
less  soluble  in  water  than  either  of  its  components. 

Isorhamnose.  — 

CH3 

CHOH 
HCOH 
HOCH 
HCOH 
CHO 

This  methylpentose  has  not  been  found  in  nature;  it  has  been  prepared 
synthetically  by  reduction  of  the  lactone  of  isorhamnonic  acid  (made 
by  heating  rhamnonic  acid  and  pyridine  to  150°  C.). 

Properties.  —  Isorhamnose  has  not  been  isolated  as  yet  in  the 
crystalline  form;  as  prepared  by  Fischer  and  Herborn  f  the  sugar  was 
obtained  as  a  sweet  easily  soluble  sirup  which  showed  a  value  for  [a]D 
of  about  -30. 

Tests.  —  Isorhamnose  gives  methylfurfural  upon  distillation  with 
hydrochloric  acid  and  gives  the  other  reactions  of  the  methylpentoses. 
Oxidation  with  bromine  gives  isorhamnonic  acid,  the  lactone  of  which 
shows  after  solution  [a]D  =  —  62,  which  however  sinks  in  24  hours  to 
about— 5,  owing  to  decomposition  of  the  lactone  into  free  acid.  The 
phenylosazone  of  isorhamnose  is  identical  with  that  of  rhamnose;  this 
of  course  follows  necessarily  from  the  structural  relationship  of  the  two 
sugars. 

Quinovose.  —  CH3  •  C5H905. 

Occurrence.  —  This  methylpentose  has  been  found  as  a  constituent 
of  the  glucoside  quinovin,  which  occurs  in  the  bark  of  different  varieties 
of  the  cinchona  tree. 

Preparation.  —  Quinovin  upon  hydrolysis  with  hydrochloric  acid  in 
alcoholic  solution  yields  quinovose,  which  in  presence  of  the  alcohol  and 
acid  is  converted  into  ethyl  quinovoside,  C6HnO5  •  C2H5.  This  com- 

*  Ber.,  37,  3859.  t  Ber.,  29,  1961. 


THE   MONOSACCHARIDES  569 

pound,  first  called  quinovite,  was  long  regarded  as  a  direct  product  of 
hydrolysis,  until  Fischer  and  Liebermann  *  ascertained  its  composition 
and  showed  it  to  be  the  result  of  a  secondary  reaction.  The  ethyl 
quinovoside  upon  heating  1|  hours  with  3  parts  of  5  per  cent  sulphuric 
acid  is  hydrolyzed  into  alcohol  and  quinovose.  The  solution  is  diluted 
with  1  vol.  of  water,  the  alcohol  evaporated,  the  acid  neutralized  with 
barium  carbonate  and  then,  after  decolorizing  with  bone  black,  the  liquid 
filtered.  The  filtrate  is  extracted  with  ether  to  remove  any  unhydro- 
lyzed  quinovoside  and  then  evaporated,  when  the  quinovose  is  obtained 
as  a  yellowish  sirup. 

Properties.  —  Quinovose  has  been  obtained  only  as  a  yellowish 
sirup  of  strong  dextrorotation,  easily  soluble  in  water  and  absolute 
alcohol. 

Tests.  —  Quinovose  reduces  Fehling's  solution,  and  yields  large 
amounts  of  methylfurfural  upon  distillation  with  12  per  cent  hydro- 
chloric acid.  Its  solutions  when  heated  with  phenylhydrazine  give 
quinovose-phenylosazone  which  consists  of  fine  yellow  needles  melting  at 
193°  to  194°  C.  When  heated  with  hydrochloric  acid  in  alcoholic  solu- 
tion quinovose  gives  the  ethylglucoside  previously  referred  to.  Ethyl- 
quinovoside  is  an  amorphous  hygroscopic  substance  melting  at  60°  C. 
and  when  pure  should  be  perfectly  soluble  in  ether.  The  compound 
is  dextrorotatory,  [oi]D  =  +78.1. 

Isorhodeose.  —  CH3  •  C5H905.  This  methylpentose  of  unknown 
configuration  was  found  by  Votocek  f  together  with  rhodeose  among 
the  hydrolytic  products  of  convolvulin.  The  sugar  has  been  obtained 
only  as  a  yellowish  sirup  of  low  dextrorotation  ([a]D  —  +20  about). 
Isorhodeose-phenylosazone  consists  of  fine  yellow  crystals  melting  at 

190°  C. 

i 

SUGARS    OF    UNKNOWN    CONSTITUTION,    ISOMERIC    OR    RELATED    TO    THE 

METHYLPENTOSES 

Antiarose.  —  C6Hi205.  This  sugar  was  obtained  by  Kiliani  t  in 
the  hydrolysis  of  the  glucoside  antiarin  which  is  found  in  the  sap  of  the 
upas  tree  (Antiaris  toxicaria),  the  milky  juice  of  which  is  used  by  Ma- 
layans as  an  arrow  poison.  Antiarose  has  only  been  obtained  as  a 
sirup;  it  gives  the  reactions  of  an  aldose  and,  oxidized  with  bromine, 
yields  antiaronic  acid  whose  lactone,  C6Hi005,  is  levorotatory,  [a]D  =  —  30°. 

*  Ber.,  26,  2415. 

t  Ber.,  43,  476. 

j  Archiv.  Pharm.,  234,  438. 


570  SUGAR  ANALYSIS 


Digitalose.  —  C?!^^.  This  sugar,  discovered  by  Kiliani,*  is 
supposed  to  be  a  dimethylpentose.  It  is  formed  by  the  hydrolysis  of 
the  glucoside  digitalin,  which  is  found  in  different  species  of  digitalis. 

C35H56Oi4  +  2  H20  =  CaH»p,  +  C7H1405  +  C6H12O6  +  2  H2O. 

Digitalin  Digitaligenin  Digitalose  Glucose 

Digitalose  has  been  obtained  only  as  a  sirup  and  gives  the  reactions 
of  an  aldose  sugar.  Oxidation  with  bromine  gives  digitalonic  acid 
C7Hi406,  whose  lactone  is  levorotatory  ,  [a]D  =  —  79.4. 

HEXOSES 


ALDOHEXOSES 

• 

D-GLUCOSE.  —  Dextrose.    Grape  sugar.    Starch  sugar.     Diabetic 
sugar,  etc. 


^^j 

HOC] 


CHjOH 
lL 

/V^-tl 

HOCH 

HCOH 
HOCH 


Occurrence.  —  d-Glucose  is  the  most  widely  distributed  sugar  in 
nature;  it  is  found  in  the  free  condition  in  the  blood  and  tissues  of 
most  animals,  and  in  the  juices  of  nearly  all  plants.  The  sugar  occurs 
most  abundantly,  however,  in  the  combined  form  in  such  substances 
as  the  vegetable  glucosides,  the  higher  sugars  and  the  polysaccharides. 

The  Vegetable  Glucosides.f  —  The  reactivity  of  the  glucose 
molecule  in  nature  is  best  exemplified  by  the  vegetable  glucosides,  con- 
densation products  of  glucose  with  alcohols,  acids,  aldehydes,  phenols 
and  other  compounds.  Reference  was  made  to  several  glucosides 
which  yielded  rhamnose  upon  hydrolysis  under  the  description  of  the 
latter  sugar.  The  glucosides,  which  contain  glucose  as  their  sugar  con- 
stituent, are,  however,  the  most  widely  distributed  in  nature.  It  is 
impossible  to  describe  all  of  these,  but  a  few  typical  examples  are  given. 

*  Ber.,  26,  2116;  31,  2454. 

t  For  a  full  account  of  the  various  glucosides,  their  preparation,  properties,  etc., 
see  the  section  by  Euler  and  Lundberg  in  the  Biochemisches  Handlexicon  (1911), 
Vol.  II,  pp.  578-722;  also  Armstrong's  "Simple  Carbohydrates  and  Glucosides" 
(1910)  and  Plimmer's  "  Chemical  Changes  and  Products  resulting  from  Fermenta- 
tions "  (1903). 


THE  MONOSACCHARIDES  571 

The  glucosides  are  usually  colorless  crystalline  compounds  with  a  bitter 
taste,  and  for  the  most  part  levorotatory. 

Salicin.-  —  A  glucoside  found  in  the  bark  of  the  willow  and  used  as 
a  remedy  for  rheumatism.  It  is  hydrolyzed  by  the  enzyme  emulsin  to 
glucose  and  salicyl  (o-oxybenzyl)  alcohol. 

C13H1807  +   H20    =    CflH1206   +   C6H4(OH)CH2OH. 

Salicin  Glucose  Salicyl  alcohol. 

Populin.  —  A  glucoside  found  in  the  bark  of  several  species  of 
poplar  (Populus).  It  is  hydrolyzed  as  follows: 

C20H2208  +   H20   =    C6H1206   +   C6H5COC6H3(OH)CH2OH. 

Populin  Glucose  Benzoyl-aalicyl  alcohol. 

Coniferin.  —  A  glucoside  found  in  the  fir  and  other  coniferous  trees. 
It  is  hydrolyzed  as  follows: 

C16H2208  +  H20  .=    C6H1206 

Coniferin  Glucose  Coniferyl  alcohol. 

Arbutin.  —  This  glucoside  together  with  methylarbutin  is  found  in 
the  leaves  of  the  evergreen  bearberry  (Arbutus  uva  ursi).  The  two  glu- 
cosides are  hydrolyzed  as  follows: 

C12H1607  +  H20  =  C6H1206  +  C6H4(OH)2. 

Arbutin  Glucose  Hydroquinone. 

Ci3Hi8O7+  H2O    =  CfHaOi  +  CeH4Qjj 

Methylarbutin  Glucose  Methylhydroquinone. 

Phloridzin.  —  A  glucoside  found  in  the  bark  of  the  apple,  pear  and 
other  trees  belonging  to  the  Rosaceae.  It  possesses  the  peculiar  prop- 
erty of  causing  glucosuria  when  taken  internally;  the  amount  of  glucose 
in  the  urine  may  reach  from  6  per  cent  to  as  high  as  13.5  per  cent  after 
ingestion  of  phloridzin.  It  is  hydrolyzed  by  acids  as  follows: 

C2iH24Oio  -f-  H2O  =  CBH^OG  -f-  CuHuOk* 

Phloridzin  Glucose  Phloretin. 

Gauliherin.  — -  A  glucoside  found  in  the  wintergreen.  It  is  hydro- 
lyzed by  acids  as  follows: 

Ci4H1808  +  H20  =  C6Hi206  +  C6H4OHCOOCH3. 

Gaultherin  Glucose  Methyl  salicylate. 

Indican.  —  A  glucoside  found  in  the  Indigo  plant.     It  is  hydro- 
lyzed by  acids  or  by  the  enzyme  indimulsin  as  follows: 

/NH 

C14H17N06  +  H20  =  C6H1206  +  C6H4       ^CH 

XCOH 

Indican  Glucose  Indoxyl. 


572  SUGAR  ANALYSIS 

The  indoxyl  of  the  above  reaction  is  colorless,  but  undergoes  rapid 
oxidation  to  indigotin  the  blue  coloring  matter  of  indigo. 

/  NH  /  NH          /  NH 

2C6H4         ^>CH+O2  =  CCH4       >C:C        >C6H4  +  2H2O. 
X  COH  ^CO  ^CO 

Indoxyl  Indigo-blue. 

Ruberythric  Add.  —  A  glucoside  found  in  the  root  of  the  madder 
(Rubia  tinctorum)  and  other  plants.  It  is  hydrolyzed  by  a  specific 
enzyme  or  by  acids  into  glucose  and  the  coloring  substance  alizarin. 

/co\ 
14  +  2  H20  =  2  C6H1206  +  C6H4  '  C6H2(OH)2 


Ruberythric  acid  Glucose  Alizarin. 

Amygdalin.  —  ••  A  glucoside  found  in  bitter  almonds  and  in  the  ker- 
nels of  peaches,  plums  and  other  fruits  of  the  same  family.  Amygdalin 
was  the  first  glucoside  to  attract  investigation;  it  was  discovered  in 
1830  by  Robiquet*  and  7  years  later  Liebig  and  Wohlerf  discovered 
the  manner  in  which  it  was  hydrolyzed  by  emulsin,  an  enzyme  found 
with  amygdalin  in  the  almond.  Amygdalin  is  the  most  interesting  of 
the  glucosides  not  only  historically  but  also  from  the  peculiarity  of 
giving  off  hydrocyanic  acid  upon  hydrolysis. 

CaoHsAiN  +  2  H20  =  2  C6H1206  +  C6H5CHO  +  HCN. 

Amygdalin  Glucose  Benzaldehyde      Hydrocyanic  acid. 

It  has  been  supposed  that  the  two  glucose  molecules  in  amygdalin 
are  united  to  form  a  disaccharide.  The  HCN  in  amygdalin  occurs  as 
the  nitrile  of  1-mandelic  acid  C6H5CH(OH)  •  CN.  The  monoglucose 
compound  of  1-mandelonitrile  was  obtained  by  Fischer  by  hydrolyzing 
amygdalin  with  an  enzyme  found  in  yeast;  it  has  the  following  formula, 
C6H5CH(CN)  -  O  -  C6Hn05.  This  glucoside  is  also  found  in  nature 
in  the  bark  of  the  wild  cherry  and  other  trees.  There  are  a  large 
family  of  glucosides  belonging  to  the  mandelonitrile  class.  Besides 
amygdalin  and  its  derivative  1-mandelonitrile  glucoside,  the  following 
are  mentioned: 

Sambunigrin.  —  A  glucoside  found  in  the  leaves  of  the  common 
elder  (Sambucus  nigra).  It  is  the  monoglucose  compound  of  d-mandelo- 
nitrile,  the  optical  antipode  of  the  derivative  obtained  by  Fischer  t  from 
amygdalin.  It  is  hydrolyzed  by  acids  and  emulsin  as  follows: 

C14H1706N  +  H20  =  C6H1206  +  C6H5CHO  +      HCN. 

Sambunigrin  Glucose  Benzaldehyde        Hydrocyanic  acid. 

Prulaurasin.  —  A  glucoside  found  in  the  leaves  of  the  cherry 
laurel.  It  is  a  racemic  mixture  of  d-mandelonitrile  glucoside  (sam- 

*  Robiquet  and  Boutron,  Ann.  chim.  phys.  [2],  44,  352-382  (1830). 
t  Ann.,  22,  1-24  (1837).  J  Ber.,  28,  1508. 


THE   MONOSACCHARIDES  573 

bunigrin)  and  1-mandelonitrile  glucoside.     It  is  hydrolyzed  in  the  same 
way  as  sambunigrin. 

Dhurrin. —  A  glucoside  found  by  Dunstan  and  Henry*  in  the  leaves 
and  stalks  of  Sorghum  vulgar e.  It  is  a  para-hydroxymandelonitrile 
glucoside  and  is  hydrolyzed  by  emulsin  and  acids  as  follows : 

Ci4H1707N  +  H20  =  C6Hi206  +  C6H4(OH)CHO  +      HCN. 

Dhurrin  Glucose  p-Oxybenzaldehyde          Hydrocyanic  acid. 

The  poisoning  of  cattle  by  eating  sorghum  at  certain  stages  of  its 
growth  is  due  to  the  hydrocyanic  acid  derived  from  this  glucoside. 

Phaseolunatin.  —  A  glucoside  found  by  Dunstan  and  Henry  f  in 
Lfrna  beans  (Phaseolus  lunatus),  flax  and  cassava  (also  termed  lini- 
marin) .  It  yields  the  following  hydrolytic  products : 

C10H1706N  +  H20  =  C6H1206  +  CH3COCH3  +      HCN. 

Phaseolunatin  Glucose  Acetone  Hydrocyanic  acid. 

Sinigrin.  —  A  glucoside  found  in  the  seed  of  black  mustard  (Sina- 
pis  or  Brassica  nigra).  It  is  one  of  the  most  interesting  of  the  glu- 
cosides,  as  it  contains  sulphur  and  yields  a  mustard  oil  as  one  of  its 
hydrolytic  products.  The  glucoside  was  first  isolated  by  Bussy  who 
called  it  potassium  myronate.  It  is  hydrolyzed  by  acids  or  by  the 
enzyme  myrosin  (which  accompanies  it  in  mustard  seed)  as  follows: 
Ci0Hi6O9NS2K  +  H20  =  C6Hi206  +  CH2:CHCH2NCS  +  KHS04. 

Sinigrin  Glucose  Allyl  mustard  oil  Potassium 

bisulphate 

The  mustard-oil  glucosides  constitute  a  separate  class  and  are 
peculiar  to  the  plants  of  the  Cruciferae. 

Sinalbin.  —  This  is  the  glucoside  of  the  white  mustard  (Sinapis  or 
Brassica  alba).      It  is  hydrolyzed  by  the  enzyme  myrosin  which  ac- 
companies it  in  the  following  manner: 
C3oH42O15N2S2  +  H20  =  C6H12O6  +  C7H7ONCS  +  Ci6H24O5N  •  HS04. 

Sinalbin  Glucose  Sinalbin  mustard  Sinapin  acid-sulphate. 

oil 

Glucose  is  also  found  associated  with  tannic  and  gallic  acids  as  a 
constituent  of  another  very  widely  distributed  group  of  plant  sub- 
stances. These  have  been  regarded  by  some  chemists  as  true  glu- 
cosides and  by  others  as  mere  complexes. 

Glucotannin,  a  so-called  glucoside  of  this  class,  is  supposed  to  be 
hydrolyzed  by  the  enzyme  tannase  as  follows: 

C27H22017  +  4  H20  =  C6H1206  +  3  C«H2(OH)?COOH. 

Glucotannin  Glucose  Gallic  acid. 

The  literature  upon  the  tannin  glucosides  is  in  such  a  contradictory 
state  that  no  definite  compounds  can  be  cited  by  way  of  illustration. 
*  Phil,  trans.  Roy.  Soc.,  1902,  A  199,  399. 
t  Proc.  Roy.  Soc.,  72,  285. 


574  SUGAR  ANALYSIS 

Preparation  of  Glucosides.  —  The  glucosides  are  best  isolated  from 
plant  materials  by  extraction  with  alcohol.  The  extraction  should  be 
begun  as  soon  as  possible  after  the  material  is  gathered  in  order  to  pre- 
vent hydrolysis  by  accompanying  enzymes.  In  many  cases  the  glu- 
coside  will  crystallize  directly  from  the  alcohol  extract;  in  other  cases, 
where  the  yield  is  small,  the  extract  must  be  concentrated  before  crys- 
tallization will  begin.  When  large  amounts  of  other  organic  substances 
are  present,  clarification  with  lead  salts  may  be  necessary,  in  which 
case  any  excess  of  lead  is  afterwards  removed  by  means  of  hydrogen 
sulphide. 

Glucose  as  a  Constituent  of  Higher  Sugars.  —  Besides  forming 
condensation  products  with  plant  alcohols,  aldehydes,  phenols,  acids, 
etc.,  to  form  glucosides,  glucose  may  unite  in  other  ways;  it  may  com- 
bine with  one  or  more  molecules  of  itself,  or  with  one  or  more  mole- 
cules of  other  sugars,  to  form  the  higher  crystalline  saccharides.  The 
latter  are  readily  hydrolyzed  into  the  component  sugars  by  acids  and 
specific  enzymes  in  the  same  manner  as  the  glucosides.  The  following 
examples  are  given  of  the  higher  sugars  found  in  nature  which  yield 
glucose  upon  hydrolysis. 

Sugar  Hydrolytic  Products 

Maltose Glucose  +  glucose. 

Trehalose Glucose  +  glucose. 

Gentiobiose Glucose  +  glucose. 

Sucrose Glucose  +  fructose. 

Turanose Glucose  +  glucose.  (?) 

Lactose Glucose  +  galactose. 

Melibiose Glucose  +  galactose. 

Melezitose Glucose  +  glucose    +  glucose.  (?) 

Gentianose Glucose  +  glucose    +  fructose. 

Raffinose Glucose  -j-  fructose  +  galactose. 

Tetra-       f 
saccharides,  |  Stachyose Glucose  +  fructose  +  galactose  +  galactose. 

C24H42O21-      I 

Glucose  as  a  Constituent  of  Polysaccharides.  —  In  addition  to 
forming  higher  sugars  by  condensation  of  its  own  molecule,  glucose 
may  unite  with  itself  to  form  the  very  complex  polysaccharides,  such  as 
dextrin,  dextran,  starch  and  cellulose.  The  number  of  molecules  of 
glucose  which  enter  into  the  structure  of  these  higher  derivatives  is 
difficult  to  determine.  Researches  by  Brown  and  Morris  *  indicate 
that  dextrin,  the  simplest  member  of  the  class,  contains  40  molecules  of 
glucose  in  the  condensed  form  and  that  the  molecule  of  starch  is  at 
least  5  times  as  large  as  that  of  dextrin,  in  other  words  contains  200 

*  Chem.  Centralbl.  (1890),  I,  845.  See  also  Brown  and  Millar,  J.  Chem.  Soc., 
76,  315. 


Di- 

saccharides, 


Tri- 
saccharides, 


THE  MONOSACCHARIDES  575 

molecules  of  glucose.  Cellulose,  the  most  highly  condensed  polysac- 
charide,  has  without  doubt  a  molecule  much  greater  even  than  starch. 
The  chemical  properties  of  the  higher  polysaccharides  can  only  be  re- 
ferred to  very  briefly. 

Cellulose.  —  (C6Hi0O5)n.  This  is  the  most  abundant  constituent 
in  the  vegetable  kingdom;  cellulose  in  all  its  various  forms  probably 
makes  up  one-half  of  the  total  dry  vegetable  matter  of  the  world. 
Cellulose  occurs  in  the  pure  condition  only  in  the  fiber  of  the  cotton 
ball  and  in  a  few  similar  substances;  as  a  constituent  of  the  cellular 
tissue  of  plants  cellulose  is  usually  combined  with  lignin,  pentosans  and 
other  hemicelluloses  to  form  a  complex  of  varying  composition.  By 
treatment  of  plant  membranes  with  hot  solutions  of  dilute  alkalies  and 
acids  the  lignin,  pentosans  and  other  so-called  "  encrusting  sub- 
stances "  are  split  off  from  the  complex  leaving  the  cellulose  behind  as 
an  insoluble  residue.  The  latter  upon  bleaching  with  chlorine  is  ob- 
tained in  a  perfectly  white  fibrous  form.  The  average  approximate 
percentage  of  cellulose  in  the  water-free  substance  of  different  plant 
materials  is  as  follows: 

Material  (water  free)  Approximate  per  cent  of  Cellulose 

Wood 60 

Bark 40 

Straw 40 

Leaves 20 

Seeds  (including  husks) 15 

Roots,  tubers,  etc 10 

Cellulose,  as  prepared  from  its  different  sources,  consists  of  a  white 
fibrous  material  insoluble  in  ordinary  solvents  but  easily  soluble  in  an 
ammoniacal  copper  solution.  It  is  reprecipitated  from  the  latter  by 
acids  as  a  gelatinous  mass.  Cellulose  swells  up  in  concentrated  sul- 
phuric acid  and  after  short  contact  is  converted  into  a  starch-like  sub- 
stance (amyloid)  which  is  colored  blue  by  iodine.  In  the  same  manner 
cellulose  gives  a  blue  coloration  with  zinc  chloride  and  iodine  solution 
(Schulze's  reagent).  Cellulose  after  long  contact  with  concentrated 
sulphuric  acid  is  dissolved;  upon  diluting  the  mixture  with  water  and 
boiling  the  cellulose  is  hydrolyzed  to  d-glucose. 

Starch.  —  (C6HioO5)2oo.  (?)  Starch  is  next  to  cellulose  the  most 
widely  distributed  glucose  condensation  product  in  the  vegetable 
kingdom.  It  is  stored  up  as  a  reserve  material  in  many  roots,  tubers, 
grains  and  seeds,  in  which  parts  it  may  constitute  over  90  per  cent  of 
the  total  dry  substance.  It  has  been  estimated  by  Nageli  *  that  10 
per  cent  of  the  Phanerogams  or  flowering  plants  produce  starchy  seeds. 

*  "Die  Starkekdrner"  (1858),  p.  378. 


576 


SUGAR  ANALYSIS 


The  starch-yielding  capacity  of  certain  plants,  as  the  cereals,  potato, 
yam,  cassava,  etc.,  is  so  pronounced  as  to  give  them  great  value  in 
the  production  of  starch  for  food  and  industrial  purposes.  The  oc- 
currence of  starch  in  the  leaves  and  chlorophyll  tissue  of  plants  has  al- 
ready been  referred  to. 

Starch  is  deposited  in  plant  cells  in  the  form  of  minute  grains, 
whose  size  and  shape  are  peculiar  to  each  botanical  species  (see  Fig. 
192).  By  reducing  the  starchy  parts  of  the  plant  to  a  fine  pulp  with 


Wheat  starch. 


Rice  starch. 


Corn  starch.  Potato  starch. 

Fig.  192.  —  Forms  of  starch  grains.     After  Moller.     (Magnified  400.) 

water  and  straining  the  milky  liquid  into  a  tall  cylinder  the  grains  of 
starch  will  be  deposited  as  a  sediment.  The  latter  is  then  washed 
several  times  by  decantation  with  0.25  per  cent  sodium  hydroxide 
solution,  which  removes  protein  and  other  impurities,  and  then  washed 
with  water  to  remove  all  traces  of  alkali.  The  starch  thus  prepared 
is  filtered  off  and  dried  at  a  gentle  heat.  In  a  similar  way,  by  a 
process  which  is  largely  mechanical,  starch  is  prepared  commercially 
from  the  potato,  cassava,  Indian  corn,  wheat,  rice  and  other  plants. 

Pure  starch,  which  has  not  been  subjected  to  heat  or  strong  chemi- 
cal treatment,  occurs  in  the  form  of  white  microscopic  granules  vary- 
ing in  size  from  about  0.002  mm.  to  0.2  mm.  diameter.  The  granules 
are  insoluble  in  cold  water,  but  when  heated  with  hot  water  burst  and 
partially  dissolve  forming  a  thick  mucilaginous  paste. 

The  conversion  of  starch  by  means  of  diastase  and  acids  is  described 
under  maltose. 

Starch  upon  contact  with  cold  hydrochloric  acid  is  converted  into 


THE  MONOSACCHARIDES  577 

soluble  starch.  In  Lintner's  *  method  the  starch  is  treated  for  7  to  8 
days  with  7.5  per  cent  hydrochloric  acid,  after  which  it  is  washed  free 
from  acid  and  dried.  The  product  thus  obtained  dissolves  readily  in 
hot  water  to  form  a  clear  limpid  solution.  The  [a]D  of  soluble  starch 
ranges  from  about  +  195  to  +  200. 

Dextrin.  —  (C6Hio05)4o.  (?)  Dextrin  is  formed  in  nature  and  in  the 
arts  by  the  conversion  of  starch.  It  occurs  in  malted  grain  and  in  all 
starchy  seeds  during  germination.  The  dextrin  molecule  is  regarded 
by  many  chemists  as  varying  in  character  and  the  following  classifica- 
tion is  sometimes  made. 

(1)  Amylodextrin,  first  dextrin  of  conversion;  blue  iodine  reaction. 

(2)  Erythrodextrin,  second  dextrin  of  conversion ;  red  iodine  reaction. 

(3)  Achroodextrin,  third  dextrin  of  conversion;  no  iodine  reaction. 

(4)  Maltodextrin,  final  dextrin  of  conversion;  no  iodine  reaction. 
Numerous  subdivisions  of  dextrins  under  each  of  the  above  groups 

have  also  been  proposed.  The  theories  concerning  the  formation  of 
dextrin  from  starch  are  discussed  under  maltose. 

A  stable  dextrin  was  prepared  by  Brown  and  Millar  f  by  precipi- 
tating a  diastatic  starch  conversion  with  alcohol,  dissolving  the  preci- 
pitate in  water,  fermenting  away  occluded  sugars  with  yeast,  and  again 
precipitating  with  alcohol.  After  several  such  purifications  and  frac- 
tional precipitations  with  alcohol,  a  dextrin  was  obtained  of  only  slight 
reducing  power  and  giving  for  [a]D  +  195  to  +  195.7.  The  formula 
39(C6Hio05)  •  CGHi206  was  assigned  to  this  dextrin  (see  p.  687). 

Dextrin  is  prepared  commercially  by  heating  starch  with  about 
0.2  per  cent  nitric  acid  in  ovens.  The  temperature  of  heating  varies  ac- 
cording to  the  color  and  character  of  product  desired,  and  ranges  from 
110°  to  170°  C.  The  dextrin  thus  prepared  resembles  that  obtained 
from  starch  by  diastatic  conversion.  It  is  easily  soluble  in  water,  and 
is  precipitated  from  aqueous  solution  by  strong  alcohol.  The  specific 
rotation  of  commercial  dextrins  will  vary  according  to  the  method  of 
manufacture  (see  p.  510).  Such  dextrins,  purified  by  repeated  precipi- 
tation with  alcohol,  will  give  a  value  for  [a]D  of  about  +195,  the  same 
as  that  of  the  stable  dextrin  prepared  by  diastase. 

Dextrin  upon  heating  with  dilute  hydrochloric  or  sulphuric  acid  is 
hydrolyzed  into  d-glucose.  The  reaction  is  not  perfectly  quantitative, 
however,  owing  to  a  slight  destruction  of  the  glucose.  The  rate  of  hydrol- 
ysis was  found  by  W.  A.  Noyes  |  and  his  co-workers  to  be  only  about  one- 
half  that  for  maltose. 

*  J.  prakt.  Chem.,  34  [2],  381.  t  J-  Chem.  Soc.,  76,  315. 

t  J.  Am.  Chem.  Soc.,  26,  266. 


578  SUGAR  ANALYSIS 

Other  Glucose-yielding  Polysaccharides.  —  In  addition  to  the 
substances  previously  mentioned  glucose  occurs  in  the  condensed  form 
in  many  other  plant  products,  such,  for  example,  as  lichenin*  (C6Hio05)n, 
a  constituent  of  many  mosses  and  lichens;  dextran  (C6Hio05)n,  a  muci- 
laginous substance  secreted  by  many  bacteria  and  resembling  dextrin  in 
its  properties;  paradextran^  (CeHuAOn,  a  cellular  constituent  of  many 
fungi  and  mushrooms;  plant  dextrins  and  gums,  vegetable-glycogen,^.  and 
other  materials  belonging  to  the  so-called  hemicelluloses. 

In  the  animal  kingdom  glucose  is  found  free  in  the  blood  (about  0.1 
per  cent)  and  also  in  very  slight  amounts  in  normal  urine  (usually 
under  0.01  per  cent  or  less  than  0.5  gm.  per  day).  In  diabetes  mellitus 
and  other  diseases  where  glucosuria  occurs,  the  per  cent  of  glucose  in 
the  urine  may  exceed  10  per  cent  with  a  daily  excretion  of  500  or  even 
1000  gms.  Temporary  glucosuria  may  be  produced  by  ingestion  of 
phloridzin  (p.  571),  various  alkaloids,  potassium  chlorate  and  other 
compounds. 

Glucose  occurs  most  abundantly  in  the  animal  kingdom  in  the  form 
of  its  condensation  product  glycogen. 

Glycogen.§  —  (CeHnAOn  is  a  constituent  of  all  growing  animal 
cells.  It  is  usually  regarded  as  a  reserve  product,  playing  the  same 
role  in  the  animal  economy  as  starch  in  the  vegetable.  The  surplus 
carbohydrates  of  the  food  are  stored  up  in  the  body  as  glycogen,  about 
one-half  of  this  being  deposited  in  the  liver  and  one-half  in  the  muscles 
and  other  organs. 

The  percentage  of  glycogen  in  fresh  meat  and  muscles  varies  from  a 
trace  to  nearly  3  per  cent;  it  is  found  in  largest  amount  in  the  liver 
where  it  may  constitute  over  10  per  cent  of  the  weight  of  this  organ. 
The  amount  of  glycogen  in  the  liver  is  subject  to  considerable  fluctua- 
tion being  greatest  after  a  meal  rich  in  carbohydrates  and  lowest  after 
long  abstinence  from  food.  It  is  only  after  several  weeks'  fasting, 
however,  that  glycogen  disappears  completely  from  the  liver.  In  its 
removal  from  the  various  organs  of  the  body  glycogen  is  hydrolyzed  by 
enzymes  to  glucose,  which  is  then  transported  by  the  blood  to  the 
different  parts  of  the  organism. 

Preparation  of  Glycogen.  —  Glycogen  is  prepared  by  cooking  finely 
divided  livers  with  60  per  cent  potassium  hydroxide  solution  for  two 

*  Bauer,  J.  prakt  Chem.,  [2]  34,  46. 

t  Winterstein,  Ber.,  27,  3113. 

j  Errera,  Compt.  rend.,  101,  253. 

§  Discovered  by  Claude  Bernard  in  1855  (Compt.  rend.,  41,  461;  44,  1325; 
48,  884,  etc.).  For  a  full  account  of  this  carbohydrate  consult  Pfluger's  book  "  Das 
Glykogen,"  2nd.  Edit.  (1906),  Bonn. 


THE   MONOSACCHARIDES  579 

hours.  The  filtrate  is  then  diluted  to  15  per  cent  potassium  hydroxide 
and,  after  settling,  the  clear  solution  is  mixed  wit]?.  1  volume  of  96  per 
cent  alcohol.  The  precipitated  glycogen  is  washed  with  a  mixture  of  1 
volume  of  15  per  cent  potassium  hydroxide,  and  2  volumes  of  96  per  cent 
alcohol.  The  crude  product  thus  prepared  is  purified  by  dissolving  in 
strong  potassium  hydroxide  solution  and  reprecipitating  with  alcohol. 

Properties  of  Glycogen. —  Glycogen  is  obtained  as  an  amorphous  snow- 
white  substance.  The  product  is  usually  more  or  less  hydrated  so  that  it  is 
difficult  to  prepare  a  substance  of  uniform  composition.  Glycogen  dis- 
solves in  water  to  a  faintly  opalescent  colloidal  solution;  it  is  also  dis- 
solved by  hot  alcohol ;  the  best  solvent  is  aqueous  potassium  hydroxide 
solution.  Gly cogen  is  strongly  dextrorotatory,  [a]D  =  about  +200.  It 
is  decomposed  by  butyric  acid  bacteria  and  other  organisms,  but  is  not 
fermented  by  yeast.  Plant  enzymes  of  different  origin  convert  gly- 
cogen, some  into  maltose  and  some  into  d-glucose;  the  enzymes  of  the 
body,  however,  seem  to  hydrolyze  glycogen  only  into  d-glucose.  Gly- 
cogen is  hydrolyzed  by  acids  into  d-glucose  in  the  same  manner  as 
starch,  dextrin,  and  other  polysaccharides  of  the  glucose  class. 

Glycogen  does  not  reduce  Fehling's  solution.  Treated  with  iodine 
solution  it  gives  a  color  varying  from  brown  to  wine-red,  which  dis- 
appears upon  heating  to  60°  C.  but  returns  again  upon  cooling. 

Of  other  animal  products,  which  may  be  regarded  as  glucose  deriva- 
tives, may  be  mentioned  tunicin*  or  animal  cellulose  (C6Hio05)n,  found 
in  the  outer  membranes  of  Tunicates  and  other  animals,  and  the  so- 
called  animal  gum  found  by  Landwehr  f.  in  various  tissues  and  organs 
of  the  body. 

The  Gluco-proteids.  —  A  number  of  animal  substances,  which  are 
not  of  a  pure  carbohydrate  nature,  yield  glucose  as  one  of  their  hydrolytic 
products.  Among  these  substances  may  be  mentioned  different  nu- 
cleo-proteids,  various  albumins  and  certain  mucins  or  mucoids.  The 
chemistry  of  these  products,  however,  is  still  unsettled,  and  it  is  un- 
certain whether  the  sugar  derived  from  them  consists  of  glucose  alone 
or  of  a  mixture  of  sugars. 

Honey.  —  Another  animal  product  rich  in  glucose  is  honey,  although 
the  sugar  in  this  instance  is  primarily  of  vegetable  origin  being  derived 
by  bees  and  other  insects  from  the  nectar  of  flowers  and  other  plant 
juices.  Honey  contains  usually  about  35  per  cent  of  glucose;  strained 
honey  will  frequently  granulate  and  even  solidify  owing  to  crystallization 

*  Berthelot,  Compt.  rend.,  47,  227.  Winterstein,  Z.  physiol,  Chem.,  18, 
46-56. 

f  Z.  physiol.  Chem.,  8.  122;  9,  367;  18,  193;  19,  339;  20,  249. 


580  SUGAR  ANALYSIS 

of  its  glucose.  The  granulation  of  honey  was  known  to  the  ancients, 
and  crystallized  glucose  as  thus  observed  was  probably  the  first  sugar 
known  to  mankind. 

Synthesis  of  Glucose.  —  d-Glucose  has  been  synthetised  in  a 
number  of  ways.  It  has  been  prepared  from  d-mannose,  by  oxidizing 
this  sugar  to  d-mannonic  acid  and  converting  the  latter  by  molecular 
rearrangement  (p.  775)  into  d-gluconic  acid,  whose  lactone  upon  reduc- 
tion gives  d-glucose.  The  sugar  has  also  been  built  up  synthetically 
by  Fischer  *  by  condensation  of  formaldehyde  to  d,  1-fructose,  which 
upon  reduction  gives  d,  1-mannite  and  this  upon  oxidation  d,  1-man- 
nonic  acid.  The  latter  is  then  resolved  into  its  d-  and  1-components 
and  d-glucose  is  prepared  from  the  d-mannonic  acid  as  first  described. 

Preparation  of  Glucose.  —  d-Glucose  can  be  prepared  directly 
from  granulated  honey  by  stirring  the  mass  with  a  little  50  per  cent 
alcohol  and  filtering  upon  a  suction  plate.  The  sugar  thus  obtained  is 
purified  from  fructose,  honey  dextrin  and  other  impurities  by  recrystal- 
lization. 

In  preparing  glucose  upon  a  large  scale  hydrolysis  of  some  one  of 
its  natural  condensation  derivatives  is  employed.  For  this  purpose 
starch,  the  raw  material  from  which  commercial  glucose  is  made,  is 
usually  chosen. 

Preparation  by  Hydrolysis  of  Starch.  —  One  hundred  grams  of  pure 
potato  or  corn  starch  are  heated  to  boiling  with  1000  c.c.  of  2  per  cent 
hydrochloric  acid  in  a  flask  connected  with  a  reflux  condenser  for  2 
hours.  The  hot  solution  is  neutralized  with  lead  carbonate,  cooled 
and  filtered.  The  filtrate  is  evaporated  to  a  thin  sirup,  shaken  with  an 
equal  volume  of  hot  96  per  cent  alcohol  and  filtered  from  precipitated 
impurities.  The  alcoholic  filtrate  upon  evaporation  gives  a  sirup  which 
rapidly  crystallizes;  the  sugar  thus  obtained  is  purified  by  a  second 
crystallization. 

Preparation  by  Hydrolysis  of  Cellulose.  —  Glucose  can  also  be  pre- 
pared by  hydrolysis  of  cellulose;  100  gms.  of  clean  cotton  or  filter 
paper  are  slowly  stirred  into  500  c.c.  of  80  per  cent  sulphuric  acid. 
The  mixture  is  allowed  to  stand  24  hours;  it  is  then  diluted  to  5000  c.c. 
and  heated  in  a  boiling  water  bath  for  5  hours.  The  hot  solution  is  then 
neutralized  with  an  excess  of  calcium  carbonate,  filtered  and  the  filtrate 
concentrated  to  a  sirup.  The  latter  is  then  purified  from  gummy  decom- 
position products  by  heating  with  alcohol  and  clarified  by  filtering 
through  bone  black.  The  alcoholic  filtrate  upon  evaporation  gives  a 
sirup  which  soon  crystallizes. 

*  Ber.,  23,  799. 


THE   MONOSACCHARIDES  581 

Preparation  by  Inversion  of  Sucrose.  —  Glucose  is  also  very  easily  pre- 
pared by  inversion  of  cane  sugar.  For  this  purpose  1000  gms.  of  refined 
sugar  are  heated  for  1  hour  with  300  c.c.  of  water  and  5  c.c.  of  concen- 
trated hydrochloric  acid  in  a  flask  immersed  in  a  boiling  water  bath.  The 
yellowish  colored  sirup  is  then  poured  into  an  evaporating  dish  and  set 
aside  in  a  cool  place.  Granulation  will  begin  after  a  few  weeks'  stand- 
ing when  the  glucose  will  separate  as  a  thick  or  even  solid  mass  of 
crystals.  The  latter  are  taken  up  with  a  little  50  per  cent  alcohol, 
filtered,  washed  with  strong  alcohol  and  recrystallized  in  the  usual 
way. 

The  crystallization  of  glucose  can  always  be  hastened  by  priming 
its  sirups  with  a  small  crystal  of  glucose  from  a  previous  prepara- 
tion. 

Properties  of  Glucose.  —  Glucose  crystallizes  both  as  the  hydrate 
C6Hi206.H2O  and  the  anhydride.  The  hydrate  is  obtained  by  crystal- 
lizing from  water  at  ordinary  temperature  and  the  anhydride  by 
crystallizing  from  a  hot  saturated  alcoholic  solution.  Glucose  hydrate 
loses  its  water  of  crystallization  between  50°  and  60°  C.  To  prepare  an- 
hydrous glucose  from  the  hydrate,  the  latter  should  be  spread  in  a 
thin  layer  in  a  flat  bottomed  dish  and  heated  at  60°  C.  until  most  of  the 
water  has  been  expelled;  the  temperature  is  then  gradually  raised  to 
100°  C.  when  the  sugar  will  be  obtained  perfectly  granular  and  dry. 
Heating  the  hydrate  directly  to  100°  C.  will  cause  melting  and  when  this 
occurs  it  is  difficult  to  obtain  a  satisfactory  preparation  of  anhydrous 
glucose. 

Glucose  anhydride  consists  of  fine  crystalline  needles  melting  at 
146°  to  147°  C.  The  sugar  has  a  sweet  taste,  is  very  soluble  in  water 
(about  1  :  1  at  20°)  and  hot  alcohol,  but  insoluble  in  ether.  The  con- 
stant rotation  of  the  anhydride  is  [a]D  =  4-52.5  (directly  after  solution 
+  106  or  more).  For  glucose  hydrate  [a]D  =+48.2  (constant).  Tan- 
ret  *  has  considered  glucose  to  exist  in  3  modifications,  a  high-rotating 
form  (HD=+106),  a  constant-rotating  form  ([a^  =+52.5)  and  a 
low-rotating  form  ([a]D  =+22.5).  Tanret's  constant-rotating  glucose 
is  now  considered  to  be  simply  an  equilibrated  mixture  of  a-,  or  high- 
rotating,  glucose  and  /?-,  or  low-rotating,  glucose.  Reference  has  been 
made  to  these  modifications  under  the  subject  of  mutarotation. 

Fermentations  of  Glucose.  —  Glucose  undergoes  a  large  number  of 
fermentations  a  few  of  the  more  typical  of  which  will  be  mentioned. 

Alcoholic  Fermentation.  —  Glucose  is  fermented  to  alcohol  by  many 
species  of  Saccharomyces,  Mucor,  Torula,  Mycoderma  and  other  organ- 
*  Compt.  rend.,  120,  1060. 


582  SUGAR  ANALYSIS 

isms.  The  general  formula  for  the  fermentation  of  glucose  to  alcohol 
was  first  given  by  Gay-Lussac  *  as  follows: 

C6Hi2O6=  2  CH3CH2OH  +     2  C02. 

Glucose  Alcohol  Carbon  dioxide. 

or,  100  parts  glucose  =  51.11  parts  alcohol  +48.89  parts  carbon  dioxide. 
Pasteur, f  however,  showed  that  this  formula  was  not  absolutely  correct, 
as  he  obtained  under  the  best  of  conditions  only  48.3  parts  of  alcohol  and 
46.4  parts  of  carbon  dioxide  from  100  parts  of  glucose.  Pasteur  obtained 
in  addition  to  alcohol  and  carbon  dioxide  2.5  to  3.6  parts  of  glycerol, 
0.4  to  0.7  part  of  succinic  acid  and  1.3  parts  of  fat,  cellulose  and 
other  substances,  all  of  which  he  believed  to  be  formed  directly  from 
the  sugar.  The  latest  researches,  however,  show  that  these  minor  prod- 
ucts of  fermentation  are  the  result  of  metabolic  processes  within  the 
yeast  cells.  The  main  phase  of  the  fermentation  is  produced  by  the 
enzyme  zymase  which  is  secreted  by  the  yeast.  Buchner,|  in  fact,  has 
separated  zymase  from  crushed  yeast  and  by  its  aid  has  fermented 
glucose  into  alcohol  and  carbon  dioxide  without  the  direct  agency  of 
the  living  cells. 


Fig.  193.  —  Saccharomyces  cerevisise.    After  Hansen. 

In  the  alcoholic  fermentation  of  glucose  a  concentration  of  5  to 
20  per  cent  sugar  gives  the  best  results.  The  temperature  should 
be  maintained  between  30°  and  35°  C.,  and  a  small  amount  of  pep- 
tones, phosphates,  tartrates  and  other  salts  be  added  as  nutrient 
for  the  yeast.  A  growth  of  Saccharomyces  cerevisice,  or  beer  yeast, 
which  is  one  of  the  best  known  alcohol-producing  organisms,  is  shown 
in  Fig.  193. 

In  addition  to  ethyl  alcohol  a  number  of  other  alcohols  are  pro- 

*  Ann.  chim.  phys.  [1],  95,  311. 
t  Ann.  chim.  phys.  [3]  68,  330,  355,  362. 

t  Ber.,  30,  117,  1110,  2668;  34,  1523,  etc.     See  also  the  book  by  Buchner  and 
Hahn  "  Die  Zymasegarung,"  Munich,  1903. 


THE   MONOSACCHARIDES  583 

duced  in  the  alcoholic  fermentation  of  glucose;  the  most  important  of 
these  are  amyl,  isobutyl  and  propyl  alcohols  with  traces  of  hexyl  alco- 
hol and  higher  homologs.  These  higher  alcohols  (the  fusel  oil  of  dis- 
tilleries) according  to  the  researches  of  Ehrlich  *  are  not  formed  from  the 
sugar,  however,  but  are  secondary  products  derived  from  the  amino 
acids  of  the  yeast. 
R  •  CHNH2  •  COOH  +  H20  =  R  •  CH2OH  +  CO2  +  NH3. 

Amino  acid  Higher  alcohol  Carbon  dioxide  Ammonia. 

Lactic  Fermentation.  —  Glucose  is  fermented  to  lactic  acid  f  by  a 
large  number  of  bacilli  and  bacteria.  The  formula  for  the  fermenta- 
tion of  glucose  into  lactic  acid  in  its  simplest  terms  is  expressed  as 
follows: 

C6H1206  =  2  CH3  CHOH  COOH. 

d-Glucose  Lactic  acid. 

The  theoretical  yield  of  lactic  acid,  however,  is  never  obtained,  more 
or  less  carbon  dioxide,  hydrogen,  formic,  acetic,  butyric  and  pro- 
pionic  acids,  mannite  and  other  products  of  secondary  or  foreign  fer- 
mentative origin  being  always  formed. 

In  fermenting  glucose  to  lactic  acid  a  10  per  cent  solution  of  the 
sugar  is  prepared  (adding  minute  amounts  of  ammonium  salts,  ni- 
trates, bran  extract  or  other  substances  to  serve  as  nutrients)  and  then 
sterilized.  The  cold  solution  is  inoculated  with  a  pure  culture  of  Ba- 
cillus lactis  acidi  (or  other  lactic  acid  producing  organism)  and  incubated 
at  45°  to  55°  C.  for  3  to  6  days.  A  little  powdered  calcium  carbonate  is 
added  from  time  to  time  to  take  up  the  excess  of  free  acid  which  should 
be  kept  below  0.5  per  cent,  but  never  be  entirely  neutralized  (otherwise 
the  butyric  fermentation  may  set  in).  If  the  lactic  acid  culture  is 
pure,  98  per  cent  of  the  glucose  may  be  converted  into  lactic  acid  by 
this  method. 

The  lactic  acid  obtained  by  fermentation  is  usually  optically  in- 
active and  consists  of  a  racemic  mixture  of  the  d-  and  1-isomers.  Cer- 
tain organisms  have  been  found,  however,  which  seem  to  form  the  d-, 
or  1-,  acid  alone  or  in  excess.  In  these  cases  d,  1-lactic  acid  may  per- 
haps be  formed  first,  the  d-,  or  1-component  being  afterwards  partly  or 
wholly  destroyed  by  secondary  fermentation. 

The  conversion  of  d-glucose  into  lactic  acid,  according  to  Buchner,t 
is  due  to  the  action  of  a  special  enzyme  secreted  by  the  organisms. 

Butyric  Fermentation.  —  Glucose  is  fermented  into  butyric  acid  § 
by  a  number  of  species  of  bacteria;  among  the  best  known  of  these  is 

*  Ber.,  40,  1027-47.  t  Ber.,  36,  634. 

t  Pasteur,  Ann.  chim.  phys.  [3],  2,  257  (1842).       §  Pasteur,  Compt.  rend.,  62,  344. 


584  SUGAR  ANALYSIS 

the  Clostridium  butyricum.  The  butyric  fermentation,  which  proceeds 
only  in  the  absence  of  air,  follows  approximately  the  following  equa- 
tion: 

C6Hi206  =  CH3CH2CH2COOH  +  2  CO2  +  2  H2 

Glucose  Butyric  acid  Carbon       Hydrogen. 

dioxide 

As  by-products  of  the  butyric  fermentation  there  are  generally  formed 
butyl,  ethyl  and  propyl  alcohols,  formic,  acetic,  propionic,  valeric, 
caprylic,  capric  and  lactic  acids,  and  other  substances  either  of  second- 
ary or  foreign  fermentative  origin. 

The  butyric  acid  producing  bacteria  grow  best  at  a  temperature  be- 
tween 35°  and  40°  C.  and  require  a  medium  perfectly  free  from  acid. 
To  secure  the  latter  condition  the  butyric  fermentation  is  carried  out 
in  presence  of  an  excess  of  calcium  carbonate  which  combines  with  the 
free  acid  as  fast  as  it  is  formed. 

Viscous  Fermentation.*  —  Glucose  is  fermented  by  a  large  number 
of  different  organisms  to  a  mucilaginous  gummy  substance  known  as 
dextran.  The  gum  which  is  formed  during  fermentation  'is  probably 
a  secondary  product,  being  a  constituent  of  the  gelatinous  capsule 
which  encloses  the  organism.  Among  the  best-known  organisms, 
which  produce  the  viscous  fermentation,  is  the  Leuconostoc  mesenterioi- 
des  f  (Fig.  196)  to  which  class  belong  also  the  Bacterium  pediculatum  J 
(Fig.  197)  and  other  gum-forming  organisms  found  in  sugar  factories. 
The  bacteria  which  form  gum  thrive  best  in  the  absence  of  air,  and  at 
a  temperature  varying  from  30°  to  35°  C. 

Dextran^,  the  gum  of  the  viscous  fermentation,  and  the  cause  of 
ropiness  in  wine  and  of  the  so-called  " frog-spawn"  in  sugar  factories, 
is  precipitated  from  solution  by  means  of  alcohol.  It  is  purified  by 
dissolving  in  dilute  sodium  hydroxide,  filtering  and  reprecipitating  with 
alcohol  acidified  with  acetic  acid.  The  product,  after  drying  and  pul- 
verizing, is  obtained  as  a  white  powder,  having  the  general  formula 
(CeHioOs)^  and  yielding  glucose  upon  hydrolysis  with  sulphuric  acid. 
The  gum  swells  up  in  water  but  does  not  form  a  perfectly  trans- 
parent solution  except  upon  addition  of  a  little  alkali.  Dextran  is 
strongly  dextrorotatory,  [a]D  =  about  +200. 

Oxidizing  Fermentations  of  Glucose.  —  There  are  a  large  number  of 
fermentations  of  glucose,  which  differ  from  the  types  previously  de- 

*  Pasteur,  Bull.  soc.  chim.  (1861),  30. 
t  Van  Tieghem,  J.  fabric,  sucre,  20,  30,  32. 
j  Alfred  Koch  and  Hosaeus,  Chem.  Centralbl.,  (1894),  II,  703. 
§  For  the  copious  literature  upon  dextran  see  references  in  Lippmann's  "Chemie 
der  Zuckerarten,"  427-430. 


THE   MONOSACCHARIDES  585 

scribed,  in  that  oxygen  is  absorbed  from  the  air  with  the  formation  of 
different  acids.  Such  fermentations  belong  to  the  strictly  aerobic  class. 
The  following  are  examples: 

Gluconic  Acid  Fermentation.  —  d-Glucose  is  fermented  to  d-glu- 
conic  acid  by  the  Micrococcus  oblongus,*  Bacterium  xylinum\  and  nu- 
merous other  organisms.  In  its  simplest  phase  the  reaction  proceeds 

as  follows: 

CH2OH  CH2OH 

(CHOH)4  +  0  (CHOH)4 

CHO  COOH 

d-Glucose  d-Gluconic  acid. 

With  some  organisms  the  fermentation  proceeds  almost  quantitatively 
according  to  this  reaction.  In  other  cases  the  gluconic  acid  itself  un- 
dergoes oxidation  so  that  the  theoretical  yield  is  much  reduced. 

Citric  Acid  Fermentation.  —  Various  organisms  belonging  to  the 
Citromyces  group  ferment  glucose  into  citric  acid.  The  general  formula 
for  the  reaction  is  given  as  follows: 

CH2OH  CH2  -  COOH 

(CHOH)4  +  3O        =          C(OH)  -  COOH      +  2  H2O 
CHO  CH2  -  COOH 

Glucose  Citric  acid. 

The  citric  acid  fermentation  is  attended  as  the  formula  shows  by  a 
high  consumption  of  oxygen,  about  200  c.c.  of  oxygen  being  taken  up 
from  the  air  for  every  gram  of  glucose  fermented. 

In  fermentation  experiments  the  yield  of  citric  acid  from  glucose 
has  not  been  found  to  exceed  50  per  cent,  owing  to  the  fact  that  the 
citric  acid  itself  undergoes  oxidation  in  the  later  stages  of  the  fer- 
mentation. 

Oxalic  Acid  Fermentation.  —  Glucose  is  fermented  into  oxalic  acid 
by  a  large  number  of  moulds  and  bacteria.  The  complete  conversion 
of  glucose  in  this  direction,  however,  is  never  reached,  as  the  oxalic 
acid  at  a  certain  point  of  concentration  begins  to  exercise  a  toxic  effect 
upon  the  growth  of  the  organisms.  The  oxalic  acid,  which  is  formed 
by  the  action  of  microorganisms,  is  probably  a  respiration  product  given 
off  by  the  living  cell  rather  than  a  true  fermentation  derivative  (such 
as  alcohol)  formed  from  the  sugar  by  the  action  of  a  special  enzyme. 
The  same  is  no  doubt  also  true  of  many  other  acids. 

Other  Acid  Fermentations.  —  Glucose  is  subject  to  a  large  number 

*  Boutroux,  Compt.  rend.,  91,  236. 

t  Brown,  J.  Chem.  Soc.,  49,  432;  60,  463. 


586  SUGAR  ANALYSIS 

of  other  fermentations  in  which  acetic,  propionic,  formic,  succinic  and 
other  acids  are  formed.  In  some  of  these  cases  the  fermentation  seems 
to  be  of  a  true  enzymic  character.  Certain  bacteria,  for  example,  are 
able  to  convert  glucose  directly  into  acetic  acid. 

C6H1206  =  3  CH3COOH 

Glucose  Acetic  acid. 

Buchner  and  Meisenheimer  *  have  been  able  to  show  that  this  change 
in  certain  fermentations  is  produced  by  a  specific  enzyme  which  they 
found  possible  to  isolate.  Many  investigators  believe  that  all  other 
acid  fermentations  of  glucose  are  also  the  result  of  special  oxidizing 
enzymes  or  oxidases;  this  view,  however,  requires  considerable  more 
experimental  proof  before  it  can  be  accepted. 

Ester  Fermentation.  —  In  many  fermentations  of  glucose,  as  by  the 
Bacillus  suavolens,  the  production  of  alcohol  and  acids  proceeds  simul- 
taneously, the  result  being  the  formation  of  different  fruity  esters,  such 
as  ethyl  acetate,  ethyl  butyrate  and  ethyl  valerate. 

The  chemistry  of  the  different  compounds,  which  are  formed  in  the 
fermentation  of  glucose  and  other  sugars,  is  so  extensive  that  the 
student  is  referred  for  further  particulars  to  the  special  works  upon 
the  subject.f 

Action  of  Alkalies  upon  d-Glucose.  —  The  products  obtained  by 
heating  d-glucose  with  caustic  alkalies  have  been  briefly  referred  to. 
The  chief  product  of  this  decomposition  is  d,  1-lactic  acid,  the  occur- 
rence of  which  in  molasses  is  due  to  the  action  of  lime  during  clarifica- 
tion upon  glucose  and  fructose.  The  lactic  acid  is  easily  obtained  from 
molasses  by  acidifying  with  sulphuric  acid  and  extracting  with  ether. 

Saccharin.  —  Another  alkali-decomposition  product  of  glucose, 
which  is  found  in  sugar-house  products,  is  saccharin,  C6Hi0O5,  the  lac- 
tone  of  saccharinic  acid  C6H1206.  Saccharin  is  prepared  according  to 
Scheibler  by  dissolving  1  kg.  of  d-glucose  (or  d-fructose)  in  7  to  8  liters 
of  water,  and  adding,  with  continuous  boiling,  freshly  slacked  milk  of 
lime,  so  that  the  solution  is  still  alkaline  after  3  to  4  hours.  The  cooled 
solution  is  saturated  with  carbon  dioxide  and  the  filtrate  treated  with 
oxalic  acid  just  sufficient  to  combine  with  all  the  lime.  The  filtrate 
containing  the  saccharinic  acid  is  evaporated  to  a  sirup,  which  after 
long  standing  deposits  crystals  of  saccharin. 

Saccharinic  acid,  which  is  an  isomer  of  glucose,  is  the  a-methyl 

*  Ber.,  36,  634. 

t  Particularly  Lippmann's  "  Chemie  der  Zuckerarten  "  and  Lafar's  "  Tech- 
nische  Mykologie." 


THE   MONOSACCHARIDES  587 

derivative  of  d-arabonic  acid,  whose  structural  formula  and  that  of 
saccharin  are  as  follows  : 

CH2OH  CH2OH 

HOCH  f  -  CH 

HOCH  j         HOCH          +  H2O 
H3C-COH 

COOH  l  -  CO 

Saccharinic  acid  Saccharin 

(a-methyl-d-arabonic  acid)  (a-methyl-d-arabonic 

acid  lactone). 

Saccharin  forms  clear  rhombic  double-refracting  crystals  which  melt 
at  160°  C.  and  sublime  without  decomposition.  It  is  easily  soluble  in 
water,  alcohol  and  ether,  is  not  fermented  by  yeast,  and  does  not  re- 
duce Fehling's  solution.  The  specific  rotation  is  [a]D  =  +93.5. 

Saccharin  is  a  type  of  a  large  group  of  isomeric  substances  *  (iso- 
saccharins,   metasaccharins,  etc.)  which  are  produced  by  the  action 
of  alkalies  upon  different  sugars.     Nef  by  the  action  of  8  normal  sodium 
hydroxide  upon  d-glucose  obtained  a-  and  0-  dextro-metasaccharins. 
CH2OH  CH2OH 

HOCH  HOCH 

CH  .  --  CH 

HCH  I   HCH 

HOCH  I   HCOH 


a-Dextro-metasaccharin  j8-Dextro-metasaccharin 

[a]D  =  +25.28  [«lz>  =  +8.2 

m.p.  =  104°  C.  m.p.  =  92°  C. 

Tests  for  d-Glucose.  —  No  single  sugar  has  been  subjected  to 
such  a  variety  of  tests  as  d-glucose,  and  the  various  compounds  which 
have  been  obtained  in  its  combination  with  different  reagents  number 
many  hundred. 

Glucose  in  its  reduction  of  alkaline  solutions  of  copper,  silver,  mer- 
cury and  other  metals,  in  its  color  reactions  and  many  other  tests 
behaves  in  the  same  way  as  other  sugars  of  the  aldose  class.  The  fol- 
lowing reactions  are  given  as  among  the  more  characteristic  of  glucose 
and  its  derivatives. 

Saccharic  Acid  Test  for  Glucose.  —  Glucose  and  the  various  sub- 
stances which  yield  glucose  upon  hydrolysis  are  oxidized  by  strong 

*  For  further  particulars  upon  the  different  saccharins  see  Kiliani  (Ber.,  15, 
701,  2953;  16,  2625;  18,  631,  2514)  and  Nef  (Ann.,  376,  1). 


588  SUGAR  ANALYSIS 

nitric  acid  to  saccharic  acid,  which  is  recognized  by  means  of  its  acid 
potassium  or  silver  salt.  The  test,  according  to  Tollens  and  Gans,*  is 
best  carried  out  as  follows: 

Five  grams  of  the  material  to  be  examined  are  treated  in  a  porcelain 
dish  with  30  c.c.  of  nitric  acid  of  1.15  sp.  gr.  and  the  mixture  evapo- 
rated with  constant  stirring  upon  a  boiling  water  bath  until  evolution  of 
red  fumes  has  ceased  and  the  resulting  sirup  has  just  begun  to  take  on 
a  permanent  yellow  color.  The  sirup  is  then  taken  up  with  a  little 
water,  heated  over  a  flame  and  powdered  potassium  carbonate  added 
until  a  drop  of  the  brownish  colored  solution  gives  a  blue  reaction  with 
red  litmus  paper.  Glacial  acetic  acid  is  then  added  drop  by  drop  until 
the  mixture  gives  off  a  strong  odor  of  acetic  acid.  If  glucose  was  present 
in  the  original  substance  crystals  of  acid  potassium  saccharate  will 
usually  soon  separate;  if  crystallization  does  not  take  place  after  a  few 
hours'  standing,  as  may  happen  when  only  small  amounts  of  glucose  are 
present,  the  sirup  should  be  concentrated  further  by  gentle  evapo- 
ration. After  24  hours'  standing  the  crystals,  which  have  formed,  are 
filtered  off,  or  drained  upon  unglazed  porcelain,  and  then  recrystallized 
from  the  smallest  possible  amount  of  hot  water.  A  third  crystallization, 
using  bone  black,  will  usually  eliminate  the  last  traces  of  oxalic  acid 
and  other  impurities  and  give  a  perfectly  pure  salt.  The  yield  of  acid 
potassium  saccharate  by  this  method  is  about  30  to  40  per  cent  of  the 
original  amount  of  glucose.  The  compound  consists  of  shining  rhom- 
bic crystals  with  characteristic  trapezoidal  faces,  the  appearance  of 
which  under  the  microscope  is  unmistakable.  Acid  potassium  sac- 
charate has  the  formula  COOH  (CHOH)4  COOK. 

The  acid  potassium  saccharate  as  above  prepared  can  be  further 
identified  by  conversion  to  the  silver  salt.  For  this  purpose  the  acid 
potassium  salt,  after  drying  and  weighing,  is  dissolved  in  a  little  water, 
to  which  ammonia  is  then  added  to  the  point  of  neutrality.  The  solu- 
tion is  then  poured  into  a  cold  silver  nitrate  solution  containing 
AgNOa  to  the  amount  of  1  \  the  weight  of  the  acid  potassium  salt  taken. 
The  precipitated  saccharate  of  silver  after  standing  a  short  time  is 
filtered,  washed  free  from  silver  nitrate  and  then  dried  in  a  dark  place 
over  concentrated  sulphuric  acid.  The  silver  saccharate  has  the  for- 
mula CeHsOsAga  and  upon  ignition  in  a  porcelain  crucible  should  show 
50.91  per  cent  Ag. 

In  making  the  saccharic  acid  test  for  glucose  it  should  be  remem- 
bered that  d-gluconic,  d-glucuronic  and  d-gulonic  acids  and  d-gulose 
also  give  saccharic  acid  upon  oxidation  with  nitric  acid.  This  limita- 

*  Ber.,  21,  2149. 


THE   MONOSACCHARIDES  589 

tion,  however,  is  a  comparatively  slight  one  and  the  saccharic  acid  re- 
action upon  the  whole  is  one  of  the  best  tests  for  d-glucose  in  presence 
of  other  sugars. 

Hydrazones  and  Osazones  of  Glucose.  —  d-Glucose  forms  a  large  num- 
ber of  hydrazones  with  phenylhydrazine  and  its  substituted  deriva- 
tives. With  phenylhydrazine  itself  two  isomeric  hydrazones  are 
formed,  one  modification  melting  at  144°  to  146°  C.  and  the  other  at 
115°  to  116°  C.  The  exact  conditions  under  which  these  two  isomers 
are  formed  and  their  structural  relationship  are  not  fully  understood 
(see  p.  359). 

Fischer  *  and  Stahel  f  recommended  the  diphenylhydrazone  as  one 
of  the  best  compounds  for  identifying  glucose.  To  carry  out  the  test 
1  part  of  sugar  is  dissolved  in  as  little  water  as  possible  and  1.5  parts  of 
diphenylhydrazine  in  alcoholic  solution  are  added;  if  the  mixture  is  not 
clear  a  little  water  or  alcohol  is  added  until  the  turbidity  disappears. 
By  allowing  the  mixture  to  stand  several  days  the  diphenylhydrazone 
C6H1205  :  N  —  N(C6H5)2  will  separate  as  small  colorless  prisms, 
which,  after  recrystallizing  from  hot  water,  should  melt  at  161°  to 
162°  C.  By  heating  the  mixture  of  sugar  and  diphenylhydrazine  in  a 
flask  attached  to  a  reflux  condenser  the  formation  of  the  hydrazone  is 
completed  within  2  hours.  Upon  evaporating  the  alcohol  and  taking 
up  the  uncombined  hydrazine  with  ether  the  hydrazone  will  quickly 
separate.  The  glucose-diphenylhydrazone  is  insoluble  in  ether  and 
addition  of  the  latter  will  hasten  crystallization.  The  diphenylhydra- 
zone reaction  offers  an  easy  means  for  separation  of  d-glucose  from 
d-fructose  and  other  sugars.  In  case  of  a  mixture  of  sugars  it  is  ad- 
visable to  conduct  the  reaction  in  the  cold.  It  should  be  remembered 
in  making  the  test  that  arabinose  also  gives  a  characteristic  insoluble 
hydrazone  with  diphenylhydrazine;  the  two  compounds  can  easily  be 
separated,  however,  by  crystallization  and  are  readily  distinguished 
from  one  another  by  their  differences  in  melting  point  and  composition. 

Glucose-benzhydrazone  J  C6Hi2O5  :  N  —  NH  •  COCeH5  and  methyl- 
phenylhydrazone  §  CeH^Os:  N  —  NCH3  •  C6H5  have  also  been  em- 
ployed for  the  separation  and  identification  of  glucose.  Glucose  may 
be  separated  from  its  hydrazones  by  decomposing  the  latter  with  benzal- 
dehyde  or  formaldehyde  as  described  on  page  348.  The  free  sugar, 
which  is  thus  liberated,  may  be  crystallized  and  further  identified  by 
determining  its  specific  rotation. 

The  best-known  and  earliest  studied  hydrazine  derivative  of  glucose 

*  Ber.,  23,  805.  t  Wolff,  Ber.,  28,  160. 

t  Ann.,  258,  242.  §  Neuberg,  Ber.,  36,  965. 


590  SUGAR  ANALYSIS 

is  the  phenylosazone  C6Hi0O4(  :  N  —  NH  •  C6H5)2.  The  compound  is 
obtained  as  yellow  needle-shaped  crystals  by  heating  1  part  glucose, 
2  parts  phenylhydrazine  chloride  and  3  parts  sodium  acetate  in  20 
parts  of  water.  The  osazone  is  purified  by  recrystallizing  from  alcohol, 
and  should  have  a  melting  point  of  205°  to  206°  C.  (capillary  tube 
method). 

The  osazone  reaction  of  glucose  is  of  but  little  value  as  a  means  of 
identification,  owing  to  the  fact  that  d-mannose  and  d-fructose  both 
give  the  same  compound. 

Reduction  of  Glucose.  —  d-Glucose  upon  treatment  with  sodium 
amalgam  in  acid  solution  is  reduced  to  the  alcohol  d-sorbite. 


CH2OH 

CH2OH 

HOCH 

HOCH 

HOCH 

HOCH 

HCOH 

-H2=          | 
HCOH 

HOCH 

HOCH 

CHO 

d-Glucose 

CH2OH 

d-Sorbite. 

If  the  reaction  is  allowed  to  proceed  in  alkaline  solution  mannite  is 
also  formed,  owing  to  rearrangement  of  a  part  of  the  glucose  into 
d-mannose  and  d-fructose  previous  to  reduction. 

Glucose  is  oxidized  in  aqueous  solution  by  means  of  bromine  to 
gluconic  acid  CH2OH(CHOH)4COOH,  which  upon  evaporation  gives 
the  lactone  C6Hio06([a]Z)  after  solution  =  +  68.2). 

The  reactions  of  glucose  with  benzoyl  chloride,  formaldehyde,  acetic 
anhydride,  mercaptan,  etc.,  have  already  been  referred  to. 

The  Synthetic  Glucosides.  —  Reference  has  already  been  made  to 
the  combination  of  reducing  sugars  with  alcohols.  These  compounds, 
while  of  little  analytical  importance,  have  considerable  theoretical  in- 
terest, and  the  following  description  is  given  of  the  methyl  derivatives 
of  glucose. 

The  combination  of  d-glucose  and  methyl  alcohol,  according  to 
Fischer's  *  early  method,  is  accomplished  by  dissolving  glucose  in  cold 
methyl  alcohol  and  saturating  the  solution  with  dry  hydrochloric  acid 
gas.  Crystals  of  the  a-methyl  glucoside  are  obtained  upon  evaporating 
the  solution;  the  mother  liquor  contains  a  second  isomeric  /3-methyl 
glucoside,  which  can  be  isolated  by  careful  fractional  crystallization. 

*  Ber.,  26,  2400;  28,  1151. 


THE   MONOSACCHARIDES 


591 


The  a-  and  /3-methyl  glucosides,  although  having  the  same  general 
formula,  C7Hi4O6,  show  a  marked  difference  in  certain  of  their  properties, 
as  is  seen  from  the  following: 


a-Methyl  glucoside. 

/3-Methyl  glucoside. 

Melting  point         

165°-166°  C. 
+  158 
Hydrolyzing 
Non-hydrolyzing 

108°-110°  C. 
-32 
Non-hydrolyzing 
Hydrolyzing 

Specific  rotation 

Action  of  rnalta.se 

Action  of  emulsin 

Following  the  suggestion  of  Simon  *  the  a-  and  /3-methyl  glucosides 
of  high  and  low  rotation  are  usually  regarded  as  respective  compounds 
of  the  high  rotating  a-glucose  and  low  rotating  /3-glucose.  Armstrong,! 
in  fact,  showed  by  polariscopic  measurements  that  a-methyl  glucoside 
was  resolved  by  the  enzyme  maltase  (a-glucase)  into  a-glucose  of  high 
initial  rotation  and  /3-methyl  glucoside  by  the  enzyme  emulsin  ((3-glucase) 
into  /3-glucose  of  low  initial  rotation.  Adopting  the  formula?  given  on 
page  192  for  a-  and  0-glucose,  the  configurations  of  a-  and  /3-methyl 
glucoside  would  be. 


(J 


CH2OH 

HOCH 

1 

CH                         | 

HCOH 

1                            C 

HOCH 

1 

CH2OH 
HOCH 

in 

V/il 

HCOH 
'              | 

HOCH 
H3-0-C-H 

8-Methyl  glucoside. 

H-C-0-CH3       C 

a-Methyl  glucoside. 

Testing  the  hydrolyzing  power  of  maltase  or  emulsin  upon  the 
glucosides,  disaccharides  and  other  natural  condensation  products 
of  glucose  has  been  used  by  Armstrong  t  as  a  means  of  determin- 
ing whether  the  glucose  in  a  given  combination  belongs  to  the  a-  or 
jS-form. 

Compounds  resembling  the  a-  and  /3-methyl  glucosides  have  been 
prepared  by  condensing  glucose  with  other  alcohols.  The  compounds 
have  usually  a  sweet  taste,  do  not  reduce  Fehling's  solution,  and  ex- 
hibit none  of  the  other  aldehyde  properties  peculiar  to  glucose. 

*  Compt.  rend.,  132,  487,  596. 

t  J.  Chem.  Soc.,  83,  1305. 

t  Armstrong's  "  The  Simple  Carbohydrates  and  Glucosides  "  (1910),  43. 


592  SUGAR  ANALYSIS 

1-Glucose.  — 


\-/ 

Hi 


CH2OH 

OH 
HCOH 
HOCH 
HCOH 


1-Glucose  has  not  been  found  free  in  nature  and  possesses  only  a 
theoretical  interest  from  the  relationship  to  its  d-isomer.  The  sugar  has 
been  prepared  synthetically  *  from  the  pentose  sugar  1-arabinose. 
The  latter  upon  treatment  with  hydrocyanic  acid  and  saponincation 
of  the  addition  product  (Kiliani's  cyanhydrine  synthesis)  gives  a  mix- 
ture of  the  two  hexonic  acids. 

CH2OH  CH2OH 

HCOH  HCOH 

HCOH  HCOH 

HOCH  HOCH 

HCOH  HOCH 
CqOH  COOH 

l-Gluconic  acid.  1-Mannonic  acid. 


The  1-gluconic  and  1-mannonic  acids  are  separated  by  crystalliza- 
tion of  their  lactones.  The  lactone  of  1-gluconic  acid  is  reduced  by 
sodium  amalgam  to  1-glueose. 

Properties.  —  1-Glucose  consists  of  small  prismatic  crystals  melting 
ing  at  141°  to  143°  C.  In  its  outward  properties  the  sugar  resembles 
d-glucose.  Its  specific  rotation  was  found  by  Fischer  to  be  [a]D  =  —  51.4; 
mutarotation  was  present,  the  reading  after  solution  being  —  95.5. 

1-Glucose  is  not  fermented  by  yeast  and  in  this  respect  shows  an 
important  difference  from  d-glucose. 

Nitric  acid  oxidizes  1-glucose  to  1-saccharic  acid  whose  acid  potas- 
sium and  silver  salts  resemble  those  of  .d-saccharic  acid. 

Diphenylhydrazine  forms  with  1-glucose  a  characteristic  hydrazone, 
which  melts  at  162°  C.  and  is  in  other  respects  very  similar  to  d-glu- 
cose-diphenylhydrazone.  The  phenylosazone  of  1-glucose  is  formed  un- 
der the  same  conditions  as  d-glucose-phenylosazone  and  resembles  the 
latter  in  melting  point,  crystalline  form  and  solubility;  it  is  readily  dis- 
*  Fischer,  Ber.,  23,  2611. 


THE  MONOSACCHARIDES  593 

tinguished,  "however,  from  the  d-glucose-osazone  by  its  dextrorotation 
in  glacial  acetic  acid  solution. 

d,  1-Glucose.  —  Racemic  glucose  was  obtained  by  Fischer,*  as  a 
sweet  colorless  inactive  sirup,  by  dissolving  equal  parts  of  d-  and  1-glu- 
cose  in  water  and  evaporating. 

d,  1-Glucose  gives  with  diphenylhydrazine  a  colorless  diphenyl- 
hydrazone  of  melting  point  132°  to  133°  C.,  which  is  30°  C.  below  the 
melting  point  of  either  d-  or  1-glucose-diphenylhydrazone.  Oxidation 
of  d,  1-glucose  with  nitric  acid  gives  d,  1-saccharic  acid,  whose  acid- 
potassium  salt  is  very  similar  to  those  of  its  d-  and  1-components. 

Racemic  glucose  is  easily  resolved  by  means  of  yeast,  the  d-glucose 
being  completely  fermented  and  the  1-glucose  remaining  behind. 

D-MANNOSE.  —  Seminose. 

CH2OH 


HOCH 
HOCH 
HCO 
HCOH 


H 


CHO. 

Occurrence.  —  d-Mannose  is  found  in  the  free  condition  accord- 
ing to  different  investigators  in  the  juices  of  various  plants  and  in  many 
germinating  seeds.  The  sugar  has  also  been  found  in  certain  molasses 
from  tropical  cane-sugar  factories;  the  mannose  in  molasses,  however, 
is  not  derived  from  the  cane  but  is  formed  by  the  action  of  the  lime 
used  in  clarification  upon  the  glucose  and  fructose  of  the  cane  juice. 

d-Mannose  is  most  widely  distributed  in  nature  as  an  anhydride 
condensation  product  mannan  which  in  its  simple  or  complex  form 
makes  up  one  of  the  most  abundant  of  the  hemicelluloses. 

Mannan  (C6Hi0O6)n.  —  This  carbohydrate,  either  in  its  simple 
form  or  as  one  of  the  so-called  "  paired  mannans"  (glucomannan, 
galactomannan,  fructomannan,  etc.),  occurs  in  nearly  all  plants  from 
the  simplest  unicellular  Protophytes  to  the  most  highly  developed 
Phanerogams.  It  is  found  in  the  cellular  matter  of  yeast,  in  different 
moulds,  in  various  alga,  in  plant  gums,  in  the  wood,  bark  and  roots  of 
many  trees,  and  in  bulbs,  nuts,  grains,  seeds,  fruits,  berries,  leaves  and 
other  plant  tissues. 

*  Fischer,  Ber.,  23,  2611. 


594  SUGAR  ANALYSIS 

Yeast  Mannan.  —  A  convenient  material  for  preparing  one  of  the 
mannans  is  pressed  yeast  (manufactured  without  starch).  Salkowski's  * 
method  of  separating  and  purifying  yeast  mannan,  or  yeast  gum,  is  as 
follows:  500  gms.  of  yeast  are  boiled  gently  for  one-half  hour  with 
5  liters  of  3  per  cent  potassium  hydroxide.  The  solution  is  then  al- 
lowed to  stand,  and  the  clear  liquid,  which  is  poured  off,  heated  with 
750  c.c.  of  Fehling's  solution  upon  a  water  bath.  The  yeast  gum  is 
thrown  out  as  a  bluish  white  insoluble  copper  compound,  which  is 
purified  from  its  mother  liquor  by  boiling  and  squeezing  out  with  water. 
The  copper  compound  is  then  decomposed  by  rubbing  up  with  a  slight 
excess  of  hydrochloric  acid  and  4  to  5  volumes  of  90  per  cent  alcohol 
added.  The  acid  alcoholic  solution  is  poured  off  from  the  precipi- 
tated gum;  the  latter  is  then  dissolved  in  water  and  reprecipitated  by 
alcohol  as  before.  After  washing  with  a  little  absolute  alcohol  and 
ether,  the  gum  is  redissolved  in  25  parts  of  water,  a  few  drops  of 
hydrochloric  acid  are  added  and  the  solution  poured  into  7  volumes 
of  absolute  alcohol.  The  precipitated  gum  is  washed  with  alcohol 
and  ether  and  then  allowed  to  remain  under  ether  until  the  plastic 
mass  hardens  to  a  brittle  solid.  The  ether  is  then  poured  off,  the  gum 
ground  up  in  a  mortar  and  dried  over  sulphuric  acid. 

Yeast  mannan  consists  of  a  white  non-hygroscopic  powder,  easily 
soluble  in  warm  water  to  a  clear  limpid  solution  and  showing  a  specific 
rotation  of  WZ)=H-  90.1.  Hydrolysis  of  yeast  gum  with  hydrochloric 
or  sulphuric  acids  gives  large  amounts  of  d-mannose.  According  to 
Oshima  d-glucose  and  fucose  are  also  formed,  so  that  yeast  gum  in 
all  probability  belongs  to  the  complex  mannans. 

Salep  Mannan.  —  A  very  pure  mannan  has  been  prepared  from  the 
mucilage  of  salep,  a  drug  consisting  of  the  dried  decorticated  tubers  of 
different  orchidaceous  plants.  Salep  yields  from  40  to  50  per  cent 
of  mucilage;  the  latter  when  separated  from  insoluble  matter  con- 
sists almost  wholly  of  a  water  soluble  mannan,  which  can  be  precipitated 
from  solution  by  means  of  alcohol.  Salep  mannan  f  has  the  general 
formula  (C6HioO5)n  and  is  hydrolyzed  by  acids  first  to  lower  manno- 
saccharides  and  finally  to  d-mannose. 

Mannans  have  been  isolated  from  many  other  plant  substances, 
the  general  method  of  preparation  consisting  in  the  extraction  of  the 
material  with  hot  2  to  3  per  cent  alkali  and  precipitation  of  the  gum 
with  Fehling's  solution  as  described  under  the  method  for  yeast  gum. 
The  combining  power  of  Fehling's  solution  with  mannan  is  very  marked, 

*  Ber.,  27,  497,  925. 
t  Hilger,  Ber.,  36,  3198. 


THE   MONOSACCHARIDES  595 

the  reagent  causing  a  precipitation  of  1  part  mannan  in  1000  parts  of 
liquid. 

Preparation  of  Mannose.  —  Mannose  may  be  prepared  either  by 
hydrolysis  of  yeast  gum,  salep  mucilage  or  any  other  of  the  isolated 
mannans,  or  by  direct  hydrolysis  of  some  plant  rriaterial  rich  in  mannan. 
The  latter  method  is  the  most  direct  and  the  easiest  to  carry  out,  there 
being  several  common  vegetable  substances,  such  as  ivory  nuts,  carob 
beans,  coffee  berries,  date  seeds,  etc.,  which  yield  large  amounts  of 
mannose  upon  hydrolysis.  Ivory  nuts,  or  vegetable  ivory  (the  fruit  of 
Phytelephas  macrocarpa),  which  is  used  so  extensively  for  making  but- 
tons, is  one  of  the  best  substances  for  preparing  mannose.  The  method 
of  Fischer  and  Hirschberger  *  is  as  follows : 

Preparation  of  d-Mannose  from  Ivory  Nuts.  —  One  part  of  ivory- 
nut  shavings  (from  button  factories)  is  heated  with  2  parts  of  6  per 
cent  hydrochloric  acid  in  a  boiling  water  bath  for  6  hours  in  a  flask 
connected  with  a  reflux  condenser.  The  hot  solution  is  then  pressed 
out  from  the  insoluble  residue  and  the  latter  treated  with  a  little 
water  and  repressed.  The  combined  extract  is  then  neutralized  with 
sodium  hydroxide,  decolorized  with  bone  black,  filtered  and  treated  in 
the  cold  with  an  excess  of  phenylhydrazine  (0.3  gm.  for  every  1  gm.  of 
ivory-nut  shavings)  dissolved  in  acetic  acid.  The  very  insoluble  man- 
nose-hydrazone  soon  separates  as  a  thick  crystalline  precipitate,  which 
is  filtered  off  after  24  hours,  washed  with  cold  water  and  dried.  The 
hydrazone  may  be  purified  by  recrystallizing  from  a  large  volume  of 
hot  water  or  from  50  per  cent  alcohol  containing  a  little  pyridine,  but 
for  the  purpose  of  preparing  mannose  the  troublesome  recrystallization 
may  be  dispensed  with. 

Mannose  may  be  separated  from  its  hydrazone  by  any  of  the  methods 
previously  described  (p.  348).  The  best  procedure  according  to  Tol- 
lens  f  is  the  following:  50  gms.  of  mannose  hydrazone,  40  gms.  of  benzal- 
dehyde,  50  gms.  of  alcohol  and  50  gms.  of  water  are  heated  upon  the 
water  bath  for  about  one-half  hour  in  a  flask  connected  with  a  reflux 
condenser.  The  solution  is  then  cooled  and  filtered  from  the  insolu- 
ble benzaldehyde-hydrazone;  the  filtrate  is  shaken  out  with  ether,  de- 
colorized with  bone  black,  filtered  and  evaporated  to  a  sirup.  The 
latter  rarely  crystallizes  until  it  has  been  primed  with  a  crystal  of 
mannose  from  a  previous  preparation. 

Crystallized  mannose  has  been  prepared  by  van  Ekenstein  J  by  dis- 

*  Ber.,  22,  3218. 

t  Abderhalden's  "  Biochem.  Arbeitsmethoden  "  (1909),  II,  74. 

j  Rec.  trav.  Pays-Bas,  14,  329;  15,  222. 


596  SUGAR  ANALYSIS 

solving  mannose  sirup  in  methyl  alcohol,  adding  a  half  volume  of 
ether  and  after  24  hours  decanting  from  the  sirupy  precipitate.  The 
methyl-alcohol-ether  solution  on  long  standing  will  deposit  crystals  of 
mannose,  which  may  be  used  for  priming  impure  sirups. 

After  the  mannose-containing  sirup  has  crystallized,  the  sugar  is 
freed  from  its  mother  liquor  by  spreading  upon  porous  plates  and  then 
purified  by  recrystallizing. 

According  to  Neuberg  and  Mayer  *  mannose  is  best  separated  from 
its  hydrazone  by  means  of  formaldehyde.  The  sugar  crystallizes  at 
once  in  a  highly  pure  condition  without  a  trace  of  decomposition  prod- 
ucts. 

Preparation  of  d-Mannose  from  Carob  Beans.  —  d-Mannose  has  been 
obtained  by  Herissey  f  from  the  seeds  of  the  carob  bean  (St.  John's 
bread)  by  allowing  the  mannan  of  the  seeds  to  react  with  the  ac- 
companying enzyme,  seminase:  500  gms.  of  the  finely  ground  seeds 
are  treated  with  a  solution  of  60  gms.  sodium  fluoride  in  4000  c.c.  of 
water  and  allowed  to  stand  at  33°  to  35°  C.  The  fluoride  prevents 
fermentation  by  microorganisms,  while  the  seminase  of  the  seeds  con- 
verts the  mannan  to  d-mannose,  which  is  precipitated  from  solution 
as  the  hydrazone  according  to  the  method  described. 

Synthesis  of  d-Mannose.  —  d-Mannose  has  been  made  syntheti- 
cally in  a  number  of  ways.  d-Mannite  is  oxidized  by  dilute  nitric  acid  to 
d-mannose  which  can  then  be  separated  as  the  hydrazone.  d-Mannose 
can  also  be  formed  from  d-glucose  and  d-fructose,  through  molecular 
rearrangement  by  action  of  dilute  alkalies  (p.  303).  The  sugar  has 
also  been  built  up  by  Fischer  J  from  formaldehyde;  the  latter  by  con- 
densation gives  d,  1-fructose,  which  upon  reduction  gives  d,  1-mannite, 
and  this  upon  oxidation  with  bromine  yields  d,  1-mannonic  acid.  The 
latter  is  resolved  by  crystallization  of  its  strychnine  salts  into  the  d- 
and  1-components.  The  lactone  of  the  d-mannonic  acid  upon  reduction 
gives  d-mannose. 

Properties  of  d-Mannose.  —  d-Mannose  crystallizes  as  the  anhy- 
dride C6Hi206  in  rhombic  crystals  melting  at  132°  C.  The  sugar  has 
a  pleasant  sweet  taste  and  is  easily  soluble  in  water  and  80  per  cent 
alcohol,  very  slightly  soluble  in  hot  absolute  alcohol  and  insoluble  in 
ether. 

d-Mannose  has  a  constant  specific  rotation  of  [a]D  =  +  14.25;  the 
initial  rotation  is  to  the  left,  [a]D  3  minutes  after  solution  being  —  13.6. 

d-Mannose  is  fermented  by  yeast  to  alcohol  and  carbon  dioxide  in 

the  same  manner,  but  not  with  the  same  rapidity,  as  d-glucose.     The 

*  Z.  physiol.  Chem.,  37,  547.       f  Compt.  rend.,  133,  49,  302.       J  Ber.,  23,  370. 


THE   MONOSACCHARIDES  597 

sugar  is  also  easily  fermented  by  different  lactic  acid  organisms.  d-Man- 
nose reacts  with  alkalies  similarly  to  d-glucose. 

Tests  for  d-Mannose.  —  d-Mannose  is  best  recognized  by  means 
of  its  phenylhydrazone,  C6Hi2O5 :  N  —  NHC6H5,  to  which  repeated  refer- 
ence has  been  made.  The  compound  crystallizes  in  colorless  rhombic 
prisms,  which  melt  upon  slow  heating  at  186°  to  188°  C.,  but  with 
rapid  heating  at  195°  to  200°  C.  The  hydrazone  is  almost  insoluble  in 
cold  water,  but  is  dissolved  in  80  to  100  parts  of  hot  water;  it  is  but 
little  soluble  in  concentrated  alcohol,  ether  or  acetone;  the  best  solvent 
is  hot  60  per  cent  alcohol.  Dissolved  in  hydrochloric  acid  it  exhibits 
levorotation. 

On  long  heating  with  phenylhydrazine,  d-mannose,  or  its  hydra- 
zone,  is  converted  into  an  osazone  which  is  identical  with  that  of 
d-glucose  (p.  354). 

d-Mannose  upon  reduction  with  sodium  amalgam  is  converted  into 
its  alcohol  d-mannite,  which  melts  at  166°  C.  and  in  borax  solution  is 
dextrorotatory. 

d-Mannite  is  very  widely  distributed  in  nature  and  has  been  found 
in  ash  manna,  lilac  leaves,  mushrooms,  sea  algae  and  in  the  olive,  cactus, 
pineapple,  onion  and  many  other  plants.  The  best  natural  source  is 
ash  manna,  from  which  d-mannite  is  obtained  by  extraction  with  alcohol. 

Oxidation  of  d-mannose  with  bromine  in  aqueous  solution  gives 
d-mannonic  acid,  CH2OH(CHOH)4COOH,  whose  lactone,  C6Hi006,  is 
dextrorotatory  ([a]D  =  -f-  53.8).  Upon  oxidation  with  nitric  acid 
d-mannose  and  d-mannonic  acid  give  d-mannosaccharic  acid,  COOH 
(CHOH)4COOH,  whose  double  lactone,  C6H606,  melts  at  180°  to  190°  C. 
and  has  a  rotation  of  [a]D  =  +  201.8. 

1-Mannose.  -  CH2OH 

HCOH 
I 

rlOUxl 
HOCH 
HOCH 

CHO 

1-Mannose  has  not  been  found  in  nature  either  in  the  free  or  com- 
bined form;  it  has  been  prepared  synthetically  *  in  several  ways. 
The  best  starting  point  is  1-arabinose,  which,  as  shown  under  1-glucose, 
is  converted  by  means  of  Kiliani's  cyanhydrine  reaction  into  both 
1-gluconic  and  1-mannonic  acids.  The  lactone  of  the  latter  upon  re- 

*  Fischer,  Ber.,  23,  370. 


598  SUGAR  ANALYSIS 

duction  with  sodium  amalgam  gives  1-mannose.  The  sugar  can  also  be 
prepared  by  Fischer's  synthesis  from  formaldehyde  as  described  under 
the  synthesis  of  d-mannose.  1-Mannose  has  been  obtained  only  in 
form  of  a  colorless  unfermentable  levorotatory  sirup. 

Tests  for  l-Mannose.  —  1-Mannose  forms  with  phenylhydrazine  an 
insoluble  hydrazone,  which  resembles  d-mannose-phenylhydrazone  in 
melting  point  and  other  properties.  The  1-mannose-hydrazone,  how- 
ever, exhibits  dextrorotation,  when  dissolved  in  hydrochloric  acid,  and 
this  property  serves  to  distinguish  it  from  the  d-mannose-hydrazone. 
The  phenylosazone  of  1-mannose  is  identical  with  1-glucosazone. 

1-Mannose  upon  reduction  gives  its  alcohol  1-mannite,  which  melts 
at  166°  C.  and  in  borax  solution  is  levorotatory.  Oxidation  with  bromine 
converts  1-mannose  to  1-mannonic  acid,  whose  lactone  is  levorotatory 
([«]/>  =  ~  54.8).  Oxidation  with  nitric  acid  converts  1-mannose  and 
1-mannonic  acid  to  1-mannosaccharic  acid  whose  double  lactone  melts 
at  180°  C.  and  has  a  rotation  of  about  [a]D  =  -  200. 

d,  1-Mannose.  —  Racemic  mannose  was  obtained  by  Fischer  *  as  a 
colorless  inactive  sirup  by  reduction  of  the  lactone  of  d,  1-mannonic 
acid.  By  decomposing  d,  1-mannose-phenylhydrazone  with  formalde- 
hyde Neuberg  and  Mayer  f  obtained  d,  1-mannose  in  the  form  of  crys- 
tals which  melted  at  132°  to  133°  C.  d,  1-Mannose  forms  an  insoluble 
phenylhydrazone  melting  at  195°  C.;  its  osazone  is  identical  with 
d,  1-glucosazone.  The  sugar  upon  reduction  gives  d,  1-mannite;  oxida- 
tion with  bromine  yields  d,  1-mannonic  acid  and  with  nitric  acid  d,  1-man- 
nosaccharic acid. 

d,  1-Mannose  can  be  resolved  by  means  of  yeast  which  ferments  only 
the  d-mannose.  Indirectly  the  sugar  can  be  resolved  by  conversion  to 
d,  1-mannonic  acid.  The  strychnine  salt  of  the  latter  is  then  treated 
with  boiling  alcohol  which  dissolves  only  the  salt  of  the  d-acid.  The 
lactones  of  the  separated  mannonic  acids  yield  upon  reduction  the  re- 
spective sugars,  d-  and  1-mannose. 

D-GALACTOSE.  — 

CH2OH 
HOCH 


HCOH 
HCOH 
HOCH 


*  Ber.,  23,  381.  f  Z.  physiol.  Chem.,  37,  545. 


THE   MONOSACCHARIDES  599 

Occurrence.  —  Free  d-galactose  has  been  reported  as  occurring  in 
the  whey  of  milk  and  in  the  tissues  of  certain  seeds  during  germination; 
the  galactose  thus  found,  however,  is  purely  transitory,  being  derived 
by  enzyme  action  from  some  of  its  higher  condensation  products, 
which,  as  glucosides,  polysaccharides  and  hemicelluloses,  are  found 
widely  distributed  in  nature. 

d-Galactose  occurs  in  the  vegetable  world  as  a  constituent  of  many 
glucosides,  in  which  compounds  it  is  often  united  with  other  sugars. 
The  glucoside  xanthorhamnin,  which  gives  d-galactose  and  rhamnose 
upon  hydrolysis,  has  already  been  mentioned.  In  the  same  way  the 
glucoside  digitonin,  a  constituent  of  commercial  digitalis,  is  hydrolyzed 
by  heating  with  dilute  acids  into  galactose  and  glucose. 

C27H44013  +  2  H20  =  C6H1206  +  G6H1206  +  C15H2403. 

Digitonin  d-Galactose          d-Glucose  Digitogenin. 

Convallarin  and  convallamarin  from  Convallaria  majalis  (lily  of  the 
valley),  myrticolorin  from  the  leaves  of  Eucalyptus  macrorhyncha,  sapo- 
toxin  from  certain  species  of  Saponaria,  and  many  other  complex  glu- 
cosides, whose  constitution  remains  to  be  established,  yield  upon 
hydrolysis  d-galactose,  which  is  usually  mixed  with  other  sugars. 

d-Galactose  is  also  found  united  with  other  sugars  as  a  constituent 
of  different  higher  saccharides,  such  as  lactose,  melibiose,  raffinose,  rham- 
ninose  and  stachyose. 

Galactans.  —  d-Galactose  is  found  most  widely  distributed  in  the 
vegetable  kingdom  as  a  constituent  of  many  gums,  hemicelluloses, 
mucilages,  pectins  and  other  plant  materials.  In  these  cases  the  galac- 
tose usually  exists  as  an  anhydride  condensation  product  or  galactan. 
The  galactans  make  up  a  numerous  group  of  substances,  the  exact  con- 
stitution of  which  has  not  been  thoroughly  established.  In  the  galac- 
tans d-galactose  shows  the  same  tendency  to  form  combinations  with 
other  sugars  as  was  noted  in  the  case  of  its  glucosides  and  polysac- 
charides; there  are  arabogalactans,  xylogalactans,  mannogalactans, 
glucogalactans  and  other  combinations  each  of  which  shows  well- 
marked  differences  in  behavior  towards  alkalies  and  other  reagents. 

China  moss,  Ceylon  moss,  Irish  moss,  Iceland  moss  and  many 
other  plants  belonging  to  the  algae,  mosses  and  lichens  yield  mucilages, 
which  are  dissolved  by  hot  water  and  precipitated  therefrom  by  alcohol. 
The  substances  thus  prepared  consist  mostly  of  galactan  and  are 
hydrolyzed  by  hydrochloric  or  sulphuric  acid  to  d-galactose.  Oxida- 
tion with  nitric  acid  produces  large  quantities  of  mucic  acid. 

Arabogalactans  or  galactoarabans  are  found  in  the  seeds  of  lupines, 


600  SUGAR  ANALYSIS 

beans,  peas  and  other  legumes  *  in  amounts  varying  from  5  to  20  per 
cent.  The  cellular  tissues  of  the  crushed  seeds  are  extracted  succes- 
sively with  water,  alcohol,  ether  and  0.2  per  cent  potassium  hydroxide; 
the  residue  from  this  treatment  consists  largely  of  galactoaraban. 
The  crude  product  is  purified  by  dissolving  in  hot  2  per  cent  potassium 
hydroxide  and  precipitating  the  clear  solution  with  strong  alcohol, 
which  throws  out  the  galactoaraban  as  a  yellowish  colored  potassium 
compound.  The  latter  is  washed  with  alcohol,  decomposed  with  dilute 
acid  and  the  pure  gum  precipitated  by  addition  of  strong  alcohol. 

Galactoarabans  have  also  been  found  in  plant  exudations  and  gums, 
in  vegetable  mucilages,  in  the  slimy  envelopes  of  different  bacteria,  in 
unripe  sugar-beets  and  in  many  other  products.  The  galactoarabans 
are  easily  hydrolyzed  by  hydrochloric  and  sulphuric  acids  into  d-galac- 
tose  and  1-arabinose.  In  many  cases  this  hydrolysis  can  be  effected 
by  diastase  and  other  enzymes;  the  latter  in  the  process  of  germina- 
tion no  doubt  convert  the  galactoaraban  of  seeds  into  sugars  which 
are  then  assimilated  by  the  growing  embryo.  The  galactoarabans 
yield  mucic  acid  upon  oxidation  with  nitric  acid,  and  furfural  upon 
distillation  with  strong  hydrochloric  acid. 

Galactoxylan  f  has  been  found  as  a  gummy  constituent  of  the 
cellular  tissues  of  wheat,  barley  and  other  grains,  and  also  appears  to 
occur  in  various  complex  gums.  Gatactoxylan  is  hydrolyzed  by  dilute 
acids  to  galactose  and  xylose.  Mucic  acid  is  obtained  upon  oxidation 
with  nitric  acid,  and  furfural  upon  distillation  with  hydrochloric  acid. 

Galactomannan  I  occurs  as  a  constituent  of  many  hemicelluloses; 
it  has  been  found  in  the  coffee  berry,  in  cocoanuts,  in  the  carob  bean,  in 
the  seeds  of  Strychnos  Ignatii  (St.  Ignatius'  beans)  and  in  other  plant 
substances.  Hydrolysis  of  galactomannan  gives  galactose  and  mannose. 

Galactans  of  a  more  complex  character  than  the  above  are  also 
found  in  nature.  Among  such  galactans  may  be  mentioned  flax-seed 
mucilage,  which  upon  hydrolysis  gives  d-galactose,  d-glucose,  1-arabi- 
nose and  1-xylose. 

The  Pectins.  §  —  Closely  related  to  the  plant  mucilages  and  gums 
are  the  pectins,  an  important  group  of  substances  widely  distributed 
in  nature.  The  pectins  are  found  in  apples,  pears,  grapes  and  most 

*  Schulze,  Ber.,  22,  1192. 

t  Lintner  and  Dull,  Z.  angew.  Chem.  (1891),  538. 

t  Lippmann's  "  Chemie  der  Zuckerarten,"  p.  694. 

§  For  a  fuller  account  of  the  pectins  see  article  by  Victor  Grafe,  "  Biochem- 
isches  Handlexicon,"  pp.  80-94;  also  the  early  papers  by  Fremy  to  whom  much  of 
our  knowledge  is  due  (J.  Pharm.  [2],  26,  368  (1840);  Ann.  chim.  phys.  [3],  24,  5). 


THE   MONOSACCHARIDES  601 

other  fruits,  in  carrots,  beets  and  other  root  organs,  and  in  the  tissues 
of  many  other  plants,  as  the  flax  and  hemp. 

The  pectins,  which  are  soluble,  are  derived  from  an  insoluble  inter- 
cellular mother  substance,  called  pectose,  which  is  regarded  by  many 
chemists  as  an  oxygen,  or  acid,  derivative  of  cellulose.  The  conversion 
of  pectose  into  pectin  takes  place  in  the  ripening  of  fruits,  and  in  the 
retting  of  flax  and  hemp;  the  process  is  attributed  to  the  action  of  a 
special  enzyme  pectosinase. 

A  good  material  for  preparing  pectin  is  the  juice  of  ripe  pears.  The 
juice  is  treated  first  with  oxalic  acid  to  break  up  lime  compounds  and 
then  with  tannic  acid  to  precipitate  albumin.  The  clarified  juice  is 
filtered  and  treated  with  an  excess  of  strong  alcohol,  which  precipitates 
the  pectin.  The  latter  is  filtered  off,  purified  by  dissolving  in  water 
and  reprecipitating  with  alcohol,  and  then  dried  over  concentrated 
sulphuric  acid.  As  thus  prepared  pectin  consists  of  an  amorphous 
white  substance,  which  dissolves  easily  in  water  to  a  neutral  solution. 
The  pectins  differ  greatly  in  their  optical  properties;  the  pectin  from 
orange  skins,  for  example,  is  inactive,  while  the  pectin  from  goose- 
berries gives  [a]D  =  +  194. 

Upon  long  boiling  with  water  pectins  and  pectose  are  converted 
into  parapectin  of  weak  acid  reaction.  Boiling  with  dilute  acids  con- 
verts pectose,  pectin  and  parapectin  into  metapectin,  which  has  also 
the  properties  of  a  weak  acid. 

The  pectins  by  the  action  of  another  enzyme  pectase  are  converted 
into  pectic  acids,  the  calcium  salts  of  which  give  fruit  juices  the  prop- 
erty of  jellifying.  Pectic  acids  are  also  produced  from  pectose  and 
pectin  by  boiling  several  hours  with  dilute  alkali. 

As  precipitated  from  solutions  of  its  salts  pectic  acid  is  obtained  as 
a  white  amorphous  jellylike  mass,  insoluble  in  water,  alcohol  and  ether, 
but  easily  soluble  in  alkalies;  [a]D=+  186  to  +  300. 

Pectose,  pectin,  parapectin,  metapectin  and  pectic  acid  are  con- 
verted by  hot  alkaline  solutions  into  parapedic  acid.  The  final  prod- 
uct obtained  by  the  action  of  alkalies  upon  the  pectin  substances 
previously  named  is  metapectic  acid-,  which  is  identical  with  arabinic 
acid  described  under  1-arabinose. 

The  different  pectin  substances,  which  have  been  named,  are  all 
hydrolyzed  by  boiling  with  dilute  mineral  acids  into  d-galactose  and 
1-arabinose,  the  yield  of  each  sugar  depending  upon  the  nature  of  the 
product.  The  hydrolysis  of  the  pectins  into  galactose  and  arabinose  is 
also  supposed  by  some  to  take  place  in  nature  through  the  agency  of  a 
third  enzyme  pectinase. 


602  SUGAR  ANALYSIS 

Oxidation  of  the  pectins  with  nitric  acid  gives  a  large  yield  of 
mucic  acid,  and  distillation  with  hydrochloric  acid  produces  much 
furfural. 

The  chemistry  of  the  pectins  is  still  in  a  very  unsettled  condition. 
The  neutral  water-soluble  pectins  are  usually  regarded  as  lactones  or 
esters  of  the  various  pectic  acids,  but  the  constitution  of  the  latter, 
as  well  as  that  of  the  parent  substance  pectose,  has  not  been  deter- 
mined. 

d-Galactose  occurs  most  widely  in  the  animal  kingdom  as  a  con- 
stituent of  milk  sugar.  It  has  also  been  recognized  by  different 
investigators  among  the  saponification  products  of  protagon,  a  con- 
stituent of  nerve  and  brain  tissue.  The  galactose  in  protagon  is  sup- 
posed to  be  part  of  an  amino-phosphoric-fatty  acid  complex,  the  exact 
constitution  of  which  is  unknown.  d-Galactose  has  also  been  reported 
to  be  present  in  different  nucleo-proteids,  mucins  and  other  substances 
of  animal  origin,  but  the  identity  of  the  sugar  in  some  of  these  cases 
has  not  been  fully  established. 

Synthesis  of  d-Galactose.  —  The  synthesis  of  d-galactose  has 
been  accomplished  in  several  ways.  It  has  been  built  up  by  Fischer 
and  Ruff*  from  d-lyxose,  which,  by  addition  of  hydrocyanic  acid  and 
saponifying  (Kiliani's  cyanhydrine  synthesis),  gives  d-galactonic  and 
d-talonic  acids,  the  former,  however,  in  much  greater  amount,  f  The 
lactone  of  d-galactonic  acid  upon  reduction  gives  d-galactose. 

d-Galactose  has  also"  been  formed  by  Lobry  de  Bruyn  and  van  Eken- 
stein  |  by  heating  the  ketose  sugar  1-sorbose  with  dilute  alkalies,  a 
mutual  rearrangement  taking  place  between  these  two  sugars  similar 
to  that  noted  between  d-glucose  and  d-fructose. 

Preparation  of  d-Galactose.  From  Milk  Sugar.  —  d-Galactose  is 
most  easily  prepared  by  hydrolyzing  milk  sugar.  For  this  purpose 
1  part  of  milk  sugar  is  heated  with  10  parts  of  2  per  cent  sulphuric 
acid  in  a  boiling  water  bath  for  4  hours;  the  free  acid  is  then  neu- 
tralized with  an  excess  of  calcium  or  barium  carbonate  and  the  solution 
filtered  from  the  insoluble  residue  of  sulphate  and  carbonate.  The  fil- 
trate is  evaporated  to  a  sirup  which  will  usually  crystallize  within  a  few 
days;  crystallization  may  be  hastened  by  priming  the  sirup  with  a 
crystal  of  galactose  from  a  previous  preparation.  The  impure  galactose 

*  Ber.,  33,  2142. 

t  Fischer  calls  attention  to  the  fact  that  in  Kiliani's  synthesis  the  yield  of  the 
two  acids  is  never  the  same,  one  isomer  being  always  produced  in  larger  amount 
(Ann.,  270,  64). 

t  Rec.  trav.  Pays-Bas,  19,  1. 


THE  MONOSACCHARIDES  603 

from  the  first  crystallization  is  filtered  off,  washed  with  a  little  80  per 
cent  alcohol  and  then  redissolved  in  as  little  hot  water  as  possible; 
hot  strong  alcohol  is  then  added,  the  solution  boiled  with  a  little  bone 
black  and  filtered;  the  filtrate  upon  cooling  will  soon  deposit  crystals 
of  pure  d-galactose. 

Preparation  of  d-Galactose  from  Agar-agar.  —  d-Galactose  may  also 
be  prepared  by  hydrolysis  of  plant  materials  rich  in  galactan,  as  Agar- 
agar.  The  latter  when  heated  with  10  parts  of  2  per  cent  sulphuric  acid 
for  12  hours  in  a  boiling  water  bath  is  largely  hydrolyzed  to  d-galactose 
which  may  be  crystallized  by  neutralizing  the  acid  solution  and  evapo- 
rating to  a  sirup  as  described  in  the  preceding  method. 

Properties  of  d-Galactose.  —  d-Galactose  crystallizes  from  water 
as  a  monohydrate,  CeH^Oe.H^O,  in  the  form  of  large  prismatic  needles, 
and  from  strong  ethyl  and  methyl  alcohols  as  the  anhydride  in  the  form 
of  fine  hexagonal  crystals.  The  hydrate  melts  at  118°  to  120°  C.  and 
the  anhydride  at  about  165°  C.  The  sugar  has  a  sweet  taste,  is  easily 
soluble  in  water,  moderately  soluble  in  50  per  cent  alcohol,  but  practi- 
cally insoluble  in  absolute  alcohol  and  ether. 

d-Galactose  is  strongly  dextrorotatory;  the  value  for  constant 
rotation  is  about  [a]D  =  +  81,  the  figure  being  influenced  both  by  tem- 
perature and  concentration  (see  p.  181).  The  sugar  shows  strong 
mutarotation,  [a]D  immediately  after  solution  being  about  +140. 

Tanret  *  has  prepared  d-galactose  in  a  modification  of  low  specific 
rotation.  By  dissolving  12  gms.  of  ordinary  d-galactose  in  30  gms.  of 
water,  adding  0.03  gm.  of  sodium  phosphate  exactly  neutralized  with 
sulphuric  acid,  heating  a  few  minutes  on  the  water-bath  and  then,  after 
cooling,  strongly  agitating  with  200  c.c.  absolute  alcohol,  crystals  of  a 
galactose  are  obtained  which  give  after  solution  a  value  for  [a]D  of  only 
+53;  this  low  rotation,  however,  increases  upon  standing  of  the  solu- 
tion to  the  true  constant  value  of  ordinary  galactose.  The  transition  is 
effected  at  once  by  heating  the  solution  or  by  adding  a  trace  of  alkali 
just  as  with  the  high  rotating  form  of  galactose. 

Action  of  Alkalies  upon  d-Galactose.  —  By  the  action  of  dilute 
alkalies  d-galactose  is  transformed  into  a  mixture  of  isomeric  hexoses, 
d-talose,  d-tagatose,  1-sorbose  and  galtose  as  described  under  these 
several  sugars. 

By  the  action  of  8  normal  sodium  hydroxide  Nef  f  obtained  40  to  45 

per  cent  d,  1-lactic  acid,  10  per  cent  a-  d-galacto-metasaccharin,  5  to  10 

per  cent  0-  d-galacto-metasaccharin,  5  per  cent  a-and  /?-  d-isosaccharin, 

and   numerous   other   saccharins.      The   two   metasaccharins,  which 

*  Bull.  soc.  chim.  [3],  15,  195.  t  Ann.  376,  1. 


604  SUGAR  ANALYSIS 

are  the  most  important  of  the  group,  have  the  following  structural 

formulae: 

CH2OH  CH,OH 

HOCH  HOCH 


HC 1  HC . 

HCH  HCH 

JOH 


AJ.  \_yjL  A.  .LJ.V^JL 

[OCH        I  HC( 


oi- 


a-  d-Galactometasaccharin.  ft-  d-Galacto-metasaccharin. 

[a]g~-45.3  [a]g=- 62.96. 

m.  p.  =  144°  C.  m.  p.  =  55°  -  60°  C. 

The  a-  d-isosaccharin  is  described  under  lactose. 

Fermentation.  —  d-Galactose  is  fermented  by  yeast  in  presence 
of  suitable  nutrients  to  alcohol  and  carbon  dioxide;  the  fermentation 
proceeds,  however,  more  slowly  than  with  d-glucose  and  requires 
about  8  days  for  completion.  The  yield  of  ethyl  alcohol  with  cultures 
of  pure  yeast  is  about  45  to  46  per  cent  of  the  weight  of  galactose  taken. 
According  to  Buchner  and  Rapp  *  the  alcoholic  fermentation  of  d-ga- 
lactose  is  due  to  the  enzyme  zymase.  Different  species  of  Mucor  and 
other  moulds  also  cause  alcoholic  fermentation  of  d-galactose.f 

Many  lactic  acid  producing  organisms  cause  fermentation  of  d-galac- 
tose  with  formation  of  d,  1-lactic  acid;  with  some  organisms  the  1-lactic 
acid  is  produced  in  greater  amount. 

Bacterium  xylinum,  the  so-called  sorbose  bacterium,  oxidizes  d-ga- 
lactose  to  d-galactonic  acid. 

Tests  for  d-Galactose.  Mucic  Acid  Reaction.  —  The  test  most 
generally  employed  for  detecting  d-galactose,  either  in  the  free  or  com- 
bined form,  is  the  production  of  mucic  acid  upon  oxidation  with  nitric 
acid.  The  reaction  is  carried  out  as  described  under  the  determination 
of  galactan  (p.  459).  d-Galactose  by  this  method  t  yields  over  75  per 
cent  of  its  weight  as  mucic  acid.  It  must  be  remembered  that  mucic 
acid  is  also  formed  by  the  oxidation  of  1-galactose,  dulcite  and  d-  and 
1-galactonic  acids  so  that  other  reactions,  such  as  the  isolation  of  the 
sugar  from  its  hydrazone,  or  the  fermentation  test,  must  be  used  for 
confirmation. 

*  Ber.,  31,  1090. 

t  The  idea  of  Dubrunfaut  that  d-galactose  was  not  fermented  by  yeast  was 
shown  by  Pasteur  to  be  erroneous.  A  later  view  of  Bourquelot  that  d-galactose 
could  be  fermented  only  in  presence  of  glucose,  or  some  other  easily  fermentable 
sugar,  was  completely  disproved  by  Tollens  and  Stone. 

J  Tollens  and  Kent,  Ann.,  277,  222. 


THE  MONOSACCHARIDES  605 


Mucic  add  has  the  configuration: 

COOH 

HOCH 
HCOH 


HCOH 
HOCH 

io 


OH 

It  crystallizes  in  minute  granular  rhombic  prisms,  which  melt  on  rapid 
heating  at  212°  to  215°  C.  and  are  almost  insoluble  in  water  (1  part  in 
300  c.c.  cold  water).  Mucic  acid,  as  is  evident  from  its  symmetrical 
structure,  is  optically  inactive.  Upon  heating  with  concentrated  hydro- 
bromic  acid,  or  other  dehydrating  agents,  mucic  acid  is  converted  to 
dehydromucic  acid  (p.  781). 

Reactions  of  d-Galactose  with  Phenylhydrazine.  —  d-Galactose  when 
treated  with  phenylhydrazine  in  the  cold  in  the  proportion  of  5  parts 
sugar,  3  parts  water  and  5  parts  phenylhydrazine  deposits  within 
an  hour  a  thick  crystalline  mass  of  d-galactose-phenylhydrazone  * 
C6Hi205 :  N2HC6H5.  After  24  hours  the  crystals  are  filtered  off,  washed 
with  a  little  ether  and  recrystallized  from  hot  alcohol;  d-galactose 
phenylhydrazone  forms  fine  colorless  needles,  melting  at  158°  C.,  easily 
soluble  in  hot  water  and  alcohol,  but  insoluble  in  ether  and  chloroform. 
The  2  per  cent  aqueous  solution  is  levorotatory  f  ([a]D  =  —  21.6).  The 
phenylhydrazone  reaction  may  be  used  for  separating  d-galactose  from 
d-glucose  and  other  sugars  whose  hydrazones  separate  more  slowly. 

Methylphenylhydrazine  and  /3-naphthylhydrazine  also  form  with 
d-galactose  insoluble  hydrazones  which  may  be  employed  for  purposes 
of  identification. 

d-Galactose  may  be  separated  from  its  hydrazones  by  decomposing 
the  latter  with  formaldehyde  or  benzaldehyde  according  to  the  usual 
method. 

d-Galactose,  or  its  phenylhydrazone,  upon  heating  with  an  excess  of 
phenylhydrazine  is  converted  into  d-galactose-phenylosazone.  |  The 
latter  forms  fine  yellow  needles,  having  the  formula  CeHioO^^HCeHs^ 
and  melting  at  about  194°  to  196°C.;  presence  of  slight  impurities 
may  cause,  however,  marked  deviations  in  the  melting  point  (170°  to 
190°  C.).  d-Galactosazone  is  but  slightly  soluble  in  cold  water;  it  is 
more  soluble  in  hot  water  and  is  readily  dissolved  by  hot  60  per  cent 
alcohol. 

*  Fischer,  Ber.,  20,  821.      f  Jacobi,  Ann.,  272,  171.      J  Fischer,  Ber.,  17,  579. 


606  SUGAR  ANALYSIS 

Reduction  of  d-galactose  with  sodium  amalgam  gives  the  alcohol 
dulcite,  which  has  the  configuration : 

CH2OH 

HOCH 


OH 


Hi 
HCOH 
HOCH 
CH2 


OH 

As  is  evident  from  its  symmetrical  structure,  dulcite  is  optically 
inactive. 

Dulcite  is  found  in  nature  in  Madagascar  manna,  Melampyrum 
nemorosum  and  many  other  plants.  Its  melting  point  is  188°  C. 

Oxidation  of  d-galactose  with  bromine  in  aqueous  solution  gives 
d-galactonic  acid,  the  lactone  of  which  immediately  after  solution 
shows  a  rotation  of  about  [a]D  =  —  70. 

1-Galactose.  — 

CH2OH 


HCOH 
HOCH 
HOCH 

HCOH 


HO 

1-Galactose  has  been  found  in  nature  as  a  constituent  of  d,  1-ga- 
lactose  among  the  hydrolytic  products  of  several  plant  materials;  in 
gum  Chagual  by  Winterstein*  and  in  the  Japanese  food  product,  Nori, 
by  Tollens  and  Oshima.f 

1-Galactose  has  been  prepared  synthetically  |  by  reducing  the  lac- 
tone  of  1-galactonic  acid  which  is  formed  together  with  d-galactonic 
acid  by  reduction  of  mucic  acid  with  sodium  amalgam. 

Properties.  — ^1-Galactose  has  been  obtained  as  a  white  crystalline 
sugar  melting  at  162°  to  163°  C.,  easily  soluble  in  water  and  60  per 
cent  alcohol,  but  only  very  slightly  soluble  in  absolute  alcohol.  The 
sugar  is  strongly  levorotatory,  [a]D=  —  74°  about;  strong  mutarotation 
is  observed,  [a]D  8  minutes  after  solution  =  —  120. 

*  Ber.,  31,  1571.  t  Ber.,  34,  1422. 

t  Fischer  and  Hertz,  Ber.,  26,  1247. 


THE   MONOSACCHARIDES  607 

1-Galactose  is  not  fermented  by  yeast;  in  this  respect  the  sugar 
differs  from  the  behavior  of  d-galactose.  This  property  renders  it 
easy  to  detect  1-galactose  in  the  presence  of  d-galactose,  d-glucose, 
d-mannose,  d-fructose  and  other  fermentable  sugars. 

Tests.  —  1-Galactose  is  reduced  by  sodium  amalgam  to  dulcite  and  is 
oxidized  by  strong  nitric  acid  to  mucic  acid,  the  sugar  in  both  these  re- 
actions behaving  the  same  as  d-galactose;  this  agreement  in  behavior, 
in  fact,  follows  necessarily  from  the  configurations.  1-Galactose  is 
oxidized  with  bromine  to  1-galactonic  acid,  whose  lactone  (not  isolated 
as  yet  in  the  pure  condition)  is  dextrorotatory. 

1-Galactose  forms  with  phenylhydrazine  a  difficultly  soluble  hydra- 
zone  melting  at  158°  to  160°  C.  and  in  appearance  and  solubility  very 
similar  to  d-galactose-hydrazone.  The  aqueous  solution  of  1-galactose 
hydrazone,  however,  is  dextrorotatory,  [o:]D  =  + 21.6,  which  distin- 
guishes it  from  d-galactose  hydrazone;  1-galactose-phenylosazone  re- 
sembles in  its  appearance,  melting  point  and  solubility  the  osazone  of 
d-galactose. 

d,  1-Galactose.  —  Inactive  galactose,  as  previously  noted,  has 
been  found  in  a  few  cases  among  the  hydrolytic  products  of  certain 
plant  materials. 

The  sugar  has  been  prepared  synthetically  *  by  reducing  the  lactone 
of  d,  1-galactonic  acid,  which  is  itself  derived  by  reduction  of  the  lactone 
of  mucic  acid ;    d,  1-galactose  has  also  been  prepared  f  by  oxidizing 
dulcite  with  hydrogen  peroxide  in  presence  of  iron  salts. 
CH2OH  CH2OH          CHO 

HOCH        HOCH     HOCH 

HCOH        HCOH     HCOH 
2    I     +02=   I     -f   !      +2H20 
HCOH        HCOH  .   HCOH 

HOCH        HOCH     HOCH 
CH2OH        CHO      CH2OH 

Dulcite  d-Galactose         1-Galactose 

Properties.  —  d,  1-Galactose,  as  obtained  by  Neuberg  and  Wohl- 
gemuth,  |  was  found  to  have  all  the  properties  of  a  true  racemic  sub- 
stance. The  sugar  was  obtained  crystalline,  melted  at  143°  to  144°  C., 
was  optically  inactive  and  was  fermented  only  one-half  by  yeast,  the 
1-galactose  remaining  unattacked. 

*  Fischer  and  Hertz,  Ber.,  25,  1247. 

t  Neuberg  and  Wohlgemuth,  Z.  physiol.  Chem.,  36,  219. 

}  Ibid. 


608  SUGAR  ANALYSIS 

Tests.  —  d,  1-Galactose  is  reduced  by  sodium  amalgam  to  dulcite 
and  oxidized  by  strong  nitric  acid  to  mucic  acid,  these  reactions  being, 
of  course,  the  same  as  obtained  by  each  of  the  component  sugars. 

With  phenylhydrazine  d,  1-galactose  forms  an  insoluble  hydrazone, 
which  separates  rapidly  from  cold  solutions  of  the  sugar  and,  when 
purified,  consists  of  colorless  crystals  melting  at  158°  to  160°  C.  The 
hydrazone  is  decomposed  by  heating  with  formaldehyde  or  benzalde- 
hyde  with  liberation  of  the  free  sugar,  which  may  then  be  identified  by 
its  optical  inactivity,  by  formation  of  mucic  acid  with  nitric  acid  and 
by  leaving  a  residue  of  1-galactose  after  fermentation  with  yeast. 

Oxidation  of  d,  1-galactose  with  bromine  gives  d,  1-galactonic  acid. 
The  latter  can  be  resolved  into  its  components  by  fractional  crystalliza- 
tion of  its  strychnine  salt,  the  strychnine  compound  of  d-galactonic 
acid  separating  as  a  crystalline  deposit  while  that  of  1-galactonic  acid 
remains  in  the  mother  liquor. 

d-Gulose.  — 

CH2OH 

HCOH 

HOCH 

HCOH 

HCOH 

CHO 

d-Gulose  has  not  been  identified  with  certainty  in  any  plant  or  animal 
product.  The  sugar  has  been  prepared  synthetically*  by  reduction  of 
d-saccharic  acid,  which  is  converted  first  to  the  aldehyde  compound 
d-glucuronic  acid,  and  then  to  d-gulonic  acid. 

COOH        CHO          CH2OH 

HCOH        HCOH  HCOH 

HOCH   +  H2  =  HOCH  +  H2  =  HOCH   +  H2O 

HCOH        HCOH  HCOH 

HCOH        HCOH  HCOH 

COOH        COOH         COOH 

d-Saccharic  acid  d-Glucuronic  acid  d-Gulonic  acid 

The  lactone  of  d-gulonic  acid  upon  reduction  with  sodium  amalgam 
gives  d-gulose. 

*  Fischer  and  Piloty,  Ber.,  24,  521. 


THE   MONOSACCHARIDES  609 

d-Gulose  is  also  formed*  by  the  action  of  dilute  alkalies  upon  d-sorbose 
and  d-idose. 

Properties — d-Gulose  was  obtained  by  van  Ekenstein  and  Blanksmaf 
as  white  crystals  melting  at  165°  C.  and  giving  a  rotation  of  [a]D  = 
+  42.9.  The  sugar  is  not  fermentable. 

Tests.  —  d-Gulose  gives  upon  reduction  with  sodium  amalgam 
d-sorbite  and  upon  oxidation  with  nitric  acid  d-saccharic  acid.  In  these 
respects  the  sugar  behaves  the  same  as  d-glucose,  as  follows  necessarily 
from  the  configuration  of  the  two  sugars. 

Oxidation  of  d-gulose  with  bromine  in  aqueous  solution  gives 
d-gulonic  acid,  the  lactone  of  which  is  dextrorotatory  ([a]D  =  +  55 
about). 

The  phenylosazone  of  d-gulose  is  identical  with  that  of  d-idose  and 
of  d-sorbose,  these  three  sugars  standing  in  the  same  structural  relation- 
ship to  one  another  as  d-mannose,  d-glucose  and  d-fructose. 

1-Gulose.  — 

CH2OH 


HOCH 
HCO1 


>H 
HOCH 
HOCH 
CHO 

1-Gulose  has  not  been  found  as  yet  either  free  or  combined  in  any 
natural  product.  The  sugar  has  been  prepared  synthetically  from 
1-saccharic  acid  in  the  same  manner  as  d-gulose  from  d-saccharic  acid. 
1-Gulose  has  also  been  built  up  from  1-xylose  by  the  addition  of  hydro- 
cyanic acid  and  saponification  of  the  nitrile;  two  acids  are  formed,  as 
always,  in  this  synthesis,  1-idonic  and  1-gulonic.  The  lactone  of  the 
latter  upon  reduction  gives  1-gulose.f 

Properties.  —  1-Gulose  has  been  obtained  only  as  a  sweet  levo- 
rotatory  unfermentable  sirup  ([a]D  =  —  20.4  about). 

Tests.  —  1-Gulose  gives  upon  reduction  with  sodium  amalgam  1-sor- 
bite  and  upon  oxidation  with  nitric  acid  1-saccharic  acid.  Oxidation 
with  bromine  in  aqueous  solution  gives  1-gulonic  acid,  whose  lactone 
consists  of  large  rhombic  hemihedral  crystals  melting  at  181  °  C.  and 
showing  levorotation  ([a]D  =  —  55  about).  Oxidation  of  the  lactone 

*  Lobry  de  Bruyn  and  van  Ekenstein,  Rec.  trav.  Pays-Bas,  19,  1. 

t  Rec.  trav.  Pays-Bas,  27,  1. 

$  Fischer  and  Stahel,  Ber.,  24,  528. 


610  SUGAR  ANALYSIS 

with  hydrogen  peroxide  and  basic  ferric  acetate  gives  1-xylose,  the  start- 
ing point  for  the  synthesis  of  1-gulose. 

The  phenylosazone  of  1-gulose  is  identical  with  that  of  1-idose  and 
of  1-sorbose. 

d,  1-Gulose  is  obtained  *  by  reducing  the  lactone  of  d,  1-gulonic 
acid,  which  is  prepared  by  mixing  equal  parts  of  the  lactones  of  d-  and 
1-gulonic  acid.  The  sugar  has  been  obtained  only  as  a  sirup. 

The  lactone  of  d,  1-gulonic  acid  crystallizes  in  prisms  melting  at 
160°  C.  The  crystals  as  ordinarily  obtained  from  aqueous  solution 
show  opposite  hemihedry  f  and  the  opposite  forms  when  isolated  belong 
to  the  separate  lactones.  Such  crystals  represent,  of  course,  a  mixture 
and  not  a  true  racemic  combination,  which  should  show  only  one 
crystalline  form.  (See  page  785.) 

d-Idose.  — 

CH2OH 

HCOH 


HOCH 

HCOH 
HOCH 


d-Idose  has  not  been  found  in  nature  either  in  the  free  or  combined 
form.  It  has  been  prepared  synthetically  by  Fischer  {  by  reducing  the 
lactone  of  d-idonic  acid,  which  can  be  obtained  through  molecular  re- 
arrangement by  heating  d-gulonic  acid  with  pyridine  to  140°  C.  The 
sugar  is  also  formed  by  action  of  dilute  alkalies  upon  d-gulose  and 
d-sorbose. 

Properties  and  Tests.  —  d-Idose  has  been  obtained  only  as  a  clear 
non-fermentable  sirup.  Reduction  with  sodium  amalgam  gives  the 
alcohol  d-idite  and  oxidation  with  nitric  acid  gives  d-idosaccharic  acid, 
which  has  been  obtained  only  as  a  sirupy  mixture  of  the  acid  and  lac- 
tone ([a]D  =  over  +  100). 

d-Idose-phenylosazone  is  identical  with  that  of  d-gulose  and  d-sor- 
bose. 

*  Fischer  and  Curtiss,  Ber.,  25,  1025. 
t  Haushofer,  Ber.,  24,  530;  25,  1027. 
t  Fischer  and  Fay,  Ber.,  28,  1975. 


THE  MONOSACCHARIDES  611 

1-Idose.  — 

CH2OH 


HOCH 
HCOJ 


)H 
HOCH 
HCOH 
CHO 

1-Idose  has  not  been  discovered  as  yet  in  nature.  The  sugar  has 
been  prepared  synthetically  *  by  reducing  the  lactone  of  1-idonic  acid 
which  is  prepared  from  1-xylose  by  addition  of  hydrocyanic  acid  and 
saponifying  the  nitrile  (see  under  1-gulose). 

Properties  and  Tests.  —  1-Idose  has  been  obtained  only  as  a  colorless 
non-fermentable  sirup  ([a]D  —  +7.5).  Reduction  with  sodium  amal- 
gam gives  the  alcohol  1-idite  and  oxidation  with  nitric  acid  gives 
1-idosaccharic  acid,  which  has  been  obtained  only  as  a  sirupy  mixture 
of  acid  and  lactone  ([a]Z)  =  over  —  100). 

1-Idose-phenylosazone  is  identical  with  the  phenylosazones  of 
1-gulose  and  1-sorbose. 

d-Talose.  — 

CH2OH 

HOCH 

HCOH 

HCOH 

HCOH 

CHO 

d-Talose  has  not  been  discovered  as  yet  in  any  natural  product. 
The  sugar  has  been  prepared  synthetically  f  by  reducing  the  lactone 
of  d-talonic  acid,  which  can  be  obtained  through  molecular  rearrange- 
ment by  heating  d-galactonic  acid  with  pyridine  to  150°  C.  d-Talose 
is  also  formed  by  action  of  dilute  alkalies  upon  d-galactose. 

Properties  and  Tests.  —  d-Talose  has  been  obtained  only  as  a  sirup 
([a]D=+ 13.95) .  Reduction  with  sodium  amalgam  gives  d-talite  and  ox- 
idation with  nitric  acid  d-talomucic  acid.  The  latter  forms  microscopic 
crystals  melting  at  158°  C.  and  showing  dextrorotation,  [a]D  —  +  29.4. 
Oxidation  of  d-talose  with  bromine  in  aqueous  solution  gives  d-talonic 

*  Fischer  and  Fay,  Ber.,  28,  1975. 
t  Fischer,  Ber.,  24,  3622. 


612 


SUGAR  ANALYSIS 


acid,  which  has  been  obtained  only  as  a  levorotatory  sirup  consisting  of 
the  free  acid  and  lactone. 

d-Talose-phenylosazone  is  the  same  as  that  of  d-galactose,  this 
identity  following  from  their  structural  relationship. 

1-Talose.  — 

CH2OH 

HCOH 
HOCH 
HOCH 
HOCH 

CHO 

1-Talose  has  not  been  found  as  yet  in  nature,  nor  has  its  synthesis  been 
accomplished  so  far  as  known. 

KETOHEXOSES 

D-FRUCTOSE.  —  Levulose.     Fruit  sugar. 

CH2OH 

HOCH 
HOCH 
.HCOH 


=O 
H2OH 


Occurrence.  —  d-Fructose  is  one  of  the  most  abundant  and  widely 
distributed  sugars  found  in  nature.  In  the  free  condition  it  is  almost 
always  associated  with  glucose  as  a  constituent  of  plant  juices,  such  as 
the  must  of  fruits,  the  sap  of  green  leaves  and  stalks,  and  the  nectar 
of  flowers.  Owing  to  the  fact  that  d-glucose  and  d-fructose  occur  so 
often  in  very  nearly  equal  amounts,  it  is  supposed  that  the  two  sugars 
are  largely  formed  by  the  action  of  inverting  enzymes  upon  sucrose. 

The  relationship  of  fructose  to  glucose  and  sucrose  in  the  mixed 
sugars  of  different  plant  juices  may  be  seen  from  the  following  table: 


Fructose. 

Glucose. 

Sucrose. 

Average  of  25  different  tropical  fruits  *  

Per  cent. 

2.22 

Per  cent. 

2.63 

Per  cent. 

4.29 

Average  of  green  stalks  of  sugar  cane  f    (12  analyses) 
Average  of  green  leaves  of  sugar  cane  f    (2  analyses) 

1.56 
0.73 

1.81 
0.75 

5.20 
0.74 

*  Prinsen  Geerligs,  Chem.  Ztg.,  21,  719. 
t  Browne,  Bull.,  91,  Louisiana  Sugar  Experiment  Station. 


'THE  MONOSACCHARIDES  613 

d-Fructose  is  also  widely  distributed  in  nature  as  a  constituent  of 
various  anhydride  condensation  products,  such  as  complex  sugars  and 
polysaccharides. 

Among  the  complex  sugars,  which  give  d-fructose  upon  hydrolysis 
with  acids  or  enzymes,  may  be  mentioned  sucrose,  raffinose,  lupeose, 
stachyose,  secalose  and  gentianose. 

In  addition  to  the  complex  sugars  there  are  a  large  number  of 
plant  constituents  of  a  gummy  character  which  give  d-fructose  upon 
hydrolysis.  These  substances,  which  occur  mostly  as  a  reserve  ma- 
terial in  the  tubers  and  root  organs  of  several  families  of  plants,  are 
sometimes  called  inuloids  from  their  chief  representative  inulin.  The 
inuloids  have  the  same  general  formula  (C6Hi005)n  with  varying 
amounts  of  water  of  hydration  and  are  levorotatory,  the  values  for 
[a]D  ranging  from  about  —  20  to  —50;  they  are  all  soluble  in  hot  water, 
from  which  solution  they  are  precipitated  by  absolute  alcohol  or  by 
the  hydroxides  of  the  alkaline  earths.  The  inuloids  obtained  from  differ- 
ent sources  are  no  doubt  in  very  many  cases  identical,  the  differences 
in  analysis,  specific  rotation,  melting  point,  etc.,  being  probably  due 
to  accompanying  impurities. 

Inulin.  —  Inulin  occurs  very  widely  distributed  as  a  reserve  ma- 
terial in  the  root  organs  of  the  Compositse  and  allied  families  of  plants 
such  as  the  Campanulacese,  Lobeliaceae,  etc.  It  was  discovered  by 
Rose*  in  1804  in  the  roots  of  Inula  Helenium  (elecampane),  from 
which  plant  the  compound  derives  its  name.  The  tuberous  roots  of 
the  dahlia,  dandelion,  chicory,  Jerusalem  artichoke  (Helianihus  tuber- 
osus],  arnica  and  pyrethrum  are  other  examples  of  plant  materials  rich 
in  inulin.  Owing  to  its  use  by  plants  as  a  reserve  material  the  per- 
centage of  inulin  in  roots  and  tubers  is  subject  to  wide  fluctuations, 
being  usually  least  in  spring  and  greatest  in  autumn.  Dandelion  roots, 
for  example,  were  found  by  Dragendorff  f  to  contain  1.74  per  cent  inulin 
in  March  and  24  per  cent  in  October.  The  dahlia,  chicory,  pyr- 
ethrum and  Jerusalem  artichoke  may  contain  over  50  per  cent  inulin 
in  the  dry  substance  of  the  roots. 

Preparation  of  Inulin.  —  Inulin  may  be  prepared  according  to 
Kiliani  %  by  reducing  to  a  fine  pulp  the  ripe  tubers  (taken  in  autumn)  of 
the  dahlia,  chicory,  etc.,  boiling  the  material  with  water  in  presence  of 
calcium  carbonate  and  filtering.  The  filtrate  is  then  frozen  in  a  freez- 
ing mixture  and  after  thawing  out  the  precipitated  inulin  filtered  off; 

*  Gehlen's  Neues  allgem.  J.  Chem.,  3,  217. 
t  "  Monographic  des  Inulins  "  (1870). 
t  Ann.,  206,  147. 


614  SUGAR  ANALYSIS 

the  raw  product  thus  obtained  is  redissolved  in  hot  water  and  again 
frozen  out.  After  repeating  the  purification  in  this  way  for  several 
times  the  final  product  is  washed  with  93  per  cent  alcohol,  then  with 
a  little  ether  and  afterwards  carefully  dried  in  a  water  oven. 

Tanret*  recommends  a  preliminary  clarification  of  the  hot  root  ex- 
tracts with  lead  subacetate;  after  filtering,  the  solution  is  freed  from 
lead  by  sulphuric  acid  and  then  the  inulin  precipitated  by  adding  a 
concentrated  solution  of  barium  hydroxide  and  heating.  The  precipitate 
is  washed  with  cold  barium  hydroxide  solution  and  then  decomposed  in 
aqueous  suspension  with  carbon  dioxide;  the  solution  after  heating  is 
filtered  from  barium  carbonate,  and  the  inulin  precipitated  from  the 
filtrate  by  means  of  strong  alcohol. 


Fig.  194.  —  Sphere-crystals  of  inulin  (precipitated  from  cells  of  the  dahlia  by  means 

of  alcohol) . 

Properties  of  Inulin.  —  Inulin,  as  generally  prepared,  has  a  com- 
position of  the  formula  6(C6Hio05)  +  H2O,  i.e.,  CseH^Osi  or  a  mul- 
tiple thereof.  Brown  and  Morris  f  give  the  formula  C72Hi24062  and 
Tanret  Ci8oH3i0Oi55.  Inulin  consists  of  a  white  hygroscopic  substance, 
very  easily  soluble  in  hot  water,  in  which  it  may  form  supersaturated 
solutions.  It  is  insoluble  in  absolute  alcohol.  Its  aqueous  solution 
does  not  reduce  Fehling's  solution,  and  gives  no  color  reaction  with 
iodine  (distinction  from  soluble  starch,  plant  glycogen,  and  dextrin). 
Inulin  in  aqueous  solution  is  levorotatory,  [a]D  =  —  38  (about),  the 
values  as  determined  by  different  authorities  for  different  preparations 
ranging  from  —36  to  —40. 

*  Bull.  soc.  chim.  [3],  9,  201.  f  Chem.  News,  69,  296. 


THE   MONOSACCHARIDES 


615 


Inulin  is  rapidly  hydrolyzed  (15  to  20  minutes)  to  d-fructose  upon 
heating  with  dilute  acids.  Hydrolysis  may  also  be  effected  by  heating 
with  water  alone  under  pressure  at  110°  to  120°  C.  A  special  enzyme 
inulase  which  is  found  in  the  germinating  tubers  of  the  Jerusalem  arti- 
choke, and  other  inulin-containing  plants,  also  hydrolyzes  inulin  to 
d-fructose;  other  enzymes  such  as  diastase,  invertase,  emulsin,  etc., 
are  without  action.  Inulin  is  not  fermented  by  yeast. 

Inulin  can  usually  be  detected  in  plant  tissues  by  placing  thin 
sections  of  the  tubers,  etc.,  in  strong  alcohol  or  glycerol  and  then  ex- 
amining the  preparation  under  the  microscope.  The  inulin  will  be 
precipitated  within  the  cells  as  sphere-crystals  marked  with  radial 
fissures  (Fig.  194). 

In  addition  to  inulin  Tanret,*  by  the  fractional  precipitation  of  the 
extract  from  Jerusalem  artichokes  with  barium  hydroxide,  has  separated 
the  following  closely  allied  compounds: 

Pseudoinulin —  32.2 

Inulenin -  29.6 

Helianthenin -  23.5 

Synanthrin —  17.0. 

Among  other  inuloid  substances  f  found  in  different  plant  ma- 
terials may  be  mentioned  the  following: 


Compound. 

Source. 

MD- 

Levosin 

Unripe  grain  or  cereals                             

-36 

Phlein  

Roots  of  Phleum  pratense  (timothy  grass)  

-48 

Irisin 

Roots  of  Iris  pseudacorus  

-51.5 

Graminin 

Roots  of  different  grasses  

-38  to  -44 

Triticin  
Scillin  or          ( 

Roots  of  Triticum  repens  
Bulbs  of  Urginea  Scillo,  and  other  plants. 

-36  to  -50 

-34  to  -48 

omistrin  ( 

Levan  and  Levulan.  —  d-Fructose  also  occurs  as  an  anhydride  con- 
densation product  in  many  gums  of  bacterial  formation,  such  as  levan 
([a]D=  —  40),  which  was  found  by  Greig-Smith  and  Steel  J  to  be  pro- 
duced by  the  organism  Bacillus  levaniformans  in  the  raw  products  of 
cane  sugar  factories.  A  similar  gum  levulan  ([«]£>  =  —  221)  was  found 
by  Lippmann  §  in  beet  molasses. 

d-Fructose  is  also  found  in  animal  products  although  much  less 

*  Bull.  soc.  chim.  [3],  9,  202,  623. 

t  For  a  fuller  description  of  the  many  inuloid  substances  see  Lippmann's 
"  Chemie  der  Zuckerarten,"  800. 

$  The  Sugar  Cane,  II,  4,  481;  5,  448. 
§  Ber.,  14,  1509;  26,  3216. 


616 


SUGAR  ANALYSIS 


commonly  than  d-glucose,  and  frequently  only  as  a  result  of  disease 
or  other  abnormal  condition.  It  occurs  at  times  in  normal  urine,  as 
after  eating  excessive  amounts  of  sweet  meats  or  drinking  sweet  wines, 
champagnes,  etc.  d-Fructose  is  also  found  in  the  urine  of  certain 
diabetic  patients;  such  urine  even  when  rich  in  fructose  may  show  but 
little  levorotation  owing  to  the  counter  effect  of  the  rotation  of  d-glu- 
cose. Levorotation  in  urine  may  also  be  produced  by  glucuronic  acid 
complexes  (p.  375),  so  that  an  optical  examination  of  urine  without 
confirmatory  tests  is  not  always  to  be  relied  upon. 

Honey  and  Floral  Nectar.  —  The  occurrence  of  d-fructose  in  honey 
has  already  been  referred  to.  The  average  amount  of  fructose,  glucose 
and  sucrose  in  honey  according  to  different  authorities  is  given  as  fol- 
lows: 


Fructose. 

Glucose. 

Sucrose. 

138  European 

honeys 

(Konig*)  

Per  cent. 

38.65 

Per  cent. 

34.48 

Per  cent. 
1.76 

92  American 

honeys 

(Brownef)  

40.50 

34.02 

1.90 

*  Konig's  "  Chem.  Nahrungs-  und  Genussmittel,"  3d  ed.,  I,  766. 
t  Bull.  110,  U.  S.  Bur.  Chem.,  p.  38. 

It  is  seen  from  the  above  that  fructose  occurs  in  honey  in  slightly 
greater  excess  than  glucose.  A  part  of  the  fructose  and  glucose  of 
honey  is  due  to  the  inversion  of  sucrose  gathered  by  bees  from  floral 
nectar  and  other  sources.  The  sucrose  in  Sainfoin  nectar  according 
to  Bonnier*  constitutes  57.2  per  cent  of  the  total  sugars  and  in  Sain- 
foin honey  only  8.2  per  cent,  which  shows  that  over  85  per  cent  of  the 
sucrose  in  the  nectar  was  inverted  by  the  bees.  This  inversion  takes 
place  while  the  nectar  is  in  the  honey  sac  of  the  bee,  and  also  no  doubt 
during  evaporation  and  storage  of  the  nectar  in  the  comb;  the  inverting 
agent  is  probably  an  enzyme  secreted  by  the  bee  and  the  process  is 
found  to  continue  even  after  the  honey  has  been  strained. 

In  certain  honeys,  as  those  gathered  by  bees  from  the  flowers  of 
the  Eucalyptus  and  Tupelo,  the  fructose  is  found  in  very  large  excess, 
a  circumstance  which  is  probably  due  to  the  preponderance  of  fructose 
in  the  nectar  of  these  flowers. 

Synthesis  of  d-Fructose.  —  d-Fructose  has  been  made  synthetically 
in  a  large  number  of  ways.  Fischer's  method  of  synthesis  from  d-glu- 
cose by  reducing  its  osone  has  been  described  (p.  355) ;  also  the  method 
of  Lobry  de  Bruyn  and  van  Ekenstein  by  which  d-glucose  and  d-man- 
nose  undergo  partial  rearrangement  to  d-fructose  upon  warming  in 

*  "  Sources  of  Honey,"  Sci.  Amer.  Suppl.,  Aug.  10,  1907,  p.  92. 


THE  MONOSACCHARIDES  617 

dilute  alkaline  solution.  The  synthesis  can  also  be  accomplished  bio- 
logically from  d-mannite,  which  is  oxidized  by  the  sorbose  bacterium 
almost  quantitatively  to  d-fructose.* 

CH2OH         CH2OH 
*  HOCH         HOCH 

HOCH         HOCH 

|      +  O  =    I      +  H20 
HCOH         HCOH 

*  HCOH  C  =  O 

CH2OH         CH2OH 

d-Mannite  d-Fructose 

The  oxidation  of  d-mannite  by  the  sorbose  bacterium  may  take 
place  (p.  771)  in  the  second  or  fifth  position  (marked  by  a*)  with  for- 
mation of  d-fructose  in  either  case. 

Preparation  of  d-Fructose.  —  d-Fructose  is  most  easily  prepared 
by  hydrolyzing  some  one  of  its  condensation  products.  For  this  pur- 
pose sucrose  and  inulin  are  the  substances  generally  chosen.  The  sugar 
on  account  of  its  extreme  solubility  is  very  difficult  to  crystallize. 

Preparation  of  d-Fructose  from  Sucrose.  —  In  the  preparation  f  from 
sucrose  a  solution  of  invert  sugar  is  prepared  by  inverting  a  10  per 
cent  solution  of  sucrose  at  60°  C.,  using  for  every  100  gms.  of  sucrose 
2  c.c.  of  concentrated  hydrochloric  acid.  The  solution  after  cooling  to 
about  —  5°  C.  is  treated  for  each  100  c.c.  with  6  gms.  of  fresh  finely 
pulverized  pure  calcium  hydroxide.  After  stirring  the  solution  vigor- 
ously for  2  to  3  minutes,  the  liquid  is  filtered  rapidly  using  a  cooling 
funnel ;  the  filtrate  which  should  be  kept  cold  soon  deposits  fine  needles 
of  calcium  fructosate.  The  latter  after  standing  24  hours  is  filtered  off, 
using  a  centrifuge  or  Buchner  funnel,  washed  with  ice  water  and  then 
after  suspending  in  water  at  20°  C.  carefully  decomposed  with  the 
exact  amount  of  oxalic  acid.  Any  excess  of  the  latter  may  be  removed 
by  addition  of  a  little  of  the  calcium  fructosate  kept  back  as  a  reserve. 
The  filtrate  from  the  calcium  oxalate  is  then  evaporated  at  low  tem- 
perature in  a  vacuum  to  a  sirup.  The  latter  after  priming  with  a 
crystal  of  fructose  from  a  previous  preparation  and  setting  aside  in 
a  cool  place  over  concentrated  sulphuric  acid  will  usually  crystallize 
within  a  few  days.  Crystallization  may  also  be  effected  by  dissolv- 
ing as  much  as  possible  of  the  concentrated  sirup  in  warm  absolute 

*  Brown,  J.  Chem.  Soc.,  49.  172. 

t  Modification  of  the  original  method  of  Dubrunfaut,  Compt.  rend.,  25,  307; 
69,  1366. 


618  SUGAR  ANALYSIS 

alcohol,  and  then  pouring  off,  when  cold,  the  soluble  portion  from  the 
sirupy  residue;  the  alcoholic  solution  upon  standing  will  soon  deposit 
crystals  of  pure  d-fructose. 

Preparation  of  d-Fructose  from  Inulin.  —  d-Fructose  is  most  easily 
prepared  from  inulin.  For  this  purpose*  100  gms.  of  inulin  and  250 
c.c.  of  water  are  heated  with  a  little  hydrochloric  acid  for  30  minutes  in 
a  boiling  water  bath.  The  quantity  of  hydrochloric  acid  used  for  hydro- 
lyzing  depends  upon  the  ash  content  of  the  inulin;  for  100  gms.  inulin  of 
1  per  cent  ash  content  0.5  gm.  HC1  is  taken,  for  0.2  per  cent  ash  0.1  gm. 
HC1  and  if  the  inulin  is  ash  free  0.01  gm.  HC1.  After  hydrolysis  the 
free  acid  is  neutralized  with  an  excess  of  calcium  carbonate  and  the 
solution  filtered.  The  filtrate  is  evaporated  in  a  vacuum  at  low  tem- 
perature to  a  thin  sirup,  which  is  then  set  aside  in  a  vacuum  desiccator 
over  concentrated  sulphuric  acid.  After  standing  some  days  the  thick 
sirup  is  warmed  with  absolute  alcohol  and  after  thorough  agitation 
allowed  to  stand  24  hours.  The  clear  alcoholic  solution  is  then  poured 
off,  primed  with  a  few  crystals  of  fructose  and  set  aside  in  a  cool  place. 
Crystallization  is  usually  complete  in  3  days.  The  sugar  is  obtained 
perfectly  white  by  recrystallizing  from  hot  absolute  alcohol  using  bone 
black. 

Properties  of  d-Fructose.  —  d-Fructose  crystallizes  from  absolute 
ethyl  or  methyl  alcohol  as  the  anhydride  C6Hi206  in  fine  colorless 
needles  melting  at  95°  to  105°  C.  A  crystalline  hydrate  of  the  formula 
(C6Hi2O6)2  +  H20  has  also  been  obtained. 

d-Fructose  is  exceedingly  soluble  in  cold  water,  but  only  very  slightly 
soluble  in  cold  absolute  alcohol.  It  is  easily  soluble  in  hot  absolute 
ethyl  and  methyl  alcohol.  Unlike  most  sugars  d-fructose  is  soluble  to 
a  considerable  extent  in  mixtures  of  alcohol  and  ether. 

d-Fructose  is  very  strongly  levorotatory,  [«]^  =  —  92  although 
changes  in  temperature  and  concentration  may  produce  considerable 
variations  from  this  figure  as  shown  on  page  181. 

Diluting  a  concentrated  fructose  solution  with  water  causes  a  low- 
ering of  the  specific  rotation,  and  about  30  minutes  are  necessary  for 
the  reading  to  become  constant. 

d-Fructose  exhibits  mutarotation,  the  value  for  [a]D  immediately 
after  solution  being  about  — 106.  The  change  to  constant  rotation  pro- 
ceeds much  faster  than  with  other  mutarotating  sugars,  and  is  usually 
completed  within  an  hour. 

The  effect  of  acid  in  increasing  the  levorotation  of  d-fructose  has 
been  referred  to. 

*  Ost.  Z.  analyt.  Chem.,  29.  648. 


THE  MONOSACCHARIDES  619 

Fermentation  of  d-Fructose.  —  d-Fructose  is  fermented  in  the 
same  manner  as  d-glucose  by  various  yeasts,  moulds  and  bacteria. 
Yeast  produces  about  the  same  yield  of  alcohol  and  carbon  dioxide 
from  d-fructose  as  from  d-glucose,  but  the  fermentation  in  its  first 
stages  proceeds  more  rapidly  with  glucose.  The  alcoholic  fermentation 
of  fructose  by  means  of  the  enzyme  zymase  has  been  accomplished  by 
Buchner  in  the  same  manner  as  for  glucose. 

d-Fructose  undergoes  the  lactic  and  butyric  fermentations  with 
the  same  readiness  as  d-glucose. 

In  certain  anaerobic  fermentations  where  free  hydrogen  is  evolved 
d-fructose  is  reduced  to  d-mannite,  the  reaction  being  of  the  same 
character  as  that  obtained  with  sodium  amalgam  and  other  reducing 
agents.  The  formation  of  mannite  by  microorganisms  in  fructose- 
containing  solutions  is  often  termed  a  mannitic  fermentation. 

Tests  for  d-Fructose.  —  d-Fructose  upon  reduction  with  sodium 
amalgam  yields  equal  parts  of  d-mannite  and  d-sorbite. 


CH2OH 

CH2OH 

CH2OH 

HOCH 

HOCH 

HOCH 

HOCH 

HOCH 

HOCH 

2        |              +  2  H2 
HCOH 

1 
HCOH 

HCOH 

i-O 

HCOH 

HOCH 

CH2OH 

d-Fructose 

CH2OH 

d-Mannite 

CH2OH 

.  d-Sorbite. 

The  above  reaction,  by  which  two  alcohols  are  formed,  is  charac- 
teristic of  all  ketoses  (see  under  d-erythrulose,  page  543) . 

Oxidation  of  d-fructose  by  means  of  bromine  water  proceeds  less 
rapidly  than  with  the  aldehyde  sugars  and  this  property  has  been 
utilized  as  a  means  of  identification  (p.  363).  By  prolonged  action  of 
bromine  water  extending  over  several  weeks,  d-fructose  is  oxidized  *to 
a  mixture  of  formic,  oxalic,  glycollic  and  d-erythronic_a£Jds.  Oxida- 
tion of  d-fructose  with  nitric  acid  gives  a  mixture  of  formic,  oxalic, 
tartaric  and  glycollic  acids. 

d-Fructose  gives  a  number  of  brilliant  color  reactions  which  are 
more  typical,  however,  of  the  ketose  sugars  as  a  class,  than  of  d-fruc- 
tose alone.  The  intense  red  color  reaction  of  Seliwanoff,  obtained  upon 
heating  fructose  solutions  with  resorcin  and  strong  hydrochloric  acid, 
has  already  been  described. 

*  Herzfeld,  Ann.,  244,  291. 


620  SUGAR  ANALYSIS 

If  solutions  of  d-fructose  are  heated  to  a  high  temperature  the 
sugar  is  partly  decomposed  with  formation  of  oxymethylfurfural. 

COH 


C6H12O8  =  O     +  3  H2O 


d-Fructose  Oxymethylfurfural. 

Tests  for  Artificial  Invert  Sugar.  —  The  oxymethylfurfural  formed 
in  the  previous  reaction  is  easily  detected  by  its  coloring  aniline  ace- 
tate red  or  by  its  forming  brilliant  colorations  with  phloroglucin,  resorcin 
and  other  phenols.  This  property  has  been  made  use  of  for  detecting 
artificial  invert  sugar  in  honey,  and  other  food  products.  Artificial 
invert  sugar  is  made  commercially  by  heating  concentrated  sucrose 
solutions  with  a  small  amount  of  tartaric  or  other  acid  (about  0.1  per 
cent  of  weight  of  sucrose)  to  110°  to  120°  C.,  at  which  temperature  per- 
ceptible amounts  of  oxymethylfurfural  are  formed. 

In  making  the  test  for  oxymethylfurfural  Fiehe*  rubs  up  the 
product  (honey,  etc.)  with  ether  and  filters  the  ethereal  solution  into 
a  small  porcelain  dish.  After  evaporating  the  ether,  the  residue  is 
heated  with  a  1  per  cent  solution  of  resorcin  in  concentrated  hydro- 
chloric acid.  In  presence  of  artificial  invert  sugar  a  red  color  develops 
which  soon  changes  to  a  reddish  brown. 

A  more  rapid  but  less  sensitive  reaction  for  artificial  invert  sugar 
is  obtained  with  aniline  acetate. f  The  reagent,  which  should  be 
freshly  prepared  before  using,  is  made  by  shaking  up  5  c.c.  of  chemically 
pure  aniline  with  5  c.c.  of  water  and  adding  sufficient  glacial  acetic 
acid  (2  c.c.)  to  just  clear  the  emulsion.  In  making  the  test  5  c.c.  of  a 
concentrated  solution  of  the  honey,  etc.,  are  treated  in  a  test  tube  with 
1  to  2  c.c.  of  the  aniline  reagent.  The  latter  is  allowed  to  flow  down 
the  walls  of  the  tube  so  as  to  form  a  layer  upon  the  surface  of  the  solu- 
tion underneath.  If  a  red  ring  forms  beneath  the  aniline  solution, 
when  the  tube  is  gently  agitated,  oxymethylfurfural  is  present. 

It  should  be  borne  in  mind  that  honeys  or  other  fructose-contain- 
ing products  which  have  been  cooked  or  boiled  also  give  the  reaction 
for  oxymethylfurfural. 

The  brilliant  red  coloration  obtained  upon  heating  d-fructose  or 
sucrose  with  concentrated  hydrochloric  acid  and  sesame  oil  is  probably 

*  Z.  Nahr.  Genussmittel,  16,  75. 

t  Browne,  Bull.,  110,  U.  S.  Bur.  Chem.,  p.  68. 


THE    MONOSACCHARIDES  621 

due  to  a  condensation  product  between  oxymethylfurfural  and  some 
constituent  of  the  oil. 

Hydrobromic  acid  reacts  with  fructose  in  ether  solution  to  form 
bromomethylfurfural  CH2Br  •  C4H2O  •  CHO,  which  colors  the  solution 
a  deep  reddish  purple  and  crystallizes  in  gold  colored  prisms.  (Re- 
action of  Fenton  and  Gostling.*)  This  reaction  is  also  given  by  other 
sugars  and  carbohydrates,  but  is  most  pronounced  with  those  which 
contain  a  fructose  group. 

Reducing  Reactions  of  d-Fructose.  —  d-Fructose  is  more  sensitive  in 
reducing  power  than  most  other  sugars  and  this  property  has  been 
utilized  as  a  means  of  identification. 

Pinoff  f  recommends  for  the  above  purpose  a  4  per  cent  solution  of 
ammonium  molybdate;  10  c.c.  of  the  latter  diluted  with  10  c.c.  of 
water  containing  0.2  c.c.  of  glacial  acetic  acid  gives  upon  heating  with 
0.1  gm.  d-fructose  in  a  water  bath  at  95°  to  98°  C.  a  bright  blue  colora- 
tion; solutions  of  other  sugars  under  these  conditions  remain  colorless. 
Any  free  mineral  acid  must  be  neutralized  before  conducting  the  ex- 
periment, otherwise  other  sugars  may  give  the  reaction. 

Pieraerts  {  recommends  for  detecting  fructose  a  solution  of  copper 
hydroxide  in  potassium  carbonate  or  in  alkaline  amino-acetic  acid 
(glycocoll).  The  latter  reagent  is  prepared  by  dissolving  12  gms.  of 
glycocoll  in  water;  6  gms.  of  copper  hydroxide  are  then  added  gradu- 
ally and  when  solution  is  complete  the  hot  liquid  is  cooled  to  60°  C.; 
50  gms.  of  potassium  carbonate  are  then  added  and  the  solution  made 
up  to  1  liter.  In  testing  for  fructose  the  product  to  be  examined  is 
dissolved  in  cold  water,  clarified  if  necessary  with  a  little  lead  acetate, 
the  filtrate  freed  from  excess  of  lead  by  means  of  sodium  sulphate  and 
the  clear  solution  diluted  to  about  5  per  cent  reducing  sugar.  Upon 
heating  with  the  alkaline  glycocoll-copper  solution  to  30°  C.  reduction 
will  take  place  within  an  hour  if  fructose  is  present;  reduction  is  also 
obtained  at  ordinary  temperature  after  12  hours'  standing.  Other 
sugars  are  said  not  to  show  reduction  under  these  conditions. 

Methylphenylosazone  Reaction  of  d-Fructose.  —  d-Fructose  forms  a 
large  number  of  hydrazones  and  osazones  with  phenylhydrazine  and 
its  substituted  derivatives.  For  purposes  of  separation  and  identi- 
fication the  osazone  reaction  with  methylphenylhydrazine  is  stated  by 
Neuberg  §  to  be  of  great  value.  d-Fructose-methylphenylosazone  is 

*  J.  Chem.  Soc.,  73,  556;  75,  423;  79,  361.  t  Ber.,  38,  3317. 

J  Belg.  Ann.  de  Pharmacie,  March  and  April,  1908.  Bull,  assoc.  chim.  sucr.  dist., 
25,  830. 

§  Ber.,  35,  959.    Z.  physiol.  Chem.,  36,  227. 


622  SUGAR  ANALYSIS 

obtained  upon  heating  fructose  solutions  with  methylphenylhydrazine 
in  alcoholic  acetic  acid  for  a  few  minutes  and  then  setting  aside  in 
a  cool  place.  Crystallization  is  almost  complete  within  a  few  hours. 
The  compound  consists  of  yellowish  crystals  having  the  composition 
C2oH26N404,  and  melting  between  158°  and  160°  C.;  it  is  only  slightly 
soluble  in  water,  cold  alcohol  and  ether,  but  is  easily  soluble  in  hot 
alcohol,  acetone  and  chloroform. 

Glucose,  mannose,  galactose  and  other  aldose  sugars  do  not  form 
osazones  with  methylphenylhydrazine  owing  to  the  fact  that  the 
—  CHOH  group  adjoining  the  terminal  —  CHO  radicle  is  prevented  in 
some  way  from  reacting  with  substituted  hydrazines.  In  the  case  of 
fructose  and  other  ketoses,  where  the  reacting  —  CH2OH  group  occu- 
pies the  end  position,  the  freedom  of  osazone  formation  is  not  impeded. 

d-Fructose-phenylosazone  is  identical  with  that  of  d-glucose  and 
d-mannose.  The  formation  of  osazone  is  more  complete,  however, 
with  d-fructose  than  with  its  aldose  isomers  (see  page  350). 

d-Fructose  reacts  with  alkalies  similarly  to  d-glucose. 

1-Fructose.  — 

CH2OH 


HCOH 


HCOH 
HOCH 

|  A-O 

CH2OH 

1-Fructose  has  not  been  found  as  yet  in  nature.  The  sugar  has 
been  prepared  synthetically*  by  reduction  of  1-glucosone  (obtained 
from  1-glucose-osazone),  in  the  same  manner  as  d-fructose  is  prepared 
from  d-glucose-osazone ;  1-fructose  can  also  be  prepared  from  d,  1-fruc- 
tose  by  fermenting  away  the  d-component  with  yeast. 

1-Fructose  has  been  obtained  only  as  a  dextrorotatory  unferment- 
able  sirup.  The  sugar  has  not  been  separated  in  a  pure  crystallized 
form,  so  that  other  knowledge  of  its  chemical  and  physical  proper- 
ties is  lacking. 

d,  1-Fructose.  —  Inactive,  or  racemic,  fructose  has  not  been  found 

in  nature.     The  sugar  has  been  prepared  synthetically,  however,  by  a 

number  of  methods  and  some  of  these  have  a  special  interest  in  that 

the  sugar  was  built  up  from  simple  organic  compounds  jiot  belonging 

*  Fischer,  Ber.  23,  373,  2618,  3889;  24,  2683. 


THE  MONOSACCHARIDES  623 

to  the  sugars.  The  best  known  example  of  such  a  method  is  the  classic 
synthesis  of  Fischer  and  Tafel  *  by  which  acrolein  dibromide  in  con- 
tact with  barium  hydroxide  is  condensed  to  form  a-acrose  and  other 
hexose  sugars. 

2  C3H4Br20  +  2  Ba(OH)2  =  2  BaBr2  +  C6H1206. 

Acroleindibromide  a-Acrose. 

The  above  reaction  is  carried  out  in  ice-water.  The  solution,  after 
precipitating  barium,  is  evaporated  and  treated  with  phenylhydrazine. 
Two  osazones  are  formed,  one  insoluble  in  ether  (a-acrose-osazone) 
and  the  other  soluble  in  ether  (/3-acrose-osazone).  The  a-acrose- 
osazone  is  found  to  be  identical  with  that  of  d,  1-glucose,  which  is  also 
the  same  as  that  of  d,  1-mannose,  or  d,  1-fructose. 

a-Acrose-osazone  upon  treatment  with  zinc  dust  and  acetic  acid  is 
reduced  to  a-acrose-amine,  and  the  latter  upon  treatment  with  nitrous 
acid  is  converted  to  d,  1-fructose. 

CH2OH  CH2OH 

(CHOH)3  (CHOH)s 

2        |  +2HN02=2    |  +2N2  +  2H20 

C=0  C=0 

H2C-NH2  CH2OH 

a-Acrose-amine  d.l-Fructoae. 

Properties.  —  d,  1-Fructose  has  been  obtained  only  as  a  sweet  color- 
less optically  inactive  sirup,  easily  soluble  in  water  and  alcohol,  but  in- 
soluble in  ether.  It  reduces  Fehling's  solution  and  gives  the  other 
common  reactions  of  a  reducing  sugar.  It  is  fermented  only  one-half 
with  yeast,  the  1-fructose  remaining  in  an  unaltered  condition. 

Reduction  of  d,  1-fructose  with  sodium  amalgam  gives  d,  1-mannite, 
the  oxidation  of  which  to  d,  1-mannonic  acid  has  been  mentioned  in 
the  synthesis  of  d-mannose  and  d-glucose. 

D-SORBOSE.  —  d-Sorbinose. 

CH2OH 

HCOH 


HOCH 
HCOI 


Occurrence.  —  Although  d-sorbose  has  not  been  found  free  in  the 
natural  juices  of  plants  this  sugar  has  been  discovered  in  large  quan- 

*  Ber.,  20,  2566;  22,  97. 


624  SUGAR  ANALYSIS 

titles  in  the  fermented  juice  of  sorb-apples  (the  fruit  of  the  service-tree, 
Sorbus  domestica)  and  other  fruits  of  the  rosaceous  family.  The  sugar 
was  discovered  first  by  Pelouze,*  but  Boussingault  f  was  the  first  to 
show  that  the  sugar  was  formed  by  an  oxidizing  fermentation  of  the 
hexite  alcohol  d-sorbite  which  is  found  in  sorb-apples,  mountain-ash 
berries  and  other  fruits.  One  of  the  principal  organisms  concerned 
in  this  fermentation  is  the  so-called  sorbose  bacterium  (Bacterium 
xylinwri),  the  action  of  which  upon  d-sorbite  is  represented  as  follows: 
CH2OH  CH2OH 

HCOH         HCOH 

HOCH         HOCH 

I      +0=    I     +H20 
HCOH         HCOH 

*  HCOH          C=0 
CH2OH         CH2OH 

d-Sorbite  d-Sorbose 

The  oxidation  takes  place  only  in  the  position  marked  with  a  *,  as 
explained  on  page  771. 

d-Sorbose  is  formed  synthetically  in  small  amounts  by  the  action 
of  dilute  alkalies  upon  d-gulose  and  d-idose. 

Preparation  of  d-Sorbose.  —  d-Sorbose  is  prepared  according  to 
Bertrand's  J  method  by  evaporating  the  juice  of  sorb-apples  to  a  spe- 
cific gravity  of  1.05  to  1.06  and  then  removing  all  fermentable  sugars 
by  fermentation  with  yeast.  When  the  alcoholic  fermentation  is  com- 
pleted the  clear  solution  is  poured  into  shallow  dishes,  inoculated  with 
a  strong  pure  culture  of  Bacterium  xylinum  and  allowed  to  stand  at 
30°  C.  until  the  reducing  power  of  the  solution  has  reached  its  maxi- 
mum. The  liquid  is  then  clarified  with  lead  subacetate,  the  excess  of 
lead  removed  from  the  filtrate  with  the  exact  amount  of  sulphuric  acid 
and  the  filtrate,  which  must  be  perfectly  neutral,  evaporated  in  a 
vacuum  to  a  sirup.  The  latter  is  purified  in  the  usual  way  by  strong 
alcohol  and  set  aside  for  crystallization.  The  yield  of  d-sorbose  is  about 
80  per  cent  of  the  d-sorbite  originally  present. 

Instead  of  using  sorb-apple  juice  a  solution  of  d-sorbite  in  presence 
of  yeast  extract,  asparagine,  peptone  and  mineral  nutrients  may  be 
used  for  fermentation.  By  this  method  Lobry  de  Bruyn  and  van 
Ekenstein  §  obtained  a  yield  of  about  30  per  cent. 

Properties.  —  d-Sorbose  has  been  obtained  in  the  form  of  colorless 
rhombic  crystals  melting  at  154°  C.     The  sugar  is  very  sweet,  easily 
*  Compt.  rend.,  34,  377.  %  Compt.  rend.,  122,  900. 

t  Compt.  rend.,  74,  939.  §  Rec.  trav.  Pays-Bas,  19,  3 


THE  MONOSACCHARIDES  625 

soluble  in  water,  but  difficultly  soluble  in  alcohol.  d-Sorbose  is  levo- 
rotatory,  [a]  D  =  —  42.5,  this  value  being  slightly  influenced  by  changes 
in  temperature  and  concentration  as  shown  on  page  181. 

d-Sorbose  is  not  fermented  by  any  of  the  ordinary  varieties  of 
yeast.  The  sugar  is  also  very  resistant  to  the  attacks  of  moulds  and 
bacteria;  certain  lactic  acid  organisms,  however,  were  found  by  Ber- 
thelot  *  to  produce  lactic  and  butyric  acid. 

Tests.  —  d-Sorbose  is  reduced  by  sodium  amalgam  to  the  alcohols 
d-sorbite  and  d-idite.  Oxidation  with  nitric  acid  produces  d-tartaric, 
oxalic  and  other  acids. 

d-Sorbose  reduces  Fehling's  solution  and  gives  the  characteristic 
color  reaction  of  the  ketoses  with  resorcin  and  hydrochloric  acid. 

Upon  heating  with  3  parts  of  phenylhydrazine  chloride  and  5 
parts  of  sodium  acetate  d-sorbose  gives  an  osazone,  CisH^N^,  which 
is  identical  with  that  of  d-gulose  and  d-idose.  The  osazone  consists  of 
fine  yellow  needles  melting  at  164°  C. 

1-Sorbose.  —  1-Sorbinose. 

CH2OH 


HOC! 
HCO] 


)H 

HOCH 

i-o 

CH2OH 

Synthesis.  —  1-Sorbose  has  not  been  found  in  nature  either  free  or 
in  the  combined  form.  The  sugar  has  been  prepared  synthetically  by 
Lobry  de  Bruyn  and  van  Ekensteinf  by  warming  d-galactose  in  20 
per  cent  aqueous  solution  with  not  more  than  3  per  cent  potassium 
hydroxide  for  3  hours  at  70°  C.  The  solution,  which  has  acquired  a 
weak  acid  reaction,  is  cooled  and  the  unchanged  galactose  allowed  to 
crystallize.  The  mother  liquor  is  then  evaporated,  and  extracted  with 
methyl  alcohol  and  acetone.  The  residue  is  then  fermented  to  remove 
the  rest  of  the  galactose  and  the  solution  evaporated  to  a  sirup,  from 
which  the  1-sorbose  crystallizes  after  long  standing.  The  yield  is  6  to 
8  per  cent  of  the  d-galactose  taken. 

The  above  reaction  by  which  1-sorbose  is  formed  belongs  to  a  class 
of  secondary  rearrangements  which  are  peculiar  to  many  of  the  sugars. 
As  d-glucose  upon  warming  with  dilute  alkalies  undergoes  partial 

*  Ann.  chim.  phys.  [3],  60,  350. 

t  Rec.  trav.  Pays-Bas,  16,  262;  19,  1. 


626 


SUGAR  ANALYSIS 


rearrangement  into  d-mannose  and  the  ketone  sugar  d-fructose,  so 
d-galactose  is  transformed  into  d-talose  and  the  ketone  sugar  d-taga- 
tose.  The  ketone  sugars  which  are  formed  in  these  reactions  seem, 
however,  on  prolonged  warming  with  alkalies  to  be  partially  trans- 
formed into  isomeric  ketoses.  The  reaction  between  d-galactose, 
d-tagatose  and  1-sorbose  would  be  represented  as  follows: 


CH2OH 

CH2OH 

CH2OH 

HOCH 

HOCH 

HOCH 

HCOH       -> 

HCOH      -* 

HCOH 

HCOH       +± 

HCOH      <- 

HOCH 

HOCH 

m 

H 

CHO 

d-Galactose 

CH2OH 

d-Tagatose 

CH2OH 

l-Sorbose 

The  rearrangement  between  d-tagatose  and  1-sorbose  involves  the 
transposition  of  the  H  and  OH  groups  in  the  a  position  to  the  CO 
group,  a  change  somewhat  analogous  to  that  noted  in  the  rearrange- 
ments between  the  aldose  sugars  (as  d-glucose  to  d-mannose)  and 
between  the  sugar  acids  (as  d-gluconic  to  d-mannonic)  where  the 
transposition  of  the  H  and  OH  groups  occurs  in  the  a  position  to  the 
CHO  and  COOH  groups  respectively. 

The  rearrangement  between  d-tagatose  and  1-sorbose  is  also  ac- 
companied by  the  formation  of  other  ketoses  such  as  galtose  in  which 
the  CO  group  may  perhaps  take  the  following  position: 

CH2OH 
HOCH 
HCOH 


=  0 

HOH 

H2OH 


It  can  readily  be  seen  that  the  possible  number  of  isomeric  ketoses, 
which  successive  rearrangements  of  this  kind  may  bring  about,  is  large. 

Properties  of  l-Sorbose.  —  l-Sorbose,  as  obtained  by  the  method  of 
Lobry  de  Bruyn  and  van  Ekenstein,  consists  of  colorless  rhombic 
crystals  melting  at  154°  to  156°  C.  The  sugar  is  dextrorotatory, 
MD  —  +  42.3  without  showing  perceptible  mutarotation.  Changes  in 
temperature  seem  to  have  no  marked  influence  upon  the  rotation. 
The  sugar  is  not  fermented  with  yeast. 


THE  MONOSACCHARIDES  627 

Tests.  —  1-Sorbose  is  reduced  by  sodium  amalgam  to  the  hexite 
alcohols  1-sorbite  and  1-idite.  The  sugar  reduces  Fehling's  solution 
somewhat  stronger  than  d-galactose  and  gives  the  characteristic  color 
reaction  of  ketoses  with  resorcin  and  hydrochloric  acid. 

The  phenylosazone  is  identical  with  that  of  1-idose  and  1-gulose. 

d,  1-Sorbose.  —  This  sugar  was  prepared  by  Lobry  de  Bruyn  and 
van  Ekenstein*  by  evaporating  a  solution  containing  equal  parts  of 
d-  and  1-sorbose.  The  sugar  was  obtained  in  white  crystals  melting  at 
154°  C.  A  study  by  Adriani  f  of  its  solubility  as  compared  with  that 
of  its  two  components  showed  that  the  crystals  were  a  true  racemic 
combination  and  not  a  simple  mixture. 

d-Tagatose.  — 

CH2OH 

HOCH 
HCOH 
HCOH 


!=0 
H2OH 


Synthesis.  —  d-Tagatose  has  not  been  found  as  yet  in  nature  either 
free  or  in  any  combined  form.  The  sugar  has  been  prepared  syn- 
thetically by  Lobry  de  Bruyn  and  van  Ekenstein  I  by  the  action  of 
dilute  alkalies  upon  d-galactose  as  described  under  1-sorbose.  The 
mother  liquor  after  crystallization  of  1-sorbose  yields  upon  evaporation 
a  mixture  of  crystals  consisting  of  1-sorbose  and  d-tagatose.  The 
mixed  crystals  are  dissolved  in  5  parts  of  absolute  methyl  alcohol  and 
2  parts  aniline,  from  which  the  1-sorbose  crystallizes  at  once  and  the 
d-tagatose  after  evaporating  the  mother  liquor.  The  sugar  is  purified 
by  recrystallization. 

Properties.  —  d-Tagatose  consists  of  white  crystals  melting  at 
124°  C.  The  sugar  has  a  sweet  taste  and  is  easily  soluble  in  water, 
but  difficultly  soluble  in  alcohol.  The  aqueous  solution  is  very  weakly 
dextrorotatory,  [a]g  =  -f  1 ;  at  higher  temperatures  the  sugar  is  levo- 
rotatory,  [a]^  =  —  2.6.  d-Tagatose  is  not  fermented  by  yeast. 

Tests.  —  d-Tagatose  gives  upon  reduction  with  sodium  amalgam 
the  hexite  alcohols  dulcite  and  d-talite.  Oxidation  with  nitric  acid 

*  Rec.  trav.  Pays-Bas,  19,  1. 

t  Rec.  trav.  Pays-Bas,  19,  185. 

t  Rec.  trav.  Pays-Bas,  16,  62,  282;  18,  72. 


628  SUGAR  ANALYSIS 

causes  a  disintegration  of  the  carbon  chain  with  formation  of  1-tar- 
taric,  oxalic  and  other  acids.  The  sugar  reduces  Fehling's  solution 
somewhat  stronger  than  d-galactose  and  gives  the  characteristic  color 
reaction  of  ketoses  with  resorcin  and  hydrochloric  acid. 

The  phenylosazone  is  identical  with  that  of  d-galactose  and  d-talose. 

1-Tagatose.  — 

CH2OH 

HCOH 
HOCH 
HOCH 

i-o 

CH2OH 

1-Tagatose  has  not  been  found  as  yet  in  nature.  The  sugar  is 
formed  by  molecular  rearrangement  according  to  Lobry  de  Bruyn 
and  van  Ekenstein*  by  the  action  of  dilute  alkalies  upon  d-sorbose, 
the  transformation  being  the  same  as  that  between  1-sorbose  and 
d-tagatose. 

The  sugar  has  not  been  isolated  as  yet  in  the  crystalline  form  and  its 
properties  are  therefore  unknown.  Its  phenylosazone  is  identical 
with  that  of  1-galactose  and  1-talose. 

d,  1-Tagatose.  —  Racemic,  or  inactive,  tagatose  has  not  been 
found  in  nature,  nor  has  the  sugar  up  to  the  present  been  prepared 
synthetically.  An  inactive  ketose  sugar  f  has  been  detected  among 
the  oxidation  products  of  dulcite  obtained  by  action  of  lead  peroxide, 
and  this  sugar  in  all  probability  consists  in  part  at  least  of  d,  1-tagatose. 

KETOHEXOSES  OF  UNKNOWN  STRUCTURE 

Galtose. J  —  This  ketohexose  has  already  been  referred  to  under 
1-sorbose  as  being  formed  by  the  action  of  alkalies  upon  d-galactose 
through  secondary  rearrangement.  The  sugar  remains  in  the  mother 
liquors  after  crystallization  of  the  1-sorbose  and  d-tagatose. 

Galtose  has  been  obtained  only  as  a  sweet  sirup.  Its  aqueous  solu- 
tions have  but  little  rotatory  power  and  are  not  fermentable.  Galtose 
reduces  Fehling's  solution  only  about  half  as  strong  as  d-galactose. 
Distillation  with  hydrochloric  acid  gives  4  to  5  per  cent  of  furfural. 

*  Rec.  trav.  Pays-Bas,  16,  62,  282;  18,  72. 

t  Neuberg,  Ber.,  35,  2629. 

$  Lobry  de  Bruyn  and  van  Ekenstein,  Rec.  trav.  Pays-Bas,  16,  257,  262. 


THE  MONOSACCHARIDES  629 

Galtose-phenylosazone,  Ci8H22N404,  forms  yellow  crystals  melting 
at  182°  C. 

Glutose.*  —  This  ketohexose  is  formed  by  secondary  rearrange- 
ment through  the  action  of  dilute  alkalies  upon  d-glucose,  d-mannose 
and  d-fructose.  The  best  yields  are  obtained  by  heating  a  20  per  cent 
solution  of  d-glucose  or  d-fructose  with  10  per  cent  of  pure  moist  lead 
hydroxide  for  3  hours  at  70°  C.  The  lead  is  then  precipitated,  the 
mixture  of  sugars  fermented  with  yeast,  when  the  glutose  remains  be- 
hind. The  yield  of  glutose  by  this  method  is  about  20  per  cent  from 
d-glucose  and  40  per  cent  from  d-fructose. 

Occurrence  of  Glutose  in  Cane  Molasses.  —  While  glutose  does  not 
occur  in  nature  its  presence  can  always  be  looked  for  in  commercial 
products  where  d-glucose  and  d-fructose  have  been  subjected  to  the 
action  of  alkalies.  It  has  been  found  in  sugar-cane  molassesf  in  amounts 
varying  from  1  to  5  per  cent  as  a  result  of  the  action  of  the  lime  used 
in  clarification  upon  the  invert  sugar  of  the  juice.  Glutose,  not  being 
fermentable,  is  found  as  a  constituent  of  the  vinasse  from  molasses 
distilleries.  In  the  valuation  of  molasses  for  distilleries  the  amount 
of  glutose  and  other  non-fermentable  reducing  sugars  should  be  deter- 
mined by  a  carefully  conducted  fermentation  test. 

Properties.  —  Glutose  has  not  been  obtained  in  the  crystalline 
form,  so  nothing  is  known  of  its  physical  properties.  It  reduces 
Fehling's  solution  about  half  as  strong  as  d-glucose  and  gives  the  char- 
acteristic color  reaction  of  ketoses  with  resorcin  and  hydrochloric  acid. 
Aqueous  solutions  of  glutose  show  no  perceptible  optical  activity. 

Pseudofructose. — This  ketohexose  has  also  been  detected  among 
the  products  obtained  by  action  of  dilute  alkalies  upon  d-glucose  or 
d-fructose.  The  sugar  was  obtained  by  Lobry  de  Bruyn  and  van 
Ekenstein  t  as  a  levorotatory  sirup  ([a]D  =  —  40  about)  but  has  not  been 
isolated  in  the  pure  condition. 

Formose.  —  The  condensation  of  formaldehyde  in  presence  of 
alkalies  to  a  sweet  sugar-like  substance  was  first  observed  by  Butlerow,§ 
who  gave  the  compound  the  name  methylenitan.  A  similar  condensa- 
tion product  was  afterwards  prepared  by  Loew  ||  who  gave  it  the  name 

*  Lobry  de  Bruyn  and  van  Ekenstein,  Rec.  trav.  Pays-Bas,  16,  62,  282. 

t  Pellet,  Bull,  assoc.  chim.  sucr.  dist.,  16,  1181;  19,  834. 

t  Rec.  trav.  Pays-Bas,  16,  162. 

§  Compt.  rend.,  53,  143. 

II  J.  prakt.  Chem.  [2],  33,  321. 


630  SUGAR  ANALYSIS 

formose.  Methylenitan  and  formose  are  according  to  Fischer  identical 
in  nature,  although  this  has  been  disputed  by  Loew  and  Tollens.  To 
prepare  formose  a  4  per  cent  solution  of  formaldehyde  is  shaken  with 
an  excess  of  milk  of  lime  for  half  an  hour  and  then  filtered;  the  alkaline 
filtrate  is  allowed  to  stand  for  5  to  6  days  at  room  temperature  when 
the  condensation  is  complete.  The  solution  is  then  neutralized  with 
oxalic  acid,  filtered  and  evaporated  to  a  thin  sirup;  the  latter  is  puri- 
fied from  lime  salts  and  other  impurities  by  means  of  strong  alcohol; 
the  alcoholic  solution  upon  evaporation  gives  a  residue  which  con- 
sists mostly  of  formose. 

Properties.  —  Formose  has  been  obtained  only  as  a  yellowish  in- 
tensely sweet  sirup;  it  is  optically  inactive  and  strongly  reducing.  It 
is  not  fermented  by  yeast,  although  certain  organisms  decompose  the 
sugar  with  formation  of  lactic  acid.  The  sugar,  from  the  analysis  of 
its  osazone,  belongs  to  the  hexoses,  and  from  its  color  reaction  with 
resorcin  and  hydrochloric  acid  is  a  ketose.  The  configuration  of  for- 
mose has  not  as  yet  been  determined  and  it  is  still  a  question  whether 
formose  is  not  a  mixture  *  of  sugars  rather  than  a  single  substance. 

Formose-phenylosazone,  C^H^N^,  was  obtained  by  Fischer  f  as 
fine  yellow  needles  melting  at  144°  C. 

p-Formose  {  and  morf ose  §  are  two  other  sugars  which  Loew  has 
obtained  from  formaldehyde  by  varying  the  temperature  and  other 
conditions  of  condensation.  The  sugars  have  been  obtained  only  as 
impure  sirups;  the  existence  of  these  sugars  has  been  strongly  ques- 
tioned. 

Lycerose  ||  was  obtained  by  Loew  as  an  impure  sirup  through  con- 
densation of  glycerose  with  calcium  hydroxide  at  75°  C.  In  all  prob- 
ability lycerose  is  a  mixture  of  several  condensation  products. 

NATURAL  HEXOSES  OF  UNCERTAIN  CHARACTER 

A  large  number  of  hexose  sugars  of  unknown  configuration  have 
been  reported  at  various  times  in  the  literature.  The  existence  of 
these  in  nearly  all  cases  requires  confirmation.  It  is  possible  that  some 
of  the  sugars  in  the  following  list  belong  to  some  one  of  the  hexoses 

*  According  to  Nef  (Ann.,  376,  1)  synthetic  formose  is  probably  a  mixture  of  all 
possible  aldo-  and  keto-tetroses,  -pentoses  and  -hexoses,  in  the  equilibrium  between 
which  some  116  different  substances  take  part. 

t  Ber.,  21,  988. 

t  J.  prakt.  Chem.  [2],  34,  51. 

§  Chem.  Ztg.,  23,  542. 

II  Chem.  Ztg.,  23,  542. 


THE  MONOSACCHARIDES 


631 


previously  described,   the  variations  noted  in  specific  rotation  and 
other  properties  being  due  to  impurities. 


Sugar.* 

Source  of  sugar. 

Properties. 

Convallamarin  sugar  . 
Hederose  

Glucoside  from  lily  of  the  valley. 
Glucoside  from  ivy  
Glucoside  from  rhamnus  bark  
Glucoside  from  soapwort  

Crystals, 

Crystals, 

Crystals, 
Crystals, 

a 
a 
a 
a 
a 

«] 

D  =  +  102.7 

D  =  0 

/>  =  +  23.7 
D  =  +  17.8 
/>  =  +  24.5 

/  =-  45.8 

Locaose  

Saporubrose  

Scammonose  

Glucoside  from  scamraony  

Skimminose  

Glucoside  from  skimmia  
Glucoside  from  potato 

Solanose 

Chondroglucose 

Hydrolysis  of  cartilage 

Mucose 

Hydrolysis  of  mucin 

*  For  a  fuller  account  of  these  and  other  sugars  of  uncertain  character  the  chemist  is  referred  to  the 
long  list  in  Lippmann's  "Chemie  der  Zuckerarten  "  (1904),  975. 

METHYLHEXOSES 


a-Rhamnohexose.  — 

CH3 

CHOH 
HCOH 
HOCH 
HOCH 
HCOH 
CHO 

By  addition  of  hydrocyanic  acid  to  rhamnose  and  saponification  of  the 
nitrile  with  barium  hydroxide,  two  isomeric  rhamnohexonic  acids  should 
result.  In  this  reaction,  however,  one  isomer  is  always  formed  with  more 
readiness  than  the  other  and  so  in  the  case  of  rhamnose  a-rhamnohex- 
onic  acid  is  produced  in  much  greater  amount.  The  lactone  of  this 
acid  gives  upon  reduction  a-rhamnohexose  which  has  been  obtained  by 
Fischer  and  Piloty*  as  small  colorless  crystals  melting  at  180°  C.  and 
showing  levorotation,  [a]D=  —  61.4  constant.  The  sugar  exhibits 
mutarotation. 

Reactions.  —  a-Rhamnohexose  is  reduced  by  sodium  amalgam  to  its 
alcohol  a-rhamnohexite  ([«]/>=  +  14.0).  Oxidation  with  nitric  acid 
splits  off  the  methyl  group  and  forms  ordinary  mucic  acid;  this  reaction 


Ber.,  23,  3104,  3827. 


632  SUGAR  ANALYSIS 

serves  to  establish  the  configuration  of  the  sugar.  a-Rhamnohexose- 
phenylosazone  crystallizes  in  fine  yellow  needles  insoluble  in  water,  but 
soluble  in  hot  alcohol;  it  melts  at  200°  C. 

p-Rhamnohexose.*  — 

CH3 


:HOH 
;OH 
HOCH 


HC< 


HOC! 
HOC] 


a-Rhamnohexonic  acid  upon  heating  with  pyridine  to  150°  to  155°C. 
undergoes  partial  transformation  to  /3-rhamnohexonic  acid  whose  lac- 
tone  is  reduced  by  sodium  amalgam  to  /3-rhamnohexose.  The  sugar 
has  not  been  isolated  and  its  properties  are  for  the  most  part  unknown. 
Oxidation  with  nitric  acid  splits  off  the  methyl  group  with  formation 
of  talomucic  acid,  this  reaction  serving  to  confirm  the  configuration. 
The  phenylosazone  of  /3-rhamnohexose  melts  at  200°  C.  and  in  all  other 
respects  is  identical  with  that  of  a-rhamnohexose. 

a-Rhodeohexose.j  — 

CH3 


OH 
OH 


Hi 
HCOH 
HOCH 
HCOH 

i 


HO 

This  sugar  has  been  prepared  from  rhodeose  in  the  same  way  that 
a-rhamnohexose  was  built  up  from  rhamnose.  The  sugar  consists  of 
fine  crystals  melting  at  125°  to  126°  C.  and  showing  in  aqueous  solution 
Ma  =+11. 96. 

The  phenylosazone  consists  of  golden  needles  melting  at  231°  C. 

*  Fischer  and  Morrell,  Ber.,  27,  382. 

t  Krauz,  Ber.,  43,  482;  Z.  Zuckerind.  Bohmen,  35,  570. 


THE  MONOSACCHARIDES  633 

p-Rhodeohexose.*  — 

CH3 

CHOH 
HCOH 
HCOH 
HOCH 
HOCH 
CHO 

This  sugar  is  formed  from  rhodeose  in  the  same  way  as  /3-rhamno- 
hexose  from  rhamnose.  The  sugar  has  not  been  isolated  in  the  pure 
crystalline  form. 

HEPTOSES 
C7H1407 


a-Glucoheptose.  — 


ALDOHEPTOSES 

CH2OH 
HOCH 
HOCH 

HCOH 
HOCH 
HOCH 
CHO 


The  sugar  is  formed  by  reducing  the  lactone  of  a-glucoheptonic 
acid.  The  sugar  has  been  obtained  by  Fischer  f  in  the  form  of  large 
crystals  melting  at  180°  to  190°  C.,  and  showing  levorotation, 
[a]D=  —  19.7  (after  solution  =  —  25).  The  sugar  is  slightly  sweet  and 
is  but  slightly  soluble  in  cold  water  (easily  soluble  in  hot  water) .  a-Gluco- 
heptose  reduces  Fehling's  solution  but  to  a  less  extent  than  d-glucose. 
Reduction  with  sodium  amalgam  gives  inactive  a-glucoheptite  and 
oxidation  with  nitric  acid  gives  inactive  a-glucopentoxypimelic  acid. 

a-Glucoheptose-phenylosazone  forms  fine  yellow  needles  melting  at 
195°  C. 

*  Krauz,  Ber.,  43,  482;  Z.  Zuckerind.  Bohmen,  35,  570. 
t  Ann.,  270,  64. 


634  SUGAR  ANALYSIS 

B-Glucoheptose.*  — 

CH2OH 

HOCH 
HOCH 

HCOH 
HOCH 
HCOH 
CHO 

This  sugar  is  formed  by  reducing  the  lactone  of  /3-glucoheptonic 
acid,  but  has  not  been  isolated  as  yet  in  the  crystalline  form. 

Oxidation  of  /3-glucoheptose  with  nitric  acid  gives  the  dibasic  0-pen- 
toxypimelic  acid  whose  lactone,  CyHioOs,  is  dextrorotatory  ([a]D  =  +68.5). 
/3-Glucoheptose-phenylhydrazone  forms  fine  colorless  needles  melt- 
ing at  190°  to  193°  C.;  the  phenylosazone  of  0-glucoheptose  is  in  every 
respect  identical  with  that  of  a-glucoheptose. 

d-Mannoheptose.  — 

CH2OH 

HOCH 
HOCH 
HCOH 
HCOH 
CHOH 
CHO 

d-Mannoheptose  was  obtained  by  Fischer  and  Passmoref  from 
d-mannose  by  addition  of  hydrocyanic  acid,  and  reduction  of  the  lactone 
of  the  resulting  d-mannoheptonic  acid.  The  sugar  was  obtained  in  the 
form  of  fine  needles,  melting  at  134°  to  135°  C.;  it  has  a  sweet  taste,  is 
easily  soluble  in  water  but  difficultly  soluble  in  alcohol.  The  sugar  is 
dextrorotatory  showing  mutarotation,  [a]g  =  +  85,  10  minutes  after 
solution;  [a]^  constant  =  +  68.64.  No  perceptible  fermentation  was 
noted  in  presence  of  yeast. 

Identity  of  d-Mannoheptite  and  Perseite.  —  Reduction  of  d-manno- 

heptose  with  sodium  amalgam  produces   d-mannoheptite  which  was 

found  by  Fischer  and  Passmore  to  be  identical  with  the  natural  heptite 

alcohol  perseite,  first  found  by  Avequinf  in  the  fruit  of  the  alligator 

*  Fischer,  Ann.,  270,  87.  t  Ber.,  23,  2226. 

t  Ann.  chem.  med.  Ph.  et  Toxic.,  7,  467  (1831). 


THE  MONOSACCHARIDES 


635 


pear  (Per sea  gratissima) ,  and  identified  by  Maquenne*  in  1888.  The 
relationship  in  properties  of  d-mannoheptite  and  perseite  is  shown  in 
the  following  table  (Fischer  and  Passmore) : 


d-Mannohepti  te 

(synthetic). 

Perseite 
(natural). 

Melting  point 

188°  C 

188°  C 

Melting  point  of  heptacetyl  compound.  . 

119°  C. 

119°  C 

100  parts  of  the  saturated  aqueous  solution  at  | 
14°  C.  contain         \ 

6.  39  parts 

6.  26  parts 

Rotation  of  0.4  gm.  substance  in  5  c.c.  saturated  ) 
borax  solution  in  a  1  dcm  tube                          j 

+0.38° 

+0.39° 

The  relationship  shown  above  was  confirmed  by  the  fact  that  per- 
seite upon  careful  oxidation  with  nitric  acid  (1.14sp.  gr.)  at  45°  C.  is 
changed  to  d-mannoheptose. 

The  identity  established  between  perseite  and  mannoheptite  is 
but  one  illustration  of  the  increasing  value  which  sugar  synthesis  has 
in  the  more  refined  problems  of  sugar  analysis. 

d-Mannoheptose-phenylhydrazone  CTHnOe  :  N2HCeH5  crystallizes 
in  fine  colorless  needles  melting  at  197°  to  200°  C.  The  phenylosazone 
C7H1205(N2HC6H5)2  consists  of  fine  yellow  needles  melting  at  200°  C. 

1-Mannoheptose.  — 

CH2OH 

HCOH 
HCOH 
HOCH 
HOCH 
CHOH 
CHO 

1-Mannoheptose  was  obtained  by  Smithf  from  1-mannose,  in  the 
same  manner  as  d-mannoheptose  from  d-mannose.  The  sugar  was 
not  obtained  in  the  crystalline  form.  A  10  per  cent  solution  of  the 
sirup  showed  no  fermentation  with  yeast.  Reduction  with  sodium 
amalgam  gave  1-mannoheptite  (m.  p.  187°  C.). 

1-Mannoheptose-phenylhydrazone  consists  of  colorless  needles  melt- 
ing at  196°  C.;  the  phenylosazone  forms  yellow  needles  (m.  p.  203°  C.). 

d,  1-Mannoheptose    was    obtained   by   Smith  f  by  reducing  the 
lactone  of  d,  1-mannoheptonic  acid.     It  was  obtained  only  as  an  un- 
*  Compt.  rend.,  107,  583.  t  Ann.,  272,  182. 


636  SUGAR  ANALYSIS 

fermentable  optically  inactive  sirup.  Reduction  of  the  sugar  gave 
d,  1-mannoheptite  melting  at  203°  C.,  which  is  higher  than  that  ob- 
served for  either  of  its  components  (187°  C.).  The  same  racemic  com- 
pound was  obtained  by  mixing  equal  parts  of  d-,  and  1-mannoheptite 
and  allowing  the  aqueous  solution  to  crystallize. 

a-Galaheptose.  — 

CH2OH 


HOCH 
HCJOH 
COH 


H 


HOC] 


ino 

a-Galaheptose  was  obtained  by  Fischer*  from  d-galactose  by  ad- 
dition of  hydrocyanic  acid  and  reduction  of  the  lactone  of  the  resulting 
a-galaheptonic  acid.  The  sugar  was  obtained  only  as  a  sweet,  unfer- 
rnentable,  levorotatory  sirup. 

a-Galaheptose-phenylhydrazone  was  obtained  as  fine  colorless  needles 
melting  at  200°  C. ;  the  phenylosazone  consists  of  fine  yellow  needles, 
(m.  p.  218°  C.) 

p-Galaheptose  was  obtained  by  Fischer*  by  reducing  the  lactone 
of  0-galaheptonic  acid,  the  latter  being  formed  from  d-galactose  by 
addition  of  hydrocyanic  acid  at  the  same  time  as  its  isomer  a-gala- 
heptonic  acid.  The  sugar  has  the  same  structure  as  a-galaheptose, 
excepting  the  H  and  OH  groups  in  the  second  carbon  atom  which  are 
opposite  in  the  two  sugars;  the  particular  arrangement  belonging  to 
each  sugar  has  not  as  yet  been  established. 

/3-Galaheptose  crystallizes  in  the  form  of  large  prisms  melting  at 
190°  to  194°  C.  It  has  a  sweet  taste  and  is  easily  soluble  in  hot  water. 
The  sugar  is  levorotatory  showing  mutarotation,  [a]D  =  —  22.5  (10 
minutes  after  solution)  and  [a]^  constant  =  —  54.4. 

Volemose,  C7Hi407.  —  This  heptose  sugar  was  obtained  by  Fischer  f 
by  oxidation  of  the  naturally  occurring  heptite  alcohol  volemite,  which 
was  discovered  by  BourquelotJ  in  the  fungus  Lactarius  volemus. 

*  Ann.,  288,  139. 
t  Ber.,  28,  1973. 
j  Bull.  Soc.  Mycol.  de  France,  5,  132;  Chem.  Ztg.,  16,  190. 


THE  MONOSACCHARIDES  637 

Volemose  was  obtained  only  in  form  of  an  impure  sirup.  The 
phenylosazone  has  the  formula  CrHtfCM^HCeHs^  and  consists  of 
yellow  crystals  melting  at  196°  C. 

The  alcohol  volemite  CyRieO?  consists  of  fine  needles  melting  at 
149°  to  151°  C.,  and  showing  in  10  per  cent  aqueous  solution  a  dex- 
trorotation  of  [a]D+  1.92. 

The  configurations  of  volemose  and  volemite  have  not  as  yet  been 
established. 

KETOHEPTOSES 

Perseulose.  —  C7Hi407. 

This  ketoheptose  was  obtained  by  Bertrand*  through  the  action 
of  the  sorbose  bacterium  upon  perseite.  The  sugar  was  obtained  in  a 
pure  crystalline  form,  the  yield  being  about  45  per  cent  of  the  perseite 
taken. 

Perseulose  is  strongly  levorotatory  and  exhibits  mutarotation, 
[a]D  after  solution  =  —  90  and  [a]g  constant  =  —  81°. 

Perseulose-phenylosazone,  CyH^CW^HCeH^,  consists  of  yellow 
needles  melting  at  233°  C. 

METHYLHEPTOSES 
Rhamnoheptose.  — 


CH3 
CHOH 
HCOH 
HOCH 
HOCH 
HCOH 
CHOH 

CHO 

V. 
This  sugar  was  prepared  by  Fischer  and  Pilotyf  by  addition  of 
hydrocyanic  acid  to  a-rhamnohexose  and  reduction  of  the  lactone  of 
the  resulting  rhamnoheptonic  acid.     Rhamnoheptose  was  obtained  only 
as  a  colorless  sweet  sirup  of  weak  dextrorotation,  ([a]D  =  +  8.4  about). 
The  phenylhydrazone  of  rhamnoheptose  is  characterized  by  low 

*  Compt.  rend.,  147,  201;  149,  225. 
t  Ber.,  23,  3102. 


638 


SUGAR  ANALYSIS 


solubility  in  water  and  separates  with  great  readiness.  It  consists  of 
colorless  needles  having  the  composition  CgHieOe^HCeHs  and  melting 
at  200°  C.  The  phenylosazone,  CsHuCMNsHCeHB^,  consists  of  fine  yel- 
low needles  difficultly  soluble  in  water  and  hot  alcohol;  its  melting 
point  is  about  200°  C. 


a-Glucooctose.  — 


OCTOSES 

C8H1608 

CH2OH 

HOCH 

HOCH 
HCOH 

HOCH 

HOCH 
CHOH 
CHO 


This  sugar  was  synthetized  by  Fischer*  from  a-glucoheptose ;  the 
latter  by  addition  of  hydrocyanic  acid  yields  2  stereo-isomers,  a-  and 
/3-glucooctonic  acid.  The  lactone  of  a-glucooctonic  acid  gives  upon 
reduction  a-glucooctose. 

a-Glucooctose  crystallizes  from  water  in  fine  white  needles  as  a 
hydrate  having  the  formula  C8Hi6O8  +  2  H20.  The  sugar  is  levo- 
rotatory  and  shows  mutarotation;  [a]^  =  —  50.5  (constant  for  the  an- 
hydride C8H16O8). 

a-Glucooctose  has  a  sweet  taste  and  gives  all  the  ordinary  reac- 
tion of  a  reducing  sugar. 

a-Glucooctose-phenylhydrazone,  CsHieOy^HCeHs,  separates  very 
readily  as  a  difficultly  soluble  compound,  consisting  when  pure  of  fine 
colorless  needles  melting  at  about  190°  C.  The  phenylosazone  forms 
fine  yellow  crystals  melting  at  210°  to  212°  C.  and  having  the  com- 
position C8Hi406(N2HC6H5)2. 

Upon  reduction  with  sodium  amalgam  a-glucooctose  gives  its  alcohol 
a-glucooctite,  C8Hi808,  which  melts  at  141°  C. 

/3-Glucooctose,  formed  by  reducing  the  lactone  of  |8-glucooctonic 
acid,  has  not  been  studied. 

*  Ann.,  270,  64. 


THE  MONOSACCHARIDES  639 

d-Mannooctose.  — 

CH2OH 

HOCH 


HOCH 
HCOH 
Hi 


OH 

HOH 
CHOH 
CHO 

This  sugar  was  built  up  from  d-mannoheptose  by  Fischer  and  Pass- 
more  *  by  addition  of  hydrocyanic  acid  and  reducing  the  lactone  of  the 
resulting  d-mannooctonic  acid.  The  sugar  was  obtained  only  as  a  sweet 
colorless  unfermentable  sirup  with  slight  levorotation,  (WZ)=  —  3.3). 

d-Mannooctose  upon  reduction  gives  d-mannooctite  CaHigOs,  which 
consists  of  colorless  very  difficultly  soluble  crystals  melting  at  258°  C. 

The  phenylhydrazone  CsHieOy^HCeHs  forms  colorless  needles 
very  insoluble  in  water  and  melting,  when  quickly  heated,  at  about 
212°  C.  The  phenylosazone  forms  fine  yellow  needles  very  insoluble 
in  hot  water  and  alcohol,  and  melting  at  about  223°  C. 

a-Galaoctose.  — 

CH2OH 

HOCH 

HCOH 

HCOH 
HOCH 


HOH 
HOH 
HO 


a-Galaoctose  was  built  up  by  Fischer  f  from  a-galaheptose  by 
adding  hydrocyanic  acid  and  reducing  the  lactone  of  the  resulting 
a-galaoctonic  acid.  The  sugar  was  obtained  as  colorless  crystals  of  the 
monohydrate  C8H]6O8  +  H2O  melting  at  109°  to  111°  C.  The  sugar  is 
levorotatory,  [a]D  =  —  40°  about. 

*  Ber.,  23,  2226. 
t  Ber.,  27,  3198. 


640  SUGAR  ANALYSIS 

a-Galaoctose  gives  upon  reduction  a-galaoctite  CsHisOs  which  con- 
sists of  colorless  needles  melting  at  220°  to  225°  C.  The  phenylhy- 
drazone  of  a-galaoctose  has  the  formula  CsHieOT^HCeHs  and  melts 
at  200°  to  205°  C.  The  osazone  GgHuOe^HCsHfi),  forms  fine  yellow 
needles  melting  at  220°  to  225°  C. 

METHYLOCTOSES 
CH3  •  C8H1508 

Rhamnooctose.  — 

CH3 

CHOH 
HCOH 
HOCH 
HOCH 
HCOH 
CHOH 
CHOH 
CHO 

This  sugar  was  prepared  by  Fischer  and  Piloty*  from  rhamno- 
heptose  by  adding  hydrocyanic  acid  and  reducing  the  lactone  of  the 
resulting  rhamnooctonic  acid.  The  sugar  was  not  separated  in  the  pure 
condition  and  its  properties  have  not  been  determined. 

NONOSES 
C9H1809 

o-Glucononose.  — 

CH2OH 

HOCH 
HOCH 

HCOH 
HOCH 
HOCH 
CHOH 
CHOH 
CHO 
*  Ber.,  23,  3102. 


THE  MONOSACCHARIDES  641 

a-Glucononose  was  prepared  by  Fischer*  from  a-glucooctose  by 
adding  hydrocyanic  acid  and  reducing  the  lactone  of  the  resulting 
a-gluconononic  acid.  The  sugar  was  obtained  only  as  a  colorless 
non-fermentable  sirup  with  slight  dextrorotation. 

Reduction  of  a-glucononose  gives  the  alcohol  a-glucononite,  CgH^Og, 
which  consists  of  colorless  crystals  melting  at  194°  C. 

a-Glucononose-phenylhydrazone  CgHigOs^HCeHs  forms  white  nee- 
dles only  slightly  soluble  in  cold  water  and  alcohol  and  melting  at 
about  194°  C.  The  phenylosazone  CgHuA^HCeHs^  consists  of  fine 
yellow  needles  almost  insoluble  in  hot  water  and  alcohol,  and  melting 
at  220°  to  223°  C. 

d-Mannononose.  — 

CH2OH 

HOCH 
HOCH 


Hci 
HC< 


OH 


HOH 


d-Mannononose  was  prepared  by  Fischer  and  Passmoref  from 
d-mannooctose  by  adding  hydrocyanic  acid  and  reducing  the  lactone  of 
the  resulting  d-mannonononic  acid.  The  sugar  was  obtained  as  white 
crystals  melting  at  130°  C.  and  showing  in  aqueous  solution  dextro- 
rotation ([«]*[  =+50  about). 

d  -Mannononose  is  fermented  by  yeast  with  the  same  ease  and  com- 
pleteness as  d-glucose. 

d-Mannononose-phenylhydrazone,  CgHigOs^HCeHs,  forms  crystals 
easily  soluble  in  hot  water  and  melting  at  223°  C.  The  phenylosazone 
CgHisOr^HCeHj,^,  forms  yellow  needles  almost  insoluble  in  hot  water 
and  alcohol  and  melting  at  217°  C. 

A  peculiarity  of  d-mannononose  is  its  striking  resemblance  to  d-glu- 
cose. The  resemblance  in  composition,  melting  point,  specific  rotation 
and  fermentability  could  easily  cause  confusion;  an  analysis  of  the  osa- 
zone  easily  serves,  however,  to  fix  the  class  of  the  sugar  (see  page  371). 

*  Ann.,  270,  64. 
t  Ber.,  23,  2226. 


642  SUGAR  ANALYSIS 

DECOSES 


a-Glucodecose.  — 

CH2OH 

HOCH 
HOCH 

HCOH 
HOCH 
HOCH 

CHOH 

CHOH 

CHOH 

CHO 

This  sugar  has  recently  been  prepared  by  Phillippe*  from  a-gluco- 
nonose,  following  the  usual  method  of  adding  hydrocyanic  acid,  saponi- 
fying and  reducing  the  lactone  of  the  resulting  a-glucodeconic  acid  by 
means  of  sodiiim  amalgam. 

a-Glucodecose  crystallizes  in  needle-shaped  crystals,  which  show 
in  aqueous  solution  a  dextrorotation,  [a]™  '=  +  50.4  (constant)  ;  in 
fresh  solution  [a]^  =  +  37.  Under  certain  conditions  the  sugar  may 
crystallize  in  plates  having  one  molecule  of  water  of  crystallization. 
The  sugar  reduces  Fehling's  solution  about  76  per  cent  as  strongly  as 
glucose;  it  forms  a  phenylhydrazone  melting  at  about  278°  C. 

a-Glucodecose  is  reduced  by  sodium  amalgam  to  the  correspond- 
ing alcohol  a-glucodecite,  which  consists  of  prismatic  needles,  melting 
and  subliming  at  222°  C.  and  showing  in  aqueous  solution  [df£ 
=  +  1.2. 

*  Compt.  rend.,  151,  986;  152,  1774. 


CHAPTER  XX 

THE  DISACCHARIDES 

DIPENTOSE  SACCHARIDES 

/  C5H904 
O 
x  C5H<A 

Diarabinose,  CioHi809.  —  This  disaccharide  was  obtained  by 
O'Sullivan*  in  heating  Gedda  gum  with  sulphuric  acid  (0.3  —  0.5  per 
cent).  Its  formation  is  probably  due  to  the  breaking  down  of  higher 
condensation  substances  of  the  gum  (arabinic  acids)  into  diarabinose 
and  other  hydrolytic  products.  Diarabinose  (also  called  arabinon, 
arabiose  and  arabinobiose)  was  obtained  by  O'Sullivan  as  an  amor- 
phous vitreous  hygroscopic  substance  of  sweet  taste  and  very  soluble 
in  water  from  which  it  is  precipitated  by  strong  alcohol.  The  prod- 
uct melts  at  about  75°  to  80°  C.,  and  is  strongly  dextrorotatory, 
[a]D  =  +  198.8.  It  reduces  Fehling's  solution  about  58.8  per  cent  as 
strong  as  d-glucose.  Analysis  of  the  sugar  and  determination  of  its 
molecular  weight  by  the  freezing  point  method  indicate  the  formula 

Upon  heating  with  2  per  cent  sulphuric  acid,  diarabinose  is  hydro- 
lyzed  quantitatively  into  1-arabinose. 

Diarabinose  1-Arabinoae. 

PENTOSE-HEXOSE  SACCHARIDES. 

/  C5H904 
°\ 

Glucoapiose,  CnH2oOio.  —  This  disaccharide  has  not  been  isolated 
as  yet  although  its  presence  has  been  recognized  by  Vongerichtenf 
among  the  constituents  of  the  glucoside  apiin,  which  is  obtained  from 
parsley.  The  formation  of  glucoapiose  from  apiin  should  proceed  ac- 
cording to  the  following  equation: 

C*       TJ       f\  I  TT    /"I  r^TTO  -4-  f\eTTinOe 

O26-tl28<Ji4      T      il2U          —          VU-tl»vlO        T^         ^isp-ioys- 
Apiin  Glucoapiose  Apigenm. 

*  J.  Chem.  Soc.,  57,  59;  59,  1029. 
t  Ber.,  9,  1124;  33,  2334,  2904. 
643 


644 


SUGAR  ANALYSIS 


The  glucoapiose,  however,  is  itself  decomposed  by  the  hydrolytic  agent 
into  glucose  and  apiose  (p.  544). 

CTT/^      _i_    TT  n  r^Ti/^     _i_r^Tj^ 

Il£l20wio      ~r      Jl2v/  v^6-n-l2V-'6      T      v^5-T«-10^5> 

Glucoapiose  d-Glucose  Apiose. 

so  that  the  separation  of  the  disaccharide  itself  has  not  been  accom- 
plished by  this  means. 

Galactoarabinose,  CnH20Oi0.  —  This  sugar  has  not  been  found  as 
yet  in  nature.  It  has  been  prepared  synthetically  by  Ruff  and  Ollen- 
dorf*  from  ordinary  lactose,  by  first  oxidizing  the  sugar  by  means  of 
bromine  to  lactobionic  acid  and  then  oxidizing  the  calcium  salt  of  the 
latter  with  hydrogen  peroxide  in  presence  of  basic  ferric  acetate;  the 
COOH  group  of  the  acid  is  thus  destroyed  and  a  disaccharide  sugar 
obtained  with  11  C  atoms. 
(  CH2OH 


d-Galactose!      /nuYYtn 

radical     1      ^Y11 
I       CO 

CH2 

HOCH 

d-Gluconic 

HOCH 

acid 
radical 

HCOH 

| 

HOCH 

COOH 

Lactobionic  Acid 

+  0 


CH2OH 

d-Galactose. 
radical 

(CHOH)4 
CO 

f      CH2 

HOCH 

d-Arabinose^ 
radical 

HOCH 
HCOH 

CHO 

C02  +  H20 


Galactoarabinose 

The  process  is  similar  to  those  previously  described  by  which  the 
monobasic  acids  of  sugars  are  degraded  into  sugars  of  one  less  carbon 
atom.  (See  under  d-erythrose,  page  540). 

Galactoarabinose  has  been  obtained  only  as  a  colorless  dextro- 
rotatory sirup.  Upon  heating  with  dilute  acids  it  is  hydrolyzed  into 
d-galactose  and  d-arabinose. 

Galactoarabinose  d-Galactose  d-Arabinose'. 

METHYLPENTOSE-HEXOSE  SACCHARIDES 


\ 

No  sugar  of  the  constitution  Ci2H22Oi0  has  as  yet  been  discovered, 
A  methyl  glucoside  of  mannorhamnose,  however,  has  been  isolated. 

*  Ber.,  32,  552;  33,  1806. 


THE  DISACCHARIDES  645 

Methyl  mannorhamnoside,*  Ci^Ao  •  CH3.  —  This  glucoside  has 
been  obtained  by  hydrolysis  of  strophanthin,  the  poisonous  principle 
of  the  seeds  of  Strophanthus  Korribe,  used  by  the  natives  of  eastern 
Africa  as  an  arrow  poison.  Strophanthin  is  decomposed  by  dilute 
acids  as  follows: 


=      (C27H3807  +  2  H20)      -f-      C12H21010  •  CH3. 

Strophanthin  Strophanthidin  Methyl  mannorhamnoside. 

One  part  of  strophanthin  is  dissolved  in  5  parts  of  cold  0.5  per 
cent  hydrochloric  acid  and  then  warmed  for  some  time  at  70°  to  75°  C. 
and  then  at  75°  to  80°  C.  The  strophanthidin  which  crystallizes  out  is 
filtered  off  and  the  cold  filtrate  freed  from  hydrochloric  acid  by  means 
of  silver  oxide.  The  clear  filtered  solution  is  then  concentrated  in  a 
vacuum  to  a  sirup  from  which  the  methyl  mannorhamnoside  can  be  pre- 
cipitated by  means  of  ether.  The  compound  upon  recrystallizing  from 
alcohol  is  obtained  as  white  crystals  melting  at  207°  C.  The  glucoside 
is  easily  soluble  in  water,  fairly  soluble  in  hot  alcohol,  but  almost  insol- 
uble in  ether.  It  is  dextrorotatory  ([a]D  =  +  8.24  about),  unfermentable 
and  does  not  reduce  Fehling's  solution.  Upon  heating  with  an  excess 
of  strong  mineral  acid,  methyl  mannorhamnoside  yields  large  amounts 
of  methylfurfural  and  levulinic  acid.  The  glucoside  is  hydrolyzed  by 
heating  with  5  parts  of  1  per  cent  sulphuric  acid  as  follows: 

C12H21Oio  •  CH3  +  2  H20    =    C6H1206  +  C6H12O5  +    CH3OH. 

Methyl  mannorhamnoside  Mannose  Rhamnose  Methyl  alcohol. 

DIHEXOSE  SACCHARIDES 


^  CeHiiO. 

This  group,  by  far  the  most  important  of  the  higher  saccharides,  in- 
cludes the  three  well-known  sugars  :  sucrose,  maltose  and  lactose. 

SUCROSE.  —  Saccharose.     Cane  sugar. 

Ci2H22On. 
Occurrence.  —  Sucrose  occurs  very  widely  distributed  throughout 

the  vegetable  kingdom;  from  its  importance  as  a  commodity  and  food 

product  it  is  the  best  known  of  the  sugars. 

The  approximate  distribution  of  sucrose  in  different  fresh  plant 

materials  is  as  follows:  Percent. 

Juice  of  green  leaves  .....................................     0.1  —    2.0 

Juice  of  stalks  from  maize,  sugar  cane,  etc  ..................     2.0  —  20.0 

Sap  of  maple,  birch,  palm  and  other  trees  ............  .  .....     1.0  —    5.0 

Apples,  berries,  oranges,  prunes,  bananas  and  other  fruits  ----     0.5  —  14.0 

Seeds,  grains,  nuts,  etc  ...................................     0.5  —  12.0 

Buds,  blossoms  and  flowering  organs  ......................     0.1  —  15.0 

Roots,  yams,  bulbs,  tubers,  rhizomes,  etc.  .  .  ...............     0.5  —  25.0 

*  Feist,  Ber.,  31,  535;  33,  2063,  2069,  2091. 


646  SUGAR  ANALYSIS 

Sucrose  has  not  been  identified  with  certainty  in  any  products  of 
purely  animal  origin.  It  occurs  in  honey  in  amounts  ranging  usually 
from  0.0  to  10  per  cent;  in  abnormal  cases  the  percentage  of  sucrose 
may  exceed  10  per  cent.  The  sucrose  of  honey,  however,  is  derived 
primarily  from  floral  nectar  or  other  plant  sources  and  must  therefore 
be  regarded  as  of  vegetable  origin. 

Preparation  of  Sucrose.  Technical  Processes. --The  sugarcane, 
sugar  beet,  maple,  palm,  sorghum  and  maize  have  all  been  utilized  for 
the  production  of  sugar.  The  annual  production  of  raw  sucrose  for 
the  world  at  present  is  about  16,000,000  long  tons  (1  long  ton  =  2240 
Ibs.)  of  which  about  8,500,000  tons  are  made  from  sugar  cane  and 
about  7,500,000  tons  from  the  sugar  beet;  the  production  from  other 
sources  is  insignificant.  In  the  manufacture  of  raw  sugar  the  juice  is 
extracted  from  the  sugar  cane  by  means  of  mills,  and  from  the  sugar 
beet  by  means  of  diffusion  batteries.  The  extracted  juice  is  then 
clarified*  usually  with  milk  of  lime,  any  excess  of  the  latter  being  re- 
moved by  means  of  carbon  dioxide  ("  carbonatation  "),  sulphurous  acid 
("  sulphitation  "),  phosphoric  acid  or  other  precipitating  agent.  The 
clarified  juice,  which  may  contain  from  10  to  18  per  cent  of  sucrose, 
is  then  evaporated  to  crystallization.  In  primitive  countries  the 
evaporation  is  done  in  open  pans  directly  over  the  fire;  in  the  more 
modern  factories  some  form  of  vacuum  evaporator  is  used.  After 
the  evaporated  juice  has  crystallized,  the  thick  magma  of  crystals 
("  massecuite "  or  "  fillmass ")  is  purged  from  its  mother  liquor,  or 
molasses,  a  process  which  is  usually  carried  out  in  centrifugals;  the 
product  thus  obtained  constitutes  the  raw  sugar  of  commerce  and 
varies  in  purity  from  80  per  cent  to  almost  100  per  cent  pure  sucrose. 

Refining.  —  The  raw  sugar  of  commerce  is  afterwards  refined. 
The  process  of  refining  comprises  usually  (1)  washing  the  crystals  of 
raw  sugar  with  concentrated  sirups  to  remove  adhering  molasses,  a 
process  sometimes  termed  "affining,"  (2)  dissolving  the  purified  crystals 
in  hot  water  and  clarifying  the  solution  with  lime  or  other  agents; 
(3)  filtering  the  clarified  solution  over  bone  black  f  to  remove  coloring 
matter  and  other  impurities;  (4)  evaporating  the  filtered  and  decolor- 
ized solution  to  a  magma  of  crystals;  (5)  centrifuging  the  "masse- 
cuite "  or  " fillmass"  and  drying  the  pure  white  crystals  of  sucrose  in 

*  The  number  of  substances  which  have  been  proposed  for  clarifying  sugar 
juices  is  almost  unlimited.  A  classification  of  clarifying  agents  made  by  Lippmann 
(Die  Deutsche  Zuckerind.,  34,  9)  includes  620  different  materials  or  processes. 

t  The  use  of  bone  black  has  been  largely  discontinued  in  the  refining  of  beet 
sugar. 


THE  DISACCHARIDES  647 

granulators,  or  in  cones,  cubes,  dominos  or  other  forms  according  to 
the  demands  of  the  trade.  Refined  sugar  is  usually  about  99.8  to 
99.9  per  cent  pure,  the  remaining  0.1  to  0.2  per  cent  consisting  mostly  of 
moisture  with  occasional  traces  of  ash,  invert  sugar,  raffinose  and  cara- 
mel substances. 

To  obtain  sucrose  perfectly  pure  the  best  grade  of  refined  sugar  is 
recrystallized  from  neutral  redistilled  96  per  cent  alcohol.  The  method 
described  upon  page  121  may  be  used  to  advantage. 

Isolation  of  Sucrose  from  Plant  Substances.  —  For  the  separation  of 
sucrose  from  plant  substances,  when  only  small  amounts  of  the  sugar 
are  present,  Schulze*  has  made  use  of  the  difficultly  soluble  strontium 
bisaccharate  C^H^On  •  2  SrO.  The  fresh  material,  in  presence  of  an  ex- 
cess of  pure  finely  powdered  calcium  carbonate  to  neutralize  any  acidity, 
is  extracted  with  hot  90  per  cent  alcohol.  After  cooling,  the  extract  is 
filtered  and  then  heated  to  boiling  with  the  addition  of  a  hot  saturated 
solution  of  strontium  hydrate  using  over  3  parts  of  Sr(OH)2  for  every 
1  part  of  sucrose  supposed  to  be  present.  After  boiling  30  minutes  the 
precipitate  is  filtered,  washed  with  alcohol  and  again  boiled  for  30 
minutes  with  strontium  hydrate  solution.  The  precipitate  is  filtered 
hot,  using  a  hot  water  funnel,  and  then,  after  suspending  in  water,  de- 
composed with  a  stream  of  carbon  dioxide.  The  solution  is  filtered  from 
strontium  carbonate  and  then  evaporated  to  a  sirup  which  is  purified  by 
means  of  neutral  95  per  cent  alcohol  in  the  usual  way.  The  alcoholic  solu- 
tion is  reevaporated  to  a  sirup  and  repurified  as  before,  the  process  of 
evaporation  and  extraction  of  the  sirup  with  alcohol  being  repeated 
several  times.  The  final  sirup  is  placed  over  concentrated  sulphuric  acid 
in  a  cool  place  for  crystallization. 

PROPERTIES   OF   SUCROSE 

Crystalline  Form. — Sucrose  crystallizes  in  beautiful  colorless  crys- 


i 

Fig.  195.  —  Monoclinic  crystals  of  sucrose.     I,  Tabular  form;   II,  Form  with 

hemihedral  faces. 

tals  belonging  to  the  monoclinic  system.    The  crystals  have  hemihedral 

surfaces  and  show  the  greatest  variety  of  form  (Fig.  195).     The  shape 

*  Z.  Ver.  Deut.  Zuckerind.,  38,  221. 


648  SUGAR  ANALYSIS 

of  sucrose  crystals  is  greatly  modified  by  other  substances,  the  effect 
of  raffinose  in  this  respect  being  especially  pronounced  (p.  735).  Crys- 
tals of  sucrose  may  take  up  soluble  coloring  matter  from  the  mother 
liquor  during  growth  and  such  crystals  often  show  a  variation  in  tint 
when  viewed  in  different  directions  (pleochroism) .  Although  sucrose  in 
solution  is  optically  active,  its  crystals,  as  was  first  noted  by  Biot,*  do 
not  rotate  the  plane  of  polarized  light. 

Melting  Point  and  Specific  Gravity. —  The  melting  point  of  sucrose 
is  given  by  different  observers  as  varying  between  160°  to  180°  C.,  the 
variations  being  due  apparently  to  differences  in  method  and  in  the 
physical  character  of  the  sugar.  The  specific  gravity  of  solid  sucrose 
is  given  by. different  authorities  as  between  1.58  and  1.61,  the  differ- 
ences being  probably  due  to  variations  in  the  character  of  the  crystals. 
The  recent  determinations  of  Plato  f  give  for  chemically  pure  sucrose 
d  j|s  =1.591.  The  specific  gravity  of  the  hypothetical  solid  sucrose  in 
aqueous  solution  is  given  by  Plato  as  d^  =  1.55626; '  the  difference 
between  this  figure  and  that  for  the  actual  solid  being  due  to  the  con- 
traction in  volume  during  solution.  The  part  which  this  phenomenon 
plays  in  the  determination  of  sucrose  by  densimetric  methods  has  already 
been  considered  (p.  33). 

Solubility.  —  The  solubility  of  sucrose  in  water  of  different  tem- 
peratures and  the  character  of  the  solutions  thus  obtained  are  given  by 
HerzfeldJ  in  Table  XCI. 

Sucrose  is  soluble  in  80  parts  of  boiling  absolute  alcohol,  more 
easily  soluble  in  dilute  alcohol  but  insoluble  in  ether. 

SOLUBILITY  OF  SUCROSE  AND  THE  MELASSIGENIC  ACTION  OF  SALTS 

The  solubility  of  sucrose,  as  of  all  other  sugars,  is  affected  to  a  marked 
degree  by  the  presence  of  foreign  organic  and  inorganic  substances. 
Such  impurities  play  an  important  part  technically  in  prevent- 
ing the  recovery  of  sucrose  from  sugar-house  molasses.  A  satu- 
rated solution  of  sucrose  in  contact  with  sucrose  crystals  can  dissolve 
no  more  sucrose  at  constant  temperature;  if  solid  potassium  acetate, 
or  sodium  chloride,  or  many  other  salts  be  stirred  into  the  solution, 
however,  it  will  not  only  be  dissolved  but  more  of  the  sucrose  will  also 
enter  solution.  In  other  words  more  sugar  will  be  dissolved  than  can 
be  held  in  solution  by  the  water  alone.  This  phenomenon  is  explained 
by  many  authorities  as  being  due  to  the  formation  of  sucrose-salt  com- 

*  M6moires  de  l'Acad6mie,  13,  59,  126.       f  Z.  Ver.  Deut.  Zuckerind.,  50,  1012. 
|  Z.  Ver.  Deut.  Zuckerind.,  42,  181,  232. 


THE  DISACCHARIDES 


649 


pounds,  or  complexes,  which  have  a  greater  solubility  than  the  sucrose 
alone. 

TABLE  XCI. 

Solubility  of  Sucrose  in  Water  at  Different  Temperatures. 


Temperature. 

Grama  sucrose  in 
100  grams  solution. 

Grams  sucrose  dis- 
solved by  100 
grams  water. 

Grams  water  corre- 
sponding to  1  gram 
dissolved  sucrose. 

Specific  gravity  of 
solution,  17.5°  C. 

Deg.  C. 

0 

64.18 

179.2 

0.5580 

1.31490 

5 

64.87 

184.7 

0.5414 

1.31920 

10 

65.58 

190.5 

0.5249 

1.32353 

15 

66.30 

197.0 

0.5076 

1.32804 

20 

67.09 

203.9 

0.4904 

.33272 

25 

67.89 

.     211.4 

0.4730 

.33768 

30 

68.70. 

219.5 

0.4556 

.34273 

35 

69.55 

228.4 

0.4378 

.34805 

40 

70.42 

238.1 

0.4200 

.35353 

45 

71.32 

248.7 

0.4021 

.35923 

50 

72.25 

260.4 

0.3840 

1.36515 

55 

73.20 

273.1 

0.3662 

1.37124 

60 

74.18 

287.3 

0.3418 

1.37755 

65 

75.18 

302.9 

0.3301 

1.38404 

70 

76.22 

320.5 

0.3120 

1.39083 

75 

77.27 

339.9 

0.2942 

1.39772 

80 

78.36 

362.1 

0.2762 

1.40493 

85 

79.46 

386.8 

0.2585 

1.41225 

90 

80.61 

415.7 

0.2406 

1.41996 

95 

81.77 

448.6 

0.2229 

1.42778 

100 

82.97 

487.2 

0.2053 

1.43594 

Solubility  of  Sucrose  in  Beet  Molasses.  —  A  condition  similar  to 
that  previously  described  exists  in  sugar-beet  molasses  as  is  shown  by 
the  following  analysis: 

Per  cent. 

Water 20 

Sucrose 50 

Salts 10 

Reducing  sugars trace 

Organic  non-sugars 20 

The  20  parts  of  the  water  alone  could  hold  in  solution  at  ordinary 
temperature  only  about  40  parts  of  sucrose,  so  that  if  the  salts  and 
other  impurities  were  absent  sucrose  would  begin  to  crystallize.  Such 
a  removal  of  salts  is  the  principle  of  the  old  osmose  process  for  recover- 
ing sucrose  from  beet  molasses  first  devised  by  Dubrunfaut.  If  beet 
molasses  be  dialyzed  by  means  of  parchment  paper  against  running 
water  the  salts  will  diffuse  with  much  greater  rapidity  than  the  sucrose 
and  in  this  way  the  percentage  of  melassigenic  impurities  can  be 
considerably  reduced;  beet  molasses  thus  purified  will  deposit  upon 
evaporation  crystals  of  sucrose  up  to  the  new  saturation  point  for  the 


650  SUGAR  ANALYSIS 

solution  of  undialyzed  impurities.  This  process  has  given  place  techni- 
cally to  the  saccharate  process  of  sucrose  recovery  to  be  described  later. 
Solubility  of  Sucrose  in  Cane  Molasses.  —  In  low-grade  sugar- 
cane molasses  an  opposite  condition  exists  to  that  in  beet  molasses;  in 
cane  molasses  the  amount  of  sucrose  is  less  than  that  which  will  satu- 
rate the  quantity  of  water  present.  This  is  shown  by  the  following 
analysis  of  a  low-grade  cane  molasses. 

Per  cent. 

Water 20 

Sucrose 30 

Invert  sugar 30 

Salts • 8 

Organic  non-sugars 12 

Geerligs's  Theory  of  Melassigenic  Action.;—  A  molasses  of  the 
above  composition  can  dissolve  no  more  sucrose,  yet  the  20  parts  of 
water  alone  could  hold  in  solution  40  parts  of  sucrose  at  ordinary  tem- 
perature. This  difference  in  behavior  upon  the  part  of  cane  molasses 
is  explained  by  Prinsen  Geerligs  *  as  due  to  a  combination  between  the 
invert  sugar  and  the  salts  of  the  molasses  (the  potassium  organic  salts 
more  especially).  The  invert-sugar-salt  complexes  which  are  thus 
formed  hold  in  combination  a  large  amount  of  water  of  hydration 
which  thus  reduces  the  quantity  of  water  available  for  solution  of  the 
sucrose.  The  power  of  sucrose  to  form  salt  complexes  is  much  less 
than  that  of  invert  sugar  so  that  it  is  only  in  cane  molasses  of  very 
low  invert  sugar  content  that  sucrose-salt  complexes  exist  in  sufficient 
quantity  to  raise  the  solubility  of  sucrose  above  the  saturation  point 
of  the  water  present. 

According  to  this  theory  the  addition  of  anhydrous  glucose  to  a  sat- 
urated solution  of  a  sucrose-salt  complex  should  displace  the  sucrose 
and  cause  a  part  of  the  latter  to  crystallize  out.  This  was  verified  ex- 
perimentally by  Geerligs  who  found  that  when  225  gms.  of  anhydrous 
glucose  were  added  to  300  gms.  of  a  saturated  solution  of  sucrose  and 
potassium  acetate,  and  the  mixture  allowed  to  stand  for  several  months 
75  gms.  of  sucrose  separated  in  the  crystalline  form.  A  check  solution 
without  addition  of  glucose  showed  no  evidence  of  crystallization. 

The  melassigenic  action  of  different  organic  and  mineral  substances 
upon  sucrose  has  been  studied  by  many  investigators  and  for  a  com- 
plete review  of  the  various  physical  and  chemical  theories  upon  the 
subject  the  student  is  referred  to  the  works  of  Lippmann  f  and  Geer- 

*  Z.  Ver.  Deut.  Zuckerind,  45,  320. 

t  "  Chemie  der  Zuckerarten,"  1147-1162. 

t  "  Cane  Sugar  and  its  Manufacture  "  (1909),  301-317. 


THE  DISACCHARIDES  651 

Boiling  Point  of  Sucrose  Solutions.  —  The  boiling  point  of  aqueous 
sucrose  solutions  of  different  concentrations  is  given  by  Gerlach  *  as 
follows : 

Per  cent  sucrose   10       20       30       40       50       60         70        80     90  8 

Boiling  point  °C  ....      100.4  100.6  101.0  101.5  102.0  103.0     106.5  112.0  130.0 

Specific  Rotation.  —  The  specific  rotation  of  sucrose  has  been  the 
subject  of  greater  study  than  that  of  any  other  sugar.  The  first  de- 
terminations were  made  in  1819  by  Biot,f  who  first  introduced  the 
constant  of  specific  rotation  and  thereby  founded  the  science  of  optical 
analysis. 

The  value  for  the  specific  rotation  of  sucrose  in  aqueous  solution  is 
very  closely  [a]2£  =  +  66.5.  The  influences  of  temperature,  concentra- 
tion, solvents,  salts,  etc.,  upon  the  specific  rotation  of  sucrose  have 
already  been  considered. 

Fermentations  of  Sucrose.  Alcoholic  Fermentation.  —  In  so  far  as 
the  various  yeasts,  moulds  and  bacteria  secrete  the  enzyme  invertase 
they  are  able  to  ferment  sucrose  in  the  same  manner  as  its  products  of 
inversion,  glucose  and  fructose.  The  majority  of  the  yeasts  secrete  in- 
vertase and  ferment  sucrose  with  the  same  yield  of  alcohol  and  carbon 
dioxide  as  is  obtained  from  glucose  and  fructose;  the  process  is  some- 
what slower,  however,  in  its  first  stages  owing  to  the  retarding  effect  of 
the  inversion  which  must  precede  fermentation. 

Non-inverting  Yeasts  and  Moulds.  —  A  considerable  number  of 
alcohol-producing  organisms,  such  as  Saccharomyces  octosporus,l  Sac- 
charomyces  apiculatus,§  and  most  of  the  Mucor  genus  of  moulds  do 
not  secrete  invertase  and  pure  cultures  of  these  do  not  ferment  sucrose. 
Attempts  have  been  made  to  employ  organisms  of  this  class  such,  for 
example,  as  Mucor  circinelloides,\\  for  destroying  the  invert  sugar  of 
cane  molasses,  in  the  hope  of  obtaining  the  residual  sucrose  in  a  suit- 
able condition  for  recovery.  The  process  has  not  been  a  technical 
success.  |f 

*  Z.  Ver.  Deut.  Zuckerind,  13,  283. 

f  Memoires  de  1' Academic,  2,  41;  13,  118. 

t  Fischer  and  Lindner,  Ber.,  28,  984. 

§  Fischer  and  Lindner,  Ber.,  28,  3034. 

II  Gayon,  Ann.  chim.  phys.  [3],  14,  258. 

f  Upon  the  basis  of  Prinsen  Geerligs's  molasses  theory  it  is  evident  that  fer- 
menting away  the  invert  sugar  of  cane  molasses  would  have  but  little  effect  upon 
rendering  the  sucrose  more  crystallizable.  The  result  would  simply  be  to  change 
the  molasses  from  a  cane  to  a  beet  type.  Suppose  a  cane  molasses  of  the  following 
composition  to  have  its  invert  sugar  fermented  and  the  solution  of  sucrose,  salts 


652 


SUGAR  ANALYSIS 


Lactic  and  Butyric  Fermentations.  —  The  lactic  and  butyric  acid  fer- 
mentations can  be  produced  with  sucrose  by  the  same  organisms 
which  produce  these  fermentations  with  d-glucose  and  d-fructose.  In 
a  few  cases,  however,  where  the  particular  organism  does  not  secrete 
invertase,  fermentation  of  sucrose  does  not  take  place. 


Fig.  197.  —  Bacterium  pediculatum. 
Koch  and  Hosaeus. 


After 


Fig.  196.  —  Leuconostoc  mesen- 
terioides.  After  Zopf.  (48- 
hour  culture  in  molasses  show- 
ing slimy  envelopes  of  dextran .) 

Viscous  Fermentation.  —  One  of  the  most  common  fermentations  of 
sucrose  observed  in  sugar  factory  experience  is  the  so-called  viscous 
fermentation  by  which  sucrose  is  converted  into  the  gum  dextran. 
The  best  known  dextran-producing  organism  is  the  Leuconostoc  mesen- 


and  non-sugars  to  be  evaporated  to  the  original  concentration, 
have: 


We  would  then 


A 

Original  cane 
molasses. 

B 

Molasses  after 
fermentation  of 
invert  sugar. 

C 

B  with  8  parts 
of  water  evap- 
orated. 

D 

Percentage  com- 
position of  re- 
sidue C. 

Water  

Per  cent. 
20 

Parts. 

20 

Parts. 

12 

Per  cent. 
20 

Sucrose  

30 

30 

30 

50 

Invert  sugar.  . 

32 

o 

o 

Salts  

6 

6 

6 

10 

Organic  non-sugars. 

12 

12 

12 

20 

Total  

100 

68 

60 

100 

The  composition  of  the  evaporated  residue  after  fermenting  away  the  invert 
sugar  is  proximately  the  same  as  beet  molasses  from  which,  as  has  been  seen  (p.  649), 
no  sucrose  will  crystallize. 


THE  DISACCHARIDES  653 

terioides  (Fig.  196),  which  was  supposed  by  the  earliest  investigators 
to  ferment  sucrose  according  to  the  following  equation: 

C12H22On    =    C6H1005    +    C6H1206. 

Sucrose  Dextran  Fructose. 

Later  researches  *  showed,  however,  that  the  action  of  Leuconostoc 
and  of  many  other  "  dextran-formers  "  consisted  first  in  an  inversion  of 
the  sucrose  into  d-glucose  and  d-fructose  so  that  the  above  formula  is 
not  strictly  correct;  it  was  also  established  that  dextran  is  a  poly- 
saccharide  (C6Hio05)n  and  that  it  constitutes  the  slimy  jelly-like  capsule 
in  which  the  organisms  are  embedded.  The  dextran  is,  therefore,  to 
be  regarded  of  assimilative,  rather  than  of  fermentative  (i.e.,  enzymic) 
origin.  Very  similar  to  Leuconostoc  in  its  action  is  the  Bacterium 
pediculatum  discovered  by  A.  Koch  and  Hosaeus  in  the  sirup  of  a 
sugar  factory.  The  organism  secretes  a  slimy  capsule  of  gum  which, 
becoming  greatly  elongated  upon  one  side,  gives  it  a  stem-like  appear- 
ance (Fig.  197). 

Certain  gum-producing  organisms  have  been  found,  such  as  Micro- 
cocus  gelatigenosus,  Bacillus  gwnmosus,  Bacterium  gummosum,  etc., 
which  form  dextran  from  sucrose  but  not  from  glucose.  This  has  been 
regarded  as  a  fermentation  of  sucrose  without  preceding  inversion; 
most  of  the  members  of  this  class  of  organisms  are  found,  however,  to 
secrete  invertase  so  that  the  sucrose  in  these,  and  no  doubt  in  all  other 
cases,  where  fermentation  or  assimilation  takes  place,  is  probably  first 
inverted.  The  peculiarity  which  certain  bacteria  have  of  forming  dex- 
tran from  sucrose  but  not  from  glucose  may  be  explained  by  supposing 
that  these  organisms  are  able  to  ferment  or  assimilate  glucose  only  at 
the  time  of  its  separation  from  the  sucrose  molecule  (i.e.,  in  its  nascent 
state)  and  not  after  it  is  already  formed.  Even  in  the  case  of  Leucon- 
ostoc, which  can  assimilate  free  glucose  and  fructose,  the  formation  of 
dextran  is  several  times  more  rapid  with  sucrose. f 

Formation  of  Mannite  During  Fermentation.  —  In  the  so-called  vis- 
cous or  gummy  fermentation  of  sucrose  mannite  is  frequently  formed 
in  addition  to  dextran.  MonoyerJ  regarded  the  two  substances  as 
products  of  separate  fermentations  which  he  formulated  as  follows: 

Mannitic  fermentation: 

13  Ci2H22On  +  25  H20  =  24  C6H1406  -f- 12  C02.  (1) 

Sucrose  Mannite. 

*  For  a  full  account  of  the  action  of  Leuconostoc  upon  sucrose  see  the  work  of 
Liesenberg  and  Zopf,  Centralbl.  fur  Bakteriologie,  12,  659;  13,  339. 

t  Prinsen  Geerligs  "  Cane  Sugar  and  its  Manufacture  "  (1909),  38. 
|  These  pour  le  doctorat  en  medecine,  Strasbourg,  1862. 


654 


SUGAR  ANALYSIS 


Gum  fermentation: 
12  Cis 


n  =  12 


+  12  H20. 


Gum. 


(2) 


According  to  the  above  combined  equations  100  parts  of  sucrose 
yield  45.5  parts  of  gum  and  51.1  parts  of  mannite.  This  proportion  is 
not  fixed,  however,  the  variation  in  yield  being  explained  by  the  pre- 
dominence  of  one  or  the  other  fermentation.  It  is  more  probable, 
however,  that  the  dextran  is  formed  as  an  assimilative  and  the  mannite 
as  a  reduction  product  in  many  anaerobic  fermentations  by  a  single 
species  of  bacteria. 

The  gum,  which  is  produced  in  the  viscous  fermentation  of  su- 
crose, is  not  always  dextran.  It  may  also  consist  of  levulan  or  levan 
(p.  615),  which  give  fructose  upon  hydrolysis,  whereas  dextran  is 
hydrolyzed  only  into  glucose. 

Influence  of  Fermentation  Gums  Upon  Polarimetric  Determination 
of  Sucrose.  —  The  presence  of  highly  dextrorotatory  and  levorotatory 
gums  in  sugar-house  products  may  introduce  a  considerable  error  in  the 
polarimetric  estimation  of  sucrose.  Browne*  reported  the  following 
analyses  of  badly  fermented  sugar-cane  juices: 


Degrees  Brix. 

Polarization. 

Sucrose. 

Reducing 
sugars. 

Dextran. 

Apparent  purity 
coefficient. 

7.8 
4.8 

+  18.0 
+  10.4 

Per  cent. 
0.0 
0.0 

Per  cent. 
0.15 

trace 

Per  cent. 
5.90 
3.35 

232 
216 

The  presence  of  dextran  in  cane  sirups  and  molasses  might  cause  the 
chemist  to  suspect  an  adulteration  with  commercial  glucose  or  starch 
sirup.  In  such  cases  the  gum  should  be  precipitated  with  strong  alco- 
hol, then,  after  decanting  the  clear  solution,  dissolved  in  a  small  amount 
of  water  and  a  drop  or  two  of  iodine  solution  added;  a  red  coloration, 
indicative  of  erythrodextrin,  will  appear  if  starch  sirup  has  been  used 
as  an  adulterant.  Dextran  does  not  respond  to  this  test. 

According  to  Taggartf  the  presence  of  the  gum  levan  in  sugar 
products  may  also  introduce  a  considerable  error  in  the  polarimetric 
estimation  of  sucrose. 

Cellulosic  Fermentation.  —  Some  varieties  of  bacteria  assimilate 
sucrose  with  formation  of  cellulose.  The  Bacterium  xylinum  (sorbose 
bacterium)  thrives  in  sucrose  solutions  and  this  organism  according  to 
A.  J.  Brown  |  forms  cellulose.  Browne  §  found  in  the  cane  juices  of 
Louisiana  an  organism  which  formed  white  gelatinous  lumps  of  cellu- 

*  J.  Am.  Chem.  Soc.,  28,  462.  J  J.  Chem.  Soc.,  49,  432. 

t  J.  Ind.  Eng.  Chem.,  3,  646.  §  J.  Am.  Chem.  Soc.,  28,  463. 


THE  DISACCHARIDES  655 

lose,  weighing  in  some  cases  several  pounds.  The  product  after  purify- 
ing with  hot  sodium  hydroxide  was  colored  blue  with  zinc  chloride  and 
iodine,  was  soluble  in  ammoniacal  copper  solution  and  had  the  composi- 
tion of  cellulose.  The  amount  of  cellulose  formed  by  the  organism  was 
about  7  per  cent  of  the  total  sucrose  destroyed. 

Citric  Fermentation.  —  The  citric  fermentation  (p.  585)  may  also 
occur  with  sucrose,  the  fungus  Citromyces  glaber  yielding  50  per  cent 
of  the  sucrose  in  citric  acid.  A  Citromyces  found  by  Browne  *  upon  hot- 
room  molasses  in  Louisiana  was  found  to  contain  over  11  per  cent  chitin; 
the  latter  gave  upon  hydrolysis  with  hydrochloric  acid  over  60  per  cent 
of  pure  glucosamine  chloride  (p.  753). 

Among  other  fermentation  products  of  sucrose,  besides  those  already 
mentioned,  may  be  mentioned  butyl  and  amyl  alcohols  and  acetalde- 
hyde;  formic,  acetic,  butyric,  propionic,  valeric,  capronic,  caprylic, 
lactic  and  succinic  acids;  as  well  as  the  gaseous  products  hydrogen 
and  methane.  For  a  description  of  the  fermentations  which  give  rise 
to  these  and  other  substances  the  student  is  referred  to  the  works  of 
Lafar,f  JorgensenJ  and  Lippmann.§ 

DECOMPOSITION  OF  SUCROSE  BY  HEATING 

Sucrose  upon  heating  above  its  melting  point  begins  to  decompose 
with  evolution  of  water.  Between  170°  and  190°  C  a  mixture  of  brown- 
ish colored  substances,  known  as  caramel,  is  formed;  above  190°  C. 
large  quantities  of  carbon  dioxide  and  monoxide  are  given  off  together 
with  various  volatile  decomposition  products  such  as  aldehyde,  acetone, 
acrolein,  furfural  and  even  benzolderivatives,  as  benzaldehyde.  From 
a  technical  viewpoint  the  most  important  of  these  decomposition 
products  is  caramel. 

Caramel  is  usually  prepared  by  heating  sucrose  to  170°  to  190°  C. 
and  consists  of  a  mixture  of  decomposition  products,  the  exact  compo- 
sition of  which  has  not  been  fully  ascertained.  The  caramelization  or 
browning  of  sucrose  may  begin,  however,  at  temperatures  below  100° 
in  presence  of  moisture.  As  ordinarily  prepared  from  sucrose  caramel 
consists  of  a  brownish  colored  substance,  easily  soluble  in  water  but  in- 
soluble in  strong  ethyl  alcohol,  ether  or  chloroform.  Caramel  reduces 
Fehling's  solution  strongly;  it  is  completely  precipitated  from  solution 
by  ammoniacal  lead  subacetate.  Solutions  of  caramel  show  before  the 

*  J.  Am.  Chem.  Soc.,  28,  465. 

t  Lafar's  "  Technische  Mykologie,"  Jena  (1901-1907). 

t  Jorgensen's  "  Mikroorganismen  der  Garungsindustrie,"  Berlin. 

§  "  Chemie  der  Zuckerarten,"  1288-1317. 


656  SUGAR  ANALYSIS 

spectroscope  characteristic  absorption  bands,  the  blue  part  of  the 
spectrum  being  more  or  less  extinguished  according  to  concentration. 
If  a  caramel  solution  is  shaken  with  an  alcoholic  solution  of  paralde- 
hyde  and  allowed  to  stand  in  the  cold  for  24  hours  a  brownish  yellow 
gummy  precipitate  will  form,  the  rapidity  of  deposition  depending 
upon  the  amount  of  caramel  present.  The  paraldehyde-caramel  com- 
pound is  soluble  in  water  from  which  it  is  reprecipitated  by  strong 
alcohol;  its  composition  has  not  been  definitely  established. 

The  formation  of  caramel  from  sucrose  consists  primarily  in  the 
splitting  off  of  water  in  successive  stages,  this  giving  rise  to  a  series  of 
dehydration  and  condensation  products  of  varying  complexity.  Gelis* 
was  the  first  to  attempt  the  separation  of  caramel  into  its  components 
and  defined  three  different  constituents,  caramelane,  caramelene  and 
carameline.  Caramelane  was  prepared  by  Gelis  by  heating  sucrose  un- 
til it  lost  about  12  per  cent  in  weight  and  was  given  the  formula 
C^HigOg;  caramelene,  C^H^Ou  •  H20,  was  prepared  by  heating  sucrose 
until  it  lost  about  15  per  cent  in  weight;  and  carameline,  CgeHiooC^o  •  H20, 
by  heating  sucrose  until  it  lost  about  20  per  cent  in  weight.  Other  in- 
vestigators give  caramelane,  caramelene  and  carameline  entirely  differ- 
ent formulae;  each  of  these  substances  is  probably  a  mixture  of  de- 
composition products  so  that  the  formulae  assigned  by  Gelis  have  a 
questionable  value. 

Caramelane  was  prepared  by  Stollef  by  heating  melted  sucrose  at 
180°  C.  until  no  further  loss  occurred;  the  residue  was  dissolved  in 
water,  any  unchanged  sugar  removed  by  fermentation  and  the  residue 
evaporated  in  vacuo  to  dry  ness.  The  substance  thus  obtained  con- 
sisted of  a  brownish  mass  melting  at  134°  to  136°  C.,  its  composition 
corresponded  to  the  formula  C^HisOg  the  same  as  the  caramelane  of 
Gelis. 

The  caramel  substance  saccharan,  Ci2Hi809,  obtained  by  Ehrlich  by 
heating  sucrose  to  200°  C.,  has  already  been  described  (p.  467).  It  is 
probably  identical  with  the  caramelane  of  Gelis  and  Stolle. 

Destructive  Action  of  Heat  Upon  Sucrose  in  Solution.  —  A  knowl- 
edge of  the  destructive  changes  which  sucrose  undergoes  upon  heating 
its  aqueous  solutions  is  of  great  importance.  Unfortunately  no  fixed 
rule  can  be  given  for  this,  as  the  nature  and  extent  of  the  decompo- 
sition depend  largely  upon  the  character  of  accompanying  impurities. 

Sucrose  in  perfectly  neutral  solutions,  when  heated  for  a  few  hours 
at  100°  C.,  begins  to  undergo  decomposition  as  a  result  of  carameliza- 

*  Ann.  chim.  phys.  [3]  52,  352;  Compt.  rend.,  46,  590. 
t  Z.  Ver.  Deut.  Zuckerind,  49,  800;  51,  836;   53,  11-47. 


THE  DISACCHARIDES 


657 


tion  and  incipient  inversion,  the  latter  being  produced  according  to 
some  chemists  by  the  H  ions  of  dissociated  molecules  of  water,  and  ac- 
cording to  other  chemists  by  auto-inversion,  the  sucrose  itself  behaving 
as  an  extremely  weak  acid.  After  the  commencement  of  inversion 
the  sucrose  solution  becomes  perceptibly  acid,  and  heating  from  this 
point  causes  decomposition  and  inversion  to  proceed  with  increasing 
rapidity. 

To  determine  the  rate  of  decomposition  which  sucrose  undergoes 
upon  heating  its  solutions  when  formation  of  free  acid  is  prevented, 
Herzfeld*  conducted  experiments  with  solutions  which  were  made 
slightly  alkaline;  variations  in  the  kind  and  amount  of  alkali  were  not 
found  to  cause  any  difference  in  the  character  of  the  results.  The  fol- 
lowing table  taken  from  Herzfeld's  work  shows  the  percentage  loss  of 
total  sucrose  caused  by  heating  solutions  of  different  concentration  at 
varying  temperatures  for  1  hour. 

TABLE  XCII 

Loss  of  Sucrose  upon  Heating  Solutions  of  Different  Concentration  at  Varying 

Temperatures 


Deg.  C. 

10 
per  cent. 

15 
per  cent. 

20 
per  cent. 

25 
per  cent. 

30 
per  cent. 

35 
per  cent  . 

40 

per  cent. 

45 
per  cent. 

50 
per  cent. 

80 
90 
100 
110 
120 
130 
140 

0.0444 
0.0790 
0.1140 
0.1630 
0.2823 
2.0553 
5  1000 

0.0373 
0.0667 
0.0961 
0.1362 
0.2582 
1.7582 

0.0301 
0.0541 
0.0781 
0.1093 
0.2341 
1.4610 

0.0229 

0.0418 
0.0602 
0.0825 
0.2098 
1.1638 

0.0157 
0.0290 
0.0423 
0.0557 
0.1857 
0.8667 

0.0168 
0.0317 
0.0466 
0.0612 
0.2063 
0.9451 

0.0179 
0.0344 
0.0508 
0.0667 
0.2669 
1.0235 

0.0190 
0.0371 
0.0551 
0.0721 
0.2474 
1.0119 

0.0200 
0.0392 
0.0584 
0.0766 
0.2678 
1.1800 

The  results  show  in  every  case  a  rapid  increase  in  the  destructive 
action  between  120°  and  130°  C.  The  percentage  loss  is  greatest  with 
the  more  dilute  solutions,  but  the  absolute  loss  of  sucrose  (i.  e.,  grams 
destroyed  per  100  gms.  solution)  increases  with  the  concentration.  It 
should  be  borne  in  mind  that  the  results  of  Table  XCII  show  the  rate 
of  decomposition  under  only  one  set  of  conditions;  in  the  absence  of 
free  alkalies  the  progress  of  decomposition  would  be  much  more  rapid. 

Changes  in  Polarization  During  Heating  of  Sucrose  Solutions.  — 
Prolonged  heating  of  sucrose  solutions  causes  a  series  of  important 
changes  in  the  polarizing  power.  A  graphic  representation  of  these 
changes  is  given  in  Fig.  198,  where  the  ordinates  represent  degrees 
polarization  and  the  abscissse  hours  of  heating. 

*  Z.  Ver.  Deut.  Zuckerind,  43,  745. 


658 


SUGAR  ANALYSIS 


For  the  first  few  hours  of  heating  only  a  slight  decrease  in  polariza- 
tion is  noted,  then,  with  the  formation  of  acid  oxidation  products  and 
the  consequent  increase  in  the  rate  of  inversion,  the  polarization  quickly 
falls  until  at  B  the  polarization  of  undecomposed  sucrose,  and  that  of 
its  inversion  and  decomposition  products  (glucose,  fructose,  caramel, 
etc.),  exactly  neutralize  one  another  and  the  rotation  is  0.  Upon 
longer  heating  the  remaining  sucrose  is  inverted;  the  rotation  of  the 
fructose  becomes  the  predominant  factor  and  the  polarization  is  levo- 
rotatory.  A  maximum  levorotation  is  reached  at  C,  after  which,  with 


48^56        64        72        80        88        96 
Hours  of  Heating 


Fig.  198.  —  Showing  changes  in  polarization  of  a  sucrose  solution  by  destructive 

action  of  heat. 

the  decomposition  of  the  more  unstable  fructose,  the  rotation  again 
approaches  0  until  at  D  a  second  point  of  inactivity  is  reached,  the 
rotatory  powers  of  undecomposed  fructose,  glucose  and  other  sub- 
stances counterbalancing  one  another.  Upon  longer  heating  the 
remaining  fructose  is  destroyed;  the  rotation  of  glucose  is  now  the 
predominant  factor  and  the  polarization  of  the  solution  becomes  dex- 
trorotatory again.  A  maximum  dextrorotation  is  reached  at  E,  after 
which  with  the  destruction  of  the  glucose  the  polarization  gradually 
approaches  0,  until  at  F  a  third  and  final  point  of  inactivity  is  reached. 

The  curve  of  changes  just  described  may  be  longer  or  more  con- 
tracted than  that  shown  in  Fig.  198  according  to  the  temperature  of 
heating,  nature  of  salts  and  impurities  present,  and  other  conditions. 

High-polarizing  Sugar.  —  A  condition  exactly  opposite  to  that  just 
noted  is  sometimes  observed  in  technical  operations,  where  heating 


THE  DISACCHARIDES  659 

concentrated  sucrose  solutions  has  been  found  under  certain  conditions 
to  cause  an  increase  in  the  polarization.  This  phenomenon  has  been 
attributed  by  some  to  the  formation  of  high-rotating  dextrinoid  con- 
densation products  and  by  others  to  the  splitting  off  of  glucose  in  a 
high  mutarotating  form.  This  increase  in  polarization,  according  to 
Lippmann,*  is  observed  only  when  the  solution  is  neutral  or  very 
weakly  acid;  in  presence  of  free  alkali  it  does  not  seem  to  take  place. 

Optically  Inactive  Sugar.  —  If  sucrose  is  heated  with  only  a  small 
amount  of  water  at  150°  to  160°  C.  for  a  short  time,  a  mixture  is  ob- 
tained which  shows  almost  complete  optical  inactivity.  This  so-called 
optically  inactive,  or  neutral  sugar,  was  first  observed  by  Berzelius 
and  Mitscherlich,f  and  has  been  the  subject  of  frequent  investiga- 
tions since  their  time.  Optically  inactive  sugar  consists  of  a  mixture 
of  glucose  and  other  products  whose  rotations  neutralize  one  another. 
According  to  Wohlf  the  sucrose  is  decomposed  into  glucose  and  a  con- 
densation product  of  fructose  which  he  calls  levulosin. 
n  (CwHaOu)  =  nC6H1206  +  (C6H10O5)n. 

Sucrose  Glucose  Levulosin. 

[0^=4-66.5  ~~H^=o. 

Optically  inactive  sugar  upon  warming  with  acids  becomes  strongly 
levorotatory  and  this  is  explained  by  the  hydrolysis  of  the  levulosin 
into  d-fructose. 

(C6Hio05)n  +  n  H20  =  n  C6Hi206. 

Levulosin  d-Fructose. 

THE  INVERSION  OF  SUCROSE 

INVERSION    OF   SUCROSE    BY   ACIDS 

Early  Investigations.  —  One  of  the  earliest  facts  noted  in  connec- 
tion with  the  chemistry  of  sucrose  was  that  after  warming  with  acids 
the  sugar  could  no  longer  be  recovered  in  its  original  crystallizable 
form.  The  change  was  described  by  saying  that  the  sucrose  was  con- 
verted into  "uncrystallizable  sugar,"  a  term  which  is  still  occasionally 
used  by  certain  writers.  After  the  invention  of  the  polariscope,  Biot, 
in  1836,  noted  that  the  change  which  acids  produced  upon  sucrose  was 
attended  by  an  alteration  in  the  character  of  the  rotation  imparted  to 
the  plane  of  polarized  light;  the  direction  of  rotation  for  the  original 
sucrose  solution  was  changed  from  right  to  left,  or  from  +  to  — .  On 
account  of  this  transposition  in  sign  the  term  "  inversion  "  was  applied 

*  "  Chemie  der  Zuckerarten,"  1223;  Z.  Ver.  Deut.  Zuckerind,  35,  434. 
t  Journ.  pharm.  [3],  4,  216. 
%  Ber.,  23,  2088. 


660  SUGAR  ANALYSIS 

i 

to  the  process  and  the  name  "  invert-sugar  "  given  to  the  products 
of  the  reaction.  It  was  soon  observed  that  the  sirupy  sugar  obtained 
by  inverting  sucrose  soon  crystallized  with  separation  of  glucose; 
Dubrunfaut,*  however,  was  the  first  to  explain  the  true  character  of 
the  process  and  showed  that  the  sugars  glucose  and  fructose  were  both 
formed  during  inversion. 

Wilhelmy's  Law  of  Mass  Action.  —  It  was  noted  quite  early  in 
the  study  of  inversion  that  the  various  acids  differed  in  the  rapidity  of 
their  inverting  power,  although  the  action  of  each  acid  seemed  to  fol- 
low one  general  law.  The  nature  of  this  law  was  discovered  in  1850  by 
Wilhelmy,t  who  showed  that  the  amount  of  sucrose  inverted  by  an 
acid  in  a  given  moment  of  time  is  always  a  constant  percentage  of  the 
amount  of  unchanged  sucrose  present.  This  discovery  is  formulated  in 
Wilhelmy's  law  of  mass  action;  viz.,  the  velocity  of  a  reaction  at  any 
moment  is  proportional  to  the  concentration  of  the  reacting  substance. 

The  inversion  of  sucrose  by  acids  is  expressed  by  the  equation: 
C12H22On  +  H20  =  C6H1206  +  C6H1206. 

Sucrose  Water  Glucose  Fructose. 

Although  this  equation  involves  the  disappearance  of  one  molecule  of 
water  with  each  molecule  of  sucrose,  and  is  therefore  bimolecular,  the 
diminution  in  the  total  active  mass  of  water  is  so  slight  that  the  process 
of  inversion  can  be  treated  as  a  unimolecularf  reaction. 

Rate  of  Inversion.  —  If  a  is  the  original  amount  of  sucrose  present 
and  x  the  quantity  inverted  at  the  end  of  the  time  t  after  the  com- 
mencement of  inversion,  then  the  rate  of  inversion  for  a  unimolecular 
reaction  will  be: 

S  =  *(a-*),  (1) 

in  which  dx  is  the  infinitesimal  quantity  of  sucrose  inverted  during  the 
infinitesimal  period  of  time  dt  and  k  the  velocity  coefficient  of  the  in- 
version. The  constant  k  is  found  by  means  of  the  integral  calculus  to  be 

fc  =  -  lognat.  —    —  »  (2) 

t  d  —  x 

or,  changing  from  natural  to  common  logarithms, 
(log  nat.  =  log  com.  -T-  0.4343). 


*  Compt.  rend.,  42,  901;  69,  438. 
t  Poggend.  Ann.,  81,  413,  499. 

t  For  a  demonstration  of  this  see  Mellor's  "  Chemical  Statics  and  Dynamics" 
(1909),  pp.  40  and  41. 


THE  DISACCHARIDES 


661 


For  purposes  of  comparison,  however,  formula  (2)  using  common 
logarithms  is  often  employed. 

Determination  of  Rate  of  Inversion  by  Polariscope.  —  In  applying 
formula  (2)  the  polarimetric  observations  may  be  substituted  for  a 
and  x.  Calling  the  rotation  before  inversion  r0  and  after  inversion  rM 
and  for  any  time  t  during  inversion  r,  then 


oo 

The  following  table  shows  the  rate  of  inversion  at  20°  C.  for"  a 
normal  weight  (26  gms.)  of  sucrose  made  up  with  water  and  10  c.c.  of 
concentrated  hydrochloric  acid  to  100  true  c.c. 


TABLE  XCIII 
Showing  Rate  of  Inversion  of  Sucrose 


Time. 

Rotation 

Jc-^lr.-    ro~  roe  . 

t     gl°r-roo 

Minutes. 

Deg.  V. 

Before  inverting 

0 

+  100.00 

5 

94.05 

0.00391 

15 

82.80 

0.00394 

30 

68.20 

0.00388 

60 

45.40 

0.00374 

90 

27.40 

0.00372 

120 

13.80 

0.00367 

150 

2.80 

0.00367 

159 

0.00 

0.00368 

180 

-5.85 

0.00369 

240 

-17.35 

0.00366 

360 

-28.95 

0.00371 

Inversion  complete 

oo 

-35.20 

Aver.    0.00375 

The  results  in  the  table  show  that  while  about  40  per  cent  of  the 
total  sucrose  is  inverted  in  the  first  hour,  24  per  cent  in  the  second 
hour,  14  per  cent  in  the  third  hour,  9  per  cent  in  the  fourth  hour,  etc., 
yet  the  velocity  of  inversion  always  bears  a  constant  ratio  to  the 
diminishing  amount  of  sucrose  present,  temperature  and  other  con- 
ditions remaining  the  same.  Thus  in  the  previous  table  40  per  cent  of 
the  total  sucrose  is  inverted  during  the  first  hour,  and  during  each  suc- 
ceeding hour  always  40  per  cent  of  the  sucrose  present  at  the  beginning 
of  the  hour  is  inverted.  It  follows,  therefore,  since  the  inversion  con- 
stant k  is  the  same  for  any  concentration  of  sucrose  that  the  most  con- 
centrated solutions  of  the  latter  can  be  completely  inverted  by  relatively 
small  amounts  of  acid. 


662  SUGAR  ANALYSIS 

Errors  in  Polarimetric  Method  for  Determining  Rate  of  Inversion.  — 
The  somewhat  irregular  values  for  the  velocity  coefficient,  which  are 
often  obtained  by  the  polarimetric  method  at  the  beginning  of  inver- 
sion, have  led  some  investigators  to  suspect  an  exception  to  the  law  of 
mass  action  for  the  early  stages  of  hydrolysis.  The  method  of  deter- 
mining the  rate  of  inversion  by  observing  the  changes  in  the  rotation 
of  a  solution  in  a  polariscope  tube  is  attended  with  several  small 
errors.*  There  is,  first,  the  possible  influence  of  the  contraction  f  in 
volume  which  accompanies  inversion,  and  which  for  a  25  per  cent 
solution  of  sucrose  is  about  0.5  c.c.  per  100  c.c.  There  is,  second,  the 
change  in  polarization  of  the  liberated  glucose  and  fructose  due  to 
mutarotation,  this  error,  however,  being  greatly  reduced  by  the  accel- 
erating influence  of  the  acid.  The  supposition  that  the  increase  in 
concentration  of  fructose  during  inversion  causes  an  error  in  the  value 
of  k  has  been  proved  by  Rosanoff.  Clark  and  Sibley  to  be  untrue,  since 
the  percentage  of  water  in  the  solution  remains  practically  constant 
during  the  inversion.  Careful  experiments  by  the  above  authorities, 
in  which  varying  amounts  of  sucrose  were  inverted  in  solutions  con- 
taining the  same  weights  of  acid  and  water  per  unit  volume,  show  that 
the  velocity  coefficient  is  independent  of  the  initial  concentration  of 
sucrose  and  is  the  same  throughout  inversion  as  long  as  the  concentra- 
tion of  water  and  acid  remains  unchanged. 

Another  source  of  error  in  measuring  the  constant  k  is  due  to  the 
slight  rise  in  temperature  which  takes  place  in  mixing  the  acid  and  sugar 
solution.  The  speed  of  inversion  is  thus  slightly  accelerated  at  the 
beginning  and  this  would  explain  the  slightly  higher  values  of  k  for  the 
first  few  readings  of  the  previous  table. 

Inverting  Power  of  Different  Acids.  —  The  inverting  power  of 
different  acids  has  been  determined  by  Ostwaldf  whose  results  are 
given  in  the  following  table.  To  avoid  the  use  of  small  decimals  the 
constant  C  =  10,000  k  is  employed.  The  second  column  of  the 
table  gives  the  relative  inverting  power  of  each  acid  as  compared  with 
that  of  hydrochloric  acid  .which  is  taken  as  100.  In  making  the  experi- 
ments 10  c.c.  of  a  40  to  50  per  cent  sucrose  solution  were  inverted  at 
25°  C.  with  10  c.c.  of  a  normal  solution  of  the  acid. 

*  For  a  fuller  discussion  of  these  errors  see  paper  by  C.  S.  Hudson  (J.  Am. 
Chem.  Soc.,  32,  885),  "  Is  the  hydrolysis  of  cane  sugar  by  acids  a  unimolecular  reac- 
tion when  observed  with  a  polariscope?  "  and  the  paper  by  Rosanoff,  Clark  and 
Sibley  (J.  Am.  Chem.  Soc.,  33,  1911),  "A  reinvestigation  of  the  velocity  of  sugar 
hydrolysis." 
t  Lippmann's  "  Chemie  der  Zuckerarten  "  p.  1258.  J  J.  prakt.  Chem.  [2],  29,  385. 


THE  DISACCHARIDES 


663 


TABLE  XCIV 
Showing  Relative  Inverting  Power  of  Different  Adds 


Kind  of  acid. 

Inversion 
constant  C. 

Inverting 
power 
HC1  =  100. 

Kind  of  acid. 

Inversion 
constant  C. 

Inverting 
power 
HC1  =  100. 

Hydrobromic  
Benzolsulphonic    .  . 

24.38 

22.82 

111.4 
104.4 

Malonic  
Diglycollic. 

0.674 
0  583 

3.08 
2  67 

Chloric 

22.61 

103.5 

Methylglycollic 

0  397 

82 

Hydrochloric   .  . 

21.87 

100.0 

Citric  

0  377 

72 

Nitric 

21.87 

100.0 

Glyceric  

0  375 

72 

Methylsulphuric 

21.86 

100.0 

Formic  

0  335 

53 

Isethionic  

20.07 

91.8 

Methyllactic  

0.304 

39 

Ethylsulphonic  .... 
Trichloracetic  
Sulphuric 

19.93 
16.47 
11  72 

91.2 
75.4 
53  6 

Ethylglycollic  
Glycollic  
Malic 

0.300 
0.286 
0  278 

.37 
.31 
270 

Dichloracetic 

5  93 

27  1 

Pyrotartaric 

0  234 

072 

Oxalic 

4  00 

18.57 

Lactic  . 

0  233 

070 

Pyroracemic 

1  419 

6  49 

Oxyisobutyric  .... 

0  232 

060 

Phosphoric 

1  357 

6.21 

Succinic  

0  1192 

0  545 

Monochloracetic 

1.059 

4.84 

Acetic  

0  0876 

0  400 

Arsenic 

1.052 

4.81 

Isobutyric  

0.0733 

0.335 

Relation  of  Inverting  Power  to  Affinity  and  Electric  Conductivity.  — 
The  speed  of  inversion  is  in  general  proportional  to  the  affinity  and 
electric  conductivity  of  the  acid.  This  is  shown  in  the  following  table, 
taken  from  the  work  of  Ostwald,  where  a  number  of  acids  are  ar- 
ranged in  order  of  their  constants,  the  latter  for  purpose  of  comparison 
being  expressed  in  terms  of  HC1  =  100. 

TABLE  XCV 
Showing  Relation  of  Inverting  Power  to  Affinity  and  Conductivity  of  Acids 


Acid. 

Speed  of  inver- 
sion. 

Chemical  affin- 
ity. 

Electric  conduc- 
tivity. 

Hydrochloric 

100 

100 

100 

Nitric 

100 

100 

99.6 

Sulphuric                                                     .... 

53.6 

49 

65.1 

Oxalic                                                   

18.6 

24 

19.7 

Phosphoric    .                       

6.2 

13 

7.3 

IVIonochloracetic 

4.8 

9 

4.9 

Acetic 

0.4 

3 

0.4 

The  order  of  magnitude  of  the  constants  for  the  different  acids  is 
the  same.  This  parallelism  is  explained  by  the  dissociation  theory  of 
Arrhenius  as  due  to  the  fact  that  the  inverting  power,  affinity  and 
conductivity  of  acids  are  dependent  upon  their  degree  of  ionization, 
or,  in  other  words,  upon  the  relative  amounts  of  hydrogen  ions  in 


664  SUGAR  ANALYSIS 

solution.  The  formula  for  the  inversion  of  sucrose  is  in  fact  sometimes 
written: 

Ci2H22Oii  +  H2O  +      H  =  2  C6H1206  +  H, 

Sucrose  Water  H  ion        Invert  sugar        H  ion, 

one  H  ion  participating  in  an  unlimited  number  of  reactions.  Many 
hypotheses  have  been  proposed  to  account  for  the  catalytic  action  per- 

+ 
formed  by  the  H  during  the  inversion  of  sucrose,  such  as  vibratory 

action,  carrier  of  water,  etc.,  but  no  satisfactory  explanation  has  as 
yet  been  found. 

Influence  of  Temperature  Upon  Speed  of  Inversion.  —  Elevation  of 
temperature  produces  a  marked  increase  in  the  inverting  power  of 
acids,  the  velocity  coefficient  k  increasing  about  15  per  cent  for  each 
1°  C.  elevation.  This  rate  of  increase,  which  is  approximately  the 
same  for  all  acids,  diminishes,  however,  with  rise  in  temperature;  the 
total  increase  in  k  from  0°  to  10°  C.  was  found  by  Hammerschmidt  * 
to  be  about  500  per  cent,  from  30°  to  40°  C.  about  400  per  cent  and 
from  70°  to  80°  C.  about  300  per  cent. 

Arrhenius's  Hypothesis  of  "Active"  and  "Inactive"  Sucrose  Molecules. 
—Inasmuch  as  the  ionization  of  acids  in  aqueous  solution  is  not  greatly 

affected  by  changes  in  temperature  and  as  the  coefficient  for  the  increase 

+ 
in  speed  of  the  H  ions  for  1°  C.  increase  is  only  a  small  percentage  of  the 

increase  observed  for  the  inversion  constant  k,  Arrheniusf  adopted  the 
hypothesis  that  solutions  of  sucrose  contained  "  active"  and  "  inactive" 
molecules,  the  amount  of  "  active  sucrose"  being  relatively  small,  as 
compared  with  the  "  inactive,"  but  this  amount  increasing,  at  the 
expense  of  the  "  inactive"  sucrose,  by  about  12  per  cent  for  each  1°  C. 
increase.  This  transformation  of  "inactive"  into  "active"  sucrose  pre- 
cedes inversion  and  is  supposed  to  take  place  through  addition  of  water 
or  by  some  process  of  molecular  rearrangement.  Upon  this  hypothesis 
Arrhenius  has  derived  the  following  formula  for  expressing  the  influence 
of  temperature  upon  the  inversion  of  sucrose  between  0°  and  55°  C.  : 


in  which  Cti  and  Cto  are  the  inversion  coefficients  of  the  acid  at  the  tem- 
peratures ti  and  to,  TI  and  T0  being  the  corresponding  temperatures  in 
absolute  degrees;  e  is  the  constant  2.71828  (the  natural  logarithmic 
base)  and  q  is  the  thermal  constant  for  the  transformation  of  "in- 
active" into  "active"  sucrose  which  is  estimated  to  be  25,600  calories 

*  Z.  Ver.  Deut.  Zuckerind,  40,  408. 

t  Z.  physik.  Chem.,  4,  227. 


THE  DISACCHARIDES  665 

per  gram  molecule  of  " inactive"  sucrose.     This  formula  of  Arrhenius 
according  to  Ley*  also  holds  for  temperatures  above  55°  C. 

Hypothesis  of  Sucrose  Ions.  —  Of  other  hypotheses,  which  have  been 
proposed  to  explain  the  effect  of  temperature  upon  inversion  velocity, 
may  be  mentioned  the  so-called  "acid  nature"  of  sucrose  in  accord- 
ance with  which  sucrose  is  supposed  to  become  dissociated  into  ions. 
The  formation  of  saccharates  or  salts  of  sucrose  is  used  as  one  argu- 
ment for  this  hypothesis;  solutions  of  sucrose,  however,  show  perfect 
neutrality  to  the  most  sensitive  indicators,  and  are  absolute  non-con- 
ductors of  electricity,  so  that  no  direct  evidence  exists  to  support  the 
hypothesis  of  sucrose  H  ions. 

Influence  of  Concentration  and  of  Salts  Upon  Inverting  Power  of 
Acids.  —  The  inversion  velocity  of  sucrose  by  means  of  acids  is  in  gen- 
eral proportionate  to  the  concentration  of  H  ions;  strict  conformity  to 
this  rule,  however,  obtains  only  with  pure  dilute  solutions  of  the  acid. 
The  proportionality  of  the  inversion  constant  k  to  concentration  of 
H  ions  shows  marked  deviations  at  high  concentrations  of  acid  or  in 
presence  of  neutral  salts.  Thus  the  proportionality  in  H  ion  concen- 
tration of  0.1  normal  to  0.5  normal  nitric  acid  is  not  1:  5  but  1:  4.64; 
the  proportionality  in  inverting  power,  however,  is  1 :  6.07.  This  in- 
crease in  the  proportionality  of  the  inversion  constant  is  explained  by 
an  increase  in  the  speed  of  the  H  ions.  In  the  same  way  addition  of 
potassium  nitrate  to  nitric  acid  will  lower  the  concentration  of  H  ions, 
but  cause  an  increase  in  inversion  velocity,  this  increase  being  explained 
by  the  increase  in  speed  imparted  by  the  dissociated  molecules  of  potas- 
sium nitrate  to  the  remaining  H  ions. 

The  observations  just  noted  for  nitric  acid  and  potassium  nitrate 
hold,  however,  only  for  the  strong  acids  and  their  corresponding 
neutral  salts.  With  weak  acids  an  exactly  opposite  effect  is  noted. 
Increasing  the  concentration  of  acetic  acid,  for  example,  lowers  the 
proportionality  of  the  inversion  constant  fc;  so  also  the  addition  of  an 
equivalent  amount  of  potassium, acetate  to  acetic  acid  will  reduce  the 
value  of  k  to  •£$  of  its  original  amount. 

Additions  of  neutral  salts  of  a  different  acid  than  the  inverting 
agent  produce  variable  effects.  Thus  sodium  sulphate  diminishes 
while  sodium  chloride  increases  the  inversion  velocity  of  acetic  acid. 

In  addition  to  the  view  that  neutral  salts  alter  the  activity  of  the 
H  ions,  Arrhenius  supposes  that  the  amount  of  "  active  sucrose  "  is 
also  affected,  while  other  chemists  hold  that  the  molecules  of  water 
undergo  dissociation  to  a  greater  or  less  degree. 
*  Z.  physik.  Chem.,  30,  253. 


666  SUGAR  ANALYSIS 

Organic  non-conductors,  such  as  alcohol,  acetone,  etc.,  if  present 
in  large  amounts,  diminish  the  inversion  velocity  of  acids  to  a  marked 
degree,  although  the  electric  conductivity  of  the  solution  itself  may 
not  be  appreciably  lessened.  In  such  cases  it  is  supposed  that  the 
movement  of  the  H  ions  is  in  some  way  retarded. 

Further  discussion  of  the  numerous  hypotheses  which  have  been 
proposed  in  this  connection  must  be  passed  over;  for  a  fuller  treat- 
ment of  the  inversion  of  sucrose  by  acids  and  the  relationship  of  the 
subject  to  the  dissociation  theory  the  student  is  referred  to  Lippmann,* 
or  to  the  more  special  treatises  upon  physical  chemistry. 


INVERSION   OF   SUCROSE   BY   SALTS 

Sucrose  is  inverted  upon  heating  with  solutions  of  metallic  salts; 
the  speed  of  inversion,  as  in  the  case  of  acids,  is  in  general  proportionate 
to  the  concentration  of  hydrogen  ions,  the  latter  being  formed  by  a 
hydrolysis  of  the  salt  in  presence  of  water  according  to  the  following 
equation : 

MA     +     HOH      =      MOH       +       H-A, 

Salt  Water  Hydroxide  Dissociated  acid 

in  which  M  is  the  metal  and  A  the  acid  radical.  The  concentration  of 
H  ions,  and  hence  the  speed  of  inversion,  depends  upon  the  extent  of 
hydrolysis  and  dissociation. 

A  number  of  investigators  have  studied  the  inversion  of  sucrose  by 
salts.  Walker  and  Aston,f  working  with  sucrose  solutions  at  80°  C., 
found  the  following  inversion  constants  for  a  number  of  nitrates  : 

Cadmium  nitrate  (N/2) 0.000154 

Zinc  nitrate  (AT/2) 0.000207 

Lead  nitrate  (N/2) 0.001590 

Aluminum  nitrate  (N/2) 0.007700 

The  same  order,  Cd,  Zn,  Pb  and  Al;  has  also  been  found  by  other 
investigators.  Long,t  who  has  made  an  extensive  study  of  the  in- 
verting action  of  salts,  found  for  several  sulphates  the  inversion  to  in- 
crease in  the  order  Mn,  Zn,  Fe  and  Al.  Kahlenberg,  Davis  and 
Fowler  §  from  a  study  of  the  inverting  power  of  different  salts  at 
55.5°  C.  (the  temperature  of  boiling  acetone)  by  the  polariscopic  and 
freezing-point  methods  obtained  the  following  results: 

*  "  Chemie  der  Zuckerarten,"  1257-1303. 

t  J.  Chem.  Soc.,  67,  576. 

t  J.  Am.  Chem.  Soc.,  18,  120,  693. 

§  J.  Am.  Chem.  Soc.,  21,  1. 


THE  DISACCHARIDES 


667 


Salt. 

Concentration. 
(Gram  molecules  per 
1000  c.c.) 

Method. 

k. 

Salt. 

Sucrose. 

Manganese  sulphate  

i 

i 

! 

T 

". 

: 
• 
* 

| 
I 

Polariscope  
Polariscope  
Polariscope  

0.0000 
0.000163 
0.0014* 
0.0028* 
0.0055* 
0.0069* 
0.0057 
0.0054 
0.0303 
0.0422 

Manganese  chloride 

Cadmium  chloride  
Nickel  sulphate 

Freezing  point  
Polariscope 

Copper  sulphate  

Copper  chloride  

Freezing  point  
Polariscope  
Freezing  point 

Mercuric  chloride  

Mercuric  chloride 

Aluminum  sulphate  

Polariscope  

Aluminum  chloride  

Polariscope 

In  the  results  marked  with  a  *  the  values  of  k  were  not  found  to 
run  constant  during  the  experiment,  so  that  the  figures  represent  only 
a  rough  average. 

As  a  general  rule  it  may  be  stated  that  the  inverting  power  of  neutral 
salts  of  the  same  acid  follows  approximately  the  basicity  or  position 
of  the  metal  in  the  electro-chemical  series,  i.e.,  increasing  in  the  order: 
K,  Na,  Ba,  Sr,  Ca,  Mg,  Al,  Mn,  Zn,  Cd,  Fe,  Co,  Ni,  Sn,  Pb,  Cu,  Bi,  Sb 
and  Hg.  Important  exceptions  to  this  rule  occur,  however,  as  in  the 
case  of  aluminum,  the  salts  of  which,  notwithstanding  its  high  position  in 
the  electro-chemical  series,  have  a  higher  inversion  coefficient  than  any 
of  the  metals  thus  far  studied.  The  inverting  power  of  neutral  salts  of 
the  same  base  increases  in  general  with  the  strength  or  position  of  the 
acid  in  the  electro-chemical  series,  i.e.,  increasing  in  the  order:  acetic, 
tartaric,  oxalic,  sulphuric,  nitric,  hydrochloric,  etc.  Chlorides,  for  ex- 
ample, invert  sucrose  faster  than  sulphates  of  the  same  metal,  since 
they  are  more  easily  dissociated  and  hence  produce  a  greater  concen- 
tration of  H  ions. 

The  salts  of  the  weakest  bases  and  strongest  acids  have,  therefore, 
in  general  the  most  powerful  inverting  action. 

Influence  of  Invert  Sugar  Upon  the  Inverting  Power  of  Salts.  —  Of 
great  importance  in  this  connection  is  the  marked  increase  in  the  in- 
verting power  of  neutral  salts  produced  by  the  presence  of  reducing 
sugars.  Prinsen  Geerligs*  has  made  a  special  study  of  this  question, 
and  the  following  is  taken  from  the  results  of  his  investigations. 

The  increase  in  inverting  power  of  salts  produced  by  the  presence 
of  invert  sugar  is  shown  in  the  following  series  of  experiments  where 
50  c.c.  of  solutions  containing  50  per  cent  sucrose,  1  gm.  sodium 
*  Deut.  Zuckerind,  23,  292. 


668  SUGAR  ANALYSIS 

chloride,  and  5,  10,  20  and  30  per  cent  invert  sugar  were  heated  to  100° 

for  3  hours. 

Per  cent  invert  sugar 5  10  20  30 

Per  cent  sucrose  inverted 7.47        15.05        21.93        27.50 

The  influence  of  different  salts  of  the  same  acid  is  shown  in  the  fol- 
lowing series,  where  50  c.c.  of  solutions  containing  40  per  cent  sucrose 
and  25  per  cent  invert  sugar  were  heated  at  100°  C.  for  2  hours  with  a 
quantity  of  different  chlorides  equivalent  to  1.75  gm.  Cl. 

Salt..  KC1     NaCl    LiCl     CaCl2SrCl2     BaCl2  MgCl2 

Per  cent  sucrose  inverted 33.80    35.46    39.68    40.65    47.60    50.01     50.01 

The  influence  of  different  salts  of  the  same  base  is  shown  in  the  fol- 
lowing series,  where  50  c.c.  of  solutions  containing  40  per  cent  sucrose 
and  10  per  cent  invert  sugar  were  heated  at  100°  C.  for  2  hours  with 
a  quantity  of  different  potassium  salts  equivalent  to  1.75  gms.  Cl  in  KC1. 

Salt K-acetate  K-tartrate  K-oxalate  KC1O3  K2SO4  KNO3  KI  KBr  KC1 

Per  cent  sucrose  (    Q  Q()  Q07  Q  3Q         3  32      3  go      4.944.946.276.27 

inverted ( 

The  inverting  power  of  the  different  salts  is  seen  to  follow  the  posi- 
tions of  the  metal  and  acid  in  the  electro-chemical  series,  the  salts  of  the 
weakest  bases  and  strongest  acids  having  the  highest  power  of  inversion. 

The  substitution  of  other  reducing  sugars  was  found  by  Geerligs  to 
produce  the  same  effect  as  glucose  and  fructose  in  increasing  the  in- 
verting power  of  neutral  salts.  Non-reducing  sugars,  such  as  rafnnose, 
had  no  sensible  action. 

The  action  of  reducing  sugars  in  increasing  the  inverting  power  of 
salts  has  been  explained  by  the  formation  of  basic  sugar  compounds, 
the  hydrolysis  of  the  salt  and  formation  of  H  ions  being  thus  facilitated. 

MA  +  C6H12O6  +  HOH  =  MOH  •  C6Hi206  +    H  •  A. 

Salt  Glucose  Water  Basic  glucose  Ionized  acid. 

compound 

Deerr,*  who  has  recently  made  a  study  of  the  question,  concludes 
that  the  combined  influence  of  glucose  and  neutral  salts  does  not  pro- 
duce inversion.  This  conclusion,  which  is  exactly  opposite  to  that  of 
Geerligs,  leaves  the  subject  open  to  further  investigation. 

The  inverting  power,  which  different  salts  may  have  upon  sucrose, 
under  the  varying  conditions  of  manufacture  and  analysis,  is  a  factor 
which  the  chemist  must  always  bear  in  mind. 

INVERSION   OP   SUCROSE   BY   INVERTASE 

Occurrence  of  Invertase.  —  The  most  important  inverting  agent 
of  sucrose  from  a  physiological  point  of  view  is  invertase.     This  enzyme 
is  found  widely  distributed  in  the  vegetable  and  animal  kingdom,  being 
*  Bull.  35,  Hawaiian  Sugar  Planters'  Experiment  Station. 


II 


THE  DISACCHARIDES  669 

secreted  by  all  living  cells  where  sucrose  undergoes  metabolism.  In- 
vertase  occurs  in  many  bacteria,  in  nearly  all  yeasts,  in  different 
moulds,  as  Aspergillus  and  Penidllium,  and  in  the  leaves,  buds,  fruit, 
reserve  organs  and  other  tissues  of  many  higher  plants,  where  sucrose 
is  utilized  either  for  the  building  up  of  new  tissue  or  for  transportation 
to  points  of  growth. 

In  the  animal  kingdom  invertase  is  found  in  the  intestinal  juice  and 
other  fluids  of  the  body.  Extracts  prepared  from  the  mucous  mem- 
brane of  the  intestines,  from  the  kidneys  and  other  organs  are  strongly 
inverting.  Invertase  is  also  found  in  the  digestive  tract  of  many  in- 
sects; its  presence  in  the  honey  sac  of  the  bee  has  already  been  referred 
to.  While  the  invertases  from  different  sources  resemble  one  another 
in  their  hydrolytic  action  upon  sucrose,  they  show  certain  differences 
in  behavior.  It  is  supposed,  therefore,  that  the  inverting  enzymes 
constitute  a  group,  the  different  members  of  which  are  not  strictly 
identical.  On  account  of  the  difficulty  of  preparing  perfectly  pure 
preparations  of  invertase,  it  has  been  impossible  to  determine  the 
identity  or  difference  of  the  enzyme  from  the  various  plant  and  animal 
sources. 

Preparation  of  Invertase.  —  Invertase  is  best  obtained  from  yeast, 
and  various  methods  have  been  devised  for  preparing  the  enzyme  from 
this  source.  Some  authorities  recommend  mixing  fresh  washed  yeast 
with  powdered  glass  or  sand  and  air  drying.  The  mass  is  then  ground 
in  a  mill  or  mortar  and  extracted  with  cold  water  using  a  powerful 
press  to  increase  the  extraction. 

A  more  active  preparation  of  invertase  than  that  obtained  by  the 
above  process  is  obtained  by  the  method  of  O'Sullivan  and  Tompson* 
in  which  yeast  is  subjected  to  autolytic  digestion.  Pure  fresh  brewer's 
yeast  is  washed,  drained  and  then  set  aside  in  a  covered  jar  for  several 
weeks  at  ordinary  temperature  until  the  mass  has  liquefied.  A  dark 
yellow  solution  is  obtained  which  can  be  purified  and  decolorized  by 
filtering  through  bone  black.  The  autolysis  may  be  hastened  by  first 
destroying  the  life  of  the  yeast  cell  with  chloroform  as  recommended  by 
Fischer,  f 

The  method  of  Hudson  J  for  preparing  a  stock  solution  of  invertase 
is  as  follows:  "  Break  up  5  pounds  of  pressed  yeast,  which  may  be 
either  baker's  or  brewer's  yeast,  add  30  c.c.  of  chloroform  to  it  in  a 
closed  flask  and  allow  it  to  stand  at  room  temperature  (20°  C.)  over 
night.  By  the  morning,  the  solid  mass  will  have  become  fluid  and  it 

*  J.  Chem.  Soc.,  57,  834-931.  t  Ber.,  27,  2985. 

t  J,  Ind.  Eng.  Chem.,  2,  143. 


670  SUGAR  ANALYSIS 

should  then  be  filtered  through  filter  paper,  allowing  several  hours 
for  draining.  To  the  filtrate  add  neutral  lead  acetate  until  no  further 
precipitate  forms  and  again  filter.  Precipitate  the  excess  of  lead  from 
the  filtrate  with  potassium  oxalate  and  filter.  To  this  filtrate  add  25 
c.c.  of  toluene  and  dialyze  the  mixture  in  a  pig's  bladder  for  2  or  3  days 
against  running  tap  water.  The  dialyzed  solution  is  colorless,  per- 
fectly clear  after  filtration,  neutral  to  litmus,  has  a  solid  content  of  about 
one-half  of  one  per  cent,  an  ash  content  of  a  few  hundredths  of  one 
per  cent,  will  keep  indefinitely  in  an  ice  box  if  a  little  toluene  is  kept  on 
its  surface  to  prevent  the  growth  of  microorganisms,  and  is  exceed- 
ingly active  in  inverting  cane  sugar.  The  invertase  solution  does  not 
reduce  Fehling's  solution."  The  solution  of  invertase  prepared  by  this 
method  gives  a  dextrorotation  of  1°  V.  in  a  400-mm.  tube. 

Invertase  is  precipitated  from  solution  by  adding  about  3  vols.  of 
strong  alcohol.  The  precipitate  is  filtered  off,  and  finally  dried  in  a 
vacuum  over  concentrated  sulphuric  acid.  The  product  can  be  purified 
by  redissolving  in  water  and  again  precipitating  by  means  of  alcohol; 
such  purification,  however,  is  always  attended  by  loss  in  inverting 
power. 

Properties  of  Invertase.  —  Dry  invertase  consists  of  a  white 
powdery  substance  easily  soluble  in  water  with  formation  of  a  yellowish 
neutral  solution.  Unless  previously  dialyzed  the  product  contains 
considerable  mineral  matter,  the  quantity  sometimes  exceeding  20  per 
cent.  The  chemical  composition  of  invertase  is  not  fully  known. 
Barth*  found  for  an  ash-free  preparation  43.9  per  cent  C,  8.40  per 
cent  H,  6.00  per  cent  N  and  0.63  per  cent  S.  Osbornef  found  44.54 
per  cent  C,  6.52  per  cent  H  and  6.1  per  cent  N.  The  high  percentage 
of  nitrogen,  the  positive  reaction  with  Millon's  reagent  and  the  biuret 
test  indicate  the  presence  of  an  albuminoid  group.  Carbohydrates,  con- 
sisting probably  of  mannan  and  pentosan  groups,  have  also  been  found 
in  invertase.  It  is  uncertain  whether  these  carbohydrate  groups  are  a 
constituent  part  of  the  enzyme  or  like  the  mineral  matter  consist  only 
of  accompanying  impurities.' 

Conditions  Affecting  the  Activity  of  Invertase.  —  The  inversion  of 
sucrose  by  invertase  consists  in  the  addition  of  one  molecule  of  water 
to  each  molecule  of  sugar,  but  the  mechanism  of  this  process  is  not  as 
yet  understood.  It  is  supposed  by  some  that  the  configuration  of  the 
enzyme  must  conform  in  certain  respects  to  that  of  the  sugar  hydrolyzed 
and  this  is  used  as  an  argument  for  the  presence  of  a  carbohydrate 
group  in  invertase.  Fischer  has  likened  the  relation  of  enzyme  to 
*  Ber.,  11,  474.  t  Chem.  News,  79,  277. 


THE  DISACCHARIDES  671 

sugar  to  that  existing  between  a  key  and  lock,  the  shape  of  the  key  per- 
mitting it  to  unfasten  only  that  lock  to  whose  structure  it  corresponds. 
The  action  of  invertase  being  purely  catalytic,  a  small  amount  of 
enzyme  can  invert  almost  unlimited  quantities  of  sucrose.  O'Sullivan 
and  Tompson  found  in  fact  that  a  preparation  of  invertase,  which  had 
already  inverted  100,000  parts  of  sucrose,  had  lost  none  of  its  activity. 

Influence  of  Acids  and  Alkalies  on  Activity  of  Invertase.  —  To  secure 
the  maximum  inverting  power  invertase  must  be  allowed  to  act  in  a 
weakly  acid  solution.  The  acidity  for  acids,  which  are  largely  disso- 
ciated as  hydrochloric  acid,  should  not  greatly  exceed  ft/ 1000.  An 
acidity  much  above  n/100  HC1  will  completely  destroy  invertase.  For 
acids  which  are  only  slightly  dissociated,  as  acetic,  the  acidity  may  ex- 
ceed 100  times  the  concentration  permissible  for  hydrochloric  acid. 

In  analytical  work  it  is  best  to  use  invertase  in  an  acetic  acid  solu- 
tion; an  acetic  acidity  just  sufficient  to  redden  litmus  was  found  by 
Hudson*  to  give  the  best  results. 

Invertase  is  rendered  completely  inactive  by  small  amounts  of 
alkali;  in  such  cases  the  original  activity  may  be  regained  by  restor- 
ing the  proper  degree  of  acidity.  Addition  of  alkalies  in  large  amount 
destroys  the  enzyme  completely. 

Rate  of  Inversion  by  Invertase.  —  The  inversion  velocity  of  sucrose 
by  means  of  invertase  has  been  a  subject  of  considerable  study  and  the 
conclusion  of  early  observers  has  been  that  the  inversion  does  not  fol- 
low the  formula  for  a  unimolecular  reaction,  such  as  is  obtained  by  in- 
version with  acids.  O'Sullivan  and  Tompson,f  however,  showed,  in 
1890,  that  in  following  the  inversion  with  invertase  a  serious  error 
existed  in  the  polarimetric  reading  if  the  mutarotation  of  the  freshly 
liberated  sugar  was  not  considered.  To  quote  from  these  authors: 

"The  dextrose  formed  by  the  action  of  invertase  on  cane  sugar  is 
initially  in  the  birotary  state,  and,  therefore,  the  optical  activity  of  a 
solution  undergoing  inversion  is  no  guide  to  the  amount  of  inversion 
that  has  taken  place.  If  a  caustic  alkali  be  added  to  a  solution  under- 
going inversion,  and  the  optical  activity  be  allowed  sufficient  time  to 
become  constant,  it  is  a  true  indicator  of  the  amount  of  inversion  that 
had  taken  place  at  the  moment  of  adding  the  alkali." 

When  the  error  due  to  mutarotation  is  thus  corrected,  the  inversion 
by  invertase  was  found  by  O'Sullivan  and  Tompson  to  follow  the  same 
unimolecular  formula  as  by  inversion  with  acids. 

The  action  of  invertase  upon  sucrose  has  recently  been  studied  by 

*  J.  Ind.  Eng.  Chem.,  2,  143. 
t  J.  Chem.  Soc.,  57,  927. 


672 


SUGAR  ANALYSIS 


Hudson  *  and  the  conclusions  of  O'Sullivan  and  Tompson  were  fully 
confirmed.  Hudson,  for  example,  found  for  the  apparent  and  real 
rate  of  inversion  by  invertase  the  following  values: 

TABLE  XCVI 

Apparent  and  Real  Rates  of  Inversion  of  Sucrose  by  Invertase 


Time  (t). 

Rotation. 

k=  \  log 

r0  —  TO, 

r-roo 

Without  alkali 
(apparent  rate). 

With  alkali 
(real  rate). 

Without  alkali. 

With  alkali. 

0 
30 
60 
90 
110 
130 
150 

00 

24.50 
16.85 
10.95 
4.75 
1.95 
-0.55 
-2.20 
-7.47 

24.50 
14.27 
7.90 
3.00 
0.80 
-1.49 
-2.40 
-7.47 

0.00396 
0.00399 
0.00464 
0.00482 
0.00511 
0.00522 

0.00558 
0.00530 
0.00539 
0.00534 
0.00559 
0.00533 

The  values  of  k  without  alkali  show  an  apparently  increasing  in- 
version velocity,  a  circumstance  which  led  the  early  investigators  to 
conclude  that  the  rate  of  inversion  with  invertase  did  not  follow  the 
same  law  as  for  acid  inversion.  The  value  of  k,  after  destroying  mu- 
tarotation  with  a  little  sodium  carbonate,  is,  however,  constant  within 
the  limits  of  experimental  error  and  shows  that  the  inversion  with  in- 
vertase follows  the  law  of  a  unimolecular  reaction. 

Hudson's  Equation  for  Inversion.  —  The  inversion  of  sucrose  is  rep- 
resented by  Hudson  as  follows : 


Sucrose' 


r<*-glucose 
la-fructose 


0-glucose 
^-fructose. 


The  freshly  liberated  glucose  and  fructose  are  in  the  mutarotating 
form.  With  acid  inversion  the  mutarotations  are  so  accelerated  that 
the  errors  in  polarimetric  observation  largely  disappear;  with  inver- 
tase inversion,  however,  the  mutarotations  are  not  accelerated  and, 
unless  destroyed  with  alkali,  follow  the  ordinary  rate  of  mutarotation 
for  aqueous  solutions,  which,  according  to  the  determinations  of  Osaka 
(p.  187),  is  about  10  times  as  fast  for  fructose  as  for  glucose. 

Hudson  has  studied  the  mutarotation,  which  follows  the  nearly  in- 
stantaneous inversion  of  sucrose  with  strong  invertase  at  0°  C.,  and 
concludes  that  the  freshly  liberated  or  a-glucose  has  a  specific  rotation 

*  J.  Am.  Chem.  Soc.,  30,  1160,  1564;  31,  655;  32,  985,  1220,  1350. 


THE  DISACCHARIDES 


673 


of  about  +109  and  the  freshiy  liberated  or  a-fructose  a  rotation  of 
about  •+  17,  the  combination  of  these  values,  when  the  a-glucose  and 
a-fructose  are  molecularly  united,  giving  the  specific  rotation  of  su- 
crose, i.e., 

(109  X  180)  +  (17  X  180) 
[a]D  sucrose  =  ^ 


Influence  of  Concentration  of  Invertase  on  Rate  of  Inversion.  —  The 
velocity  of  inversion  with  invertase  was  found  by  O'Sullivan  and 
Tompson  to  be  proportional  to  the  concentration  of  enzyme.  This 
proportionality  was  tested  by  Hudson  and  found  to  be  true  for  sucrose 
solutions  of  varying  concentration.  The  following  table  by  Hudson 
shows  the  percentage  inversion  of  three  sucrose  solutions  using  different 
concentrations  of  invertase  for  different  periods  of  time.  In  making 
the  experiments  small  quantities  of  invertase  solution  were  diluted  to 
|,  J,  J  and  |,  and  10  c.c.  of  these  dilutions  added  to  100  c.c.  of  stock 
solutions  of  sucrose,  the  concentration  of  the  resulting  solutions  being 
45.5  gms.,  90.9  gms.  and  273  gms.  sucrose  per  liter. 


TABLE  XCVII 

Influence  of  Concentration  of  Invertase  on  the  Rate  of  Inversion  at  30°  C. 


Per  cent  inversion. 

Concentration  of 
invertase. 

Time  of  action. 

Concentration, 
X  time. 

45.5  gms. 
per  liter. 

90.9  gms. 
per  liter. 

273  gms. 
per  liter. 

Minutes 

2.00 

15 

30 

73.2 

45.3 

11.2 

2.00 

30 

60 

93.0 

74.2 

22.0 

1.50 

20 

30 

73.2 

44.8 

11.2 

1.50 

40 

60 

92.8 

74.5 

22.7 

1.00 

30 

30 

72.9 

45.3 

11.5 

1.00 

60 

60 

93.0 

74.7 

22.3 

0.50 

60 

30 

72.9 

45.2 

11.4 

0.50 

120 

60 

92.7 

74.5 

22.6 

0.25 

120 

30 

73.1 

45.2 

10.9 

0.25 

240 

60 

92.7 

74.7 

21.9 

The  solutions  of  the  same  sucrose  concentration  show  the  same  ex- 
tent of  inversion  when  the  product  of  invertase  concentration  and  time 
of  action  is  the  same.  In  other  words  the  times  are  inversely  propor- 
tional to  the  concentrations  of  invertase,  from  which  it  follows  that  the 
velocity  of  inversion  is  directly  proportional  to  the  concentration  of  in- 
vertase. 


674 


SUGAR  ANALYSIS 


Influence  of  Concentration  of  Sucrose  on  Activity  of  Invertase.  —  The 
activity  of  invertase  is  greatly  influenced  by  the  concentration  of  su- 
crose. This  is  shown  in  the  preceding  table  by  Hudson  from  which  the 
following  figures  are  taken: 


I. 

II. 

III. 

Concentration  of  sucrose  per  100  c.c. 

4.55  gms. 

9.09  gms. 

27.3  gms. 

Per  cent  sucrose  inverted  in  15  minutes  .  , 

73.2 

45.3 

11.2 

Per  cent  sucrose  inverted  in  30  minutes  .  . 

93.0 

74.2 

22.0 

Grams  sucrose  inverted  in  15  minutes  .... 

3.32 

4.12 

3.06 

Grams  sucrose  inverted  in  30  minutes  .... 

4.23 

6.74 

6.01 

It  will  be  seen  that  the  percentage  inversion  is  greater  the  more 
dilute  the  sucrose  solution.  This  is  not  true,  however,  as  regards  the 
absolute  weight  of  sucrose  inverted  which  is  greatest  for  the  solution  of 
9.09  gms.  concentration.  In  50  per  cent  sucrose  solutions  the  activity 
of  invertase  at  ordinary  temperature  is  almost  suspended  and  in  satu- 
rated sucrose  solutions  is  completely  so. 

Influence  of  Temperature  on  Activity  of  Invertase.  —  The  activity  of 
invertase  is  intensified  by  increase  in  temperature  up  to  the  point 
where  the  enzyme  begins  to  undergo  destruction.  The  optimum  tem- 
perature for  the  maximum  action  of  invertase  is  generally  placed  at 
about  55°  C.,  although  variations  in  concentration  of  sugar,  changes 
in  acidity  of  solution,  presence  of  alcohol  and  other  substances  may 
raise  or  lower  this  figure  considerably. 

Perfectly  dry  invertase  may  be  heated  to  100°  C.  and  even  to 
160°  C.  without  losing  its  activity.*  In  presence  of  water,  however, 
the  enzyme  is  much  more  susceptible  to  the  action  of  heat.  Hudson 
and  Paine  f  found  that  the  rate  of  destruction  by  acids  and  alkalies  in- 
creased as  the  temperature  rose  above  0°  C.  At  about  60°  C.  distilled 
water  begins  to  destroy  the  enzyme,  this  destruction  becoming  very 
rapid  at  65°  C. 

Influence  of  Alcohol  on  Activity  of  Invertase.  —  Alcohol  was  found  by 
O'Sullivan  and  Tompson  to  lessen  the  activity  of  invertase  very  strongly, 
5  per  cent  of  alcohol  diminishing  the  velocity  constant  by  nearly  50 
per  cent.  Hudson  and  Paine  found  that  above  20  per  cent  alcohol  the 
inactivation  w.as  attended  by  a  destruction  of  the  enzyme;  the  rate  of 
destruction  for  alcohol  of  different  concentrations  is  given  in  the  fol- 
lowing table: 

*  Salkowski,  Z.  physiol.  Chem.,  31,  304.         f  J.  Am.  Chem.  Soc.,  32,  985. 


THE  DISACCHARIDES 


675 


TABLE  XCVIII 

Rate-  of  Destruction  of  Invertase  by  Alcohol 


Concentration  of 
alcohol 
(volume  per  cent) 

Rate  of  destruc- 
tion. 

Concentration  of 
alcohol 
(volume  per  cent). 

Rate  of  destruc- 
tion. 

0 

0 

50 

850 

10 

0 

55 

570 

20 

3 

60 

240 

30 

44 

70 

74 

40 

260 

80 

7 

45 

487 

90 

2 

It  is  seen  that  the  rate  of  destruction  attains  its  maximum  at  about 
50  per  cent  alcohol;  addition  of  alcohol  beyond  50  per  cent  begins  to 
precipitate  the  invertase,  and  this  no  doubt  protects  the  enzyme  as  is 
shown  by  the  rate  of  destruction  falling  nearly  to  0  at  90  per  cent 
alcohol. 

The  rate  of  destruction  of  invertase  by  alcohol,  acids,  alkalies  and 
hot  water  was  found  by  Hudson  and  Paine  to  follow  the  course  of  a 
unimolecular  reaction. 

TABLE  XCIX 

The  Action  of  Fructose  in  Protecting  Invertase  from  Destruction  by  Acids,  Alkalies,  and 

Hot  Water 


Temperature. 

Concentration  of  destroying  agent. 

Concentration  of 
fructose. 

Rate  of  destruc- 
tion. 

Deg.  C. 
30 

0.04  normal  HC1  «| 

0.0 

2.7 

100 
26 

30 

0  03  normal  NaOH    .                    J 

5.4 
10.9 
0.0 
2.7 

12 
2 
100 
3 

30 

50  per  cent  alcohol  j 

5.4 
10.9 
0.0 

2.7 

3 
4 
100 
1 

61 

Distilled  water         -\ 

5.4 
10.9 
0.0 

2.7 

1 
1 
100 
32 

5.4 
10.9 

16 
24 

Protective  Action  of  Sucrose  and  Fructose  Upon  Invertase.  —  An  im- 
portant fact  to  be  noted  in  this  connection  is  the  protective  action 
which  sucrose  and  fructose  have  in  retarding  the  destruction  of  inver- 
tase.    Kjeldahl,*  O'Sullivan  and  Tompson,  Hudson  and  Paine  and 
*  Lippmann's  "  Chemie  der  Zuckerarten,"  p.  1297. 


676  SUGAR  ANALYSIS 

others,  who  have  investigated  this  phenomenon,  show  that  in  presence 
of  sucrose  invertase  can  withstand  higher  temperatures  and  higher  con- 
centrations of  alcohol  than  where  no  sucrose  is  present.  The  action  of 
fructose  in  protecting  invertase  from  destruction  by  acids,  alkalies  and 
hot  water  is  shown  in  Table  XCIX  by  Hudson  and  Paine*  where 
the  rates  of  destruction  are  expressed  as  per  cent  of  the  rate  for  the  de- 
stroying agent  when  no  fructose  is  present. 

The  property  which  sugars  have  of  protecting  invertase  from  de- 
struction has  been  noted  in  case  of  other  enzymes  (as  diastase);  the 
phenomenon  can  be  explained  by  assuming  that  the  invertase  forms  a 
combination  with  the  sugar  which  is  less  easily  destroyed  than  the 
pure  enzyme. 

COMPOUNDS   OF   SUCROSE 

Owing  to  the  absence  of  free  aldehyde  or  ketone  groups  sucrose  does 
not  form  hydrazones,  osazones,  oximes  or  other  compounds  such  as  are 
characteristic  of  the  reducing  sugars.  Acetic  anhydride  under  varying 
conditions  gives  a  number  of  acetates,  and  benzoyl  chloride  in  presence 
of  sodium  hydroxide  gives  several  benzoates  of  sucrose.  These  com- 
pounds have,  however,  but  little  importance  and  their  description  is 
passed  over. 

The  most  important  compounds  of  sucrose  from  the  analytical  and 
technical  standpoint  are  the  saccharates,  or  sucrates,  which  are  formed 
by  the  combination  of  sucrose  with  various  metallic  bases. 

Saccharates  of  the  Alkalies.  —  By  treating  alcoholic  sucrose  solu- 
tions with  concentrated  potassium  or  sodium  hydroxide,  gelatinous  sac- 
charates are  precipitated  of  the  formulae  Ci2H2iKOn  and  Ci2H2iNaOn. 
The  compounds  are  soluble  in  water  and  dilute  alcohol,  but  insoluble 
in  strong  alcohol.  The  alkali  monosaccharates  are  also  formed  in 
aqueous  solutions  of  sucrose  after  addition  of  potassium  or  sodium  hy- 
droxide, even  in  slight  amounts.  Dubrunfaut  in  fact  noted  that  after 
addition  of  sodium  hydroxide  to  sucrose  in  equal  molecular  proportions 
the  specific  rotation  sank  to  a  fixed  value,  further  addition  of  alkali  pro- 
ducing no  change.  The  specific  rotation  of  sodium  saccharate  accord- 
ing to  Thomsenf  follows  the  equation : 

[a]D  =  +  56.84  +  0.011359  q  +  0.00039944  q2, 

in  which  q  is  the  per  cent  water  in  solution.  The  depressing  influence 
of  sodium  hydroxide  and  potassium  hydroxide  upon  the  rotation  of 
sucrose,  through  formation  of  saccharates,  may  introduce  an  error  in 

*  J.  Am.  Chem.  Soc.,  32,  988. 
t  Ber.,  14,  1647. 


THE  DISACCHARIDES  677 

certain  polarimetric  measurements  unless  the  free  alkali  is  first  neu- 
tralized (preferably  by  means  of  acetic  acid). 

Saccharates  of  the  Alkaline  Earths.  —  The  most  important  sac- 
charates  from  the  technical  standpoint  are  those  of  the  alkaline  earths. 
In  the  formation  of  these  the  sucrose  molecule  can  combine  with  one 
or  more  molecules  of  the  base.  In  case  of  calcium  there  are  three  well 
characterized  sucrose  compounds  the  mono-,  bi-  and  trisaccharates; 
tetra-,  hexa-  and  octosaccharates  have  also  been  described.  The 
structural  constitution  of  these  and  other  saccharates  is  not  as  yet 
understood,  the  place  and  manner  of  attachment  of  the  base  to  the 
sucrose  molecule  not  having  been  established.  It  is  supposed  that  the 
bivalent  metals  are  attached  to  the  sucrose  molecule  by  only  one  va- 
lency, as,  for  example,  Ci2H2iOn  —  Ca  —  OH  in  calcium  monosaccha- 
rate.  The  existence  of  sucro-carbonates  in  which  the  bivalent  metal  is 
united  both  with  sucrose  and  the  carbonic  acid  radical  is  explained  upon 
this  supposition. 

Calcium  monosaccharate  is  formed  by  dissolving  sucrose  and  fresh 
finely  powdered  quick  lime  in  equal  molecular  proportions  in  water  at 
low  temperature.  The  compound  is  then  precipitated  from  solution  by 
strong  alcohol;  as  thus  prepared  it  has  the  formula: 

Ci2H22On  -  CaO  +  2  H2O, 

the  water  of  crystallization  being  expelled  by  drying  at  100°  C.  Cal- 
cium monosaccharate  consists  of  a  white  amorphous  substance,  easily 
soluble  in  cold  water  but  insoluble  in  strong  alcohol;  its  aqueous 
solutions  upon  warming  become  turbid,  but  the  turbidity  disappears 
on  recooling.  Upon  heating  its  solutions  calcium  monosaccharate  is 
decomposed  into  calcium  trisaccharate  and  free  sucrose. 

3  CuHzaOn  -  CaO   =    Ci2H22On  •  3  CaO  +  2Ci2H22On. 

Calcium  monosaccharate  Calcium  trisaccharate  Sucrose. 

Calcium  bisaccharate  is  best  prepared,  according  to  Lippmann,*  by 
adding  fresh  finely  powdered  quick  lime,  free  from  hydroxide,  to  a  cold 
aqueous  solution  of  sucrose  using  2  molecular  parts  of  CaO  to  1  of 
Ci2H22On.  Upon  cooling  the  solution  with  ice  beautiful  white  crystals 
will  separate  of  the  composition  Ci2H22On  •  2  CaO.  Crystallization  at 
higher  temperatures  takes  place  with  difficulty,  and  the  bisaccharate, 
which  is  then  obtained,  contains  water  of  crystallization.  Calcium 
bisaccharate  is  soluble  in  about  33  parts  of  cold  water;  upon  boiling 
the  solution  it  is  decomposed  into  the  trisaccharate  and  free  sucrose. 
3  Ci2H22On  -  2  CaO  =  2  Ci2H22On  -  3  CaO  +  Ci2H22On. 

Calcium  bisaccharate  Calcium  trisaccharate  Sucrose. 

*  Z.  Ver.  Deut.  Zuckerind,  33,  883. 


678  SUGAR  ANALYSIS 

Calcium  trisaccharate  is  formed  upon  boiling  solutions  of  the  mono- 
and  bisaccharate  as  above  described.  It  is  also  produced  as  a  granular 
precipitate  by  adding  fresh  finely  pulverized  quick  lime  to  an  alco- 
holic solution  of  sucrose  using  3  molecular  parts  of  CaO  to  1  of 
Ci2H22On;  the  compound  thus  obtained,  after  drying  over  concentrated 
sulphuric  acid,  has  the  formula  Ci2H22On  •  3  CaO  +  4  H2O,  one  mole- 
cule of  water,  however,  being  given  off  in  vacuo.  The  trisaccharate  as 
prepared  from  hot  aqueous  solutions  has  3  molecules  of  water.  Calcium 
trisaccharate  is  a  white  granular  compound,  soluble  in  100  parts  of  cold 
and  in  200  parts  of  hot  water. 

Calcium  trisaccharate  is  employed  technically  in  the  separation  of 
sucrose  from  beet  molasses.  In  the  old  elution  process  of  Scheibler* 
the  molasses  was  mixed  with  an  excess  of  freshly  burned,  finely  powdered 
quick  lime,  and  the  porous  mass  of  saccharate  thus  obtained  freed  from 
impurities  by  washing  with  dilute  alcohol.  The  elution  method  is  sup- 
planted at  present  by  the  trisaccharate  process  of  Steffen  *  which  is 
carried  out  as  follows.  The  molasses  after  diluting  to  12  to  14  Brix  is 
treated  in  the  cold  with  freshly  burned  quick  lime,  reduced  to  the  fine- 
ness of  dust,  in  the  ratio  of  80  to  150  parts  by  weight  of  CaO  to  100  of 
sucrose.  Constant  agitation  of  the  solution  is  necessary  in  order  to 
secure  proper  distribution  of  the  lime  and  to  prevent  too  great  an  in- 
crease in  temperature.  The  granular  precipitate  of  trisaccharate  is 
filtered  cold  through  filter  presses,  washed  with  cold  water  and  then 
either  used  for  saturating  the  diffusion  juice,  or  worked  up  separately 
for  sucrose  by  decomposing  with  carbon  dioxide  in  aqueous  suspension. 
CwHaOii  •  3  CaO  +  3C02  =  Ci2H22On  +  3  CaCO3. 

Calcium  trisaccharate  Carbon  dioxide  Sucrose  Calcium  carbonate. 

Double  saccharates,  in  which  one  molecule  of  CaO  in  the  trisaccha- 
rate is  replaced  by  K2O  or  Na2O,  have  also  been  formed.  Sucro-carbon- 
ates  have  also  been  prepared;  the  exact  nature  of  the  latter,  to  which 
such  formulae  as  Ci2H22On  •  6  CaO  •  3  C02  have  been  given,  is  unknown. 

Strontium  monosaccharate  is  best  obtained  according  to  Scheiblerf  by 
treating  a  20  to  25  per  cent  solution  of  sucrose  at  70°  to  75°  C.  with  equal 
molecular  parts  of  crystallized  strontium  hydroxide  (Sr(OH)2  +  8  H2O) 
and  allowing  the  supersaturated  solution  to  cool  with  exclusion  of  the 
carbon  dioxide  of  the  air.  By  adding  a  few  crystals  of  monosaccharate 
from  another  preparation  and  agitating  the  solution,  strontium  mono- 

*  For  a  very  complete  description  of  the  osmose,  elution,  strontia  and  other 
processes  for  desaccharifying  molasses  see  Ware's  "  Beet  Sugar  Manufacture  and 
Refining  "  (1907),  Vol.  II,  466-510,  or  the  works  of  Claassen,  Newlands,  Rumpler, 
Stohmann  and  others. 

t  Her.,  16,  984. 


THE  DISACCHARIDES  679 

saccharate  will  separate  out  in  cauliflower-like  masses  of  white  crystals 
with  a  composition  corresponding  to  the  formula  Ci2H22Ou  •  SrO  +  5  H20. 
The  compound  dissolves  in  warm  water  with  great  readiness  to  form 
supersaturated  solutions,  which  may  be  cooled  again  without  separation 
of  crystals.  Upon  heating  its  solutions  above  60°  C.  strontium  mono- 
saccharate  is  decomposed  into  bisaccharate  and  free  sucrose. 

2  Ci2H22Oii  •  SrO    =    Ci2H22Oii  •  2  SrO   +   Ci2H22On. 

Strontium  monosaccharate  Strontium  bisaccharate  Sucrose. 

Strontium  bisaccharate  is  best  prepared  according  to  Scheibler*  by 
dissolving  crystallized  strontium  hydroxide  in  a  boiling  15  per  cent 
sucrose  solution.  As  soon  as  the  molecular  proportion  of  strontium  to 
sucrose  exceeds  2  :  1  the  bisaccharate  begins  to  separate.  When  the 
molecular  proportion  of  strontium  to  sucrose  exceeds  3 : 1  the  separation 
of  sucrose  as  strontium  bisaccharate  is  almost  quantitative  after  8  to  10 
minutes'  boiling.  Strontium  bisaccharate  consists  of  white  granular 
crystals  of  the  formula  Ci2H22On  •  2  SrO.  The  compound  is  soluble 
in  about  84  parts  of  boiling  water  but  is  insoluble  in  alcohol  and  in 
strongly  alkaline  aqueous  solutions.  For  the  complete  precipitation  of 
sucrose  as  bisaccharate  the  third  molecule  of  strontium  hydroxide  can, 
therefore,  be  replaced  by  other  alkalies  such  as  sodium  or  potassium 
hydroxide. 

When  strontium  bisaccharate  is  mixed  with  cold  water  it  is  de- 
composed, there  being  obtained  a  solution  of  the  monosaccharate  and 
free  strontium  hydroxide,  the  latter  separating  out  in  the  crystalline 
form. 

Ci2H22On  •  2  SrO  +  H20  =  Ci2H22On  -  SrO  +  Sr(OH)2. 

If  the  filtrate  from  the  strontium  hydroxide  be  saturated  with  carbon 
dioxide  the  monosaccharate  is  decomposed  into  sucrose  and  strontium 
carbonate.  By  evaporating  the  clear  filtered  solution,  the  sucrose  is 
recovered  in  the  crystalline  form. 

The  method  of  precipitating  sucrose  as  strontium  bisaccharate  is 
employed  analytically  for  detecting  sucrose  in  plant  materials  (p.  647) ; 
it  also  constitutes  the  basis  of  the  strontium  process  for  recovering 
sucrose  from  beet  molasses.  In  the  Scheibler  t  strontium  process  the 
diluted  molasses  and  strontium  hydroxide  (2J  to  3  molecules  of  stron- 
tium to  1  of  sucrose)  are  heated  to  100°  C.  with  constant  agitation  for 
about  30  minutes.  The  precipitated  bisaccharate  is  then  filtered  off 
and  washed  hot  with  10  per  cent  strontium  hydroxide  solution,  until  the 

*  Z.  Ver.  Deut.  Zuckerind.,  31,  867. 

t  Ware's  "  Beet  Sugar  Manufacture  and  Refining  "  (1907),  Vol.  II,  502. 


680  SUGAR  ANALYSIS 

soluble  impurities  are  removed  and  the  precipitate  is  nearly  white.  The 
washed  bisaccharate  is  then  cooled  for  1  to  2  days  at  a  temperature  of 
5°  to  10°  C.,  when  it  decomposes,  according  to  the  preceding  equa- 
tion, into  a  solution  of  the  monosaccharate  and  crystallized  strontium 
hydroxide.  The  latter  is  separated  by  centrifugals  and  the  solution  of 
monosaccharate  carbonated.  The  filtrate  from  the  strontium  carbonate 
(which  is  reconverted  into  strontium  hydroxide)  is  a  sucrose  solution  of 
about  97  per  cent  purity,  and  can  be  worked  up  directly  into  white 
sugar.  The  strontium  bisaccharate  process  at  the  present  time  is  largely 
replaced  by  the  Steffens  calcium  trisaccharate  method. 

Barium  monosaccharate  is  obtained  by  warming  100  parts  of  a  6  per 
cent  aqueous  sucrose  solution  with  20  parts  of  a  20  per  cent  barium 
hydroxide  solution  and  allowing  to  cool  unexposed  to  the  carbon  dioxide 
of  the  air.  The  compound  may  be  prepared  more  easily  by  employing 
alcoholic  instead  of  aqueous  solutions  of  sucrose.  Barium  monosac- 
charate is  a  white  crystalline  compound  with  a  composition  correspond- 
ing to  the  formula  Ci2H22Oii  •  BaO.  It  is  soluble  in  47.6  parts  of  water 
at  15°  C.,  easily  soluble  in  aqueous  sucrose  solutions,  but  insoluble  in 
alcohol  or  in  aqueous  barium  hydroxide  solutions.  The  compound  is 
decomposed  in  contact  with  water  by  carbon  dioxide,  but  the  last  traces 
of  barium  are  precipitated  only  with  difficulty;  to  facilitate  the  sepa- 
ration, the  solution  after  carbonating  may  be  heated  with  gypsum  or 
ammonium  sulphate,  the  traces  of  barium  remaining  in  solution  being 
precipitated  as  sulphate. 

On  account  of  the  poisonous  character  of  some  of  its  salts,  the  use  of 
barium  for  separating  sucrose  from  molasses  is  forbidden  in  many  coun- 
tries. In  Italy,*  however,  the  barium  saccharate  method  has  proved 
successful  and  is  still  employed  on  a  large  scale,  no  injurious  effects 
seeming  to  attend  the  use  of  the  sugar  thus  prepared.  In  the  Italian 
process  the  barium  hydroxide  solution  is  made  up  at  38  to  40  degrees 
Be.,  and  the  molasses  of  38  to  42  degrees  Be*,  added  at  a  tempera- 
ture of  45°  to  50°  C.  The  mixture  is  rapidly  stirred  and  the  barium 
monosaccharate,  which  soon  becomes  granular,  allowed  to  settle.  With 
normal  molasses  the  barium  hydroxide  is  used  in  the  proportion  of 
1  molecule  for  each  molecule  of  sucrose,  plus  an  extra  TV  molecule  for 
the  non-sugars.  The  monosaccharate  is  then  washed,  decomposed 
in  aqueous  suspension  with  carbon  dioxide  and  the  filtrate  from  the 
barium  carbonate  evaporated  to  crystallization.  The  yield  of  sugar  by 
the  process  is  about  one-third  the  weight  of  beet  molasses. 

In  both  the  barium  and  strontium  saccharate  processes  the  barium 
*  Viewegh,  Z.  Zuckerind.,  Bohmen,  34,  38. 


THE  DISACCHARIDES  681 

and  strontium  are  recovered  and  worked  up  again  into  hydroxides  for 
continued  use. 

Miscellaneous  Metallic  Compounds  of  Sucrose.  —  In  addition  to  the 
saccharates  of  the  alkalies  and  alkaline  earths  a  large  number  of  com- 
pounds of  sucrose  with  other  metals  have  been  prepared,  such  as 
saccharates  of  iron,  aluminum,  chromium,  manganese,  nickel,  copper, 
lead  and  mercury.  Some  of  the  saccharates  mentioned,  as  those  of  iron, 
are  used  medicinally.  Lead  saccharates  of  the  formulae  Ci2H22On  •  PbO, 
Ci2H22On  •  2  PbO  and  Ci2H22Oii  •  3  PbO  are  described  in  the  literature, 
and  these  compounds  are  sometimes  formed  in  the  clarification  of  alka- 
line sucrose  solutions  by  lead  subacetate  with  introduction  of  consider- 
able errors  in  the  work  of  analysis.  Soluble  lead  saccharates  may  affect 
the  polarimetric'  reading,  and  precipitation  of  insoluble  lead  saccharates 
introduces  a  loss  in  the  determination  of  sucrose. 

In  connection  with  the  formation  of  soluble  saccharates  there 
should  be  mentioned  the  property  which  sucrose  has  of  preventing  or 
retarding  the  precipitations  of  iron,  aluminum,  cobalt,  nickel,  copper 
and  other  metals  from  solution  by  means  of  sodium,  potassium  and 
ammonium  hydroxides.  In  such  cases  metallic-sucrose  complexes  are 
formed,  the  exact  constitution  of  which  is  not  understood.  The  follow- 
ing are  examples  of  the  formulae  which  have  been  given  to  a  few 
such  compounds  as  have  been  isolated,  Ci2H22On  •  5  CuO  +  Na20; 
2  Ci2H22On  •  Fe2O3  +  2  Na^O.  Kahlenberg*  from  a  study  of  the  electric 
conductivity  of  solutions  of  such  complexes  believes  that  the  metals  do 
not  exist  in  the  dissociated  condition  of  an  ordinary  salt  solution  but 
in  the  form  of  complex  sucrose-metal  ions. 

Tests  for  Sucrose.  —  Characteristic  qualitative  tests  for  detecting 
small  amounts  of  sucrose  in  presence  of  other  sugars  are  wanting.  In 
such  cases  the  only  certain  means  of  identification  is  to  precipitate  the 
sucrose  as  one  of  its  saccharates,  preferably  strontium  bisaccharate, 
and  to  determine  the  optical  and  chemical  properties  of  the  sugar 
after  liberation  from  its  compound  by  means  of  carbon  dioxide.  The 
determination  of  specific  rotation  or  reducing  power  before  and  after 
inversion  with  hydrochloric  acid  or  invertase  is  also  valuable  as  a 
means  of  identification.  Sucrose  in  presence  of  inverting  agents  will 
of  course  give  any  of  the  reactions  described  for  d-glucose  and  d-fructose. 
The  deep  violet  coloration  which  even  very  dilute  sucrose  solutions  give 
with  a-naphthol  and  sulphuric  acid  is  also  given  by  solutions  of  invert 
sugar.  The  violet  coloration  obtained  by  heating  sucrose  with  an  alka- 
line solution  of  cobalt  nitrate  was  formerly  regarded  as  a  characteristic 
*  Z.  physik.  Chem.,  17,  616. 


682 


SUGAR  ANALYSIS 


reaction;  other  sugars,  however,  give  similar  colorations  so  that  the 
test  is  not  reliable.  The  colorations  which  sucrose  gives  with  mor- 
phine, codeine,  aconitine,  veratrine  and  other  alkaloids  in  presence  of 
sulphuric  acid  is  also  given  by  invert  sugar;  the  same  is  also  true  of 
the  blue  coloration  obtained  by  treating  a  sucrose  solution  with  am- 
monium molybdate  in  presence  of  sulphuric  acid. 

Configuration  of  Sucrose.  —  A  number  of  constitutional  formulae 
have  been  assigned  to  sucrose.  The  following  arrangement  by  Wohl* 
and  Fischer  f  is  the  one  most  generally  preferred,  although  the  exact 
configuration  is  still  a  matter  of  doubt: 


CH2OH 
HOCH 


CH2OH 


H 

d-Glucose  radical. 


d-Fructose  radical. 


The  above  arrangement  contains  no  free  aldehyde  or  ketone  group 
which  explains  the  non-reducing  property  of  sucrose.  The  cleavage 
into  d-glucose  and  d-fructose  by  inversion  is  supposed  to  take  place  at 
the  O  atom  marked  with  a  *. 

The  synthesis  of  sucrose  from  glucose  and  fructose  has  not  as  yet 
been  accomplished. 

MALTOSE.  —  Maltobiose.     Malt  sugar.     Cerealose. 


The  formation  of  a  hitherto  unknown  sugar  by  the  action  of  malt 
extract  upon  starch  was  noted  by  De  Saussure  J  in  1819;  some  years 
later  Dubrunfaut§  made  a  further  study  of  the  sugar  and  gave  it  the 
name  maltose. 

Occurrence.  —  Maltose  is  one  of  the  most  widely  distributed 
disaccharides.  The  fact,  however,  that  maltose  is  found  in  plants 
almost  entirely  as  a  transition,  and  not  as  a  reserve,  carbohydrate  ren- 
ders it  difficult  to  isolate  the  sugar  from  ordinary  plant  substances  in 
large  amounts.  In  the  vegetable  kingdom  maltose  has  been  observed 
in  the  leaves  of  many  plants,  in  young  twigs  and  buds,  in  yeast,  soja 

*  Ber.,  23,  2084.  J  Ann.  chim.  phys.  [2],  11,  379. 

t  Ber.,  26,  2405.  §  Ann.  chim.  phys.  [3],  21, 178. 


THE  DISACCHARIDES 


683 


beans,  rice  and  other  substances;  it  is  found  most  abundantly  in 
starchy  seeds  at  the  time  of  germination  when  it  is  formed  together  with 
dextrin  by  the  action  of  diastatic  enzymes  upon  starch.  The  maltose, 
which  is  thus  formed,  is  itself  quickly  hydrolyzed  by  other  enzymes 
(glucases),  so  that  the  amount  of  free  maltose  occurring  at  any  one 
time  is  relatively  small.  In  the  animal  kingdom  maltose  has  been  ob- 
served in  abnormal  urines,  in  the  intestinal  tract,  in  the  blood,  liver 
and  muscular  tissues.  Its  occurrence  in  the  animal  organism  is  no 
doubt  largely  due  to  the  action  of  amylolytic  enzymes  upon  the  starchy 
matter  of  the  food. 

Diastatic  Enzymes.  —  Diastatic  enzymes  or  amylases  are  widely 
distributed  in  both  the  vegetable  and  animal  kingdoms.  Aqueous  ex- 
tracts of  barley,  oats,  rye,  rice  and  other  cereal  grains  as  well  as  of 
many  seeds;  extracts  of  the  blossoms,  buds,  leaves,  roots,  etc.,  of 
many  plants,  and  also  of  many  moulds,  bacteria,  fungi,  lichens,  etc., 
possess  the  property  of  converting  starch  into  maltose  and  dextrin. 
In  the  animal  kingdom  amylases  are  found  in  the  saliva  (ptyalin),  in 
the  pancreatic  juice  (pancreatin),  in  the  mucous  secretions  of  the 
stomach  and  intestines,  and  in  the  liver,  kidneys  and  other  organs; 
their  presence  has  also  been  reported  in  blood  serum,  in  the  lymph 
and  even  in  urine  and  milk. 

The  fresh  aqueous  extract  of  many  plant  substances,  such  as  starchy 
grains  and  seeds,  have  relatively  but  little  diastatic  power;  if  such 
grains  and  seeds,  however,  are  moistened  and  allowed  to  germinate 
before  making  the  extract,  the  starch  converting  power  is  found  to 
undergo  a  marked  increase.  In  such  cases  the  amylase  is  supposed  to 
be  derived  from  an  anterior  substance,  or  zymogen,  which  is  itself  in- 
active. The  following  experiments  by  Salamon*  show  the  increase  in 
diastatic  power  during  the  germination  of  barley.  The  values  are  ex- 
pressed in  terms  of  Lintner's  scale  (p.  513)  and  are  calculated  in  each 
case  to  a  common  basis  of  2  per  cent  moisture. 


Day. 

Diastatic  power. 

Day. 

Diastatic  power. 

1st 

6.5 

8th 

90.4 

2nd 

7.0 

9th 

81.3 

3rd 

10.7 

10th 

77.4 

4th 

49.2 

llth 

85.5 

5th 

78.1 

12th 

108.2 

6th 

74.1 

13th 

125.0 

*  J.  Fed.  Inst.  Brewing  (1902),  8,  2. 


684  SUGAR  ANALYSIS 

The  results  show  a  20-fold  increase  in  diastatic  power  during  the 
13  days  of  germination,  although  at  certain  stages  there  was  an  ap- 
parent decrease  upon  succeeding  days. 

Malt.  —  The  diastases  of  germinated  barley  (malt)  are  of  great 
importance  in  the  brewing  industry  and  have  for  this  reason  been 
studied  more  than  any  of  the  amylases.  In  the  preparation  of  malt,  raw 
barley  is  first  steeped  for  2  to  3  days  in  water  at  10°  to  13°  C.  until  it 
has  absorbed  about  50  per  cent  its  weight  of  moisture.  The  barley  is 
then  allowed  to  germinate  for  9  to  12  days  upon  a  floor  in  heaps  about 
1  foot  in  depth.  The  heaps  are  turned  several  times  each  day  with 
wooden  shovels  in  order  to  secure  proper  aeration  and  even  distribution 
of  temperature,  the  latter  being  maintained  as  nearly  as  .possible  at 
15°  C.;  the  grain  is  also  sprinkled  with  water  at  intervals  in  order  to 
maintain  proper  conditions  of  moisture.  After  germination  has  pro- 
ceeded to  the  desired  extent,  as  determined  by  the  growth  of  the  root- 
lets and  acrospire,  the  fresh  malt  is  transferred  to  a  drying  kiln, 
where  it  is  heated  at  about  25°  to  35°  C.  for  the  first  day,  at  40°  to 
45°  C.  for  the  second  day,  at  50°  to  55°  for  the  third  day  and  at  60°  to 
65°  for  the  fourth  day.  The  kiln  is  then  gradually  raised  to  a  final 
temperature  varying  from  85°  to  110°  C.,  according  to  the  character 
of  the  malt  desired.  The  gradual  elevation  of  temperature  is  neces- 
sary, as  diastase,  like  invertase  and  other  enzymes,  is  extremely  sensi- 
tive to  heat  in  presence  of  moisture,  although  when  perfectly  dry  the 
enzyme  can  withstand  a  much  higher  temperature.  The  diastatic 
power  of  the  green  malt  is  considerably  reduced  by  the  drying 
process,  however,  being  only  one-sixth  to  one-third  of  its  original 
amount. 

In  the  process  of  malting  a  series  of  important  changes  take  place 
in  the  carbohydrates  of  the  grain.  In  the  first  place  a  considerable 
amount  of  the  conversion  products  of  the  starch  are  consumed  by  res- 
piration, over  10  per  cent  of  carbon  dioxide  being  given  off  by  the  malt 
during  germination.  The  maltose,  which  is  produced  by  the  action  of  the 
amylase  upon  the  starch,  is  hydrolyzed  into  glucose  by  the  glucase. 
Synthetic  processes  also  take  place;  the  reducing  sugars  absorbed  by 
the  aleurone  cells  and  scutellum  are  built  up  into  sucrose,  the  latter,  in 
turn,  as  it  contributes  to  the  growth  of  the  plant  embryo,  being  hydro- 
lyzed into  glucose  and  fructose.  The  following  analyses  by  O'Sullivan* 
give  the  per  cent  of  different  sugars  in  two  samples  of  barley  before  and 
after  germination. 

*  J.  Chem.  Soc.  (1886),  p,  58. 


THE  DISACCHARIDES 


685 


Barley  No.  I. 

Barley  No.  II. 

Before  ger- 
mination. 

After  ger- 
mination. 

Before  ger- 
mination. 

After  ger- 
mination. 

Sucrose    

Per  cent. 
0.9 

Per  cent. 
4.5 
1.2 
3.1 

0.2 

Per  cent. 
1.39 

Per  cent. 
4.50 
1.98 
1.57 
0.71 

IVI&ltose 

Glucose 

1.1 

0.62 

Fructose 

2.0 

9.0 

2.01 

8.76 

Preparation  of  Malt  Diastase.  —  For  the  preparation  of  diastase 
fresh  green  malt,  or,  when  this  is  not  available,  fresh  dry  malt,  is  finely 
ground  and  digested  for  2  to  3  hours  with  5  parts  of  cold  water.  The 
filtered  extract  is  then  treated  with  a  large  excess  of  strong  alcohol  and 
the  precipitated  enzyme  filtered  off,  redissolved  in  water  and  again  pre- 
cipitated with  alcohol.  The  product  thus  prepared  is  washed  with  strong 
alcohol  and  ether,  and  then  dried  in  vacuum  over  concentrated  sulphuric 
acid.  Diastase  was  prepared  by  Osborne*  by  precipitating  the  enzyme 
from  malt  extract  by  means  of  ammonium  and  magnesium  sulphates, 
and  then  removing  water-soluble  impurities  by  dialysis.  In  this  way  the 
purity  of  the  diastase  was  increased,  but  its  activity  was  diminished 
owing  no  doubt  to  the  removal  of  certain  salts  or  other  ingredients 
necessary  for  the  activation  of  the  enzyme. 

Properties  of  Malt  Diastase.  —  Diastase  as  ordinarily  prepared 
consists  of  a  white  chalky  powder,  soluble  in  water  to  a  clear  frothy 
solution,  but  insoluble  in  alcohol  and  ether.  It  is  precipitated  from 
solution  by  tannic  acid,  magnesium  sulphate  and  other  salts.  As  pre- 
pared by  Osborne  diastase  has  the  composition:  C,  52.50  per  cent; 
H,  6.72  per  cent;  N,  16.10  per  cent;  S,  1.90  per  cent;  0,  22.12  per  cent; 
and  ash,  0.66  per  cent.  Preparations  of  the  enzyme  give  the  ordinary 
tests  for  protein  and  also,  according  to  Wroblewski,f  for  araban.  Malt 
diastase  has  not  been  prepared,  however,  of  sufficient  purity  to  de- 
termine its  exact  composition. 

THE  CONVERSION  OF  STARCH 

CONVERSION    OF   STARCH   BY   ENZYMES 

In  the  study  of  the  action  of  malt  diastase  upon  starch,  use  has 
generally  been  made  of  malt  extract  rather  than  of  the  precipitated 
enzyme.  Following  the  early  work  by  Dubrunfaut,  O'Sullivan,t  in 

*  J.  Am.  Chem.  Soc.,  17,  587.  t  Ber.,  30,  2289;  31,  1127. 

J.  Chem.  Soc.  (1872),  25,  579. 


686  SUGAR  ANALYSIS 

1872,  was  the  first  to  subject  the  action  of  malt  diastase  upon  starch  to 
a  careful  study,  and  since  then  a  large  number  of  investigators  have 
made  the  question  an  object  of  research. 

Steps  in  Diastatic  Conversion.  —  Owing  to  the  complexity  of  the 
starch  molecule  and  the  indefinite  number  of  intermediate  transition 
products  which  are  formed  between  starch  and  maltose,  such  as 
amylodextrin,  erythrodextrin,  achroodextrin,  malto  dextrin,  etc.,  the 
conversion  of  starch  is  a  vastly  more  complicated  reaction  than  the  in- 
version of  sucrose.  It  is  generally  agreed  that  malt  diastase  is  a  mix- 
ture of  enzymes;  the  primary  phase  of  starch  conversion,  consisting  in 
the  formation  of  soluble  starch,  is  attributed  to  a  liquefying  enzyme  or 
cytase;  the  remaining  steps  of  the  conversion  are  assigned  to  an  amylo- 
dextrinase,  which  converts  the  soluble  starch  into  dextrin,  and  to  a 
dextrinomaltase,  which  converts  the  dextrin  into  maltose;  an  amylo- 
maltase  which  converts  soluble  starch  directly  into  maltose  has  also 
been  supposed  to  exist.  The  difference  in  behavior  of  diastases  from 
different  sources  is  no  doubt  due  in  part  to  variations  in  amount  of  the 
constituent  enzymes. 

Theory  of  Brown  and  his  Coworkers.  —  The  conversion  of 
starch  into  maltose  by  means  of  diastase  under  ordinary  conditions  is 
not  complete,  the  reaction  coming  to  a  resting  stage  or  condition  of 
equilibrium.  This  is  represented  according  to  Brown  and  Heron,*  and 
Brown  and  Morris  f  by  the  equation: 

10C12H20010     +     8H20      =      8C12H22On     +     2  C12H20O10. 

Starch  Maltose  Dextrin. 

Brown  and  Millar  {  in  a  later  research  show  that  the  dextrin  thus 
formed,  upon  prolonged  treatment  with  diastase,  breaks  up  into  glu- 
cose as  well  as  maltose,  and  to  explain  this  and  other  facts  give  the 
equation  : 


100  (Ci2H2oOio)  +  81  H20    =    80  Ci2H22On  +  (C6H1005)39  •  C6H1206. 

Starch  Maltose  Dextrin. 

In  other  words  100  parts  of  starch  yield  84.44  per  cent  of  maltose. 
In  this  connection  it  is  interesting  to  note  that  Sherman  and  Kendall  § 
found  with  pancreatin  a  tendency  to  equilibrium  when  the  weight  of 
maltose  reached  about  85  per  cent  of  the  initial  weight  of  starch. 

Starch  according  to  Brown  and  Millar  ||  has  a  molecular  weight  of 

*  J.  Chem.  Soc.  Trans.  (1879),  35,  596. 
t  J.  Chem.  Soc.  Trans.  (1885),  47,  527. 
}  J.  Chem.  Soc.  Trans.  (1899),  75,  333. 
§  J.  Am.  Chem.  Soc.,  32,  1087. 
II  J.  Chem.  Soc.  Trans.  (1899),  75,  333. 


THE  DISACCHARIDES  687 

34,200  and  consists  of  four  similar  maltan  groups,  (Ci2H2oOi0)2o,  and  one 
dextran  group,  (C6Hi005)4o,  combined  in  the  following  arrangement: 


Upon  hydrolysis  with  diastase  the  dextran  complex  A  is  split  off, 
forming  the  stable  dextrin  39  (C6Hio05)  •  C6Hi2O6,  which  undergoes  no 
further  change  under  the  ordinary  conditions  of  conversion.  The 
maltan  complexes,  B,  on  the  other  hand,  are  decomposed  at  the  O  linkages 
which  join  the  Ci2-groups  and  give  rise,  as  the  hydrolysis  proceeds,  to  a 
series  of  maltodextrins  of  diminishing  molecular  weight  with  maltose 
as  the  final  end  product. 

The  above  formula  for  starch  and  the  theory  of  its  conversion  by 
diastase  require,  however,  much  additional  confirmation  before  final 
acceptance.  The  example  serves,  however,  as  a  good  illustration  of  the 
complex  problems  which  are  involved. 

Theory  of  Maquenne  and  Roux.  —  According  to  the  recent  con- 
clusions of  Maquenne  and  Roux  *  starch  is  to  be  regarded  not  as  a  com- 
*  Ann.  chim.  phys.,  9,  179. 


688  SUGAR  ANALYSIS 

pound  but  as  a  mixture  of  amylocellulose,  or  amylose,  and  amylopectin. 
The  following  conclusions  are  taken  from  the  work  of  these  authors: 

Amylocellulose  is  identical  with  the  granulose  or  soluble  amylose  of 
previous  writers,  and  constitutes  80  per  cent  to  85  per  cent  of  natural 
starch  grains.  Under  amyloses  are  comprised  those  substances  which 
are  colored  blue  by  iodine,  are  perfectly  soluble  in  potash  solution  or 
superheated  water  and  are  saccharified  without  producing  residual 
dextrins.  The  less  condensed  amyloses  form  the  different  soluble 
starches;  the  more  highly  condensed  members  are  not  soluble  in  the 
pure  state  except  under  pressure,  at  150°  to  155°  C.,  but  they  form  with 
the  lower  members  eutectic  mixtures,  perfectly  soluble  in  boiling  water. 
The  transformation  of  a  lower  amylose  into  a  higher,  less  soluble  homo- 
logue  does  not  appear  to  take  place  outside  the  living  cell.  Amylose 
can  assume  at  the  same  temperature  two  distinct  forms;  a  soluble  form 
immediately  saccharified  and  colored  by  iodine,  and  a  solid  form  which 
resists  malt  and  gives  no  reaction  with  iodine.  The  latter  is  perhaps  a 
polymeric  form  of  the  first.  Solutions  of  amylose  give  with  iodine  a 
coloration  about  one-fourth  more  intense  than  those  of  natural  starch. 
Starch  grains  are  colored  with  iodine  because  a  part  of  its  amylose  ex- 
ists as  a  solid  solution.  Starch  paste  may  retrograde,  owing  to  the 
crystallization  of  amylose  which  the  fresh  paste  holds  in  solution.  By 
means  of  this  property  the  crude  amylose  may  be  purified,  and  obtained 
in  grains  which  resemble  the  original  starch  in  microscopic  appearance. 
Besides  amylose,  natural  starch  contains  15  to  20  per  cent  of  a  mucilagi- 
nous substance,  amylopectin,  which  differs  from  amylose  by  swelling  up 
without  dissolving  in  boiling  water  or  alkaline  solutions,  by  being  only 
very  slowly  saccharified  by  ordinary  diastase  and  by  giving  no  reaction 
with  iodine.  Starch  paste  is  simply  a  perfect  solution  of  amylose, 
rendered  viscous  by  amylopectin.  The  saccharification  of  starch  paste 
proceeds  in  two  successive  phases,  a  rapid  phase  of  a  few  hours  and  a 
slower  phase  which  lasts  several  days.  The  saccharification  of  the 
amylose  makes  up  the  rapid  phase.  The  so-called  residual  dextrins, 
which  accompany  maltose  in  those  worts  which  are  imperfectly  sac- 
charified, result  from  the  liquefaction  and  incomplete  hydrolysis  of  the 
amylopectin.  Malt  extract  is  susceptible  to  auto-excitation  as  a  prob- 
able result  of  the  proteolysis  of  its  albuminoids;  this  excitation  is  ob- 
served at  all  temperatures  at  which  the  amylase  may  exist  undestroyed, 
and  is  always  accompanied  by  a  partial  coagulation.  Acids  stimulate- 
the  activity  of  malt  by  producing  the  same  condition  of  equilibrium 
which  results  from  auto-excitation.  Their  effect,  however,  is  generally 
less  favorable  than  that  of  the  latter,  since  the  stability  of  the  amylase 


THE  DISACCHARIDES 


689 


is  diminished.  Diastatic  saccharification,  to  obtain  a  maximum  effect, 
should  be  carried  out  in  an  alkaline  medium.  The  optimum  is  obtained 
by  first  neutralizing  the  paste  and  then  adding  to  the  malt  solution 
enough  sulphuric  acid  to  neutralize  from  one-third  to  one-half  the  alka- 
linity present,  using  methyl  orange  as  indicator.  The  second  or  slow 
phase  of  ordinary  saccharification  corresponds  to  the  hydrolysis  of  the 
residual  dextrins  (amylopectin)  by  means  of  a  special  diastase  (dex- 
trinase)  formed  during  the  auto-excitation  of  the  malt. 

The  following  results  by  Maquenne  and  Roux  show  the  action  of 
malt  extract  at  50°  C.  upon  starch  paste  and  upon  a  solution  of  amylose: 


Time. 

Percentage  of  maltose  on  origi- 
nal starch  substance. 

Time. 

Percentage  of  maltose  on  origi- 
nal starch  substance. 

Starch  paste. 

Amylose. 

Starch  paste. 

Amylose. 

5  minutes 
15  minutes 
30  minutes 
45  minutes 
1  hour 

Per  cent. 
66.7 
74.9 

76.9 

Per  cent. 

94.4 
98.1 
99.7 
99.6 
99.7 

1.5  hours 
2      hours 
2  .  5  hours 
3      hours 
28      hours 

Per  cent. 

"si.i" 

Per  cent. 
100.0 
100.1 
100.0 
101.4 
104.2 

82.0 
91.8 

79.0 

It  is  seen  that  the  yield  of  maltose  from  amylose  is  almost  the  theo- 
retical (105.5  per  cent).  The  apparent  halt  in  the  reaction  with  starch 
paste,  when  about  80  per  cent  maltose  is  formed,  is  the  same  as  that  in- 
dicated by  Brown  and  Morris,  and  is  explained  by  Maquenne  and 
Roux  on  the  assumption  that  the  saccharification  of  the  amylose  is 
then  nearly  complete. 

The  numerous  other  hypotheses  which  have  been  proposed  to  ex- 
plain the  saccharification  of  starch  with  malt  extract  show  the  same 
divergence  of  opinion  as  exists  between  the  views  of  Brown  and  Millar, 
and  of  Maquenne  and  Roux.  The  only  points  of  general  agreement 
are  that  the  principal  products  of  conversion  by  diastase  are  maltose 
and  dextrin,  and  that  this  residual  dextrin  by  a  process  of  slow  hydroly- 
sis is  also  eventually  converted  into  maltose. 

While  starch,  under  special  methods  of  preparation,  suitable  con- 
ditions of  temperature,  proper  activation  of  diastase  and  sufficient  in- 
terval of  time,  may  undergo  an  apparent  complete  conversion  into 
maltose,  the  question  is  still  open  whether  the  final  product  of  such 
conversion  is  pure  maltose  or  a  mixture,  consisting  largely  of  maltose 
with  a  certain  amount  of  isomaltose,  glucose  and  dextrin,  whose  com- 
bined rotations  and  reducing  powers  agree  closely  with  those  of  maltose. 
It  is  not  surprising,  therefore,  when  the  mixed  character  of  the  enzymes 


690 


SUGAR  ANALYSIS 


in  malt  diastase  and  the  complexity  of  the  various  reactions  are  con- 
sidered, that  the  efforts  to  establish  a  simple  law  of  mass  action  for 
starch  conversion,  such  as  that  observed  for  the  inversion  of  sucrose, 
should  have  met  with  failure.  The  fact  that  the  starches  of  different 
vegetable  origin  have  in  all  probability  a  different  molecular  structure 
still  further  complicates  the  problem. 

Influence  of  Temperature  upon  Diastatic  Conversion.  —  The 
optimum  temperature  for  saccharification  of  starch  by  malt  diastase 
is  about  45°  C.,  although  the  point  of  maximum  conversion  may  lie 
considerably  above  or  below  45°  C.,  according  to  conditions.  Diastase 
solutions  undergo  a  great  reduction  in  activity  upon  warming  above 
60°  to  65°  C.;  above  75°  C.  the  saccharifying  power  is  completely  de- 
stroyed. 

Effect  of  Mashing  at  High  and  Low  Temperature.  —  The  effect  of  tem- 
perature upon  the  different  enzymes  of  malt  extract  is  variable.  Malt 
extract,  which  has  been  heated  to  75°  C.  and  which  has  thus  lost  its 
saccharifying  power,  still  liquefies  starch  as  strongly  as  ever,  converting 
it  almost  quantitatively  into  dextrin.  The  optimum  temperature  for 
the  liquefying  and  dextrin-forming  enzymes  of  malt  extract  lies,  in  fact, 
between  70°  and  75°  C.  It  is  evident,  therefore,  that  the  yield  of 
maltose  and  dextrin  from  starch  can  be  controlled  to  a  considerable 
extent  by  the  temperature  of  conversion,  and  this  fact  is  utilized  in 
the  technical  operations  of  brewing.  Mashing  at  70°  C.  will  produce 
more  dextrin,  and  hence  give  a  beverage  of  greater  body  (solid  content), 
than  mashing  at  45°  C.  Mashing  at  45°  C.,  on  the  other  hand,  will 
produce  more  maltose  and  hence  give  a  beverage  of  higher  alcohol  con- 
tent than  mashing  at  70°  C.  The  composition  of  worts  by  the  high  and 
low  temperature  methods  of  mashing  is  given  in  the  following  table:* 


Character  of  Wort. 

Wort  No.  1  (low  temperature). 

1  hour  at  45°  C. 
20  min.  at  45°-80°  C. 
25  min.  at  80°  C. 

Wort  No.  2  (high  temperature). 

10  min.  at  60°-80°  C. 
25  min.  at  80°  C. 

Maltose. 

Dextrin. 

Maltose. 

Dextrin. 

Grams  in  100  c.c.  of  wort  
Per  cent  in  dry  extract  

8.93 
70.39 

2.17 
17.00 

7.25 
58.34 

3.14 
25.30 

Restriction  of  Malt  Extract.  —  Ling  and  Davis  f  found  that  when 
malt  extract  is  heated  above  55°  C.  not  only  does  the  saccharifying 

*  F.  Fischer's  "  Handbuch  der  chem.  Technologie  "  (1902),  II,  337-8. 
t  J.  Fed.  Inst.  Brewing,  8,  475  (1902). 


THE  DISACCHARIDES  691 

power  undergo  a  decrease  but  glucose  begins  to  be  formed  as  one 
of  the  products  of  conversion.  Malt  extracts  whose  saccharifying 
power  has  been  weakened  by  heating  are  said  to  be  restricted;  the 
maximum  yield  of  glucose  (12  per  cent  of  total  conversion  products)  is 
obtained  by  malt  extracts  which  have  been  heated  at  68°  to  70°  C.  for 
15  to  30  minutes.  Ling  and  Davis  explain  the  phenomena  of  restriction 
by  assuming  that  an  alteration  has  been  produced  in  the  enzyme 
molecule  so  that  glucose  becomes  the  end  product  of  conversion  in- 
stead of  maltose.  Prior,*  however,  explains  the  facts  by  assuming 
that  a  glucose-forming  enzyme  (amyloglucase)  exists  in  malt  extract  and 
is  more  resistant  to  heat  than  the  amylomaltase. 

The  presence  of  glucose  in  malt  sirups  was  at  one  time  regarded  as 
an  evidence  of  adulteration  with  commercial  dextrose  or  glucose  sirup. 
Perfectly  pure  malt  sirupsf  may  contain,  however,  several  per  cent  of 
glucose  if  the  diastase  of  the  malt  has  undergone  restriction.  A  large 
amount  of  glucose  may  also  be  derived  from  the  malt  itself,  as  shown 
by  the  analysis  of  cold  water  extracts  (see  table,  page  511). 

Influence  of  Acids,  Alkalies,  Salts,  Etc.,  Upon  Amylolytic  Action. — 
The  addition  of  acids  in  minute  amounts  accelerates  the  activity  of 
malt  diastase;  in  larger  amounts  acids  have  a  marked  retarding  in- 
fluence upon  the  enzyme,  the  degree  of  retardation  following  apparently 
the  same  rule  noted  lor  invertase  and  being  proportional  to  the  con- 
centration of  hydrogen  ions. 

Alkalies  and  alkaline-reacting  salts  are  very  injurious  to  the  action 
of  malt  diastase  if  present  beyond  the  merest  trace.  A  perfectly  neu- 
tral medium  is  believed  by  some  to  be  the  most  favorable  for  diastatic 
action,  while  others  maintain  that  the  reaction  should  be  slightly  acid 
or  even  faintly  alkaline.  The  explanation  of  these  differences  of 
opinion  is  probably  the  same  as  that  given  by  Sherman  and  Kendall 
for  pancreatin  (p.  694). 

Small  amounts  of  the  neutral  salts  of  the  alkalies  and  alkaline  earths 
(chlorides,  sulphates,  phosphates,  etc.),  usually  accelerate  the  activity 
of  malt  diastase,  frequently  to  a  very  marked  degree.  Calcium  and 
barium  chlorides  seem,  however,  to  have  a  retarding  influence.  Addi- 
tion of  sulphates  or  of  salts  of  the  heavy  metals  in  large  amounts  check 
the  activity  of  the  enzyme,  owing  probably  to  precipitation.  Traces  of 
silver  nitrate  or  of  mercuric  chloride  destroy  diastatic  action  completely. 

Of  organic  substances  albumin  and  asparagine  seem  to  favor  dia- 
static action.  Alcohol  in  slight  amounts  exerts  no  appreciable  influence; 

*  Wochenschr.  f.  Brauerei,  21,  349  (1904). 
t  Long  and  Rendle,  Analyst  (1904). 


692  SUGAR  ANALYSIS 

in  larger  quantities,  however,  the  activity  of  the  enzyme  is  reduced, 
owing  to  destruction  or  precipitation .  Formaldehyde  in  amounts  exceed- 
ing 0.005  per  cent  has  a  marked  retarding  influence. 

The  destructive  action  of  heat,  acids,  alkalies,  salts,  alcohol,  etc., 
upon  diastase  is  considerably  reduced,  if  starch  or  its  conversion  prod- 
ucts, maltose  and  dextrin,  are  present;  the  protective  action  of  these 
substances  is  similar  to  that  noted  for  sucrose  and  fructose  upon  in- 
vertase  (p.  675). 

Action  of  Other  Amylases.  —  As  to  the  action  upon  starch  of 
other  diastases  than  those  of  malt,  mention  will  be  made  only  of  taka- 
diastase  and  of  the  animal  amylases  ptyalin  and  pancreatin. 

Takadiastase,  the  best  known  example  of  a  fungus  diastase,  has 
been  employed  in  Japan  for  an  unknown  period  of  time  in  saccharify- 
ing starchy  materials  for  the  production  of  alcoholic  beverages.  The 
enzyme  has  been  separated  by  Takamine*  and  is  now  a  standard 
pharmaceutical  preparation  for  the  relief  of  starch  indigestion.  The 
patented  process  of  Takamine  for  its  production  is  as  follows: 

Wheat  bran  is  steamed  and  then,  after  cooling,  sown  with  the  spores 
of  the  mould  Aspergillus  or y zee.  The  moist  bran  is  kept  at  a  tem- 
perature of  about  25°  C.;  in  about  24  hours  the  spores  have  germinated 
and  the  growth  of  mycelium  becomes  visible;  after  about  48  hours, 
when  the  production  of  diastase  has  reached  its  maximum,  further 
growth  of  the  mould  is  checked  by  cooling.  The  material  in  this  con- 
dition, consisting  of  bran  felted  together  by  the  threads  of  mycelium, 
is  called  "taka-koji  "  in  Japan,  where  it  is  used  in  the  same  manner  as 
malt.  To  prepare  the  enzyme  " taka-koji"  is  extracted  with  water, 
the  aqueous  extract  concentrated  at  low  temperature,  and  then  treated 
with  an  excess  of  alcohol.  The  takadiastase,  which  is  precipitated,  is 
filtered  off,  pressed  and  carefully  dried;  the  enzyme  as  thus  prepared 
consists  of  a  white  powder,  easily  soluble  in  water,  and  has  a  very 
strong  converting  power. 

Stone  and  Wright  f  have  made  a  comparative  study  of  the  action 
of  a  pharmaceutical  preparation  of  takadiastase  at  40°  C.  and  of  a 
laboratory  preparation  of  malt  diastase  at  60°  C.  Following  the  con- 
version of  potato  starch  it  was  noted  that  the  takadiastase  was  more 
rapid  in  its  action  during  the  initial  conversion  than  malt  diastase, 
there  being  an  almost  immediate  change  from  the  typical  blue  of  the 
starch-iodine  compound  to  the  reddish  and  violet  tints.  "On  the 
other  hand  the  complete  conversion  of  the  starch  into  forms  which  no 

*  Am.  Jour.  Pharm.,  70,  No.  3;  J.  Soc.  Chem.  Ind.,  17,  No.  2. 
t  J.  Am.  Chem.  Soc.,  20,  639. 


THE  DISACCHARIDES  693 

longer  gave  color  reactions  with  iodine  was  effected  much  earlier  by 
the  malt  diastase."  The  same  results  were  obtained  when  the  sac- 
charification  was  followed  by  studying  the  decrease  in  specific  rotation 
and  the  increase  in  copper  reducing  power. 

The  results  of  the  work  of  Stone  and  Wright  show  that  for  a  given 
short  period  (15  minutes  to  2  hours)  the  saccharifying  power  of  the 
takadiastase  was  superior  to  that  of  the  malt-diastase  preparation,  but 
that  for  the  complete  saccharification  of  starch,  especially  in  cellular 
materials,  where  the  starch  granules  were  retained  and  not  readily 
brought  into  solution,  the  malt  diastase  was  more  effective;  the  cel- 
lular residues  after  7  hours'  digestion  with  takadiastase  at  40°  C.  still 
gave  the  iodine  reaction  when  observed  under  the  microscope,  while 
the  residues  after  7  hours'  digestion  with  malt  diastase  at  60°  C.  gave 
no  such  reaction.  These  results  were  obtained,  however,  with  only  one 
set  of  enzyme  preparations  and  under  only  one  set  of  conditions.  With 
different  enzyme  preparations,  and  other  conditions  of  temperature, 
activation,  etc.,  than  were  employed  by  Stone  and  Wright,  different  re- 
sults would  no  doubt  be  obtained. 

Ptyalin,  the  amylase  of  saliva,  plays  an  important  part  in  the  di- 
gestion of  starchy  foods;  it  occurs  most  abundantly  in  the  saliva  of 
herbivorous  animals.  Ptyalin  can  be  prepared  from  saliva  by  precipi- 
tating with  alcohol,  as  described  under  invertase  and  diastase.  The 
optimum  temperature  for  its  action  is  about  40°  C.,  at  which  point 
starch  paste  is  saccharified  almost  immediately.  Raw  starch  in  the 
process  of  mastication  is  also  quickly  converted  into  80  to  100  per  cent 
sugar.*  Ptyalin,  similar  to  diastase,  contains  several  enzymes,  a 
liquefying  enzyme,  an  amylomaltase,  an  amyloglucase,  etc.  In  some 
cases  the  product  of  conversion  seems  to  be  almost  pure  maltose;  in 
other  cases  a  mixture  of  maltose,  glucose  and  isomaltose  (?).  The  vari- 
ability of  its  action  is  no  doubt  due  to  differences  in  the  amount  of  the 
constituent  enzymes.  Minimal  quantities  of  acid  (under  0.002  normal) 
accelerate  the  action  of  ptyalin;  large  amounts  of  acid  have  a  retarding 
influence.  Alkalies  and  alkaline  reacting  salts  are  depressing  in  their 
action.  The  chlorides,  sulphates,  etc.,  of  the  alkalies  also  retard  the 
activity  of  ptyalin  if  present  in  large  amounts. 

Pancreatin,  the  amylase  of  the  pancreatic  juice,  has  recently  been 
subjected  to  a  careful  study  by  Sherman  f  and  his  co workers  and  the 
following  facts  are  cited  from  their  work. 

Commercial  pancreatin,  which  had  been  freed  from  accompanying 

*  Miiller,  Chem.  Centralbl.  (1901),  637. 

t  J.  Am.  Chem.  Soc.,  32,  1073,  1087;  33,  1195. 


694 


SUGAR  ANALYSIS 


salts  by  dialysis,  was  without  action  upon  dialyzed  soluble  starch. 
When,  however,  a  neutral  salt  was  added  the  enzyme  was  activated  as 
shown  in  the  following  experiment: 

0.35  mg.  pancreatin  in  50  c.c.  of  1  per  cent  dialyzed  starch  at  40°  C. 
for  1  hour  showed  for  various  additions  of  salt  the  following  activities, 
expressed  by  weights  of  reduced  cuprous  oxide  obtained  upon  heating 
with  Fehling's  solution: 

Sodium  chloride,  mgs.  0.01  0.1  1.0  10  30  60  90  121 
Cuprous  oxide,  mgs.  0  10  51  87  91  86  85  85 

Experiments  with  potassium  and  ammonium  chlorides  gave  similar 
results.  The  presence  of  salts  are,  therefore,  not  only  helpful  but  are 
essential  to  the  action  of  the  enzyme. 

Excess  of  acid  or  alkali  destroys  the  activity  of  pancreatin.  The 
influence  of  acid  and  alkalies  in  minimal  amounts  is  given  in  the  follow- 
ing table  which  shows  the  action  of  0.125  mg.  pancreatin  upon  0.25  gm. 
soluble  starch  at  40°  C.,  sufficient  NaCl  being  added  to  activate  the 
enzyme.  Results  are  given  as  milligrams  of  reduced  cuprous  oxide. 

TABLE  C 

Conversion  of  Starch  by  Pancreatin 
(Effect  of  Added  Acid  and  Alkali  on  Solutions  Containing  Neutral  Electrolyte) 


Time. 

10  min. 

30  min. 

1  hr. 

2hrs. 

3hre. 

5hrs. 

25  hrs. 

8  c.c.  1 

0 

6  c.c. 

0 

4  c.c.    ! 

•0.01  normal  sulphuric  acid 

3 

7 

3  c.c.    f 

per  100  c.c. 

87 

151 

222 

277 

2  c.c. 

153 

218 

251 

272 

1  c.c.  J 

223 

242 

254 

271 

Neutral 

227 

243 

254 

270 

1  c.c.   1 



143 

207 

235 

240 

252 

2  c.c. 
3  c.c. 
4  c.c. 

156 
124 

204 
191 

226 
214 
200 

222 

244 
241 

250 
244 
239 

256 

6  c.c. 

0.01  normal  sodium  hy- 

154 

196 

232 

250 

8  c.c. 

droxide  per  100  c.c. 

124 

186 

227 

250 

20  c.c. 

19 

40 

163 

30  c.c. 

11 

18 

40 

40  c.c. 

3 

9 

11 

50  c.c.  , 

o 

4 

6 

It  is  seen  that  the  highest  degree  of  saccharification  is  obtained  in 
faintly  acid  solution  at  the  end  of  25  hours;  on  the  other  hand  the  con- 
version during  the  first  hour  is  more  rapid  in  faintly  alkaline  solution. 
The  influence  of  alkalies  seems  to  depend  upon  the  initial  concentra- 


THE  DISACCHARIDES 


695 


tion  of  starch,  the  effect  at  first  being  to  accelerate,  and  then,  as  the 
starch  is  changed,  to  retard  the  speed  of  saccharification.  For  a  short 
period  of  time  an  alkaline  (and  for  a  long  period  of  time  an  acid)  re- 
action gives  the  maximum  yield  of  maltose.  This  is  no  doubt  one  ex- 
planation for  the  variable  conditions  reported  by  different  investigators 
for  the  optimum  conversion  of  starch  by  pancreatin  and  other  amylases. 


•o  w 
0180 

03 

l80 


a 

2120 


100 

s 

80 


20 


10 


40 


50          60          70 
Minutes.     • 


'JO 


100 


110       120 


Fig.  199.  — Time  curves  showing  effect  of  concentration  of  soluble  starch  upon  the 
rate  of  conversion  by  pancreatin.  .A,  curve  for  0.5  per  cent;  B,  curve  for  2.0  per 
cent;  and  C,  curve  for  4.0  per  cent  starch  solution.  (Sherman  and  Kendall.) 

The  effect  of  concentration  of  starch  upon  the  rate  of  conversion  by 
pancreatin  is  shown  in  Fig.  199.  A  constant  quantity  of  enzyme  was 
allowed  to  act  upon  starch  solutions  of  0.5  per  cent,  2.0  per  cent  and 
4.0  per  cent  strength. 

It  is  seen  that  the  initial  speed  of  conversion  for  a  constant  amount 
of  enzyme  is  the  same  for  the  different  concentrations,  but  that  this 
speed  diminishes  more  rapidly  the  smaller  the  initial  concentration  of 
starch.  With  increasing  concentration  of  starch  the  time  curves  ap- 
proach a  straight  line. 

The  effect  of  temperature  upon  the  activity  of  pancreatin  is  shown 


696 


SUGAR  ANALYSIS 


in  the  following  table:  0.5  mg.  of  enzyme  was  allowed  to  act  upon 
100  c.c.  of  starch  solution  for  1  hour,  in  presence  of  a  sufficient  amount 
of  activating  salts. 


Temperature. 

Cuprous  oxide. 

Temperature. 

Cuprous  oxide. 

Deg.  C. 

Mgs. 

Deg.  C. 

Mgs. 

21 

65 

50 

345 

30 

122 

55 

378 

40 

238 

60 

256 

45 

298 

65 

66 

"  Between  20°  C.  and  40°  C.  the  speed  is  about  doubled  every  10°  C., 
in  accordance  with  van't  Hoff  s  rule  for  normal  chemical  reactions;  be- 
tween 40°  C.  and  55°  C.  the  acceleration  is  less,  but  temperature  still 
has  a  great  effect.  Beyond  55°  C.,  where  the  maximum  activity  was 
obtained,  the  rate  of  change  decreases  very  rapidly."  When  no  ac- 
tivating salts  are  present  increase  of  temperature  above  20°  C.  de- 
presses the  activity  of  pancreatin  and  this  "  may  be  due  to  the  fact 
that  water  itself  has  a  greater  paralyzing  effect  at  the  higher  tempera- 
ture." "  Pure  water,  acting  on  pancreatic  amylase  free  from  neutral 
electrolyte,  gradually  destroys  it,  but  if  a  trace  of  salt  and  alkali  are 
present  it  will  remain  active  for  a  long  time." 

The  saccharincation  of  starch  with  pancreatin  is 'not  usually  com- 
plete. Sherman  and  Kendall*  found  that  "working  with  1  per  cent 
starch,  however  favorable  the  conditions  of  salt  and  alkalinity,  and 
however  large  the  amount  of  enzyme,  the  hydrolysis  tended  to  come  to 
equilibrium  when  the  weight  of  maltose  reached  about  85  per  cent  of 
the  initial  weight  of  starch.". 

Converting  Power  of  Amylases  of  High  Activity.  —  Sherman  and 
Schlesingerf  found  by  extracting  dry  commercial  pancreatin  with  50 
per  cent  alcohol,  precipitating  the  amylase  with  absolute  alcohol  or 
alcohol-ether,  redissolving  in  50  per  cent  alcohol,  dialyzing  against  50 
per  cent  alcohol  in  presence  of  maltose  (to  protect  the  enzyme  against 
deterioration)  and  then  reprecipitating,  that  a  very  pure  amylase  re- 
sulted which  had  a  diastatic  power  at  40°  C.  of  3480  on  Sherman's 
scale,  corresponding  to  over  5000  on  Lintner's  scale  or  to  D&  =  500,000 
on  Wohlgemuth's  scale.  This  preparation  acting  at  40°  C.  on  soluble 
starch  formed  6000  times  its  weight  of  maltose  in  20  minutes  and 
211,000  times  its  weight  in  30  hours.  It  digested  400,000  times  its 
weight  of  starch  to  the  "  erythrodextrin  stage  "  in  less  than  22  hours, 
and  to  products  giving  no  reaction  with  iodine  in  48  hours." 

*  J.  Am.  Chem.  Soc.,  32,  1087.  f  J.  Am.  Chem.  Soc.,  33,  1195. 


THE  DISACCHARIDES  697 


CONVERSION    OF   STARCH   BY   ACIDS 

When  starch  is  heated  with  acids  it  is  converted  into  glucose  ac- 
cording to  the  equation: 

(C6HioOB)n  +  nH2O  =  nC6H12O6. 

Starch  d-Glucose. 

With  strong  acids  the  conversion  may  be  made  in  dilute  solution  at 
100°  C.;  with  weak  acids  it  is  necessary  to  employ  a  higher  concentra- 
tion of  acid  and,  in  certain  cases,  to  conduct  the  hydrolysis  under 
pressure  at  temperatures  considerably  above  100°  C.  in  order  to  secure 
complete  conversion  into  glucose. 

While  the  acid  conversion  of  starch  in  its  final  phase  proceeds  very 
closely  according  to  the  above  equation,  the  different  stages  of  the  con- 
version, as  starch  to  dextrin,  dextrin  to  maltose,  maltose  to  glucose 
etc.,  present  the  same  complexities  and  uncertainties  observed  in  the 
conversion  by  diastase. 

Formation  of  Maltose  During  Acid  Conversion.  —  The  best  recog- 
nized products  of  the  incomplete  conversion  of  starch  by  acid  are  glu- 
cose and  dextrin.  The  occurrence  of  maltose  among  the  products  of 
incomplete  acid  conversion  has  been  a  subject  of  much  dispute;  many 
chemists  hold  that,  while  maltose  exists  as  an  intermediate  product  in 
the  conversion,  it  is  hydrolyzed  into  glucose  almost  as  quickly  as  formed, 
and  that  the  apparent  values  found  for  the  specific  rotation  and  reduc- 
ing power  of  maltose  are  in  reality  only  the  values  for  mixtures  of  glu- 
cose and  dextrin.  Maltose  has  been  separated,  however,  as  its  osazone 
by  Rolfe  and  Haddock*  from  the  acid  conversion  products  of  starch 
and  its  presence  has  also  been  recognized  by  Sieben,t  Vogel,|  Weber 
and  MacPherson  §  and  other  investigators. 

Formation  of  Dextrins  and  Reversion  Products.  —  A  great  differ- 
ence of  opinion  also  exists  as  to  the  nature  of  the  dextrins  which  are 
formed  during  the  acid  conversion  of  starch.  Some  chemists  believe 
that  only  one  dextrin  (of  about  [a]D  +  200)  is  formed;  other  chemists, 
however,  hold  that  there  exists  a  series  of  dextrins  having  different 
rotations  and  reducing  powers  and  resembling  the  amylo-,  erythro-, 
achroo-  and  maltodextrins  of  diastatic  conversion.  An  additional 
complication  is  the  formation  of  reversion  products,  —  especially  when 
the  starch  is  hydrolyzed  by  more  concentrated  acid,  —  a  part  of  the 
glucose  being  recombined  to  form  isomaltose  and  different  synthetic 
dextrins. 

*  J.  Am.  Chem.  Soc.,  25,  1015.  t  Chem.  Ztg.,  19,  408. 

t  Z.  Ver.  Deut.  Zuckerind,  34,  837.  §  J.  Am.  Chem.  Soc.,  17,  312. 


698  SUGAR  ANALYSIS 

Manufacture  of  Commercial  Glucose  and  Dextrose.  —  The  acid 
conversion  of  starch  is  of  great  technical  importance,  being  used  in  the 
manufacture  of  starch  sirups  (commercial  glucose)  and  commercial 
dextrose  or  grape  sugar.  In  the  manufacture  of  glucose  sirups  starch 
(usually  corn  starch)  is  mixed  with  water  to  a  cream  of  about  20  degrees 
Be.  and  then  heated  with  about  0.06  per  cent  its  weight  of  hydrochloric 
acid  in  copper  converters  under  a  pressure  of  about  30  pounds.  The  con- 
version is  controlled  by  iodine  tests  and  requires  about  1  hour.  The 
liquid,  which  has  a  density  of  about  18  degrees  Be.,  is  then  neutralized 
with  sodium  carbonate,  filtered  through  bone  black  and  evaporated  in 
vacuum  pans  to  the  required  density,  which  varies  between  41  and  45 
degrees  Be.  according  to  the  demands  of  the  trade.  In  some  factories 
sulphuric  acid  is  used  as  the  hydrolyzing  agent,  in  which  case  calcium 
carbonate  is  used  for  neutralizing. 

In  the  manufacture  of  dextrose  or  grape  sugar,  a  much  larger 
amount  of  acid  is  used  for  conversion,  —  frequently  1  per  cent  or  more 
of  the  weight  of  starch,  —  and  the  heating  is  continued  until  all  dextrin 
is  hydrolyzed,  the  end  point  being  indicated  by  the  absence  of  a  precipi- 
tate when  a  little  of  the  solution  is  poured  into  strong  alcohol.  The 
liquid  is  then  neutralized,  filtered  through  bone  black,  evaporated  in 
vacuum  to  a  thick  sirup  and  poured  into  pans  or  moulds  where  it  is 
allowed  to  solidify;  the  contents  of  the  pans  are  usually  "  seeded  "  or 
primed  with  a  little  crystallized  dextrose  to  hasten  the  crystalliza- 
tion. 

Rolfe  *  Upon  the  Acid  Conversion  of  Starch.  —  The  progression  of  the 
hydrolysis  of  starch  by  means  of  acid  is  described  by  Rolfe  as  fol- 
lows: 

"  The  gradual  disintegration  of  the  starch  molecule  and  the  differ- 
ent stages  of  the  hydrolysis  of  the  products  of  this  disintegration  all 
go  on  at  the  same  time,  so  that  the  final  products  of  hydrolysis  are 
always  present  in  very  small  quantity  even  at  the  initial  stages  of  the 
hydrolysis.  The  progression  of  the  hydrolysis  manifests  itself  in  the 
following  characteristics:  The  starch  paste  gradually  loses  its  colloidal 
nature  and  passes  over  to  a  thin  sirup,  its  viscosity  continually  de- 
creasing. The  dissolved  carbohydrate  increases  in  weight  but  the 
density  effect  of  a  given  weight  of  carbohydrate  in  a  given  volume  of 
solution  continually  decreases.  The  specific  rotation  of  the  carbohy- 
drate, taken  as  a  whole,  likewise  decreases,  while  its  cupric-reducing 

*  Rolfe,  "The  Polariscope"  (1905),  p.  175.  See  also  the  paper  by  Rolfe  and 
Defren,  "An  Analytical  Investigation  of  the  Hydrolysis  of  Starch  by  Acids."  J.  Am. 
Chem.Soc.  18,  869. 


THE  DISACCHARIDES  699 

power  increases,  these  values  progressively  approaching  those  for 
dextrose. 

"  The  iodine  tests  are  also  characteristic;  a  few  drops  of  iodine  solu- 
tion giving,  with  the  hydrolyzed  solutions,  at  ordinary  temperature, 
colors  which  change  progressively  as  the  hydrolysis  proceeds  from  the 
deep  sapphire  blue  of  the  unchanged  starch,  first  to  violet  and  reddish 
purple,  then  to  a  rose  madder,  and  then  to  a  reddish  brown,  growing 
lighter  as  the  conversion  proceeds,  till  at  a  later  stage,  but  before 
hydrolysis  is  complete,  the  iodine  gives  no  color  reaction." 

Preparation  of  Maltose.  —  Maltose  is  best  prepared  by  the  follow- 
ing method  of  Herzfeld;*  500  gms.  of  starch  are  stirred  into  500  c.c.  of 
water  at  30°  C.,  4  liters  of  boiling  water  are  then  added  and  the  paste 
which  is  formed  cooled  to  60°  C.  Malt  extract,  prepared  by  digesting 
100  gms.  of  finely  ground  malt  with  500  c.c.  of  water  at  30°  to  40°  C., 
is  then  added  and  the  liquid  kept  at  60°  C.  for  2  hours.  The  solu- 
tion is  then  filtered,  evaporated  to  750  c.c.  and  87  per  cent  alcohol 
added  until  the  alcoholic  strength  of  the  solution  is  between  60  and  70 
per  cent.  After  standing  24  hours  in  a  closed  vessel,  the  alcoholic  solu- 
tion is  decanted  from  the  precipitated  dextrin;  the  alcohol  is  distilled  and 
the  solution  evaporated  to  a  thin  sirup.  The  latter  is  then  extracted 
with  1  liter  of  87  to  90  per  cent  alcohol,  by  boiling  with  successive 
portions  under  a  reflux  condenser.  The  combined  extracts,  containing 
the  maltose,  are  set  aside  in  a  closed  flask  for  24  hours,  filtered  from 
deposited  impurities,  evaporated  to  a  sirup  and  then  allowed  to  stand 
in  an  open  dish  at  20°  to  25°  C.  After  several  weeks'  standing  the 
maltose  will  crystallize  either  in  white  concretions  or  as  fine  microscopic 
needles.  If  the  sirup  be  spread  in  a  thin  layer,  and  then  primed  with  a 
few  crystals  of  maltose,  and  stirred  at  frequent  intervals,  crystalliza- 
tion will  be  complete  in  about  8  days.  The  crystalline  mass  is  then 
rubbed  to  a  paste  with  cold  methyl  alcohol,  pressed  between  filter 
paper  and  recrystallized  from  hot  methyl  alcohol,  using  bone  black. 

Properties  of  Maltose.  —  Maltose  as  ordinarily  prepared  is 
obtained  as  the  monohydrate  C^H^On  +  H20,  consisting  of  fine  pris- 
matic needles,  which  melt  upon  rapid  heating  at  about  100°  C.  The 
water  of  crystallization  is  removed  only  with  great  difficulty.  Upon 
heating  in  the  air  at  100°  to  110°  C.,  the  water  is  slowly  evolved,  but 
with  decomposition  of  the  sugar.  If  the  monohydrate  is  first  dried  over 
concentrated  sulphuric  acid  and  then  slowly  heated  up  to  90°  C.  over  a 
strong  dehydrating  agent  (as  phosphorus  pentoxide),  under  the  vacuum 
of  a  mercury  pump,  the  last  traces  of  water  are  finally  removed.  The 
*  Neue  Z.  Riibenzuckerind,  3,  150;  Ann.,  220,  200. 


700  SUGAR  ANALYSIS 

anhydrous  maltose,  as  thus  prepared,  consists  of  a  white  amorphous  mass 
and  is  extremely  hygroscopic,  absorbing  moisture  upon  exposure  to  the 
air  with  the  same  avidity  as  calcium  chloride. 

Specific  Rotation.  —  The  values  given  in  the  literature  for  [a]D  of 
maltose  range  from  +  136  to  +  150,  the  extreme  figures  being  due  no 
doubt  to  impure  preparations  of  sugar  contaminated  with  water  of 
hydration  or  with  higher  rotating  dextrins.  The  values  for  carefully 
crystallized  and  dehydrated  preparations  of  maltose  range  from  about 
+  137  to  +  139,  the  variations  in  this  instance  being  due  to  the  influ- 
ence of  temperature  and  concentration.  For  ordinary  purposes  the 
mean  value  +138  may  be  used.  The  general  equation  for  concentra- 
tion and  temperature  is  given  on  page  181. 

The  specific  rotation  of  maltose  hydrate  is  95  per  cent  of  that  for  the 
anhydride. 

Freshly  prepared  solutions  of  maltose  exhibit  mutarotation,  the 
initial  rotation,  however,  as  Dubrunfaut  first  observed,  being  less  than 
the  constant  value.  Parcus  and  Tollens*  found  for  1.9074  gms. 
of  maltose  anhydride  dissolved  to  20  c.c.  the  following  values: 

8  minutes  after  solution +  119.36 

15  minutes  after  solution -j-  121.01 

30  minutes  after  solution +  123.35 

1  hour  after  solution ' +  128.07 

2  hours  after  solution -j-  132.97 

5  hours  after  solution -j-  136.52 

24  hours  after  solution +  136.96 

Schulze  and  Tollens  f  noted  for  2  gms.  of  maltose  hydrate  dissolved 
to  20  c.c.  an  initial  rotation  of  +  95.83  and  a  constant  value  of  +  129.42. 
An  addition  of  a  trace  of  ammonia  destroys  the  mutarotation  and  gives 
the  constant  value  within  a  few  minutes.  As  first  shown  by  Brown 
and  Morris  {  maltose  at  the  moment  of  its  formation  from  starch  by 
means  of  diastase  exists  in  the  low  rotating  form. 

Reactions  of  Maltose.  —  Maltose  reduces  Fehling's  solution  about 
60  per  cent  as  strongly  as  d-glucose.  If  after  the  end  of  the  reduction 
the  solution  is  acidified  with  hydrochloric  acid  and  then  again  boiled 
with  Fehling's  solution,  a  second  quantity  of  copper  is  reduced,  in  about 
half  the  original  amount.  Maltose  is  distinguished  from  the  simple 
reducing  sugars  by  its  failure  to  reduce  Barfoed's  copper  acetate  solu- 
tion (p.  336). 

Oxidation  of  Maltose.  —  By  the  action  of  bromine  in  aqueous  solution 
maltose  is  oxidized  to  maltobionic  acid.     This  was  obtained  by  Fischer 
and  Meyer  §  as  a  sirup,  which  upon  boiling  with  5  per  cent  sulphuric 
*  Ann.,  257,  173.  J  Chem.  News,  71,  123. 

t  Ann.,  271,  219.  §  Ber.,  22,  1941. 


THE  DISACCHARIDES  701 

acid  was  hydrolyze'd  into  d-glucose  and  d-gluconic  acid.  This  re- 
action and  the  reducing  properties  of  maltose  indicate  that  one  of  the 
glucose  radicals  of  maltose  has  its  aldehyde  group  in  the  free  reactive 
condition.  The  oxidation  to  maltobionic  acid  is  shown  as  follows: 


C5H1oO5CH-0-C5H1oO4  •  CHO  +  O  =  CsHioOsCH-O-CsHmCX  -  COOH 

d-Glucose  d-Glucose  d-Glucose  d-Gluconic  acid 

radical  radical  radical  radical 


Maltose  Maltobionic  acid 

Oxidation  of  maltose  with  nitric  acid  gives  d-saccharic  acid. 

Action  of  Alkalies.  —  Maltose  upon  heating  with  dilute  alkalies  un- 
dergoes an  almost  complete  loss  of  optical  activity,  the  sugar  molecule 
undergoing  partial  hydrolysis  and  rearrangement*  with  formation  of 
d-glucose,  d-mannose  and  other  products  of  unknown  composition. 
Upon  warming  with  concentrated  alkalies  maltose  solutions  turn  dark 
brown,  the  maltose  being  broken  up  into  lower  decomposition  products 
among  which  lactic  acid  is  the  most  important.  The  lactic  acid  thus 
formed  consists,  according  to  Duclaux,f  of  a  mixture  of  d-  and  d,  1- 
lactic  acid,  and  under  favorable  conditions  may  equal  50  per  cent  of 
the  original  weight  of  maltose. 

Action  of  Acids.  —  Maltose  on  heating  with  2  to  3  per  cent  hydro- 
chloric or  sulphuric  acid  for  several  hours  upon  a  boiling  water  bath  is 
hydrolyzed  into  d-glucose. 

+  H2O  =  2 


Maltose  d-Glucose. 

The  hydrolysis  proceeds  much  more  slowly  than  the  inversion  of  su- 
crose and  the  yield  of  d-glucose  is  nearly  but  not  absolutely  quantita- 
tive, being  98  per  cent  to  99  per  cent  of  the  theoretical;  the  1  to  2  per 
cent  loss  is  due  to  destruction  of  sugar  with  formation  of  levulinic 
acid,  humus  substances,  reversion  products,  etc. 

The  hydrolysis  of  maltose  by  acids,  according  to  Sigmond,J  fol- 
lows Wilhelmy's  law  for  a  reaction  of  the  first  order,  the  velocity  con- 
stant k  increasing  with  concentration  and  rising  temperature.  W.  A. 
Noyes§  and  his  coworkers  found,  however,  that  the  values  for  k}  as 
determined  from  copper  reducing  power,  show  a  rapid  decrease  in  the 
later  stages  of  hydrolysis.  The  hydrolyzing  power  of  the  different 
acids  upon  maltose  follows  the  same  order  observed  by  Ostwald  for 
the  inversion  of  sucrose. 

Fermentation  of  Maltose.  —  In  so  far  as  the  various  yeasts, 
moulds  and  bacteria  secrete  the  enzyme  maltase  or  maltoglucase  they 

*  Rec.  trav.  Pays-Bas,  14,  156,  203.  t  Z.  physik.  Chem.,  27,  386. 

f  Chem.  Centralbl.  (1894),  169.  §  J.  Am.  Chem.  Soc.,  26,  266. 


702  SUGAR  ANALYSIS 

ferment  maltose  in  the  same  manner  as  d-glucose.  In  case,  however, 
the  organism  does  not  form  maltoglucase,  as,  for  example,  Sacchar- 
omyces  Marxianus,  maltose  is  not  fermented.  Maltoglucase  is  formed 
in  large  amount  by  many  varieties  of  yeasts,  a  classification  of  which 
is  given  in  Table  CII,  page  714. 

Ordinary  beer  yeast  is  especially  rich  in  maltoglucase  and  ferments 
maltose  with  the  same  ease  and  rapidity  as  d-glucose,  100  parts 
of  maltose  anhydride,  according  to  Jodlbauer,  yielding  51.08  per  cent 
alcohol,  49.04  per  cent  carbon  dioxide,  3.95  per  cent  succinic  acid  and 
glycerol  and  0.90  per  cent  of  other  products  —  a  total  of  105  per  cent, 
which  corresponds  to  the  theoretical  yield  of  d-glucose  from  maltose. 

Maltoglucase.  —  The  preparation  of  maltoglucase  presents  consider- 
ably more  difficulty  than  that  of  invertase  owing  to  the  greater  resist- 
ance of  the  enzyme  towards  extraction  and  its  greater  sensitiveness 
towards  antiseptic  agents.  According  to  Fischer  and  Lindner*  the 
enzyme  is  best  prepared  by  washing  the  yeast  with  water,  drying 
upon  an  unglazed  earthen-ware  plate  for  3  days  at  ordinary  tempera- 
ture, then  pulverizing  the  dried  yeast  in  a  porcelain  mortar  and  ex- 
tracting with  20  times  its  weight  of  water  for  20  hours  at  33°  C.  As 
antiseptic  agents  thymol  or  toluol f  are  less  injurious  than  chloroform. 
Maltoglucase  has  not  been  isolated  as  yet  in  the  pure  form;  its  solu- 
tions and  preparations  are  always  contaminated  by  other  enzymes, 
(invertase,  amylase,  etc.).  The  temperature  optimum  for  the  activity 
of  maltoglucase,  according  to  Lintner  and  Krober,J  is  about  40°  C. 

In  addition  to  yeast  different  varieties  of  Mucor,  Aspergillus,  Mo- 
nilia,  Torula,  as  well  as  various  Amylomyces,  form  maltoglucase  and 
ferment  maltose  with  production  of  alcohol. 

Maltoglucases  are  also  found  in  many  grains,  in  malt  and  in  most 
starchy  seeds  during  germination,  in  peas,  beets,  potatoes,  in  the  green 
leaves  of  many  plants  and  in  other  vegetable  organs;  the  enzyme 
occurs  mostly  associated  with  amylases.  The  same  association  also 
exists  in  the  animal  kingdom,  maltoglucases  being  found  in  saliva,  in 
pancreatic  juice  and  in  the  secretions  of  the  intestines,  liver,  etc. 

Maltose  is  fermented  by  nearly  all  the  lactic  and  butyric  acid  or- 
ganisms in  the  same  manner  as  d-glucose.  The  same  is  also  true  of 
most  oxidizing  fermentations.  Citromyces  Pfefferianus  yields  about  50 
per  cent  citric  acid  from  maltose,  Bad.  oxydans  produces  acetic  acid. 
Oxalic  acid,  butyl  and  other  alcohols  and  ethyl  acetate  are  among  the 
products  of  special  fermentations.  Leuconostoc  mesenterioides  produces 

*  Ber.,  28,  984.  t  Fischer,  Ber.,  28,  1429. 

t  Ber.,  28,  1050. 


THE  DISACCHARIDES  703 

lactic  acid  from  maltose  but  does  not  produce  dextran  as  is  the  case 
with  sucrose. 

Compounds  of  Maltose.  —  Maltose  contains  a  free  aldehyde  group 
and  the  sugar  is  consequently  much  more  reactive  than  sucrose,  form- 
ing methyl  and  ethyl  maltosides,  mercaptals,  ureides,  etc.,  in  the  same 
manner  as  the  simple  reducing  sugars.  In  the  same  way  maltose  re- 
acts with  phenylhydrazine  and  its  substituted  derivatives  forming  a 
large  number  of  hydrazones  and  osazones.  The  most  important  of 
the  latter  from  the  analytical  standpoint  is  maltose-phenylosazone, 
Ci2H2o09(N  •  NHCeH5)2,  which  is  formed  by  heating  maltose  solutions 
with  an  excess  of  phenylhydrazine  acetate  for  1  hour.  The  osazone, 
owing  to  its  solubility  in  hot  water,  does  not  crystallize  out  until  after 
cooling,  when  it  separates  in  the  form  of  fine  yellow  needles ;  the  com- 
pound after  recrystallizing  melts  upon  rapid  heating  at  206°  C.  with 
decomposition.  Maltose-phenylosazone  is  only  slightly  soluble  in 
cold  water,  is  soluble  in  75  parts  hot  water,  in  150  parts  hot  absolute 
alcohol,  but  is  insoluble  in  ether.  It  undergoes  decomposition  upon 
long  heating  with  boiling  water,  so  that  the  action  of  hot  solutions 
must  not  be  prolonged;  if  the  heating  is  continued  too  far  the  melting 
point  of  the  osazone  may  be  reduced  to  150°  C.  Maltosazones  of  low 
melting  point  are  also  obtained  when  the  reaction  is  carried  out  with 
too  little  phenylhydrazine  or  in  too  small  an  amount  of  water.  The 
melting  point  and  character  of  the  osazone  are  also  greatly  modified  by 
other  sugars  and  especially  by  the  different  dextrins  of  starch  conversion. 

Maltose  forms  with  acetic  anhydride  a  number  of  acetates  of 
which  the  octacetate,  CfcHi4(CjHjO)sQii,  is  the  most  characteristic; 
it  consists  of  white  crystals  with  bitter  taste,  melting  at  157°  to  159°  C., 
and  giving  in  benzol  solution  [0:]^  =  +76.54,  in  chloroform  [a]D  =  +61.01 
and  in  alcohol  [a]D  =  +  60.02. 

Maltose  forms  with  alkalies  and  alkaline  earths  a  series  of  malto- 
sates,  none  of  which,  however,  has  the  importance  of  the  corre- 
sponding sucrose  derivatives. 

Upon  treatment  with  hydrocyanic  acid  maltose  forms  a  nitrile  which 
yields  after  saponification  maltose  carboxylic  acid;  the  latter  consists  of  a 
colorless  sirup  and  gives  upon  hydrolysis  d-glucose  and  a-glucoheptonic 
acid.  The  reaction  is  expressed  as  follows: 

C5H1005CH-0-C6H1205COOH  +  H20  =  C6H12O6+  C6H13O6COOH. 

v v '  d-Glucose         a-Glucoheptonic  acid. 

Maltose  carboxylic  acid 

Tests.  —  Characteristic  qualitative  tests  for  maltose  in  presence 
of  other  sugars  are  lacking.  The  osazone  reaction  is  one  of  the  best 


704  SUGAR  ANALYSIS 

means  of  identification,  the  greater  solubility  of  maltosazone  affording 
an  easy  means  for  its  separation  from  the  less  soluble  osazones  of  other 
sugars;  the  influence  of  impurities  in  modifying  the  character  of 
maltosazone  must,  however,  always  be  borne  in  mind.  The  test  has 
been  modified  by  Grimbert*  by  treating  the  impure  maltosazone  with 
a  little  cold  aqueous  50  per  cent  acetone  and  filtering;  the  maltosazone 
separates  from  the  filtrate  in  pure  crystalline  form. 

The  inability  of  certain  yeasts^as  Saccharomyces  Marxianus  and 
yeast  No.  538  of  the  Berlin  Experimental  Brewery,  to  ferment  maltose 
is  another  means  of  separation  and  identification  which  may  be  em- 
ployed under  certain  conditions. 

Configuration.  —  The  configuration  of  maltose  has  not  been 
established  with  certainty.  The  following  provisional  formula  sug- 
gested by  Fischer  answers,  however,  to  most  of  the  chemical  properties 
and  reactions  of  maltose: 

H   H    OHH    H  H    H    H  OH  H 

HOH2C-C-C-C-C-C  -  O  -  C-C-C-C-C-CHO 

I      I      I       I      !  I       I      I      I      I 

OH      H     OH  H     OHOHH    OH 

I o 1 

Synthesis  of  Maltose.  —  Maltose  has  not  been  synthetized  as  yet 
with  certainty  by  purely  chemical  means.  The  synthesis,  however, 
seems  to  have  been  accomplished  by  the  action  of  certain  enzymes 
upon  glucose  in  concentrated  solution.  Croft  Hillf  was  the  first  to 
discover  the  synthetic  action  of  enzymes;  Hill  observed,  when  extract 
of  dried  yeast,  or  takadiastase,  was  placed  in  concentrated  glucose  solu- 
tions, that  a  disaccharide  sugar  was  formed.  This  sugar  he  believed 
at  first  to  be  maltose,  and  explained  its  formation  by  assuming  the 
action  of  the  enzyme  to  be  reversible.  Emmerling,J  however,  in  re- 
peating Hill's  work,  believed  the  disaccharide  to  be  Fischer's  isomaltose, 
and  the  same  conclusion  was  also  reached  by  E.  F.  Armstrong.  Hill  in 
a  later  work,  while  reaffirming  his  belief  in  the  formation  of  some  mal- 
tose, states  that  a  different  isomeric  sugar,  which  he  calls  revertose,  is  the 
main  product  of  the  condensation. 

Armstrong  Upon  Enzymic  Synthesis.  —  By  action  of  the  enzyme 
emulsin  upon  d-glucose  for  a  long  period  of  time  Armstrong§  observed 
the  formation  of  a  disaccharide  which  he  believed  to  be  mainly  maltose. 
Emulsin  itself  does  not  hydrolyze  maltose,  and,  according  to  Arm- 

*  J.  Pharm.  Chim.  [6],  17,  225. 
t  J.  Chem.  Soc.,  73,  634;  83,  578. 
j  Ber.,  34,  600,  2206,  3810. 
§  Proc.  Roy.  Soc.  (1905),  76  B,  592. 


THE  DISACCHARIDES  705 

strong,  in  enzymic  syntheses  an  isomeric  sugar  is  obtained  different 
from  the  one  which  the  enzyme  itself  hydrolyzes.     Thus: 

Sugar.  Enzyme.  Product  of 

reaction. 

1  maltose          +  maltoglucase      =  2  d-glucose 

2  d-glucose        -j-  —  1  isomaltose 

1  isomaltose      +  emulsin  =  2  d-glucose 

2  d-glucose        -j-  =1  maltose 

Armstrong  is  of  the  opinion  that  both  maltose  and  isomaltose  are 
formed  by  the  action  of  concentrated  hydrochloric  acid  upon  glucose  (see 
under  isomaltose).  The  products  of  this  condensation  after  neutraliza- 
tion were  treated  with  emulsin,  which  hydrolyzed  the  isomaltose,  and 
then  with  Saccharomyces  Marxianus,  which  fermented  the  glucose  but 
not  the  maltose.  The  disaccharide  remaining  in  solution  gave  an  osazone 
corresponding  to  that  of  maltose;  this  and  the  biological  behavior  of 
the  sugar  are  strong  indications  of  the  formation  of  maltose.  The 
question  must  be  regarded,  however,  as  unsettled  until  the  sugar  has 
been  actually  isolated  in  its  pure  crystalline  form. 

The  hydrolyzing  enzymes  undoubtedly  exercise  a  synthetic  action 
in  the  living  cell,  but  the  conditions  under  which  this  is  accomplished 
are  not  understood  sufficiently  as  yet  to  enable  the  chemist  to  control 
the  reaction  in  the  laboratory. 

ISOMALTOSE,  C^H^Ou.  —  No  other  sugar  has  given  rise  to  so 
much  difference  of  opinion  and  uncertainty  as  isomaltose,  a  circum- 
stance due  to  the  fact  that  the  so-called  isomaltoses  of  different  investi- 
gators are  in  all  probability  different  compounds.  The  name 
isomaltose  was  first  given  by  Fischer*  to  a  synthetic  disaccharide 
prepared  as  follows. 

Preparation.  —  One  hundred  grams  of  d-glucose  were  dissolved  in 
400  gms.  of  cold  fuming  hydrochloric  acid  and  the  solution  maintained 
for  15  hours  at  10°  to  15°  C.;  4  kgs.  of  absolute  alcohol  were  then  added, 
the  solution  filtered  from  precipitated  dextrins  (reversion  products)  and 
the  filtrate  treated  with  a  large  excess  of  ether.  The  precipitate  was 
filtered  off,  washed  with  alcohol  and  ether,  pressed  between  filter  paper, 
dissolved  in  a  little  water,  the  solution  carefully  neutralized  with  sodium 
carbonate,  any  alcohol  and  ether  expelled  by  gentle  warming  and  the  ex- 
cess of  d-glucose  removed  by  fermenting  with  yeast  at  30°  C.  The  un- 
fermented  residue  (30  to  35  gms.)  was  dissolved  in  about  150  c.c.  of 
water,  exactly  neutralized,  and  then  heated  with  a  solution  of  phenylhy- 
drazine  (30  gms.)  in  50  per  cent  acetic  acid  (20  gms.)  for  1|  hours  upon 
the  water  bath.  The  hot  solution  was  then  filtered  from  the  slight 

*  Ber.,  23,  3687. 


706  SUGAR  ANALYSIS 

deposit  of  d-glucose-osazone;  the  filtrate  upon  cooling  deposited  crystals 
of  isomaltose-osazone,  which  differed  from  maltose-osazone  by  its  greater 
solubility  in  water  and  by  its  lower  melting  point,  150°  C. 

Theories  Regarding  the  Formation  of  Isomaltose.  —  Armstrong, 
as  previously  mentioned,  believes  that  maltose,  as  well  as  isomaltose, 
is  formed  in  the  above  synthesis.  The  maltose  by  Fischer's  method  of 
purification  is  destroyed,  however,  by  the  action  of  the  yeast. 

Isomaltose  was  also  obtained  by  Scheibler  and  Mittelmeier*  by  the 
action  of  strong  acids  upon  starch,  the  glucose  which  is  first  formed 
being  afterwards  recondensed  to  form  isomaltose  and  other  reversion 
products.  The  isomaltose  thus  formed  is  no  doubt  similar  to  that  of 
Fischer. 

Isomaltose  is  also  believed  by  Lintner,f  Prior,  J  Albert  §  and  many 
other  investigators  to  be  formed  during  the  diastatic  conversion  of 
starch.  Opinions  differ,  however,  as  to  whether  this  isomaltose  is 
formed  before  or  after  maltose;  the  following  schemes  illustrate  a  few 
of  the  numerous  theories  which  have  been  proposed  in  this  connection: 

Starch  — •»  amylodextrin  — » isomaltose  — >  maltose. 

~  isomaltose  — >  maltose. 
Starch  — >  amylodextrin 

*  maltodextrin  — >  maltose. 
Starch  — •»  amylodextrin  .  .  .  — >  maltose  — >  d-glucose  — >  isomaltose. 

Lintner  and  Dull  ||  prepared  their  isomaltose  by  saccharifying  starch 
paste  with  malt  extract  at  70°  C.  The  solution  was  then  evaporated 
to  a  sirup,  treated  with  strong  alcohol,  filtered  from  precipitated  dextrin 
and  the  filtrate  evaporated  to  expel  alcohol;  the  d-glucose  and  maltose 
were  then  fermented  away  with  yeast,  the  solution  clarified  with  bone 
black,  evaporated  to  a  sirup,  treated  again  with  strong  alcohol  to 
precipitate  remaining  dextrins  and  the  filtrate  evaporated.  In  this 
manner  a  white  amorphous  hygroscopic  residue  was  obtained,  which 
corresponded  to  the  formula  and  molecular  weight  of  C^H^On  +  H20. 
The  substance  was  easily  soluble  in  water  and  80  per  cent  alcohol,  and 
showed  in  aqueous  solution  a  specific  rotation  of  [a]D  =  -+-  139  to  + 140. 
The  yield  of  isomaltose  by  this  method  was  about  20  per  cent  the 
weight  of  starch.  Lintner  and  Dull  believe  that  the  hydrolysis  of 
starch  consists  in  a  change  of  amylodextrin,  or  soluble  starch,  into 
lower  dextrins  which  are  then  transformed  into  isomaltose  and  the 
latter  in  turn  into  maltose. 

*  Ber.,  24,  301.  §  Chem.  Centralbl.  (1894),  1131. 

t  Chem.  Ztg.,  16,  15.  II  Ber.,  26,  2540. 

t  Z.  angew.  Chem.  (1892),  312,  872. 


THE  DISACCHARIDES  707 

Ling  and  Baker,*  repeating  the  work  of  Lintner  and  Dull,  obtained 
a  residue  which  gave  with  phenylhydrazine  a  mixture  of  osazones,  cor- 
responding to  d-glucose,  maltose  and  an  unknown  trisaccharide.  Ling 
and  Baker  also  showed  that  a  mixture  of  maltose  and  dextrin  gave  a 
crystallizable  osazone  which  resembled  in  every  way  the  so-called 
Isomaltose-osazone. 

Ost,|  Ulrich,|  Brown  and  Morris  §  and  rnany  other  investigators 
also  deny  the  formation  of  isomaltose  during  the  diastatic  conversion 
of  starch  and  claim  that  the  compound  so  designated  is  only  a  mixture 
of  maltose  with  different  dextrins.  Lintner  claims,  however,  that  the 
isomaltose  prepared  by  his  method,  although  not  absolutely  pure,  is 
sufficiently  so  to  justify  his  conclusions  as  to  its  formation. , 

The  views  of  Emmerling  and  Armstrong  regarding  the  formation  of 
isomaltose  by  action  of  maltoglucase  upon  glucose  have  already  been 
mentioned.  (See  page  704.) 

It  is  impossible  to  review  in  greater  detail  the  copious  literature 
upon  isomaltose.  No  two  authorities  hold  exactly  the  same  opinion 
and  the  case  is  only  an  additional  example  of  the  lack  of  knowledge 
which  still  prevails  regarding  the  different  stages  of  starch  conversion. 

Properties  of  Isomaltose.  —  Isomaltose,  as  prepared  by  different 
investigators  using  different  methods,  shows  certain  differences  in  physi- 
cal and  chemical  properties.  All  preparations  of  the  sugar  reduce 
Fehling's  solution,  Fischer's  isomaltose  having  a  reducing  power  66 
per  cent  and  Lintner's  80  per  cent  of  that  of  maltose.  All  prepara- 
tions of  the  sugar  upon  heating  with  acids  are  hydrolyzed  into  d-glucose. 
Fischer's  isomaltose  is  unfermented  by  yeast;  that  of  Lintner  in  pres- 
ence of  considerable  yeast  is  fermented  but  with  considerable  difficulty. 

Tests  for  Isomaltose.  —  The  osazone  test  for  isomaltose  is  regarded 
as  the  most  characteristic,  the  greater  solubility  and  lower  melting  point 
distinguishing  the  osazone  of  isomaltose  from  that  of  maltose.  The 
melting  point  of  Fischer's  isomaltose-osazone  on  rapid  heating  is  158°  C. 
Ost,  however,  gives  145°  C.  The  osazone  of  .Lintner's  isomaltose 
melts  between  145°  C.  and  155°  C.  The  osazone  of  both  Fischer's 
and  Lintner's  isomaltose  corresponds  to  the  formula  C24H32N40g. 

The  fact  that  maltose  in  presence  of  impurities  gives  an  osazone  of 
the  same  melting  point  greatly  lessens  the  value  of  the  osazone  test  for 
isomaltose.  || 

*  J.  Chem.  Soc.  Trans.  (1895),  43,  702,  739.          J  Chem.  Ztg.,  19,  1527. 
t  Chem.  Ztg.,  19,  1504;  20,  762.  §  Chem.  News,  72,  45. 

I!  For  fuller  accounts  of  both  maltose  and  isomaltose  see  Lippmann's  "  Chemie 
der  Zuckerarten"  and  Sykes  and  Ling's  "Principles  and  Practice  of  Brewing.? 


708 


SUGAR   ANALYSIS 


LACTOSE.  —  Milk  sugar. 


Lactobiose. 
HaOu  +  H20. 


Occurrence.  —  Lactose  is  a  sugar  of  distinctly  animal  origin,  no 
well-authenticated  evidence  as  yet  existing  of  its  occurrence  in  the 
vegetable  kingdom.  The  sugar  is  formed  in  the  lacteal  glands  of  all 
mammals  and  is  built  up  from  the  glucose  of  the  blood,  although  the 
manner  in  which  this  synthesis  takes  place  is  not  understood.  Lactose 
is  found  in  milk  in  amounts  varying  from  less  than  1  per  cent  to  over 
12  per  cent,  according  to  the  kind  of  animal,  period  of  lactation  and 
other  factors.  The  percentage  of  lactose  in  the  milk  of  different  animals 
is  given  in  the  following  table: 


Animal. 

Lactose. 

Animal. 

Lactose. 

Cow  

Per  cent. 
3.67-6.07 

Camel  

Per  cent. 
5.00-5.80 

Dog.  . 

0.98-3.85 

Ass  

5.29-7.63 

Pic 

1  59-3  84 

Reindeer 

2  61-3  02 

Goat  

3.26-6.65 

Buffalo  

4.16-5.34 

Sheep 

3  43-6  62 

Elephant  .  . 

7  27-7  39 

Horse  .  .  . 

4.72-7.32 

Woman 

4.00-8  30 

The  percentage  of  lactose  is  usually  less  in  colostrum  than  in  nor- 
mal milk.  Pfeiffer*  found  in  woman's  milk  just  after  birth  2.7  per 
cent  lactose,  at  the  end  of  one  week  4  per  cent,  after  2  weeks  4.8  per 
cent,  after  3  weeks  5.2  per  cent,  and  after  5  months  6.5  per  cent. 
Similar  changes  have  been  observed  in  the  case  of  the  cow  and  other 
animals. 

When  the  secretion  of  milk  is  interfered  with,  as  by  interruption  of 
nursing,  or  by  some  functional  disorder,  the  lactose  finds  its  way  from 
the  mammary  glands  into  the  blood  and  is  then  eliminated  in  the 
urine.  Even  in  healthy  cows,  just  prior  to  calving,  lactose  has  been 
found  in  the  urine  to  the  extent  of  0.5  per  cent. 

Preparation  of  Lactose.  —  Lactose  is  manufactured  commercially 
from  the  whey  of  cheese  factories.  The  curd,  which  is  precipitated 
from  milk  by  means  of  rennet,  and  which  contains  the  casein  and 
fat,  is  filtered  off  and  made  into  cheese.  The  filtrate  from  the  curd 
is  the  whey  and  contains  upon  the  average  about  93.50  per  cent  water, 
4.80  per  cent  lactose,  1.00  per  cent  proteids,  0.50  per  cent  ash  and 
0.20  per  cent  fat.  For  the  manufacture!  of  milk  sugar  the  whey  is 
heated  to  75°  to  85°  C.  and  then  treated  with  6  to  10  per  cent  of  milk 

*  Chem.  Ztg.  18,  1543. 

t  F.  Fischer's  "  Handbuch  der  chem.  Technologic  "  (1902),  II,  282. 


,    THE  DISACCHARIDES 


709 


of  lime  at  20  degrees  Be.  The  free  lactic  acid  is  thus  neutralized,  in- 
soluble calcium  phosphate  is  formed,  albuminoids  are  coagulated  and 
fat  and  other  suspended  impurities  mechanically  precipitated.  The  pre- 
cipitate is  filtered  off  and  the  filtrate  saturated  with  carbon  dioxide, 
filtered,  evaporated,  boiled  to  grain  and  centrifuged  in  the  same  manner 
as  for  beet  sugar  manufacture.  The  yield  of  crystallized  milk  sugar 
by  this  method  is  about  3.4  per  cent  of  the  whey. 

Properties  of  Lactose.  —  Milk  sugar,  as  ordinarily  prepared,  con- 
sists of  large  rhombic  hemihedral  crystals  corresponding  to  the  formula 
Ci2H220n  +  H20.  The  water  of  crystallization  is  given  up  with  con- 
siderable difficulty.  The  best  method  of  dehydration  is  to  precipi- 
tate a  hot  concentrated  aqueous  solution  with  5  volumes  of  absolute 
alcohol.  The  fine  crystalline  powder  thus  obtained  is  dried  first  at 
100°  C.,  and  then  at  127°  to  130°  C  ,  when  the  last  traces  of  water  are 
given  off  without  change  in  color  or  other  evidences  of  decomposition. 

Lactose  hydrate  is  soluble  in  5.87  parts  of  water  at  10°  G.  and  2.5 
parts  of  water  at  100°C.;  it  easily  forms  supersaturated  solutions. 
The  sugar  is  insoluble  in  absolute  ethyl  and  methyl  alcohols  and  in 
ether.  The  presence  of  free  alkali,  and  of  different  salts  of  the  alkalies, 
increases  the  solubility  of  lactose  in  much  the  same  manner  as  with 
sucrose. 

Lactose  hydrate  is  dextrorotatory,  [a]D  =  +  52.50  which  value  is 
practically  constant  for  concentrations  up  to  c  =  36.  The  influence 
of  temperature  upon  the  [a]D  of  lactose  has  already  been  referred  to. 

The  specific  rotation  of  lactose  anhydride  is +55. 3.  (The  same  value 
is  obtained  by  calculation  from  the  [a]D  of  the  hydrate,  +  52.50  X  ffrj.) 

Freshly  prepared  solutions  of  lactose  hydrate  exhibit  mutarotation. 
Tollens  and  Parcus*  found  for  a  solution  of  4.841  gms.  lactose  hydrate 
dissolved  to  100  c.c.  the  following  values: 


Time  after 
solution. 

Specific  rotation. 

Time  after  solu- 
tion. 

Specific  rotation. 

Minutes. 

8 
10 
20 
45 
60 

+82.91 
82.52 
79.69 
73.26 
70.04 

Hours. 
2 

4* 

6 
24  (constant) 

62.17 

54.32 
53.43 
52.53 

Upon  boiling  the  solution  or  adding  0.1  per  cent  ammonium  hydrox- 
ide the  mutarotation  is  destroyed  almost  'immediately.  Addition  of 
mineral  acids  accelerates  the  change  to  constant  rotation. 

*  Ann.,  267,  170. 


710  SUGAR  ANALYSIS 

Low-Rotating  Modification  of  Lactose.  —  Upon  rapidly  evaporating 
a  solution  of  2  to  3  gms.  of  ordinary  lactose  hydrate  in  10  c.c.  of  water 
in  a  platinum  dish  and  drying  the  residue  at  98°  C.,  Schmoger*  ob- 
tained a  form  of  lactose  which  showed  after  solution  a  rotation  of 
only  +  34.4  (calculated  to  Ci2H22Oii  +  H2O)  but  after  24  hours'  stand- 
ing increased  to  the  normal  constant  value  of  +52.5.  Erdmannf 
obtained  the  same  form  of  lactose  by  rapidly  boiling  down  a  solution 
of  lactose  hydrate  in  a  metal  dish  until  the  supersaturated  solution 
suddenly  solidified  to  a  porous  mass  of  small  water-free  crystals.  Tan- 
ret  t  obtained  the  low-rotating  milk  sugar  (his  so-called  7  modification) 
by  rapidly  evaporating  a  solution  of  ordinary  lactose  (Tanret's  so-called 
a  modification)  at  108°  C.,  drying  the  crystals  over  concentrated  sul- 
phuric acid,  dissolving  rapidly  in  3  parts  of  water  and  precipitating  at 
once  with  a  large  excess  of  alcohol.  This  process,  after  repeating  several 
times,  gives  the  pure  7  modification  in  the  form  of  water-free  crystals, 
soluble  in  2.2  parts  of  water  at  15°  C.,  which  solution,  however,  on 
standing  deposits  crystals  of  the  ordinary  hydrate.  Tanret's  7  milk 
sugar  5  minutes  after  solution  gave  [a]D  =  +  34.5,  which  value  slowly 
increased  upon  standing  to  that  of  constant  rotation.  The  change  was 
effected  immediately  by  adding  a  trace  of  alkali. 

Tanret's  ^-lactose.  —  Tanret  obtained  an  apparent  third  modifica- 
tion of  lactose  by  allowing  a  concentrated  solution  of  the  hydrate  to 
crystallize  at  exactly  85°  to  86°  C.,  or  by  treating  the  warm  solution 
with  3  to  4  times  its  amount  of  absolute  alcohol.  Crystals  were  ob- 
tained, corresponding  to  the  formula  C]2H22On  +  J  H2O,  which  gave 
immediately  after  solution  in  water  the  constant  rotation  +55.3 
(calculated  to  the  anhydride  Ci2H22On). 

Hudson  Upon  the  Modifications  of  Lactose.  —  Hudson  §  in  a  recent 
study  of  lactose  and  its  modifications  came  to  the  conclusion  that 
Tanret's  so-called  0  or  constant  rotating  lactose  was  not  a  definite  com- 
pound but  a  mechanical  mixture  of  the  high  and  low  rotating  forms. 
The  same  conclusion  was  arrived  at  by  Roux  ||  and  also  by  Trey-TT 
Hudson,  Roux,  and  Trey  all  confirm  the  earlier  observation  of  Erd~ 
mann  that  the  velocities  of  mutarotation  for  the  high  and  low  rotating 
forms  of  lactose  are  the  same  in  value,  and  draw  from  this  the  con- 
clusion that  the  two  changes  in  rotation  are  only  opposite  parts  of  one 
balanced  reaction,  which  in  its  ultimate  form  may  be  expressed  by  the 
equation  a-lactose  <=±  /3-lactose.  (The  symbol  (3  is  given  at  present  to 

*  Ber.,  13,  1915.  §  Z.  physik.  Chem.,  44,  487. 

t  Ber.,  13,  2180.  II  Ann.  chim.  phys.  [7],  30,  422  (1906). 

%  Bull.  soc.  chim.  [3],  13,  625.  IF  Z.  physik.  Chem.,  46,  620. 


THE  DISACCHARIDES 


711 


the  low  rotating  modifications  of  all  sugars  instead  of  7  as  first  used  by 
Tanret.)  This  identity  in  mutarotation  for  the  high  and  low  rotating 
forms  of  lactose  is  shown  by  the  following  results  of  Hudson :  * 

TABLE  CI 
Mutarotation  at  0°  C.  of  Lactose  Hydrate  and  fi-Lactose  Anhydride 


Time  in  hours. 

[a]D    calculated  for  C^H^Ou. 

Velocity  of  mutarot 

itinn     1  ln<r     r°~r°° 

{               r—  TOO 

Ordinary  lactose. 

/3-  Lactose. 

Ordinary  lactose. 

ft-  Lactose. 

0 
2 
4 
6 

8 
10 

GO 

+89.13 
+84.96 
+80.79 
+77.48 
+74.45 
+72.06 
+55.16 

+39.6 
+41.6 
+43.4 
+44.9 
+46.3 
+47.6 
+55.2 

0.0284 
0.0306 
0.0299 
0.0307 
0.0303 

0.0298 
0.0306 
0.0300 
0.0305 
0.0312 

The  anhydrous  low  rotating  /3-lactose  was  obtained  by  Hudson  in 
large  crystals  by  slowly  evaporating  a  solution  of  ordinary  lactose 
hydrate  at  from  95°  C.  to  100°  C.  The  transition  temperature  above 
which  the  /3-lactose  separates  was  found  by  Hudson f  to  be  93°  C.  These 
two  forms  of  lactose  differ  greatly  in  solubility  and  other  physical 
properties  as  well  as  in  optical  activity.  Thus  the  final  solubility  (cal- 
culated to  Ci2H22On)  in  water  at  0°  C.  was  found  by  Hudson  to  be 
10.6  per  cent  for  ordinary  lactose  and  42.9  per  cent  for  the  /3-lactose. 
The  much  greater  solubility  of  the  /3-lactose  has  rendered  this  form  of 
milk  sugar  especially  suitable  for  certain  medicinal  and  other  purposes. 

Reactions  of  Lactose.  —  Upon  heating  at  170°  to  180°  C.  lactose  is 
converted  into  lacto-caramel,  a  dark  brown  substance  which  resembles 
in  many  of  its  properties  the  caramel  of  sucrose. 

Lactose  reduces  Fehling's  solution  about  70  per  cent  as  strongly  as 
d-glucose.  If,  after  the  end  of  the  reduction,  the  solution  be  filtered 
from  cuprous  oxide,  the  filtrate  be  weakly  acidified  with  hydrochloric  acid 
and  again  boiled  with  Fehling's  solution,  a  second  quantity  of  copper  is 
reduced  t  and  in  about  one-half  the  original  amount.  The  cause  of  the 
phenomenon,  which  is  similar  to  that  noted  for  maltose,  has  not  been 
fully  explained.  Barfoed's  copper  acetate  solution  is  not  reduced  by 
lactose. 

By  action  of  sodium  amalgam  lactose  is  broken  up  and  reduced 
with  formation  of  mannite,  dulcite,  lactic  acid  and  other  decompo- 
sition products. 

*  J.  Am.  Chem.  Soc.,  26,  1065.  t  J-  Am.  Chem.  Soc.,  30,  1767. 

J  Herzfeld,  Ann.,  220,  200. 


712  SUGAR  ANALYSIS 

By  action  of  bromine  in  aqueous  solution  lactose  is  oxidized  to  lacto- 
bionic  acid.  The  latter  was  first  obtained  by  Fischer  and  Meyer,*  as 
a  colorless  sirup  soluble  in  water,  less  soluble  in  alcohol  but  insoluble 
in  ether.  Lactobionic  acid  is  hydrolyzed  by  dilute  acids  into  d-galac- 
tose  and  d-gluconic  acid.  This  reaction  and  the  reducing  properties 
of  lactose  indicate  the  presence  of  a  free  aldehyde  group  attached  to  a 
glucose  residue.  The  oxidation  of  lactobionic  acid  is  explained  as 
follows  : 


+  O  =  Cs 

d-Galactose  d-Glucose  d-Galactose  d-Gluconic  acid 

radical  radical  radical  radical 


Lactose  Lactobionic  acid. 

Lactobionic  acid  upon  oxidation  with  hydrogen  peroxide  in  pres- 
ence of  basic  ferric  acetate  is  degraded  to  galactoarabinose  (p.  644). 

Oxidation  of  lactose  with  nitric  acid  produces  d-saccharic  acid  by 
oxidation  of  the  d-glucose  radical,  and  mucic  acid  by  oxidation  of  the 
d-galactose  radical.  The  discovery  of  mucic  acid  as  a  result  of  this 
oxidation  was  made  by  Scheele  in  1780.  The  yield  of  mucic  acid  from 
lactose  by  the  following  method  of  Kent  and  Tollensf  is  about  40  per 
cent: 

100  gms.  of  pulverized  lactose  are  dissolved  in  1200  gms.  nitric  acid  of  1.15  sp. 
gr.;  the  solution  is  evaporated  to  between  150  c.c.  and  200  c.c.  upon  the  water 
bath  and,  after  cooling,  200  c.c.  of  water  added.  The  crystals  of  mucic  acid  are 
filtered  off  after  24  hours'  standing. 

Action  of  Alkalies.  —  Lactose  upon  heating  with  dilute  alkaliesj  un- 
dergoes an  almost  complete  loss  of  optical  activity,  the  sugar  molecule 
undergoing  partial  hydrolysis  and  rearrangement  with  formation  of 
d-galactose,  pseudotagatose  and  other  products  of  unknown  compo- 
sition. Upon  heating  with  concentrated  alkalies  lactose  solutions  are 
colored  brown,  the  lactose  being  broken  up  into  lower  decomposition 
products  among  which  lactic  acid  occurs  in  greatest  amount.  Lactose 
exposed  to  the  action  of  alkalies  in  the  sunlight  yields  according  to 
Duclaux  over  50  per  cent  lactic  acid. 

Lactose  upon  long  treatment  with  calcium  hydrate  is  converted 
into  isosaccharinic  acid.  The  reaction  according  to  Kiliani  §  is  best 
conducted  as  follows:  A  cold  solution  of  1  kg.  milk  sugar  in  9  liters  of 
water  is  treated  with  450  gms.  calcium  hydroxide  and  allowed  to  stand 

*  Ber.,  22,  361. 

t  Z.  Ver.  Deut.  Zuckerind.,  36,  38. 

t  Lobry  de  Bruyn  and  van  Ekenstein,  Rec.  Trav.  Pays-Bas,  14,  156,  203. 

§  Ber.,  16,  2625;  18,  631. 


THE  DISACCHARIDES  713 

at  room  temperature  with  frequent  shaking  for  5  to  6  weeks.  The 
clear  brown  solution  is  saturated  with  carbon  dioxide,  filtered  from 
calcium  carbonate,  heated  to  boiling,  again  filtered  and  concentrated  to 
2  liters.  Calcium  isosaccharinate  crystallizes  out  and  calcium  meta- 
saccharinate  remains  in  solution.  The  precipitate  of  the  former  is  fil- 
tered off,  washed  with  cold  water  and  dried.  A  weighed  quantity  of 
the  salt  is  then  dissolved  in  water  and  decomposed  with  an  exact 
amount  of  oxalic  acid.  The  filtered  solution  contains  free  isosac- 
charinic  acid,  C6Hi2O6,  which  upon  evaporation  splits  off  water,  and 
crystallizes  out  as  its  lactone  or  isosaccharin,  C6Hi0O5. 

Isosaccharin  consists  of  beautiful  double-refracting  crystals,  easily 
soluble  in  water,  alcohol  and  ether.  It  melts  at  95°  C.  and  sublimes 
without  decomposition.  It  is  dextrorotatory  ([oj^  =  +  63),  is  not 
fermented  by  yeast  and  does  not  reduce  Fehling's  solution. 

Kiliani's  isosaccharin  is  identical  with  Nef's  a-isosaccharin,  ob- 
tained by  the  action  of  sodium  hydroxide  upon  d-galactose  (p.  603),  and 
has  the  following  structural  formula : 

CH2OH 


H 


HOH2C 


HCH 
-COH 


Hydrolysis  of  Lactose  by  Acids.  —  Lactose  upon  heating  on  a 
boiling  water  bath  with  4  parts  of  2  per  cent  sulphuric  acid  is  hydro- 
lyzed  *  into  equal  parts  of  d-glucose  and  d-galactose : 

C12H22On  +  H20  =  C6H1206  +  C6H1206. 

Lactose  d-Glucose         d-Galactose. 

The  hydrolysis  may  also  be  carried  out  with  hydrochloric  acid,  the 
reaction  proceeding  at  ordinary  temperature  with  sufficient  concentra- 
tion of  acid.  Urechf  found  that  a  solution  containing  12  gms.  lac- 
tose and  32  gms.  hydrochloric  acid  to  100  c.c.  was  hydrolyzed  almost 
completely  after  12  hours'  standing  at  23°  C.  The  hydrolysis  of  lactose 
by  means  of  acids  proceeds  with  much  greater  difficulty  than  that 
of  sucrose  or  maltose.  As  in  the  case  of  maltose  the  prolonged  action 
of  acid  causes  a  slight  loss  of  reducing  sugar  due  to  formation  of  lev- 
ulinic  acid,  humus  substances,  reversion  products,  etc. 

Fermentation  of  Lactose.  —  In  so  far  as  the  different  yeasts, 
bacteria,  moulds,  etc.,  contain  the  lactose-splitting  enzyme  lactase,  they 
ferment  lactose  in  the  same  manner  as  d-glucose  and  d-galactose. 
*  Ost,  Ber.,  23,  3006.  t  Ber.,  18,  3048. 


714 


SUGAR  ANALYSIS 


Many  organisms  which  ferment  d-glucose  and  d-galactose  are  without 
action  upon  lactose,  and  in  such  cases  it  is  generally  supposed  that 
lactase  is  absent.  But  whether  in  all  lactose  fermentations  the  sugar 
must  first  be  hydrolyzed  by  a  lactase  is  uncertain,  although  many  au- 
thorities at  present  incline  to  this  opinion. 

Ordinary  baker's  and  brewer's  yeasts  exercise  no  pronounced  fer- 
mentation upon  lactose.  Hansen,*  in  fact,  found  that  none  of  the  com- 
mon alcohol-producing  yeasts  in  pure  culture  was  able  to  ferment 
lactose.  Invertase,  maltase,  zymase  and  the  other  enzymes  of  ordi- 
nary yeast  have  in  fact  no  action  upon  lactose.  The  action  of  differ- 
ent yeasts  upon  lactose  and  other  sugars  is  given  by  Fischerf  and 
Thierfelder  in  Table  GIL 

TABLE  CII 

Showing  Action  of  Yeasts  Upon  Different  Sugars 


Kind  of  yeast. 

| 

3 

1 

1 

1 

I 

1 

'o 

a 

a 

! 

1 

1 

i 

I 

g 

£ 

H 

£ 

o 

£ 

2 

a 

,ci 

§ 

3 

3 

03 

1 

-o 

"° 

4 

~ 

2 

o 

e 

1 

S.  Pastorianus  I  

AAA 

AAA 

AAA 

0 

0 

0 

0 

0 

0 

0 

0 

AAA 

AAA 

0 

S.  Pastorianus  II  

AAA 

AAA 

AA 

0 

0 

0 

0 

0 

0 

0 

AAA 

AAA 

0 

S.  Pastorianus  III  

AAA 

AAA 

AAA 

0 

0 

0 

0 

0 

0 

0 

AAA 

AAA 

0 

S.  cerevisiae  I   

AAA 

AAA 

AAA 

0 

0 

0 

0 

0 

0 

0 

AAA 

AAA 

0 

S.  ellipsoideus  I  

AAA 

AAA 

AA 

0 

0 

0 

0 

q 

0 

0 

AAA 

AAA 

0 

S.  ellipsoideus  II  

AAA 

AAA 

A 

0 

0 

0 

f) 

0 

0 

0 

AAA 

AAA 

0 

S.  Marxianus 

AAA 

AAA 

AAA 

0 

0 

0 

o 

0 

0 

0 

AAA 

o 

o 

S.  rnembranaefaciens  .... 

0 

0 

0 

f) 

0 

0 

0 

0 

0 

0 

0 

0 

0 

Brewery  yeast  

AAA 

AAA 

AAA 

0 

0 

0 

0 

0 

0 

0 

0 

AAA 

AAA 

0 

Distillery  yeast  

AAA 

AAA 

A 

(J 

0 

0 

0 

0 

0 

0 

0 

AAA 

AAA 

0 

S.  productivus  

AAA 

AAA 

0 

0 

0 

0 

0 

0 

0 

0 

A 

AAA 

0 

Milk-sugar  yeast 

A  A 

AAA 

^ 

0 

0 

0 

0 

o 

o 

o 

AAA 

o 

AAA 

AAA  =  complete  fermentation  after  8  days. 
A  A     =  almost  complete  fermentation  after  8  days. 
A         =only  partial   fermentation  after  8  days. 
0          =no  fermentation  after  8  days. 

A  large  number  of  so-called  "  milk-sugar  yeasts  "  have  been  iso- 
lated from  the  products  of  cheese  factories  and  from  such  milk  bever- 
ages as  Kumiss,  Kefir,  Mazun,  etc.  It  is  a  disputed  question,  however, 
whether  these  so-called  yeasts  belong  to  the  Saccharomyces  or  to  the 
Torulacece.  The  latter  ferment  lactose  with  production  of  alcohol! 
and  according  to  Beyerinck§  contain  considerable  amounts  of  the 
enzyme  lactase. 


*  Chem.  Centralbl.  (1888),  1209.     J  Adametz,  Chem.  Centralbl.  (1889),  260. 
t  Ber.,  27,  2031.  §  Chem.  Centralbl.  (1897),  II,  1012. 


THE  DISACCHARIDES  715 

Lactase.  —  Lactase  is  best  prepared  according  to  Fischer*  by  washing 
Kefir  corns  (the  granular  concretions  of  yeasts  and  bacteria  which 
constitute  the  Kefir  ferment)  with  water,  grinding  the  air-dried  mass 
with  pulverized  glass  and  extracting  with  water.  Lactase  is  much  less 
sensitive  to  the  paralyzing  action  of  alcohol,  acids,  etc.,  than  invertase, 
amylase,  maltase  and  other  enzymes. 

In  addition  to  its  occurrence  in  the  Torulaceae  and  other  organisms 
lactase  is  found  in  several  species  of  moulds  and  fungi  and  also  in 
higher  plants.  The  crude  emulsin,  obtained  by  extracting  almonds 
and  the  seeds  of  other  Rosaceae,  contains  a  lactase,  although  the  emul- 
sin from  Aspergillus  niger,  the  cherry  laurel  and  several  other  sources 
has  no  hydrolyzing  action  upon  lactose. 

Lactases  are  very  abundant  in  the  animal  kingdom  and  this  would 
be  expected  from  the  importance  which  lactose  plays  in  animal  nutrition, 
especially  during  the  nursing  period.  Lactases  have  been  found  in  the 
mucous  membranes  of  the  stomach  and  intestines  of  newly  born  in- 
fants and  in  the  same  tissues  of  the  young  of  most  mammals.  Lactase 
also  occurs  in  the  membranes  of  the  digestive  tract  of  older  animals 
and  is  found  in  preparations  of  such  enzymes  as  ptyalin,  pepsin,  trypsin, 
rennet,  etc.  It  is  a  significant  fact  that  the  secretion  of  lactase  is  in- 
tensified by  increasing  the  amount  of  milk  or  milk  sugar  in  the  food. 

Lactic  and  Butyric  Fermentations.  —  Lactose  is  more  easily  subject 
to  the  lactic  and  butyric  fermentations  than  any  other  sugar.  In  fact, 
nearly  all  the  organisms  which  produce  lactic  acid  from  d-glucose  and 
sucrose  ferment  lactose  in  the  same  way.  On  the  other  hand,  there  are 
a  very  large  number  of  organisms  which  produce  lactic  acid  from  lac- 
tose but  not  from  sucrose  or  glucose. 

The  lactic  fermentation  to  secure  best  results  must  be  conducted  in 
presence  of  suitable  nutrients  and  also  in  presence  of  calcium  carbonate 
(or  similar  substance)  to  neutralize  the  free  acid  as  soon  as  formed. 
The  presence  of  much  free  acid  checks  the  fermentation,  so  that  in 
milk,  for  example,  the  percentage  of  free  lactic  acid  under  ordinary  con- 
ditions never  exceeds  0.5  to  0.6  per  cent.  In  presence  of  sufficient 
calcium  carbonate  the  fermentation  of  lactose  into  lactic  acid  under 
favorable  conditions  may  be  almost  quantitative. 

The  various  lactic  organisms  differ  greatly  in  their  action  upon 
lactose..  While  the  ordinary  optimum  temperature  is  about  30°  C., 
some  bacteria  produce  fermentation  as  low  as  10°  C.,  and  others  as 
high  as  52°  C.  Some  lactic  organisms  are  retarded  and  others  stimu- 
lated by  the  influence  of  atmospheric  oxygen.  The  lactic  bacteria  also 

*  Ber.,  27,  3479. 


716  SUGAR  ANALYSIS 

differ  as  to  the  kind  of  lactic  acid  which  they  produce,  some  organisms 
form  d-lactic  acid,  others  1-lactic  acid,  others  d,  1-lactic  acid  and  others 
mixtures  of  d-  and  1-lactic  acids  in  varying  amounts. 

The  literature  upon  the  lactic  acid  bacteria  is  exceedingly  copious 
and  for  a  review  of  the  subject  reference  should  be  made  to  the  works 
of  Lafar,*  J6rgensen,f  Emmerling,J  and  others. 

In  the  butyric  fermentation  of  lactose  the  butyric  acid  may  be 
formed  either  primarily  from  the  lactose  or  secondarily  from  the  lactic 
acid  produced  by  the  lactic  fermentation.  A  large  class  of  both  aerobic 
and  anaerobic  bacteria  ferment  lactose  with  production  of  butyric  acid, 
but  the  action  of  only  a  few  of  these  has  been  studied.  In  addition  to 
butyric  acid,  formic,  acetic,  propionic,  valeric  and  succinic  acids,  butyl 
alcohol,  acetone,  carbon  dioxide,  hydrogen  and  methane  have  been 
found  among  the  products  of  different  butyric  fermentations. 

A  large  number  of  organisms  ferment  lactose  with  formation  of  a 
viscous  gum.  The  bacteria  of  this  class  have  been  especially  studied 
in  connection  with  the  slimy  or  ropy  fermentation  of  milk.  The  Leu- 
conostoc  mesenterioides  and  many  other  organisms  which  form  dextran 
from  sucrose  do  not  exercise  this  action  upon  lactose. 

Compounds  of  Lactose.  —  Lactose,  the  same  as  maltose,  contains 
a  reactive  aldehyde  group  and  forms  hydrazones,  osazones,  methyl 
lactosides,  ureides,  mercaptals,  etc.,  in  the  same  manner  as  other  re- 
ducing sugars.  The  most  important  of  these  compounds  from  the 
analytical  standpoint  is  lactose-phenylosazone,  C^H^oOg  ( :  N  —  NHC6H5)2, 
which  was  first  prepared  by  Fischer  §  by  heating  1  part  lactose,  1J  parts 
phenylhydrazine  chloride,  2  parts  sodium  acetate  and  30  parts  water 
for  1J  hours.  The  osazone  separates  from  the  cold  solution  in  the 
form  of  yellow  needles,  which  after  recrystallizing  melt  at  200°  C. 
Lactose  phenylosazone  is  soluble  in  80  to  90  parts  boiling  water,  in  hot 
alcohol  and  in  hot  glacial  acetic  acid;  it  is  insoluble  in  ether,  benzol 
and  chloroform. 

Lactose  forms  with  nitric  acid,  in  presence  of  ice-cold  strong  sulphuric 
acid,  tri-,  tetra-,  penta,-  hexa-  and  octonitrates;  and  with  acetic 
anhydride  mono-,  di-,  tetra-,  hexa-  and  octacetates.  The  octacetate 
is  the  best  known  acetate,  and  is  obtained  ||  by  heating  5  gms. 
lactose  with  20  gms.  acetic  anhydride  and  5  gms.  water-free  sodium 

*  "  Technische  Mykologie." 

t  "  Microorganismen  der  Garungsindustrie." 

t  "  Zersetzung  Stickstoffreier  organ.  Substanzen  durch  Bacterien,"  Braun- 
schweig (1902),  pp.  25-84. 

§  Ber.,  17,  579;  20,  821. 
II  Schmoger,  Ber.,  25,  1452. 


THE  DISACCHARIDES  717 

acetate  just  to  boiling  and  then  pouring  the  mass  into  water.  The  pre- 
cipitated compound  is  recrystallized  from  alcohol.  Lactose  octacetate 
consists  of  white  crystals  of  the  formula  Ci2Hi4(C2H3O)8Oii,  and  melt- 
ing according  to  different  observers  between  86°  C.  and  106°  C.  The 
variation  in  melting  point  is  attributed  by  some  chemists  to  the  ex- 
istence of  two  isomers.  The  rotation  of  the  carefully  purified  com- 
pound is  given  by  Schmoger  as  [a]D  ='—  3.5°  (in  chloroform). 

Lactose  forms  with  alkalies  and  alkaline  earths  a  number  of  lacto- 
sates,  none  of  which,  however,  has  any  analytical  or  technical  impor- 
tance. 

Upon  treatment  with  hydrocyanic  acid  lactose  forms  a  nitrile,  which 
yields  after  saponification  lactose  carboxylic  acid;  the  latter  consists  of 
a  colorless  sirup  and  gives  upon  hydrolysis  d-galactose  and  a-gluco- 
heptonic  acid. 
C5H1005CH-0-C6H1205COOH  +  H20  =  C6H1206+C6H1306  •  COOH. 

Lactose  carboxylic  acid  d-Galactose        a-Glucoheptonic  acid. 

Tests  for  Lactose.  —  Characteristic  qualitative  tests  for  lactose  in 
presence  of  other  sugars  are  wanting.  The  formation  of  mucic  acid  upon 
oxidation  with  nitric  acid  is  a  valuable  confirmatory  test;  although  it 
must  always  be  borne  in  mind  that  the  same  reaction  is  also  given  by 
d-  and  1-galactose,  galactonic  acid  and  galactan.  Separation  of  lac- 
tose osazone,  after  careful  recrystallization  and  purification,  offers  a 
fairly  reliable  means  of  identification.  In  case  several  reducing  sugars 
are  present,  the  mixture  of  osazones  should  be  heated  with  boiling 
water  and  filtered;  the  osazones  of  lactose,  maltose  and  other  di- 
saccharides  will  be  found  in  the  filtrate,  from  which  crystallization  takes 
place  upon  cooling. 

In  case  of  mixtures,  the  destruction  of  d-glucose,  d-fructose,  d-man- 
nose,  sucrose,  maltose  and  other  fermentable  sugars  by  means  of  pure 
cultures  of  yeasts  which  do  not  ferment  lactose  (Table  CII)  may  be 
employed  to  advantage  before  making  tests  for  lactose. 

Configuration.  —  The  configuration  of  lactose  has  not  been  estab- 
lished with  certainty.  The  following  constitutional  formula  proposed 
by  Fischer*  answers,  however,  to  most  of  the  chemical  properties  and 
reactions  of  lactose : 

I ° 1 

H          OHH  H    H    H    OHH 

HOH2C-C-C-i-C-C-0-C-C-C-C-C-CHO 
inH   H    OHH          H    OHOHH    OH 

d-Galactose  radical  d-Glucose  radical 

*  "  Untersuchungen  uber  Kohlenhydrate  "  (1909),  p.  92. 


718  SUGAR  ANALYSIS 

Synthesis.  —  The  synthesis  of  lactose  has  not  yet  been  accomplished 
either  chemically  or  by  means  of  enzymes. 

Isolactose.  —  C^H^Ou. 

Isolactose  has  not  been  found  in  nature.  The  name  was  given  by 
Fischer  and  Armstrong*  to  a  disaccharide,  which  they  obtained  through 
the  synthetic  action  of  Kefir  lactase  upon  a  concentrated  solution  of 
equal  parts  d-glucose  and  d-galactose. 

Fifty  grams  of  finely  shredded  Kefir  corns  were  shaken  up  with 
300  c.c.  water  and  5  c.c.  toluol  for  48  hours  at  ordinary  temperature; 
200  c.c.  of  the  extract,  100  gms.  each  of  d-glucose  and  d-galactose,  and 
10  c.c.  of  toluol  were  placed  in  a  closed  flask  and  allowed  to  stand  15 
days  at  35°  C.  After  diluting  with  1  volume  of  water,  boiling  10  minutes 
and  cooling,  the  filtered  solution  was  fermented  with  top  yeast  to  re- 
move the  residual  d-glucose  and  d-galactose.  The  isolactose  remain- 
ing in  solution  was  separated  only  in  form  of  isolactose-phenylosazone, 
C24H32N4O9,  which  consisted  of  fine  needles  melting  at  190°  to  193°  C. 

TREHALOSE.  —  Trehabiose.     Mycose.     Mushroom  sugar. 
Ci2H22On  +  2  H20. 

Occurrence.  —  Trehalose  is  a  disaccharide  discovered  by  Wiggersf 
in  ergot  (the  sclerotium  growth  produced  by  the  fungus  Claviceps  pur- 
purea  upon  rye  and  other  grasses),  and  later  found  to  occur  in  nearly 
all  fungi  and  mushrooms.  Muntz  {  found  in  the  dry  substance  of 
Agaricus  muscarius,  A.  sulfureus,  A.  sambucinus,  Fungus  sambuci  and 
Boletus  cyanescens  as  much  as  10  per  cent  trehalose.  Bourquelot§ 
also  found  trehalose  in  varying  amounts  in  Sclerotinia  tuberosa,  Phal- 
lus impudicus,  Boletus  satanas  and  in  36  other  varieties  of  Boletus, 
Amanita,  Pholiota,  Hypholoma  and  Lactarius.  Trehalose  is  unequally 
distributed  through  the  several  tissues  of  mushrooms;  the  stems  of  Bole- 
tus edulis,  for  example,  were  found  by  Bourquelot  to  contain  2.45  per  cent 
trehalose,  the  caps  1.38  per  cent  and  the  pores  none  at  all.  The  quan- 
tity of  trehalose  also  varies  according  to  the  period  of  vegetation,  being 
greatest  just  before  the  formation  of  spores.  After  the  mushroom  is 
picked,  the  trehalose  is  rapidly  hydrolyzed  by  the  enzyme  trehalase  into 
d-glucose,  the  latter  being  afterwards  reduced  through  some  unknown 
biological  process  to  mannite. 

Trehala-manna  and  Trehalum.  —  Trehalose  was  also  found  by 
Berthelot  ||  in  the  so-called  Trehala-manna,  a  drug  long  used  in  the 

*  Ber.,  35,  3144.  §  Compt.  rend.,  108,  568;  111,  578;  117,  826. 

t  Ann.,  1,  173  (1832).  ||  Ann.  chim.  phys.  [3],  56,  272. 

J  Compt.  rend.,  79,  1182. 


THE  DISACCHARIDES  719 

Orient,  and  consisting  of  the  cocoon  or  gall-like  concretions  formed  by 
a  species  of  beetle  upon  certain  spiny  plants  of  Syria  and  Persia. 
Trehala-manna  also  contains  a  polysaccharide  trehalum,  discovered 
by  Guibourt*  and  later  investigated  by  Scheibler  and  Mittelmeier.f 
Trehala-manna  is  first  extracted  with  successive  quantities  of  boiling 
alcohol  to  remove  the  trehalose  and  then  with  boiling  water.  The 
hot-water  extract  is  filtered  through  a  hot-water  funnel  and  the  treha- 
lum  separates  from  the  cold  filtrate  as  a  white  tasteless  crystalline 
powder,  with  a  composition  corresponding  to  the  provisional  formula 
C24H4202i.  Trehalum  is  soluble  in  56  parts  of  boiling  water,  is  dextro- 
rotatory ([a]I)  =  +  179),  and  is  hydrolyzed  by  hydrochloric  or  sulphuric 
acids  into  d-glucose;  it  is  not  reducing  and  forms  no  compound  with 
phenylhydrazine.  Solid  trehalum  is  colored  by  alcoholic  iodine  solution 
violet  and  solutions  of  trehalum  wine  red.  Trehalum  has  a  certain 
resemblance  to  starch  and  it  possibly  bears  the  same  relation  to  trehalose 
that  starch  bears  to  maltose. 

Preparation  of  Trehalose.  —  Finely  shredded  trehala-manna  or 
mushrooms  (freshly  picked)  are  boiled  with  strong  alcohol  and  the 
filtered  extract  set  aside  to  cool.  Crystals  of  trehalose  will  usually 
separate  immediately;  if  crystallization  does  not  take  place  the  alco- 
holic extract  is  concentrated  by  evaporation  and  again  set  aside. 

Properties.  —  Trehalose,  as  ordinarily  prepared,  is  Obtained  in 
the  form  of  large  colorless  rhombic  crystals  having  the  formula 
Ci2H22Oii  +  2  H2O.  The  crystals  have  a  sweet  taste,  are  soluble  in 
1.7  parts  of  water  and  in  100  parts  of  hot  alcohol,  but  are  insoluble  in 
ether.  The  hydrate  begins  to  melt  in  its  water  of  crystallization  at 
94°  C.,  and  liquefaction  is  complete  between  96.5°  C.  and  97.5°  C. 
The  water  of  crystallization  is  lost  at  about  130°  C.  and  the  trehalose 
anhydride  thus  obtained  melts  at  about  200°  C. 

Trehalose  is  strongly  dextrorotatory;  SchukowJ  found  for  the  hy- 
drate (c  =  7.282)  [a]%  =;  -f-  178.3,  from  which  the  calculated  value  for 
the  anhydride  would  be  [a]g  =+197.1.  Apping  §  determined  for  the 
anhydride  [a]D  =  +  197.28.  Mutarotation  is  not  observed. 

Reactions.  —  Trehalose,  like  sucrose,  does  not  reduce  Fehling's 
solution.  The  absence  of  aldehyde  or  ketone  properties  is  also  shown 
by  the  failure  of  trehalose  to  form  hydrazones  or  osazones,  by  its  re- 
sistance towards  solutions  of  boiling  alkalies,  and  by  the  non-forma- 
tion of  acid  oxidation  products  in  aqueous  solution  by  means  of  bro- 
mine at  ordinary  temperature.  Upon  warming  with  dilute  nitric  acid 

*  Compt.  rend.,  46,  1213.  t  Z.  Ver.  Deut.  Zuckerind,  60,  818. 

t  Ber.,  26,  1331.  §  Dissertation,  Dorpat.,  1885. 


720  SUGAR  ANALYSIS 

trehalose  is  oxidized  to  d-saccharic  acid  and  by  strong  nitric  acid  to 
oxalic  acid. 

Upon  heating  with  dilute  hydrochloric  or  sulphuric  acids  for  several 
hours,  trehalose  is  hydrolyzed  into  2  molecules  of  d-glucose. 


v-a2-H22v)ii  -j-  -H^jO  =  2 

Trehalose  d-Glucose. 

The  hydrolysis  is  accomplished  only  with  considerable  difficulty. 
According  to  Winterstein*  6  hours'  boiling  with  5  per  cent  sulphuric 
acid  is  necessary  to  secure  complete  conversion;  the  yield  of  d-glucose 
obtained  at  the  end  of  this  time  was  99.45  per  cent  of  the  theoretical. 

Trehalose  forms  a  number  of  acetates  upon  heating  with  acetic 
anhydride  and  a  number  of  benzoates  upon  treatment  with  benzoyl 
chloride.  Compounds  of  trehalose  with  calcium,  strontium  and  lead 
have  also  been  prepared. 

Fermentation.  —  Trehalose  is  not  readily  fermented  by  ordinary 
baker's  or  brewer's  yeast.  The  sugar  is  fermented,  however,  by  a  num- 
ber of  wild  yeasts;  according  to  Dubourgf  a  large  number  of  yeasts 
can  ferment  trehalose  after  special  methods  of  cultivation  and  adapta- 
tion. A  number  of  moulds,  as  Mucor  mucedo,  ferment  trehalose  in 
absence  of  air  with  production  of  alcohol. 

The  fermentation  of  trehalose  is  apparently  conditioned  by  the 
presence  of  a  special  hydrolyzing  enzyme  trehalase,  which  was  first  iso- 
lated by  Bourquelot  t  from  a  culture  of  Aspergillus  niger  at  the  time  of 
spore  formation.  The  mould  was  distintegrated  by  grinding  with 
sand,  dehydrated  by  washing  with  95  per  cent  alcohol  and  then  dried 
in  a  vacuum  at  low  temperature.  The  dried  mass  was  then  extracted 
with  water,  and  the  trehalase  precipitated  from  the  filtered  extract  by 
strong  alcohol.  The  purified  enzyme  consisted  of  a  white  amorphous 
substance,  easily  soluble  in  water  and  having  below  53°  C.  a  strong 
hydrolytic  action.  Its  activity  was  destroyed  by  heating  to  63°  C. 

Trehalase  is  found,  according  to  Bourquelot,  in  other  moulds  and  in 
higher  fungi,  such  as  Morchella  and  Polyporus.  It  has  also  been  de- 
tected in  green  malt.  In  the  animal  kingdom  its  presence  has  been  re- 
ported in  human  urine,  in  the  pancreas  and  intestines  of  rabbits,  in  the 
intestines  of  calves,  horses,  etc.,  and  in  the  blood  serum  of  certain 
fishes. 

Emulsin,  invertase,  diastase  and  ptyalin  have  no  hydrolytic  action 
upon  trehalose. 

Tests.  —  No  reliable  qualitative  tests  are  known  for  the  detection 
of  trehalose  in  mixture  with  other  sugars.  According  to  Bourquelot,  if 

*  Ber.,  26,  3094.        f  Compt.  rend.,  128,  440.        J  Compt.  rend.,  117,  826. 


THE  DISACCHARIDES  721 

a  glass  plate  be  gently  rubbed  with  a  crystal  of  trehalose  and  a  drop  of 
sirup  containing  trehalose  be  spread  over  the  rubbed  area,  crystalliza- 
tion will  develop  and  the  lines  of  contact,  where  the  trehalose  crystal 
touched  the  glass,  will  appear  visible. 

Configuration.  —  The  constitutional  formula  of  trehalose  has  not 
been  established.  Owing  to  the  absence  of  reducing  properties,  it  is 
supposed  that  the  aldehyde  groups  of  the  two  glucose  radicals  are  com- 
bined together.  The  following  arrangement  has  been  proposed: 

H    H    OHH   H 
HOH2C-C-C-C-C-C\ 
OH  I     H    OH  I  \ 

i o J    >o 

H    H    OHH    H/ 
HOH2C-C-C-C-C-C 
OH  I     H    OH  | 


H 
I O 


I 


MELIBIOSE.  —  Ci2H22On  +  2  H20. 

Occurrence.  —  This  disaccharide  has  not  been  found  in  nature  as 
yet  in  the  free  condition.  It  was  first  prepared  by  Scheibler  and 
Mittelmeier*  by  a  partial  hydrolysis  of  the  trisaccharide  raffinose  by 
means  of  mineral  acids  (see  page  737) . 

CisH32Oi6  +  H2O  =  CeH^Oe  +  Ci2H22On. 

Raffinose  d-Fructose  Melibiose. 

The  same  hydrolysis  is  effected  by  means  of  invertase.  A  pure  cul- 
ture of  top-fermentation  yeast  will  hydrolyze  raffinose  into  melibiose 
and  d-fructose  and,  after  fermenting  the  latter,  leave  a  solution  contain- 
ing melibiose.  Bottom-fermentation  yeast  cannot  be  used  owing  to  the 
occurrence  of  an  enzyme,  melibiase,  which  hydrolyzes  melibiose  as  fast 
as  it  is  formed. 

Preparation.  —  For  the  preparation  of  melibiose  either  of  the 
methods  proposed  by  Bauf  may  be  used. 

Preparation  of  Melibiose  from  Raffinose  by  Fermentation.  —  A  steri- 
lized solution,  containing  20  gms.  raffinose  in  250  c.c.  of  water,  is 
fermented  with  30  gms.  of  a  pressed  pure  culture  of  Frohberg  top-fer- 
mentation yeast  at  31°  C.  for  one  day.  The  solution  is  filtered,  sterilized 
and  again  fermented  with  10  gms.  of  yeast  at  31°  C.  for  several  days. 
The  filtered  solution,  after  decolorizing  by  means  of  bone  black,  is 
evaporated,  the  hot  sirup  poured  into  hot  95  per  cent  alcohol,  and  the 
cold  solution,  after  decanting  from  precipitated  impurities,  treated  with 
an  excess  of  ether.  The  impure  melibiose,  which  is  thus  precipitated, 

*  Ber.,  22,  1678;  23,  1438.  t  Chem.  Ztg.,  26,  69. 


722  SUGAR  ANALYSIS 

is  dissolved  in  70  per  cent  alcohol  and  precipitated  again  at  0°  C.  as  its 
barium  compound  by  adding  cold  aqueous  barium  hydroxide  solution 
and  cold*  92  per  cent  alcohol.  The  barium  melibiate  is  filtered  off, 
washed  with  cold  alcohol,  pressed,  suspended  in  water  and  decomposed 
by  means  of  carbon  dioxide.  Any  barium  remaining  in  solution  is  pre- 
cipitated by  adding  the  exact  amount  of  dilute- sulphuric  acid  (avoiding 
even  the  slightest  excess)  and  the  filtrate  evaporated  below  80°  C.  to  a 
sirup;  92  per  cent  alcohol  is  added  until  the  alcoholic  strength  of  the 
diluted  sirup  is  70  per  cent  and  ether  is  added  just  beyond  the  point  of 
precipitation.  The  ether-alcohol  solution  after  filtration  is  set  aside  and 
gradually  deposits  crystals  of  melibiose,  which  may  be  purified  by 
recrystallizing  from  78  per  cent  alcohol. 

Preparation  of  Melibiose  from  Raffinose  by  Hydrolysis  with  Acid.  — 
A  10  to  20  per  cent  solution  of  raffinose  is  boiled  with  2  per  cent  acetic 
acid;  the  solution  is  concentrated  in  a  porcelain  dish  to  a  thick  sirup 
which  after  cooling  is  rubbed  up  with  2  volumes  of  95  per  cent  alcohol. 
The  alcoholic  solution  is  decanted  and  ether  added  with  shaking  to  the 
point  of  permanent  turbidity;  the  solution  after  standing  2  days  is  filtered 
from  the  precipitate  and  allowed  to  stand  for  several  weeks  in  a  closed 
flask.  Crystallization  gradually  takes  place;  the  process  may  be 
hastened  by  priming  with  a  little  melibiose  from  a  previous  preparation. 
The  crude  melibiose  thus  obtained  is  purified  by  recrystallizing  from 
alcohol. 

Properties.  —  Melibiose  is  obtained  from  aqueous  solution  in  the 
form  of  monoclinic  crystals  having  the  formula  Ci2H22Oii  +  2  H20. 
The  sugar  has  a  mild  sweet  taste,  and  when  warmed  begins  to  melt  in 
its  water  of  crystallization  at  75°  to  80°  C.  Upon  heating  in  a  thin 
layer  gradually  to  110°  C.  all  water  is  expelled.  The  anhydride  is  ex- 
ceedingly hygroscopic  and  reabsorbs  water  from  the  air  with  great 
avidity.  One  gram  of  crystallized  melibiose  is  dissolved  by  0.4186 
gms.  of  water  at  17.5°C.,  by  6.8137  gms.  of  methyl  alcohol  and  by  175.67 
gms.  of  ethyl  alcohol. 

Melibiose  is  strongly  dextrorotatory.  Bau  found  for  the  hydrate 
MS  =  +  129.50,  from  which  the  value  for  the  anhydride  =  +  143. 
The  sugar  exhibits  mutarotation,  the  initial  value,  for  [a]D  being  less 
than  the  constant  reading  ([a]™  after  5  minutes  =  +  108.68). 

Reactions.  —  Melibiose  reduces  Fehling's  solution,  the  reducing 
power  as  C^H^On  being  about  95  per  cent  that  of  maltose.  Reduction 
with  sodium  amalgam  gives  a  complex  alcohol,  melibiotite,  Ci2H24On, 
which  consists  of  an  easily  soluble  non-reducing  sirup,  and  is  hydrolyzed 
by  acids  into  d-galactose  and  d-mannite.  Upon  heating  with  hydrochloric 


THE  DISACCHARIDES  723 

or  sulphuric  acid  melibiose  is  slowly  hydrolyzed  into  d-glucose  and 
d-galactose. 

CuHaOu  +  H20  =  C6H1206  +  C6H1206. 

Melibiose  d-Glucose         d-Galactose. 

Melibiose  is  thus  seen  to  yield  the  same  products  of  hydrolysis  as 
lactose.  Hydrolysis  is  not  effected  by  acetic,  tartaric,  citric  or  lactic 
acids.  Melibiose  is  rapidly  hydrolyzed  by  the  enzyme  melibiase,  and 
also,  but  more  slowly,  by  emulsin. 

Owing  to  the  presence  of  a  reactive  aldehyde  group  melibiose  forms 
a  considerable  number  of  hydrazones  and  osazones.  The  sugar  also 
forms  an  octacetate  upon  boiling  with  acetic  anhydride  and  sodium 
acetate.  The  compound  consists  of  needle-shaped  crystals  with  very 
bitter  taste,  having  the  formula  CwHuCCkHaO^Oii,  only  slightly  soluble 
in  water,  soluble  in  alcohol,  chloroform  and  benzol  and  showing  dextro- 
rotation  ([a]D  =  +  94.2.) 

Fermentation. — Melibiose  is  readily  fermented  into  alcohol  and  car- 
bon dioxide  by  all  bottom-fermentation  yeasts,  but  not  by  pure  cultures  of 
the  ordinary  top  yeasts.  Certain  exceptions  to  the  latter  rule  have  been 
noted  in  a  few  cases,  but  fermentation  in  these  instances  may  have  been 
due  to  contamination  or  to  the  unexplained  phenomenon  of  transition 
by  which  a  bottom  yeast  acquires  top-fermentation  characteristics,  or 
vice  versa.  Pure  cultures  of  Saaz  and  Frohberg  top  yeast,  Saccha- 
romyces  ellipsoideus  II,  as  well  as  other  varieties,  were  found  by  Bau* 
to  have  no  action  upon  melibiose  even  after  1  to  1  \  years;  this  property 
has  been  proposed  by  Bau  as  a  means  of  distinguishing  between  top 
and  bottom  yeasts;  the  dangers  of  contamination  and  transition 
nullify  somewhat  the  value  of  this  test. 

A  large  number  of  wild  yeasts,  mycoderms,  moulds  and  other 
fungi  ferment  melibiose;  in  all  such  cases  the  presence  of  a  special 
enzyme  melibiase  is  assumed.  Melibiase,  as  prepared  by  Bau  from 
bottom  yeast,  can  be  heated  to  110°  C.  (after  drying)  without  destruc- 
tion; in  solution,  however,  its  activity  is  destroyed  at  70°  C.  The 
optimum  temperature  for  its  action  is  about  50°  C. 

Tests.  —  Reliable  qualitative  tests  for  melibiose  in  presence  of 
other  sugars  are  lacking.  The  best  method  of  procedure  in  case  of  mix- 
tures is  to  remove  fructose,  glucose  and  other  sugars  so  far  as  possible 
by  a  pure  culture  of  top  yeast.  The  melibiose  may  then  be  precipitated 
as  its  phenylosazone;  the  latter  after  recrystallization  from  hot  water 
consists  of  fine  yellow  needles  melting  at  178°  to  179°  C.  Melibiose- 

*  Chem.  Ztg.,  19,  1874;  21,  185. 


724  SUGAR  ANALYSIS 

phenylosazone  is  decomposed  by  benzaldehyde  into  melibiosone, 
which  is  hydrolyzed  by  emulsin  into  d-galactose  and  d-glucosone. 
Oxidation  of  melibiose  or  its  osone  with  nitric  acid  yields  mucic  acid,  in 
the  same  manner  as  with  lactose. 

Synthesis. —  By  allowing  acetochloro-d-galactose  to  react  with 
d-glucose  in  alcoholic  solution  in  presence  of  sodium  alcoholate  Fischer 
and  Armstrong  *  obtained  a  disaccharide  which  reduced  Fehling's 
solution,  formed  osazones  similar  to  those  of  melibiose  and  gave  other 
reactions  resembling  this  sugar.  The  sugar  could  not  be  separated  in 
the  crystalline  form,  but  from  the  agreement  in  chemical  reactions 
and  in  behavior  towards  yeasts  and  enzymes  it  is  probably  identical 
with  melibiose. 

The  above  synthesis  is  of  importance  as  it  is  apparently  the  first  to 
be  accomplished  by  purely  chemical  means  for  a  natural  disaccharide; 
the  method  is  the  same  as  that  employed  for  other  synthetic  disac- 
charides,  and  may  be  represented  as  follows: 


H—  C—  Cl 

CH2OH 

H  —  C  —  O  CH2 

/CHOAc 

CHOH 

/  CHOAc    CHOH 

0 

CHOAc 

CHOH                                \  CHOAc    CHOH 

SSB         4 

+  C2H5ONa  = 
CHOH 

CH           CHOH 

CHOAc 

CHOH 

CHOAc    CHOH 

CH2OAc 

CHO 

CH2OAc    CHO 

r  NaCl+C2HoOH 

Acetochlorohexose 

Hexose      Sodium  alcoholate 

Disaccharide-tetracetate 

Salt       Alcohol. 

After  completion  of  the  reaction  the  mixture  is  treated  in  the  cold 
with  an  excess  of  sodium  hydroxide  which  removes  the  acetyl  groups 
with  liberation  of  the  pure  disaccharide.  In  the  above  equation  the  ter- 
minal OH  group  of  the  hexose  is  made  to  take  part  in  the  reaction;  it  is 
evident,  however,  that  some  other  OH  group  may  enter  into  combination 
with  the  acetochlorohexose.  Melibiose  and  lactose  are  both  d-gluco- 
d-galactosides,  each  consisting  of  a  combination  of  d-glucose  and 
d-galactose  with  a  functional  aldehyde  group  in  the  glucose  part  of  the 
molecule.  The  difference  between  lactose  and  melibiose  is  no  doubt 
due  to  a  difference  in  point  of  attachment  between  the  OH  groups  of 
glucose  and  the  galactoside  half  of  the  sugar.  Until  some  method  is 
found  for  determining  this  point  of  attachment  the  structural  formula 
of  melibiose  as  of  all  other  complex  sugars  must  remain  an  uncertainty. 

*  Ber.,  35,  3144. 


THE  DISACCHARIDES  725 

Turanose.  —  C^H^On. 

This  disaccharide  has  not  been  found  free  in  nature.  The  sugar 
was  obtained  by  Alekhine  *  by  a  carefully  controlled  hydrolysis  of  the 
trisaccharide  melezitose  (p.  740). 


CisH^Oie  +  H^O  =  CeH^Oe  +  C^H^On. 

Melezitose  d-Glucose  Turanose. 

Preparation  and  Properties.  —  About  5.5  gms.  of  anhydrous  melezi- 
tose are  carefully  warmed  with  100  c.c.  of  1  per  cent  sulphuric  acid 
upon  the  water  bath  until  the  specific  rotation  of  the  sugar  has  fallen  to 
M0  =  ~^~  63°*  The  solution  is  then  neutralized  with  barium  carbonate, 
and  the  nitrate  treated  with  hot  alcohol  until  turbidity  develops.  After 
cooling  the  precipitated  sugar  is  purified  by  extracting  with  boiling  abso- 
lute alcohol. 

Turanose  is  obtained  by  the  above  method  as  a  white  amorphous 
mass,  having  the  formula  C^H^On;  it  is  easily  soluble  in  water  and 
methyl  alcohol  but  not  in  absolute  alcohol,  [oj^  =  +  65  to  +68 
(c  =  30  to  35).  It  is  not  fermentable  to  any  great  extent  and  re- 
duces Fehling's  solution  about  one-half  as  strong  as  d-glucose. 

Turanose  upon  prolonged  heating  with  mineral  acids  is  hydrolyzed 
according  to  Alekhine  into  2  molecules  of  d-glucose. 

Tanret  f  has  recently  prepared  turanose  by  hydrolyzing  melezitose 
with  20  per  cent  acetic  acid  for  2  hours  on  the  water  bath.  The  acetic 
acid  was  removed  by  shaking  out  with  ether  and  the  d-glucose  by  fer- 
menting with  yeast.  The  solution  was  evaporated  to  a  sirup,  purified 
from  glycerol  and  fatty  acid  fermentation  products  by  shaking  out 
with  ether,  and  then  extracted  with  boiling  absolute  alcohol.  The 
filtrate  on  concentration  and  cooling  yielded  crystals  of  turanose 

(which  contained  one-half  molecule  alcohol  of  crystallization  and  melted 
at  60°  to  66°  C.  Upon  drying  at  100°  C.  anhydrous  turanose  was 
obtained  of  the  formula  Ci2H22Oii  and  [a]D  =  +  71.8.  The  reducing 
power  was  60  per  cent  that  of  d-glucose. 

According  to  Tanret  turanose  is  hydrolyzed  into  one  molecule  each  of 
d-glucose  and  d-fructose,  turanose  thus  being  a  true  isomer  of  sucrose. 
This  observation  cannot  be  reconciled  with  the  rotation  +51,  obtained 
by  Alekhine  after  hydrolyzing  melezitose;  additional  investigations  are 
needed  before  a  final  decision  can  be  reached. 

Turanose  upon  heating  with  a  solution  of  phenylhydrazine  forms  a 
phenylosazone  of  the  formula  C^H^NA,  consisting  of  fine  yellow 
needles,  melting  at  215°  to  220°  C.  upon  rapid  heating  and  soluble  in 

*  Ber.,  22,  759;  Ann.  chim.  phys.  [6],  18,  532. 
t  Bull.  soc.  chim.  [3],  36,  816. 


726  SUGAR  ANALYSIS 

5  parts  of  hot  water,  which  solution  upon  cooling  sets  to  a  jelly-like 
mass  of  fine  crystals. 

Gentiobiose.  —  C^H^Ou. 

This  disaccharide  has  not  been  found  free  in  nature.  In  the  com- 
bined form  it  exists  in  the  trisaccharide  gentianose  from  which  it  has 
been  obtained  by  Bourquelot  and  Herissey*  by  partial  hydrolysis 
using  invertase  or  very  dilute  sulphuric  acid. 


Gentianose  d-Fructose  Gentiobiose. 

Preparation  and  Properties.  —  Ten  grams  of  gentianose  are  warmed 
upon  the  water  bath  with  100  c.c.  of  0.2  per  cent  sulphuric  acid  for  30 
minutes.  The  solution  is  cooled,  neutralized  with  calcium  carbonate, 
filtered  and  evaporated  in  vacuum  to  dryness.  The  residue  is  worked 
up  with  absolute  alcohol  and  then  with  95  per  cent  alcohol  until  all  fruc- 
tose is  removed;  the  crude  gentiobiose  is  purified  by  crystallization. 

Gentiobiose,  when  crystallized  from  hot  alcohol,  is  obtained  in 
water-free  crystals  which,  after  drying  at  115°  C.,  melt  at  190°  to 
195°  C.  The  sugar  is  dextrorotatory  and  shows  the  phenomenon  of 
less-rotation,  [a]^  =+9.61  (after  solution).  The  sugar  is  not  fer- 
mented by  top  yeast  and  this  property  can  be  utilized  for  separation  of 
gentiobiose  from  the  hydrolytic  products  of  gentianose.  While  gentio- 
biose is  not  hydrolyzed  by  invertase,  it  is  easily  split  up  by  emulsin  into 

2  molecules  of  d-glucose.     Hydrolysis  is  also  effected  by  heating  with 

3  per  cent  sulphuric  acid. 

Ci2H220n  -|-  H^O  =  2  CeH^Oe. 

Gentiobiose  d-Glucose. 

Gentiobiose  reduces  Fehling's  solution  to  about  the  same  degree  as 
maltose.  Upon  heating  with  phenylhydrazine  an  osazone  is  formed  of 
melting  point  142°  C.  These  reactions  show  that  gentiobiose  contains 
an  aldehyde  group  in  the  free  reactive  condition. 

Cellose.  —  Cellobiose.     CuE^Ou. 

This  disaccharide  does  not  exist,  so  far  as  known,  free  in  nature. 
It  is  apparently  formed,  with  other  intermediary  carbohydrates,  in  the 
hydrolysis  of  cellulose  to  glucose  by  means  of  sulphuric  acid,  cellose 
thus  bearing  the  same  relation  to  cellulose  as  maltose  bears  to  starch. 

Preparation.  —  For  the  preparation  f  of  cellose  it  is  best  to  start 
from  cellose-octacetate,  which  is  obtained  by  treatment  of  cellulose  with 
acetic  anhydride:  —  7.5  gms.  of  finely  cut  filter  paper  are  thoroughly 
shaken  in  a  200-c.c.  flask  with  20  c.c.  of  acetic  anhydride;  after  cooling 

*  Compt.  rend.,  132,  571;  136,  290,  399.  f  Skraup,  Ber.,  32,  2413. 


THE  DISACCHARIDES  727 

to  70°  C.  the  mass  is  treated  under  constant  shaking  with  a  mixture  of 
7  c.c.  acetic  anhydride  and  4  c.c.  concentrated  sulphuric  acid  warmed 
to  70°  C.,  and  the  yellowish  brown  solution  poured  into  500  to  700  c.c. 
of  water.  The  amorphous  yellowish  colored  precipitate  is  filtered  off 
on  linen,  washed  with  water,  pressed  and  recrystallized  several  times 
from  95  per  cent  alcohol.  The  cellose-octacetate  thus  prepared  con- 
sists of  white  needles,  melting  at  228°  C.,  and  having  a  composition  and 
molecular  weight  corresponding  to  the  formula  Ci2Hi4(C2H30)8Oii.  The 
compound  is  soluble  in  hot  95  per  cent  alcohol,  but  insoluble  in  hot 
absolute  alcohol,  chloroform  or  benzol.  The  yield  of  cellose-octacetate 
from  cellulose  by  this  method  is  26  to  27  per  cent. 

To  prepare  cellose  the  finely  pulverized  octacetate  is  moistened 
with  alcohol  and  then  treated  with  successive  portions  of  a  15  per  cent 
solution  of  potassium  hydroxide  in  strong  alcohol,  using  5  c.c.  of  alco- 
holic potassium  hydroxide  for  each  gram  of  cellose-octacetate.  By  this 
treatment  the  octacetate  is  saponified  and  the  cellose  liberated. 
C12H14(C2H30)8011  +  8KOH  =  Ci2H22On  +  8CH3COOK. 

Cellose-octacetate  Cellose  Potassium  acetate. 

After  2  hours'  standing  the  crude  cellose,  in  the  form  of  a  granular 
powder,  is  filtered  off,  washed  with  absolute  alcohol,  dissolved  in  a  little 
water  and  any  free  potassium  hydroxide  exactly  neutralized  with  acetic 
acid.  The  solution  is  then  filtered,  evaporated  to  a  thin  sirup,  1  part 
absolute  alcohol  added  and  then  ether  to  the  point  of  turbidity.  After 
standing  several  hours  in  the  cold  the  precipitate  is  filtered  off,  dissolved 
in  a  little  hot  water  and  then  absolute  alcohol  added  to  the  appearance 
of  turbidity.  The  solution  is  then  set  aside  in  the  cold  when  the  cel- 
lose will  separate  after  long  standing  in  the  form  of  small  microscopic 
crystals. 

Properties.  —  Cellose  as  prepared  by  the  above  method  consists 
of  a  fine  white  crystalline  compound,  which,  after  drying  at  100°  C.  in 
a  vacuum,  has  a  composition  agreeing  with  the  formula  Ci2H220n. 
The  sugar  melts  at  225°  C.  under  decomposition.  It  has  a  mild  sweet 
taste,  is  soluble  in  8  parts  of  cold  and  1.5  parts  of  hot  water,  but  in- 
soluble in  alcohol  and  ether.  Cellose  is  dextrorotatory  and  shows 
the  phenomenon  of  less-rotation,  [«]£  =  +  26.1  (10  minutes  after  solu- 
tion) and  +33.7  (constant).  Upon  heating  on  the  water  bath  with 
5  per  cent  sulphuric  acid  for  7  hours  cellose  is  hydrolyzed  into  2  mole- 
cules of  d-glucose. 

Ci2H22On  +  H2O  =  2  C6H12O6. 

Cellose  d-Glucose. 

Hydrolysis  is  also  effected  by  means  of  emulsin. 


728  SUGAR  ANALYSIS 

Cellose  is  not  fermented  by  means  of  yeast.  The  sugar  reduces 
Fehling's  solution  somewhat  stronger  than  maltose.  Upon  heating 
with  2  parts  water,  3  parts  phenylhydrazine  and  2  parts  glacial  acetic 
acid  for  1  hour  in  a  water  bath  and  then  adding  water,  cellose  forms  an 
osazone  which  crystallizes  in  the  form  of  yellow  needles  melting  at 
198°  C.  These  reactions  show  that  cellose  contains  an  aldehyde  group 
in  the  free  reactive  condition. 


Glucosido-galactose.  — 

This  synthetic  disaccharide  was  prepared  by  Fischer  and  Arm- 
strong* from  acetochloro-d-glucose  and  d-galactose  (in  alcoholic  solu- 
tion with  sodium)  following  the  same  method  described  under  the  syn- 
thesis of  melibiose. 

The  sugar  was  obtained  only  in  the  sirupy  form;  it  was  fermented 
by  bottom  yeast,  but  not  by  top  yeast,  and  was  hydrolyzed  by  emulsin. 
It  reduced  Fehling's  solution. 

Phenylhydrazine  gave  an  osazone  C24H32N409  consisting  of  yellow 
needles,  melting  at  172°  to  174°  C.,  and  soluble  in  120  parts  of  hot 
water. 


Galactosido-galactose.  — 

This  synthetic  disaccharide  was  prepared  by  Fischer  and  Arm- 
strong* from  acetochloro-d-galactose  and  d-galactose  (in  alcoholic  solu- 
tion with  sodium)  following  their  general  method  as  described  under 
melibiose. 

The  sugar  was  obtained  only  in  the  sirupy  condition;  it  was  fer- 
mented neither  by  top  nor  bottom  yeast  but  was  hydrolyzed  by  emul- 
sin; it  reduced  Fehling's  solution. 

Phenylhydrazine  gave  an  osazone  C24H32N409  consisting  of  yellow 
needles,  melting  at  173°  to  175°  C.,  and  soluble  in  110  parts  of  boiling 
water. 

Isotrehalose.  —  C^H^Ou. 

This  disaccharide  was  prepared  synthetically  by  Fischer  and 
Delbriickf  by  a  somewhat  different  process  than  that  of  Fischer  and 
Armstrong.  /3-Acetobromoglucose  is  allowed  to  react  in  dry  ethereal 
solution  with  silver  carbonate,  traces  of  water  being  added  at  intervals  to 
promote  the  reaction  In  this  manner  two  molecules  of  acetoglucose 
are  united  by  the  elimination  of  bromine  to  form  the  octacetate  of  a 

*  Ber.,  36,  3144. 
t  Ber.,  42,  2776. 


THE  DISACCHARIDES  729 

disaccharide.  The  following  equation  illustrates  the  principle  of  the 
synthesis: 

,-CHBr 

I    CHOAc  CHOAc   I    CHOAc 

01  01  01 

I    CHOAc  I    CHOAc        CHOAc 

*UH  +A&C03=[_iH  ^          +2AgBr+C02 

CHOAc  CHOAc       CHOAc 

CH2OAc  CH2OAc       CH2OAc 

Acetobromohexose  Disaccharide  octacetate. 

The  octacetate  upon  treatment  with  cold  barium  hydroxide  solu- 
tion yields  barium  acetate  and  the  free  disaccharide. 

Isotrehalose  as  obtained  by  this  process  consists  of  a  white  amor- 
phous substance,  without  action  upon  Fehling's  solution  and  levo- 
rotatory  ([a]D  =  —  39.4).  The  absence  of  a  free  aldehyde  group  is  a 
necessary  consequence  of  this  method  of  synthesis  and  the  non-re- 
ducing properties  of  isotrehalose  are  thus  explained.  Since  the  two  C 
atoms  united  by  the  O  linkage  are  asymmetric,  three  stereoisomeric  con- 
figurations are  possible  for  isotrehalose;  which  configuration  belongs 
to  isotrehalose  is  uncertain. 

The  disaccharide  upon  boiling  with  dilute  mineral  acids  is  hydro- 
lyzed  into  d-glucose. 

Dihexose  Saccharides  of  Uncertain  Nature  and  Constitution.  - 

In  addition  to  the  dihexose  saccharides  previously  described  a  number 
of  other  sugars  with  the  apparent  formula  C^H^On  have  been  reported 
by  various  investigators.  Owing  to  the  lack  of  confirmatory  evidence 
brief  mention  is  made  of  only  a  few  of  these  compounds. 

Astragalose  reported  by  Frankforter*  in  the  poisonous  fruit  of 
Astragalus  caryocarpus.  It  reduces  Fehling's  solution  and  forms  a 
phenylhydrazone  melting  at  186°  to  188°  C. 

Parasaccharose  formed  according  to  Jodinf  by  the  action  of  a 
variety  of  Torula  upon  sucrose  solutions  in  presence  of  ammonium 
phosphate.  It  forms  fine  crystals,  is  dextrorotatory  ([a]/  =  +  108),  re- 
duces Fehling's  solution  and  is  hydrolyzed  by  heating  with  acids. 

Pharbitose  reported  by  Kromerf  in  the  seeds  of  Pharbitis  Nil. 
[a]D  =  +  109.53. 

Pseudostrophanthobiose  formed  according  to  Feist  §  in  the  hydrolysis 
of  pseudostrophanthin  a  glucoside  occurring  in  Strophanthus  hispidus. 
*  Chem.  Centralbl.  (1900)  II,  484.  t  Archiv.  Pharm.,  234,  459. 

t  Compt.  rend.,  53,  1252.  §  Ber.,  33,  2063,  2069. 


730  SUGAR  ANALYSIS 

Racefoliobiose  reported  by  Boettinger  *  in  grape  leaves. 

Revertose  (Revertobiose)  formed  according  to  Hillf  by  the  action 
of  maltase  or  takadiastase  upon  concentrated  glucose  solutions  (see 
p.  704) 

Amygdalinbiose  liberated  according  to  GiajuJ  by  the  action  of  the 
juice  of  Helix  pomatia  (the  so-called  "  edible  snail  ")  upon  amygdalin. 
It  is  non-reducing  and  gives  only  d-glucose  upon  hydrolysis. 

HEXOSE-HEPTOSE  SACCHARIDES 


XC7H1306 

Galactosido-glucoheptose.  —  dsH^O^. 

This  synthetic  disaccharide  was  obtained  by  Fischer§  through  re- 
duction of  the  lactone  of  lactose  carboxylic  acid  (p.  717)  by  means  of 
sodium  amalgam.  The  sugar,  which  has  not  been  isolated  in  the 
crystalline  form,  is  hydrolyzed  by  mineral  acids  into  d-galactose  and 
d-glucoheptose. 

Ci»H24OM  +  H2O  =  C6H1206  +  C7H1407. 

Galactosido-glucoheptose         d-Galactose       d-Glucoheptose. 

Glucosido-glucoheptose.  —  CiaH^Oia. 

This  sugar  was  prepared  by  Fischer  ||  through  reduction  of  the 
lactone  of  maltose  carboxylic  acid  (p.  703)  by  sodium  amalgam. 
The  sugar,  which  has  not  been  obtained  in  the  crystalline  form,  gives 
upon  hydrolysis  d-glucose  and  d-glucoheptose. 

*  Chem.  Ztg.,  26,  24. 

t  Chem.  News,  83,  578. 

t  Chem.  Ztg.,  34,  430. 

§  Ber.,  23,  937;  Reinbrecht,  Ann.,  272,  197. 

II  Ber.,  23,  937;  Reinbrecht,  Ann.,  272,  197. 


CHAPTER  XXI 

THE  TRISACCHARIDES  AND   TETRASACCHARTOES 

Trisaccharides 

METHYLPENTOSE-HEXOSE  SACCHARIDES 
RHAMNINOSE. 

,  (CH3C5H804) 


>  (C6Hn05) 

Occurrence  and  Preparation.  —  Rhamninose  is  formed*  by  the 
hydrolysis  of  the  glucoside  xanthorhamnin  by  means  of  the  enzyme 
rhamninase,  which  occurs  associated  with  xanthorhamnin  in  Persian 
berries  (the  fruit  of  Rhamnus  infectoria). 

Rhamninase  is  prepared  by  extracting  Persian  berries  with  water; 
the  enzyme  is  precipitated  from  the  extract  by  means  of  alcohol.  To 
obtain  rhamninose  xanthorhamnin  is  treated  in  aqueous  solution  be- 
tween 45°  and  70°  C.  with  a  solution  of  rhamninase.  The  solution  is  then 
shaken  out  with  ether  to  remove  any  unchanged  xanthorhamnin,  and 
then  after  clarification  by  means  of  bone  black  evaporated  to  a  sirup; 
the  sirup  is  extracted  with  hot  alcohol,  the  alcohol  solution  evaporated 
to  a  sirup,  and  set  aside  for  crystallization.  The  sugar  is  purified  by 
recrystallizing. 

Properties  and  Reactions.  —  Rhamninose  as  above  prepared  con- 
sists of  white  crystals  with  a  composition  and  molecular  weight  cor- 
responding to  the  formula  Ci8H32Oi4.  The  sugar  has  a  mild,  sweet 
taste,  shows  incipient  fusion  at  135°  to  140°  C.  with  decomposition 
and  is  soluble  in  water  and  hot  alcohol,  but  not  in  ether.  Rhamninose 
is  levorotatory  ([a]D=  —  41°)  and  reduces  Fehling's  solution. 

Upon  treatment  with  sodium  amalgam  rhamninose  is  reduced  to 
the  alcohol  rhamninite  Ci8H34Oi4  ([a]D  =  -  57°),  which  upon  heating 
with  dilute  acids  is  hydrolyzed  as  follows: 


2  H20  =  C6H1406 

Dulcite 


2  C6H1205. 

Rhamnose. 


Rhamninite 

Upon  treatment  with  bromine  in  aqueous  solution  rhamninose  is 
*  Tanret,  Compt.  rend.,  129,  725. 
731 


732  SUGAR  ANALYSIS 


oxidized   to  rhamninotrionic   acid    CisH^OisCMu  =  —  94.3   for   acid- 
lactone  mixture),  which  upon  heating  with  dilute  acids  is  hydrolyzed  as 

Ci8H32O15  +  2  H2O  =    C6H1207  +  2  C6H12O5. 

Rhamnino-  d-Galactonic  Rhamnose. 

trionic  acid  acid 

Upon  oxidation  with  nitric  acid  rhamninose  yields  mucic  acid. 
Upon  warming  with  dilute  hydrochloric  or  sulphuric  acid  rhamninose 
is  hydrolyzed  as  follows: 

Ci8H32Oi4  +  2  H20  =  C6H1206  +  2  C6H1205. 

Rhamninose  d-Galactose  Rhamnose. 

These  various  reactions  show  that  rhamninose  is  composed  of  2 
rhamnose  and  1  d-galactose  radicals,  the  latter  having  its  aldehyde 
group  in  a  free  reactive  condition. 

Rhamninose  is  not  fermented  by  yeast.  Invertase,  diastase  and 
emulsin  have  no  hydrolytic  action. 

Rhamninose,  through  the  presence  of  a  reactive  aldehyde  group, 
forms  a  phenylhydrazone  and  osazone,  but  these  compounds  owing  to 
their  extreme  solubility  have  not  been  obtained  in  a  pure  condition. 

TRIHEXOSE  SACCHARIDES 

/  CeHiiOs 
)C6H1004 

XC6HU0S 
RAFFINOSE.  —  Melitriose.      Gossypose. 

C18H32016  +  5  H20. 

Occurrence.  —  Raffinose  is  the  best  known  and  most  widely  dis- 
tributed of  the  trisaccharides.  The  name  raffinose  was  first  given  to  a 
new  sugar  discovered  by  Loiseau*  in  1876  in  the  impure  molasses 
obtained  from  refining  beet  sugar  (French,  raffiner  =  to  refine).  The 
same  sugar  had  been  previously  isolated,  however,  by  Johnstonf  from 
Eucalyptus  manna  in  1843,  afterwards  described  by  Berthelott  as 
melitose.  Tollens,§  however,  showed  that  melitose  was  identical 
with  Loiseau's  raffinose  and  also  proved  the  same  to  be  true  of  gossy- 
pose,  a  sugar  found  by  Ritthausen  ||  and  by  Bohm  1f  in  cottonseed  meal. 
The  identity,  thus  established  by  Tollens,  was  important  for  it  opened 
the  way  to  investigations  which  established  the  wide  occurrence  of 
raffinose  in  the  vegetable  kingdom.  In  addition  to  the  sources  just 
mentioned  raffinose  has  been  found  in  barley  and  other  grains,  in  young 
*  J.  fabr.  sucre.,  24,  52;  26,  22.  §  Ber.,  18,  26. 

t  J.  prakt.  Chem.  [1],  29,  485.  II  J.  prakt.  Chem.  [2],  29,  351. 

t  Ann.  chim.  phys.  [3],  46,  66.  If  J.  prakt.  Chem.  [2],  30,  37. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        733 

wheat  sprouts  (up  to  6.9  per  cent  of  the  dry  substance)  and  in  many 
other  plant  substances. 

Raffinose  has  attracted  most  attention  from  its  occurrence  in  sugar- 
beet  products.  It  had  been  the  opinion  of  many  chemists  that  raffinose 
was  formed  during  the  process  of  manufacture  by  the  action  of  alkalies 
upon  the  sucrose,  invert-sugar  and  other  constituents  of  the  juice; 
Lippmann,*  however,  was  able  to  separate  raffinose  directly  from  ex- 
pressed beet  juice,  thus  proving  that  the  sugar  was  formed  during  the 
growth  of  the  beet.  The  amount  ordinarily  occurring  in  sugar  beets 
is  only  from  0.01  per  cent  to  0.02  per  cent;  under  certain  conditions, 
however,  the  percentage  of  raffinose  may  greatly  exceed  this,  the  re- 
sult, perhaps,  of  abnormal  climatic  causes,  such  as  drought,  excessive 
rain,  freezing,  etc.,  the  exact  role  of  these  various  factors  being  as  yet 
not  clearly  understood.  The  synthesis  of  raffinose  in  the  plant  is  ap- 
parently connected  with  a  saccharification  of  galactan  substances 
(pectin,  etc.)  in  presence  of  sucrose,  the  result  no  doubt  of  enzyme 
action. 

Raffinose  has  also  been  reported  by  Pelletf  and  other  investigators 
in  sugar-cane  molasses,  although  the  claims  for  this  have  been  dis- 
puted by  Lippmann. J  Until  additional  evidence  is  obtained  the 
occurrence  of  raffinose  in  sugar-cane  products  must  be  regarded  as 
exceedingly  unusual. 

Preparation  of  Raffinose.  —  Raffinose  may  be  prepared  from 
Eucalyptus  manna  (a  secretion  from  certain  Eucalyptus  trees,  as  E. 
viminalis  and  E.  Gunnii)  by  extracting  the  manna  with  hot  water, 
clarifying  the  extract  with  bone  black  and  evaporating  to  the  point  of 
crystallization.  A  more  common  material  for  preparing  raffinose  is 
cottonseed  meal;  the  method  of  Zitkowski§  is  as  follows: 

Preparation  of  Raffinose  from  Cottonseed  Meal.  —  Cotton-seed  meal 
is  extracted  with  cold  water  for  1  hour  and  the  filtered  extract  made 
faintly  alkaline  with  milk  of  lime.  The  filtrate  from  precipitated  matter 
is  polarized  (in  terms  of  sucrose)  and  then  treated  at  low  temperature 
with  finely  powdered  quick  lime  in  the  proportion  of  125  parts  CaO  to  100 
parts  of  sugar.  The  precipitate  of  calcium  raffinosate  is  filtered  off, 
washed  with  cold  lime  water  and  then,  after  dissolving  in  hot  water,  car- 
bonated at  80°  C.  almost  to  neutrality.  After  filtering  from  calcium 
carbonate  the  solution  is  concentrated  to  a  sirup  of  about  75  degrees  Brix 
and  set  aside  in  the  cold  to  crystallize.  Priming  with  a  crystal  of  raffi- 
nose will  hasten  the  process.  The  crystals  of  raffinose  are  filtered  off, 

*  Ber.,  18,  3087.  t  Deut.  Zuckerind.,  22,  1439. 

t  Bull,  assoc.  chim.  sucr.  diet.,  14,  139.       §  Am.  Sugar  Ind.,  12,  324. 


734  SUGAR  ANALYSIS 

washed  with  90  per  cent  alcohol  and  purified  by  recrystallization.  In 
one  experiment  by  this  method  600  gms.  of  raffinose  hydrate  were  ob- 
tained from  150  Ibs.  of  cottonseed  meal. 

Preparation  of  Raffinose  from  Beet  Molasses.  —  A  number  of  processes 
haye  been  devised  for  preparing  raffinose  from  beet  molasses. 
Scheibler*  first  noted  that  absolute  methyl  alcohol  had  a  high  solvent 
action  upon  raffinose  (9.8  gms.  raffinose  anhydride  in  100  c.c.)  and  a 
low  solvent  action  upon  sucrose  (0.4  gm.  sucrose  in  100  c.c.).  Using 
this  observation  as  a  basis  Burkhardf  employed  the  following  method : 
A  low-grade  beet  molasses  rich  in  raffinose  (preferably  from  the  stron- 
tium monosaccharate  process)  is  absorbed  upon  clean  dry  wood  shav- 
ings and,  after  thoroughly  drying  in  a  vacuum,  extracted  with  absolute 
methyl  alcohol.  The  extract  is  diluted  with  water,  the  alcohol  evapo- 
rated and  the  solution  boiled,  during  addition  of  crystallized  strontium 
hydrate  with  constant  stirring,  until  a  permanent  crust  of  crystals  be- 
gins to  form  upon  the  surface.  The  strontium  compound  is  filtered  off, 
washed  with  hot  saturated  strontium  hydroxide  solution  and  then  car- 
bonated in  suspension  with  water.  The  solution  is  evaporated,  the  sirup 
dissolved  at  60°  to  70°  C.  in  the  exactly  necessary  amount  of  80  per 
cent  alcohol,  and  then  set  aside  for  24  to  48  hours,  when  raffinose  will 
crystallize  out. 

The  precipitation  of  raffinose  from  molasses  as  lead  raffinosate  by 
means  of  ammoniacal  lead  acetate,  lead  carbonate  or  litharge  has  also 
been  successfully  employed.  ZitkowsldJ  has  used  the  following  proc- 
ess, which  is  based  upon  the  insolubility  of  lead,  raffinosate  and  the 
solubility  of  lead  saccharate  at  high  temperature: 

Thirty  pounds  of  the  molasses  are  diluted  to  about  50  degrees 
Brix,  brought  to  a  boil  with  the  addition  of  3  pounds  of  litharge  and 
filtered,  this  being  done  for  the  purpose  of  precipitating  some  of  the 
lead  salts  that  form.  Then  3  pounds  more  of  lead  oxide  are  taken  and 
just  sufficient  of  the  purified  molasses  filtrate  added  to  form  a  thin 
paste.  The  mixture  is  stirred  for  about  an  hour  in  the  cold  when  the 
formation  of  lead  saccharate  begins;  the  mass  which  becomes  stiff  is 
then  allowed  to  set  twenty-four  hours.  The  main  portion  of  the  molasses 
solution  is  then  brought  to  a  boil  and  the  lead  saccharate  added  in  small 
portions  at  a  time  in  order  to  disintegrate  the  mass.  When  all  of  the 
lead  saccharate  is  added,  the  mixture  is  kept  at  boiling  for  about  thirty 
minutes,  then  filtered  and  thoroughly  washed  with  water.  The  lead  com- 

*  Ber.,  19,  2868. 

t  Neue  Ztschr.  Rubenzuckerind.,  20,  16. 

j  Am.  Sugar  Ind.,  13,  8. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        735 

pound  thus  obtained  is  decomposed  with  carbon  dioxide,  filtered  and 
evaporated  to  a  light  sirup.  The  sirup  is  treated  with  blood  black  and 
again  filtered,  evaporated  on  a  water  bath  to  a  heavy  sirup  and  set 
away  to  crystallize.  The  filtration  of  the  lead  raffinosate  should  be 
performed  as  hot  and  as  quickly  as  possible,  otherwise  considerable 
quantities  of  lead  saccharate  will  be  precipitated.  The  crystallization 
of  the  final  sirup  can  be  accelerated  by  priming  with  a  pinch  of  pure 
raffinose. 

Properties.  —  Raffinose  crystallizes  from  aqueous  solution  in  the 
form  of  long  pointed  needles  or  prisms,  with  a  composition  and  mo- 
lecular weight  corresponding  to  the  formula  Ci8H32Oi6  +  5  H2O.  The 
crystals  upon  gradual  warming  at  80°  C.  for  several  hours  and  then  at 
100°  to  105°  C.  lose  all  their  water  and  pass  without  melting  into  the 
anhydride.  Upon  rapid  heating  the  crystals  melt  in  their  water  of 
crystallization  below  100°  C.;  under  this  condition  the  last  traces  of 
water  are  removed  only  at  125°  to  130°  C.  when  decomposition  sets  in 
with  brown  coloration  and  odor  of  caramel.  The  sensibility  of  raffinose 
to  destructive  changes  upon  rapid  heating  is  shown  by  raffinose-con- 
taining  beet  sugar,  which  darkens  at  120°  to  125°  C.;  while  ordinary 
beet  sugar,  free  from  raffinose,  is  not  as  a  rule  affected. 

Raffinose  anhydride  has  the  formula  Ci8H32Oi6  and  consists  of  a 
white  amorphous  hygroscopic  mass  which  upon  exposure  to  moist  air 
reabsorbs  after  several  days  the  entire  amount  of  water  of  crystalliza- 
tion. 

Raffinose  hydrate  is  more  soluble  than  sucrose  in  hot  water,  but  less 
soluble  in  cold  water;  14  to  15  parts  of  water  are  necessary  to  dissolve 
raffinose  at  0°  C.,  9  parts  at  10°  C.  and  6  parts  at  16°  C.  Supersatu- 
rated solutions  are  easily  formed  from  which  the  raffinose  is  deposited 
upon  long  standing.  Raffinose  is  insoluble  in  absolute  ethyl. alcohol  or 
in  ether;  its  solubility  in  absolute  methyl  alcohol  is  considerable  as 
previously  stated.  Raffinose,  through  its  property  of  combining  with 
water  of  hydration,  seems  to  possess  the  property  of  throwing  sucrose 
out  of  solution.* 

Influence  of  Raffinose  Upon  the  Crystalline  Form  of  Sucrose.  —  The 
presence  of  raffinose  exerts  a  peculiar  effect  in  giving  crystals  of  sucrose 
a  pointed  needle-like  structure;  3  per  cent  raffinose  in  a  sugar  sirup  may 
produce  a  sensible  elongation  of  the  grain,  the  pointed  character  of  the 
crystals  increasing  with  the  amount  of  raffinose  present.  This  altera- 
tion in  grain  is  frequently  noted  in  the  crystallization  of  low-grade 
beet  products  and  is  usually  an  indication  of  the  presence  of  raffinose. 
*  Herzfeld,  Z.  Ver.  Deut.  Zuckerind.,  42,  207. 


736  SUGAR  ANALYSIS 

It  must  be  remembered,  however,  that  other  impurities  (organic  lime 
salts,  caramelization  products,  etc.)  may  produce  under  certain  con- 
ditions a  pointed  grain,  especially  when  crystallization  takes  place 
from  viscous  supersaturated  solutions.  On  the  other  hand,  raw  beet 
sugars  may  contain  4  to  5  per  cent  of  raffinose  without  alteration  of 
grain,  in  case  the  raffinose  remains  dissolved  in  the  molasses  coating  of 
the  crystals.* 

Specific  Rotation.  —  In  aqueous  solution  raffinose  is  strongly  dextro- 
rotatory, the  value  of  [a]D  for  the  hydrate  ranging  from  +  104  to  +  105.7, 
according  to  different  observers  for  different  preparations  of  sugar. 
For  purposes  of  analysis  the  value  +  104.5  may  be  used  without  serious 

(104  5  \ 

„  .   '    X  100J- 

The  observations  of  Creydtf  show  a  slight  falling  off  in  specific  rota- 
tion with  increase  in  temperature. 

Reactions.  —  Raffinose  does  not  reduce  Fehling's  solution,  be- 
having in  this  respect  similar  to  sucrose.  Raffinose  also  shows  the 
same  resistance  to  the  action  of  alkalies  as  sucrose.  Both  of  these  re- 
actions indicate  the  absence  in  raffinose  of  a  functional  aldehyde  or 
ketone  group.  Upon  oxidation  with  nitric  acid  raffinose  yields  a  mixture 
of  acids,  of  which  oxalic,  saccharic  and  mucic  are  the  most  important. 
The  yield  of  mucic  acid  from  raffinose  hydrate  by  the  method  of  Tollens 
is  22  to  23  per  cent,  which  corresponds  to  about  30  per  cent  galactose 
(yield  of  mucic  acid  from  galactose  by  same  method  is  77  to  78  per 
cent). 

Hydrolysis  of  Raffinose  by  means  of  Acids.  —  Upon  heating  with 
dilute  hydrochloric  or  sulphuric  acid  raffinose  is  hydrolyzed  according  to 
the  following  equation: 

C18H32016  +  2  H20  =  C6H1206  +  C6H1206  +  C6H1206. 

Raffinose  d-Glucose  d-Galactose          d-Fructose. 

The  total  yield  of  reducing  sugars  according  to  this  equation  would 
be  107.1  per  cent  for  the  anhydride  and  90.9  per  cent  for  the  hydrate. 
The  yield  of  galactose  from  raffinose  hydrate  according  to  theory 
would  be  30.3  per  cent,  which  agrees  closely  with  the  value  calculated 
from  the  yield  of  mucic  a'cid. 

The  hydrolysis  of  raffinose,  as  Tollens  J  first  showed,  proceeds  in  sev- 
eral phases.  The  first  step  in  the  reaction  is  the  splitting  off  of  fructose; 
glucose  and  galactose  appear  only  at  a  later  stage  of  the  reaction. 
Scheibler  and  Mittelmeier§  showed  that  by  moderate  warming  with 

*  Herzfeld,  Z.  Ver.  Deut.  Zuckerind,  39,  661.  }  Ann.,  232,  169. 

t  Z.  Ver.  Deut.  Zuckerind.   37,  153.  §  Ber.,  22,  1678,  26,  2930. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        737 

dilute  acid  (as  10  gms.  raffinose  +  90  c.c.  water  +  6  c.c.  hydrochloric 
acid  1.19  sp.  gr.  10  minutes  at  68°)  the  reaction  proceeds  as  follows: 


CisH^Oie  -f-  H^O  =  CeH^Oe  +  C^H^Ou. 

Raffinose  d-Fruotose  Melibiose. 

It  is  only  by  prolonged  heating  with  more  concentrated  acid  that 
the  melibiose  (see  p.  723)  is  hydrolyzed  into  d-glucose  and  d-galactose, 
the  complete  conversion  of  the  melibiose  being  accompanied  by  a  par- 
tial destruction  of  the  fructose.  As  a  rule  less  than  90  per  cent  of  the 
theoretical  yield  of  monosaccharides  is  obtained  by  the  acid  hydrolysis 
of  raffinose  under  the  most  favorable  conditions. 

During  the  hydrolysis  of  raffinose  the  specific  rotation  undergoes  a 
marked  decrease,  the  final  reading  depending  upon  the  extent  of  the  hy- 
drolysis. For  the  ordinary  method  of  Clerget  inversion  the  specific  rota- 
tion of  raffinose  hydrate  decreases  from  +  104.5  to  about  +  53  or  +  54, 
which  corresponds  to  the  mixture  of  fructose  and  melibiose  required  by 
the  preceding  equation  (30.30  per  cent  fructose  and  57.57  per  cent  meli- 
biose).* Upon  prolonged  heating  with  acid  the  specific  rotation  of 
raffinose  was  found  by  Tollens  to  sink  as  low  as  +-  20.  The  theoretical 
value  f  for  a  mixture  of  30.3  per  cent  each  of  d-glucose,  d-galactose  and 
d-fructose  is  about  +  12.50;  decomposition  of  fructose,  however,  sets 
in  before  this  limit  is  reached  so  that  higher  figures  of  variable  value 
are  obtained. 

Hydrolysis  of  Raffinose  by  Means  of  Enzymes.  —  The  hydrolysis  of 
raffinose  can  also  be  effected  by  means  of  enzymes,  the  nature  of  the  re- 
action depending  upon  the  character  of  the  enzyme. 

Invertase  hydrolyzes  raffinose  into  d-fructose  and  melibiose,  as  al- 
ready described  under  the  latter  sugar.  Emulsin,  on  the  other  hand, 
hydrolyzes  raffinose  into  d-galactose  and  sucrose.  The  general  formula 
for  both  of  these  reactions  is  the  same  : 

C18H32016  +  H20  =  C6H1206  +  CuHaOii. 

T?  «?          /  +  invertase      =  d-fructose       +  melibiose. 
I  4-  emulsin         =  d-galactose     +  sucrose. 

For  the  complete  hydrolysis  of  raffinose  into  its  component  mono- 
saccharides the  action  of  two  different  enzymes  is  necessary  and  it  is 

*  The  57.57  per  cent  melibiose  anhydride  would  give  a  rotation  of  0.5757 
X  +143  =  +82.3;  the  30.30  per  cent  fructose  would  give  a  rotation  of  0.303  X  —92 
=  -27.9.  The  combination  of  those  effects  would  be  +82.3  -  27.9  =  +54.4. 

t  The  30.3  per  cent  d-glucose  would  give  a  rotation  of  0.303  X  +52.5  =  +15.9; 
the  30.3  per  cent  d-galactose  would  give  0.303  X  +81  =  +24.5;  the  30.3  per  cent 
d-fructose  would  give  0.303  X  —  92  =  —27.9.  The  combination  of  these  effects 
would  be  +15.9  +  24.5  -  27.9  =+12.5. 


738  SUGAR  ANALYSIS 

evident  that  this  can  be  accomplished  by  the  action  of  invertase  and 
melibiase  (p.  723),  or  by  that  of  emulsin  followed  by  invertase. 

These  reactions  may  be  explained  by  assuming  the  following  ar- 
rangement for  the  monosaccharide  groups  in  raffinose. 

t 

C6HnO5  -  O  -  C6H10O4  -  O  -  C6Hu05. 

d-Fructose  d-Glucose  d-Galactose 

radical  radical  radical 


Sucrose  Melibiose. 

The  hydrolysis  by  means  of  invertase  or  weak  acids  takes  place  at 
the  O  atom  marked  *;  the  hydrolysis  by  means  of  emulsin  takes  place 
at  the  0  atom  marked  f- 

Fermentation  of  Raffinose.  —  The  fermentation  of  raffinose  by 
means  of  yeast  depends  upon  the  character  of  the  enzymes  which  are 
present.  Bottom  yeasts,  which  contain  both  invertase  and  melibiase 
and  can  thus  effect  a  complete  hydrolysis,  ferment  raffinose  completely, 
although  somewhat  more  slowly  than  sucrose.  Top  yeasts,  on  the  other 
hand,  which  do  not  ordinarily  contain  melibiase,  ferment  only  the 
fructose  part  of  the  molecule  with  a  corresponding  reduction  in  the 
yield  of  alcohol.  The  theoretical  equations  for  the  two  fermentations 
would  be: 
Bottom  yeast,  Ci8H32Oi6+2  H2O  =  6  C2H5OH  +  6  C02. 

Raffinose  Alcohol  (54.78  per  cent)  Carbon  dioxide. 

Top  yeast,  Ci8H32Oi6  +  H2O  =       2  C2H5OH       +  2  CO2    +  Ci2H22On. 

Raffinose  Alcohol  (18. 2 6  per  cent)        Carbon  Melibiose. 

dioxide 

The  yield  of  alcohol,  expressed  in  percentage  of  raffinose  anhydride, 
is  somewhat  less  in  actual  practice  than  indicated  above. 

A  number  of  moulds  (species  of  Monilia,  Amylomyces  and  Aspergil- 
lus)  also  hydrolyze  and  ferment  raffinose.  Other  moulds,  as  Aspergillus 
niger  and  Penicillium  glaucum,  hydrolyze  raffinose  but  instead  of  pro- 
ducing alcohol  form  acid  oxidation  products  such  as  oxalic  and  succinic 
acids. 

Special  bacteria  also  ferment  raffinose  with  production  of  lactic  and 
butyric  acids. 

Compounds  of  Raffinose.  —  Owing  to  the  absence  of  a  reactive 
aldehyde  or  ketone  group,  raffinose  does  not  form  hydrazones,  osazones, 
mercaptals,  ureides,  oximes  or  any  other  of  the  numerous  compounds 
which  are  characteristic  of  reducing  sugars. 

Upon  heating  raffinose  with  acetic  anhydride  Scheibler  and  Mittel- 
meier*  obtained  a  hendecacetate,  Ci8H2i(C2H3O)iiOi6.  After  recrys- 

*  Ber.,  23,  1438. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES 

tallizing  from  hot  absolute  alcohol,  the  compound  was  obtained  as 
white  leaflets  melting  at  99°  to  101°  C.;  it  is  soluble  in  absolute  alcohol, 
aniline,  chloroform  and  benzol  and  is  dextrorotatory,  [a]D  =  +  92.2. 
Tanret*  has  prepared  a  dodecacetate  of  raffinose,  Ci8H20(C2H30)i2Oi6; 
[a]D  =+100.3. 

S  toilet  obtained  by  the  usual  methods  a  raffinose  octobenzoate, 
Ci8H24(C7H50)8Oi6;  the  compound  consists  of  a  white  powder,  melting 
at  98°  C.  and  showing  in  glacial  acetic  acid  [oi\D  =  -f-  4.1. 

Raffinose  forms  a  number  of  compounds  with  the  alkalies,  alkaline 
earths  and  other  metals.  These  compounds  have  been  especially 
studied  by  Beythien  and  TollensJ  from  whose  work  the  following  ex- 
amples are  taken. 

Sodium  raffinosate,  Ci8H3iNaOi6,  is  obtained  by  precipitating  an  alco- 
holic raffinose  solution  with  a  one-molecular  proportion  of  sodium  alco- 
holate.  By  taking  a  two-molecular  proportion  of  sodium  alcoholate 
the  compound  Ci8H3iNaOi6  +  NaOH  is  obtained.  Both  substances  are 
white  amorphous  powders. 

Barium  raffinosates,  corresponding  to  the  formulae  Ci8H32Oi6'BaO  and 
Ci8H32Oi6«2BaO,  are  obtained  by  mixing  barium  hydroxide  and  raffinose 
solutions  in  presence  of  alcohol  in  the  proper  molecular  proportions. 
The  compounds  were  obtained  as  white  amorphous  substances  of 
imperfect  purity. 

Strontium  raffinosate,  of  the  formula  Ci8H32Oi6«2  SrO  +  H20,  is  ob- 
tained by  heating  a  solution  of  strontium  hydroxide  and  raffinose,  as 
a  sticky  mass  which  becomes  granular  upon  long  boiling  or  upon  addi- 
tion of  alcohol.  The  compound  consists  of  a  white  granular  amorphous 
powder  which  loses  its  water  of  combination  at  80°  C.  Raffinose  com- 
pounds containing  1  SrO  and  3  SrO  have  not  as  yet  been  obtained. 

Calcium  raffinosate,  Ci8H32Oi6'3  CaO  +  3  H2O,  is  obtained  by  heating 
a  raffinose  solution  saturated  with  calcium  hydroxide.  The  compound 
consists  of  a  white  amorphous  powder  which  loses  its  water  of  combina- 
tion at  100°  C. 

Lindet  §  by  dissolving  calcium  hydroxide  in  a  cold  raffinose  solution 
obtained  the  compound  Ci8H32Oi6-2  CaO  +  5  H2O.  Lindet  also  noted 
upon  treating  a  solution  of  sucrose,  raffinose  and  lime  with  alcohol  that 
calcium  raffinosate  was  dissolved  mostly  by  weak  and  calcium  saccharate 
mostly  by  strong  alcohol.  This  method  has  been  proposed  as  a  means 
of  separating  sucrose  and  raffinose,  but  is  inferior  to  the  methods  de- 
scribed under  preparation  of  raffinose. 

*  Bull.  soc.  chim.  [3],  13,  261.  t  Z.  Ver.  Deut.  Zuckerind.,  39,  894. 

f  Z.  Ver.  Deut.  Zuckerind.,  61,  33.        §  J.  fabr.  sucre,  31,  19. 


740  SUGAR  ANALYSIS 

Lead[raffinosate,  Ci8H32Oi6'3  PbO,  was  obtained  by  Lippmann* 
upon  treating  raffinose  solutions  with  ammoniacal  lead  subacetate. 
Lead  raffinosate  can  also  be  prepared  by  heating  raffinose  solutions 
with  litharge  or,  according  to  Wohl,f  more  advantageously  by  heating 
with  lead  saccharate  (see  under  preparation  of  raffinose). 

Tests  for  Raffinose.  —  As  in  the  case  of  most  other  sugars  the 
only  absolute  test  for  raffinose  is  the  separation  of  the  sugar  in  pure 
crystalline  form  and  the  determination  of  its  specific  rotation,  products 
of  hydrolysis  and  other  properties.  For  the  separation  of  raffinose 
any  of  the  methods  described  under  preparation  may  be  used. 

It  is  evident  from  its  composition  that  raffinose  after  hydrolysis 
will  give  any  of  the  reactions  described  for  d-glucose,  d-fructose  and 
d-galactose,  so  that  ordinary  qualitative  tests  are  valueless  when 
several  of  these  sugars  are  present.  The  removal  of  fermentable  sugars 
by  a  pure  culture  of  top  yeast,  and  examination  of  the  residual  sugars 
for  melebiose  may  be  used  for  corroboration.  For  quantitative  methods 
of  determining  raffinose  see  page  281. 

Configuration.  —  The  probable  arrangement  of  the  monosaccharide 
groups  in  raffinose  has  already  been  given;  the  manner  in  which  these 
different  groups  are  combined  has  not,  however,  been  established. 
The  following  configuration  is  regarded  at  present  as  the  one  which 
corresponds  most  closely  to  the  properties  of  raffinose. 

CH2OH 


d-Galactose  radical  d-Glucose  radical  d-Fructose  radical 

The  synthesis  of  raffinose  has  not  as  yet  been  effected. 

MELEZITOSE.  —  Melezitriose.     Ci8H32Oi6  +  2  H2O. 

Occurrence.  —  This  trisaccharide,  first  observed  in  1833  by  Bo- 
nastre,J  has  been  found  for  the  most  part  as  a  constituent  of  the  secre- 
tions of  different  trees,  such  as  manna  of  Pinus  larix,  manna  of  Alhagi 
Maurorum  (Turkestan  manna),  Lahore  manna,  honey  dew  of  the 

*  Z.  Ver.  Deut.  Zuckerind.,  36,  257. 

t  Deut.  Zuckerind.,  25,  1125. 

j  J.  pharm.  chim.  [2],  8,  335;  19,  443,  626. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        741 

linden,  etc.  The  sugar  was  named  melezitose  by  Berthelot*  in  1856, 
and  was  supposed  by  him  to  be  a  disaccharide;  Alekhine,f  however, 
proved  the  sugar  to  be  without  question  a  trisaccharide. 

Preparation.  —  For  the  preparation  t  of  melezitose  Turkestan 
manna  §  (Turandjabine)  is  extracted  with  warm  water,  and  the  filtered 
solution  concentrated  to  a  sirup;  an  excess  of  methyl  alcohol  is  then 
added  when  crystallization  takes  place  within  24  hours.  The  crude 
sugar  is  purified  by  means  of  bone  black;  coloring  matter  is  precipitated 
by  a  little  barium  hydroxide  solution,  any  excess  of  the  latter  being  re- 
moved with  ammonium  carbonate.  The  filtrate  is  again  concentrated  and 
crystallized  in  presence  of  methyl  alcohol.  The  yield  of  pure  melezitose 
by  this  method  is  36  per  cent  of  the  manna  taken. 

Properties.  —  Melezitose  as  ordinarily  prepared  consists  of  white 
rhombic  crystals  with  a  composition  and  molecular  weight  correspond- 
ing to  the  formula  Ci8H320i6  +  2  H2O.  The  crystals  of  the  hydrate 
effloresce  upon  exposure  to  the  air  and  with  gradual  elevation  of  tem- 
perature give  up  their  water,  passing  without  decomposition  into  the 
anhydride  Ci8H32Oi6.  The  latter  may  also  be  obtained  directly  upon 
crystallizing  melezitose  from  hot  concentrated  aqueous  or  alcoholic 
solutions.  Melezitose  anhydride  consists  of  a  white  crystalline  powder 
which  upon  rapid  heating  melts  at  148°  to  150°  C.;  it  is  soluble  in  2.73 
parts  of  water  at  17.5°  C.  and  0.32  part  at  100°  C.,  it  is  slightly  soluble 
in  hot  alcohol  but  insoluble  in  ether. 

Melezitose  is  dextrorotatory,  [a]D  for  the  anhydride  =  +  88.5  and 
for  the  hydrate  +  83.  Mutarotation  does  not  exist. 

Reactions  and  Hydrolysis.  —  Hot  solutions  of  dilute  alkalies  are 
without  action  upon  melezitose.  The  sugar  like  raffinose  does  not  reduce 
Fehling's  solution.  Upon  heating  with  dilute  hydrochloric  or  sulphuric 
acid  melezitose  is  hydrolyzed,  the  reaction  proceeding  as  Alekhinell 
found  in  two  distinct  stages. 

The  first  phase  of  the  hydrolysis  consists  in  the  conversion  of  me- 
lezitose into  d-glucose  and  the  disaccharide  turanose. 

Ci8H32Oi6  +  H2O  =  C6H12O6  +  Ci2H22On.  (1) 

Melezitose  d-Glucose  Turanose. 

This  part  of  the  hydrolysis  is  best  performed  by  means  of  20  per  cent 
hydrochloric  acid  in  the  cold  or  upon  warming  with  1  per  cent  sulphuric 

*  Compt.  rend.,  47,  224. 

t  Bull.  soc.  chim.  [2],  46,  824. 

t  Maquenne's  "  Les  Sucres."  p.  701. 

§  Turkestan  manna,  or  Turandjabine,  is  used  in  the  Orient  for  sweetening 
drinks.  It  is  sold  in  Tashkend  under  the  name  of  Koum-tchakar  (Koum  =  sand; 
tchakar  =  sugar).  II  Ann.  chim.  phys.  [6],  18,  532. 


742  SUGAR  ANALYSIS 

acid;  the  rotation  of  the  sugar  falls  from  +  83  for  the  hydrate  to  about 
-f  63  which  marks  the  completion  of  the  first  step  in  the  hydrolysis. 

Up6n  prolonged  boiling  with  dilute  hydrochloric  or  sulphuric  acid, 
melezitose  is  completely  hydrolyzed  into  d-glucose : 

CigHwOie  +  2  H20  =  3  C6H1206.  (2) 

Melezitose  d-Glucose. 

In  this  second  phase  of  the  hydrolysis  the  turanose,  which  is  first 
formed,  is  split  up  into  two  molecules  of  d-glucose,  and  the  specific 
rotation  falls  to  about  +51  which  agrees  very  closely  with  that  of 
d-glucose. 

In  the  second  stage  of  the  hydrolysis,  according  to  Tanret,  turanose 
is  hydrolyzed  into  d-glucose  and  d-fructose,  so  that  melezitose  would 
give  upon  complete  hydrolysis  2  molecules  of  d-glucose  and  1  molecule  of 
d-fructose.  The  calculated  rotation  of  the  latter  mixture  would  be 
about  +  4.5  which  does  not  agree  with  the  value  obtained  by  Alekhine 
for  hydrolyzed  melezitose.  Additional  investigation  is  needed  to  de- 
cide the  question.  (See  under  turanose,  p.  725). 

Compounds.  —  Upon  acetylating  with  acetic  anhydride  Alekhine 
obtained  a  hendecacetate,  CisH2i(C2H30)iiOi6,  which  consists  of  large 
monoclinic  prisms  melting  at  170°  C.;  it  is  non-reducing,  insoluble  in 
water,  soluble  in  alcohol  and  benzol  and  shows  in  benzol  solution 
[^  =  +110.44. 

Fermentation.  —  Melezitose  is  not  fermented  by  yeast.  Asper- 
gillus  niger  effects  a  slow  hydrolysis  at  50°  C.  into  d-glucose  and  turan- 
ose, but  is  without  further  change. 

GENTIANOSE.  —  Ci8H32Oi6. 

Occurrence.  —  This  trisaccharide  was  discovered  by  Meyer*  in 
the  roots  of  Gentiana  lutea  and,  according  to  Bourquelot  and  Nardin,f 
occurs  also  in  other  members  of  the  Gentian  family. 

Preparation.  —  Fresh  Gentian  roots  are  ground  and  extracted  for 
20  to  25  minutes  with  boiling  95  per  cent  alcohol  using  a  reflux  con- 
denser. The  alcoholic  extract  is  pressed  out,  the  alcohol  distilled  off, 
excess  of  calcium  carbonate  added  to  neutralize  acid  and  the  solution 
filtered.  The  filtrate  is  evaporated  to  a  sirup,  freed  from  gummy  matter 
by  precipitation  with  95  per  cent  alcohol,  and  the  clear  alcoholic  solu- 
tion filtered  and  set  aside.  Crystals  of  gentianose  separate  after  about 
2  weeks'  standing;  they  are  filtered  off  and  purified  by  recrystallization. 

The  Gentian  roots  employed  for  the  preparation  of  gentianose  must 
be  fresh;  old  or  dried  roots  or  aqueous  extracts  do  not  yield  gentianose 

*  Ber.,  15,  530;  Z.  physiol.  Chem.,  6,  135.  f  Compt.  rend.,  126,  280. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        743 

on  account  of  its  hydrolysis  by  an  enzyme  into  d-fructose  and  genti- 
obiose. 

Properties.  —  Gentianose  is  obtained  in  the  form  of  white  crystals, 
melting  at  209°  to  210°  C.  and  having  a  composition  and  molecular 
weight  corresponding  to  the  formula  C18H32O16.  The  sugar  is  easily 
soluble  in  cold  water,  slightly  soluble  in  boiling  alcohol,  insoluble  in 
absolute  alcohol  and  ether.  Gentianose  is  dextrorotatory,  [a]D  —  +  33.4 
(Meyer),  +  31.25  (Bourquelot  and  Nardin).  After  boiling  the  solution 
Meyer  noted  in  one  instance  [a]D  =  +  65.7.  Whether  this  is  due  to 
mutarotation  or  to  some  chemical  change  is  uncertain.  Gentianose 
does  not  reduce  Fehling's  solution. 

Hydrolysis  of  Gentianose.  —  Gentianose  upon  heating  with  acids 
undergoes  hydrolysis,  the  reaction  proceeding  as  shown  by  Bourquelot 
and  Herissey  in  two  distinct  stages.  In  the  first  phase  of  the  hydrolysis 
gentianose  is  hydrolyzed  into  d-fructose  and  the  disaccharide  genti- 
obiose  (p.  726). 

CisH^Oie     +     H20      =      CeH^Oe     +     Ci2H22On. 

Gentianose  d-Fructose  Gentiobiose. 

This  step  of  the  hydrolysis  is  best  carried  out  as  described  under  genti- 
obiose. 

Upon  heating  gentianose  with  3  per  cent  sulphuric  acid,  the  genti- 
obiose  which  is  first  split  off  is  hydrolyzed  into  2  molecules  of  d-glucose 
(p.  726).  The  complete  hydrolysis  of  gentianose  is  then  expressed  as 
follows : 

C18H32016    +    2H20      =      C6H1206    +    2C6H1206. 

Gentianose  d-Fructose  d-Glucose. 

Fermentation  and  Action  of  Enzymes.  —  Gentianose  is  only  one- 
third  fermented  by  yeast,  the  invertase  of  the  latter  splitting  off  d-fruc- 
tose, which  is  fermented,  and  the  gentiobiose  remaining  unfermented. 
Aspergillus  niger  contains  enzymes,  which  effect  the  complete  hydrolysis 
of  gentianose,  and  thus  ferment  the  sugar  entirely.  Diastase  and 
emulsin  are  without  action  on  gentianose.  Emulsin,  however,  can 
hydrolyze  gentiobiose,  so  that  yeast  in  presence  of  emulsin  can  ferment 
gentianose  completely.  According  to  Bourquelot  emulsin  seems  to  be 
accompanied  at  times  by  an  enzyme  which  hydrolyzes  gentianose  into 
d-glucose  and  sucrose. 

Configuration.  —  The  arrangement  of  the  monosaccharide  groups 
in  gentianose  is  probably  as  follows: 

t 

C«H,,05  -  O  -  C6H1004  -  O  -  C6HU06. 

d-Fructose  d-Glucose  d-Glucose 

radical  radical  radical 

Sucrose  Gentiobiose 


744  SUGAR  ANALYSIS 

The  hydrolysis  by  means  of  weak  acids  or  invertase  takes  place  at 
the  0  atom  marked  *.  The  hydrolysis  into  d-glucose  and  sucrose 
would  take  place  at  the  O  atom  marked  f-  The  non-reducing  proper- 
ties of  gentianose  show  that  none  of  its  monosaccharide  components 
contains  a  reactive  aldehyde  or  ketone  group;  the  manner  in  which  the 
monosaccharide  groups  of  gentianose  are  united  is  not  known,  so  that 
the  configuration  of  this  trisaccharide  still  remains  uncertain. 

MANNATRISACCHARIDE,  —  Ci8H32Oi6. 

Occurrence.  —  Mannatrisaccharide  was  discovered  by  Tanret  * 
in  the  manna  of  the  ash  tree  (Fraxinus  Ornus,  F.  rotundifolia,  etc.),  of 
which  it  makes  up  from  about  6  to  16  per  cent.  Ash  manna  also 
contains  from  40  to  60  per  cent  of  mannite  and  a  smaller  amount  of 
mannatetrasaccharide  or  stachyose  (see  p.  747) ;  in  the  preparation  of 
mannatrisaccharide  it  is  necessary  to  remove  these  accompanying  con- 
stituents by  fractional  crystallization  and  precipitation. 

Preparation.  —  Ash  manna  is  extracted  with  70  per  cent  alcohol, 
and  the  mannite  which  crystallizes  out  separated  by  filtration.  The 
mother  liquor  is  then  evaporated  to  dryness  and  extracted  first  with 
boiling  95  per  cent  and  then  with  boiling  85  per  cent  alcohol.  In  this 
manner  the  mannite  is  mostly  eliminated  and  a  residue  obtained  show- 
ing a  rotation  of  about  [a]D  =  +  140.  The  solution  of  the  residue  is 
then  fractionally  precipitated  with  barium  hydroxide  in  presence  of  alco- 
hol; the  two  fractions  are  decomposed  separately  with  carbon  dioxide 
to  precipitate  barium  and  the  solutions  evaporated  io  crystalliza- 
tion. The  crude  sugars  are  recrystallized  several  times  when  manna- 
trisaccharide is  obtained  from  one  portion  and  mannatetrasaccharide 
from  the  other. 

Properties. — Mannatrisaccharide  is  a  white  sweet  crystalline  sub- 
stance, very  hygroscopic  and  melting  at  about  150°  C.  It  is  easily 
soluble  in  water,  soluble  at  15°  C.  in  60  parts  85  per  cent  and  in  130 
parts  90  per  cent  alcohol  and  at  78°  C.  in  200  parts  absolute  alcohol. 
Mannatrisaccharide  reduces  Fehling's  solution  about  one-third  as 
strong  as  d-glucose  and  is  strongly  dextrorotatory,  [a]D  =  +  167. 

Upon  heating  with  dilute  acids  mannatrisaccharide  is  hydrolyzed 
into  1  molecule  of  d-glucose  and  2  molecules  of  d-galactose. 

C18H32O16        +     2H2O     =     C6H12O6     +     2C6H12O6 

Mannatrisaccharide  d-Glucose  d-Galactose. 

Upon  oxidation  with  bromine  in  aqueous  solution  mannatrisaccharide 
*  Compt.  rend.,  134,  1586. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        745 


is  oxidized  to  mannatrionic  acid,  C^H^On,  which  upon  warming  with 
dilute  acids  is  hydrolyzed  as  follows  : 

C18H32017     +     2H20    =    C6H1207     +     2C6H1206 

Mannatrionic  acid  d-Gluconic  d-Galactose. 

acid 

This  reaction  shows  that  the  functional  aldehyde  group  of  manna- 
trisaccharide  belongs  to  the  d-glucose  group. 

Mannatrisaccharide  is  slowly  fermented  by  yeast,  but  the  complete- 
ness of  this  fermentation  has  not  been  determined. 

Owing  to  the  presence  of  a  reactive  aldehyde  group  mannatrisac- 
charide  forms  with  phenylhydrazine  a  yellow  amorphous  hydrazone, 
easily  soluble  in  water  and  alcohol,  and  a  crystalline  osazone  melting 
at  122°  C.  and  quite  soluble  in  water. 

Mannatrisaccharide  forms  a  dodecacetate,  Ci8H2o(C2H3O)i2Oi6,  ([a]D 
in  alcohol  =  +135).  Barium  hydroxide,  in  presence  of  alcohol,  precipi- 
tates Ci8H32Oi6  •  BaO  and  ammoniacal  lead  subacetate,  Ci8H24Pb4Oi6. 

Lactosinose.  —  Lactosin.     Ci8H32Oi6? 

Occurrence.  —  This  sugar  was  discovered  by  Meyer*  in  the  roots  of 
Silene  vulgaris  and  other  Cariophyllacese.  It  has  also  been  found  in 
Quillai-bark  (bark  of  Quillaia  Saponaria)  and  in  Saponaria  rubra. 

Preparation.  The  expressed  juice  of  the  roots  of  Silene  vulgaris  is 
treated  with  an  excess  of  strong  alcohol.  The  precipitate  is  dissolved  in 
water,  clarified  with  lead  subacetate,  the  solution  filtered  and  treated 
with  ammoniacal  lead  acetate;  the  lead  lactosinate  is  filtered  off,  de- 
composed in  aqueous  suspension  with  hydrogen  sulphide,  the  solution 
filtered  from  lead  sulphide  and  evaporated;  the  sirup  thus  obtained  is 
treated  with  strong  alcohol  and  the  precipitated  sugar,  consisting  of  an 
amorphous  mass,  dried  first  over  concentrated  sulphuric  acid  and  then  at 
110°  C.  The  dried  product  is  then  boiled  1  to  3  days  with  80  per  cent 
alcohol  under  a  reflux  condenser;  the  quantity  of  alcohol  should  not  be 
sufficient  to  dissolve  all  the  crude  sugar.  Upon  filtering  the  alcoholic 
extract  and  cooling,  the  lactosinose  is  deposited  as  crystals,  which  may 
be  purified  if  necessary  by  recrystallization. 

Properties.  —  Lactosinose,  as  above  prepared,  consists  of  small  glis- 
tening crystals  which,  after  drying  over  concentrated  sulphuric  acid,  have 
a  composition  corresponding  to  Ci8H32Oi6(  or  C36H64O32).  The  sugar  is 
easily  soluble  in  water,  somewhat  soluble  in  50  per  cent  alcohol  and  is 
dissolved  by  350  parts  of  hot  80  per  cent  alcohol.  The  concentrated 
aqueous  solution  is  very  viscous.  Lactosinose  is  strongly  dextro- 
rotatory, [a]^=+211.7.  Upon  drying  at  110°  C.  lactosinose  be- 

*  Ber.,  17,  685. 


746  SUGAR  ANALYSIS 

comes  amorphous  and  in  this  condition  shows  a  lower  rotation, 
[a]D  =  +  168  to +  190. 

Lactosinose  is  not  affected  by  boiling  solutions  of  dilute  alkalies 
and  does  not  reduce  Fehling's  solution  except  after  long  boiling  (7 
minutes)  when  a  very  slight  reduction  may  take  place.  Upon  oxida- 
tion with  nitric  acid  a  large  amount  of  mucic  acid  is  formed.  Upon 
boiling  a  1  per  cent  solution  of  the  sugar  with  hydrochloric  or  sulphuric 
acid,  using  1  part  acid  to  1  part  sugar,  lactosinose  is  slowly  hydrolyzed, 
the  specific  rotation  diminishing  to  below  +  50.  The  products  of  the 
hydrolysis  consist  of  about  45  per  cent  d-galactose ;  the  presence  of  an 
undetermined  dextrorotatory  and  of  an  undetermined  levorotatory  sugar 
is  also  indicated. 

The  compounds  and  other  properties  of  lactosinose  have  not  been 
investigated.  More  study  is  required  upon  lactosinose  before  its  con- 
stitution and  its  exact  relationship  to  other  carbohydrates  can  be 
tabulated. 

Secalose.  —  /3-Levulin.     CigH^Ae. 

Occurrence.  —  Secalose,  formerly  called  jS-levulin,  was  discovered  by 
Schulze  and  Frankfurt*  in  green  rye  (Secale  cereale),  where  it  occurs 
to  the  extent  of  2  to  3  per  cent.  It  has  also  been  found  in  green  oats 
and  in  ray-grass  (Lolium  perenne). 

Preparation.  —  The  alcoholic  extract  of  green  rye,  or  oats,  is  treated 
with  strontium  hydroxide  solution  and  the  strontium  secalate,  which  is 
precipitated,  filtered  off,  decomposed  with  carbon  dioxide  and  the  secalose 
precipitated  from  the  evaporated  filtrate  by  means  of  strong  alcohol.  Pu- 
rification of  the  sugar  is  carried  out  in  the  same  manner  as  described 
for  stachyose. 

Properties.  —  Secalose  crystallizes  as  a  hydrate  in  the  form  of 
white  microscopic  prisms,  which  upon  heating  in  a  stream  of  dry 
hydrogen  at  100°  C.  lose  all  their  water  without  decomposition.  The 
anhydrous  sugar  has  a  composition  corresponding  to  the  formula 
Ci8H320i6.  The  sugar  is  easily  soluble  in  water,  in  which  it  exhibits 
levorotation,  [a]D  =  —  28.6  to  —31.7.  It  does  not  reduce  Fehling's 
solution. 

Secalose  upon  warming  with  dilute  hydrochloric  or  sulphuric  acid  is 
rapidly  hydrolyzed  into  d-fructose.  No  other  sugar  has  been  detected 
among  the  products  of  hydrolysis. 

Additional  investigation  is  required  upon  secalose  before  its  con- 
stitution and  its  relationship  to  other  sugars  can  be  determined. 

*  Ber.  27,  65,  3525. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        747 

The  Tetrasaccharides 
TETRAHEXOSE  SACCHARIDES 

/ 

) 
°\ 

°XC6H1105 

STACHYOSE.  —  Mannatetrasaccharide.     C24H4202i  +  4  H20. 

Occurrence.  —  The  discovery  of  a  tetrasaccharide  by  Tanret  in 
ash  manna  has  already  been  mentioned  (p.  744).  Tanret*  showed  later 
that  this  tetrasaccharide  was  identical  with  a  sugar  found  by  Plantaf 
in  the  tubers  of  Stachys  tuberifera  and  named  by  him  stachyose.  The 
sugar  has  also  been  found  in  the  roots  of  different  plants  belonging  to 
the  Labiatse,  in  the  roots  of  Lansium  altuus  and  in  the  white  jasmine. 

Preparation.  —  Stachyose  according  to  Schulze  and  PlantaJ 
makes  up  from  14.16  to  73.07  per  cent  of  the  dry  substance  of  the  tubers 
of  Stachys  tuberifera. 

To  prepare  the  sugar  the  expressed  juice  of  the  tubers  is  clarified  with 
lead  subacetate  and  mercuric  nitrate,  the  lead  and  mercury  are  precipi- 
tated from  the  filtrate  by  hydrogen  sulphide  and  the  clear  solution  neu- 
tralized with  ammonium  hydroxide,  and  evaporated  to  a  sirup.  The 
sirup  thus  prepared  is  poured  into  an  excess  of  alcohol  which  throws  down 
an  abundant  precipitate.  The  latter  is  separated,  dissolved  in  a  little 
water,  clarified  with  phosphotungstic  acid,  filtered,  the  excess  of  clarifying 
agent  removed  with  barium  hydroxide  solution,  again  filtered  and  satu- 
rated with  carbon  dioxide  to  remove  barium;  the  barium  carbonate  is 
filtered  off,  the  filtrate  concentrated  and  again  poured  into  alcohol  which 
precipitates  flakes  of  impure  stachyose.  The  stachyose  is  purified  by 
dissolving  the  flakes  in  water  and  precipitating  with  alcohol,  repeating 
the  process  several  times;  the  product  is  finally  dissolved  in  a  little 
water,  alcohol  added  till  the  strength  of  the  solution  is  91  per  cent;  any 
precipitated  stachyose  is  filtered  off  and  saved  and  the  filtrate  set  aside 
for  crystallization,  which  usually  requires  several  weeks'  standing.  If  a 
little  crystallized  stachyose  is  available  the  process  of  crystallization  may 
be  hastened  by  priming. 

Properties.  —  Stachyose  is  obtained  as  hard  rhombic  crystals  of 
sweet  taste  and  with  a  composition  corresponding  to  the  formula 
+  4  H2O.  The  water  of  crystallization  is  partially  removed 


*  Compt.  rend.,  136,  1569.  t  Landw.  Vers.  Stationen,  25,  473. 

|  Ber.,  23,  1692;  24,  2705. 


748  SUGAR  ANALYSIS 

upon  standing  over  concentrated  sulphuric  acid  or  upon  warming  to 
100  °C.  The  water  is  completely  removed  at  115°  to  120°  C. ;  decomposi- 
tion and  oxidation  set  in,  however,  below  this  temperature  so  that  the 
anhydride  cannot  be  prepared  in  this  way.  The  best  method  of  de- 
hydration is  to  heat  the  powdered  sugar  in  a  stream  of  dry  hydrogen 
at  103°  C.  for  half  an  hour;  in  this  manner  all  water  is  removed  with- 
out decomposition. 

Stachyose  is  easily  soluble  in  water,  1  part  of  the  hydrate  being 
dissolved  by  0.75  parts  water  at  13°  C.;  at  15°  C.  the  hydrate  is  soluble 
in  14  parts  60  per  cent,  in  55  parts  70  per  cent  and  in  300  parts  80  per 
cent  alcohol.  It  is  insoluble  in  absolute  alcohol. 

Stachyose  is  strongly  dextrorotatory,  [a]D  for  the  anhydride 
=  +147.9  to  +148.1  (Schulze  and  Planta)  and  +148.9  (Tanret);  [a]D 
for  the  hydrate  =+  132.75  to  +133.85  (Tanret)  and  +133.5  (Schulze). 
If  +148.5  be  taken  for  the  anhydride,  the  theoretical  [a]D  for  C24H42021 
+  4  H2O  is  +  134.0. 

Stachyose  is  not  affected  upon  heating  with  dilute  solutions  of 
alkalies  and  does  not  reduce  Fehling's  solution.  Upon  oxidation  with 
nitric  acid  stachyose  yields  37  to  38  per  cent  mucic  acid. 

Hydrolysis  of  Stachyose.  —  Upon  warming  with  acetic  acid,  or 
even  upon  prolonged  boiling  with  water,  stachyose  is  hydrolyzed  into 
d-fructose  and  mannatrisaccharide. 

C24H42O21  +  H^O   =  CeH^Oe  +  ClgHs2pl6. 

Stachyose  d-Fructose         Mannatrisaccharide. 

Upon  warming  with  dilute  hydrochloric  or  sulphuric  acid  stachyose  is 
rapidly  hydrolyzed  into  its  component  monosaccharides. 

C24H42021  +  3  H^O  =  CeH^Oe  +  CeH^Oe  +  2  CeH^Oe. 

Stachyose  d-Fructose  d-Glucose  d-Galactose. 

The  theoretical  yield  of  reducing  sugars  from  stachyose  anhydride 
according  to  the  preceding  equation  is  108.1  per  cent;  in  actual  practice, 
however;  this  yield  is  never  reached  owing  to  destruction  of  fructose. 
Winterstein*  obtained  as  a  maximum,  after  heating  stachyose  1  hour 
with  2  per  cent  hydrochloric  or  sulphuric  acid,  only  80.14  per  cent  yield 
of  reducing  sugar  which  is  less  than  75  per  cent  of  the  theoretical. 

Fermentation.  —  Stachyose  is  only  partially  fermented  by  yeast; 
invertase  hydrolyzes  the  sugar  into  d-fructose  and  mannatrisaccharide, 
the  former  being  quickly  and  the  latter  only  slowly  and  imperfectly 
fermented. 

Lupeose.  —  Lupeose,  which  was  originally  regarded  as  a  galactan 
and  afterwards  as  a  disaccharide,  is,  according  to  the  latest  researches 
*  Landw.  Vers.  Stationen,  41,  375. 


THE  TRISACCHARIDES  AND  TETRASACCHARIDES        749 

of  Schulze,*  in  all  probability  a  tetrasaccharide,  For  want  of  other 
knowledge  the  sugar  is  placed  in  this  class. 

Occurrence.  —  Lupeose  was  discovered  by  Bey  erf  in  lupine  seeds 
but  its  preparation  in  a  pure  form  was  due  first  to  Schulze  {  and  his 
coworkers.  The  sugar  occurs  as  a  reserve  substance  in  the  seeds  of 
Lupinus  luteus,  L.  angustifolius,  etc.,  and  is  completely  metabolized 
during  the  first  few  days  of  germination. 

Preparation.  —  Finely  ground  lupine  seeds  are  extracted  with  80 
per  cent  alcohol  and  the  filtered  extract  freed  of  impurities  by  succes- 
sive treatments  with  tannic  acid,  lead  acetate  and  phosphotungstic  acid. 
After  removing  the  excess  of  clarifying  agents  (see  under  stachyose)  the 
solution  is  evaporated  and  treated  with  absolute  alcohol.  The  precipi- 
tated lupeose  is  purified  by  dissolving  in  water  and  reprecipitating 
with  alcohol  as  described  under  stachyose.  The  final  product  is  dried 
over  concentrated  sulphuric  acid. 

Properties.  —  Lupeose  consists  of  a  white,  amorphous,  hygro- 
scopic powder,  which  has  not  been  obtained  as  yet  in  crystalline  form. 
It  is  easily  soluble  in  water,  less  soluble  in  80  per  cent  alcohol,  insoluble 
in  absolute  alcohol  and  ether.  Lupeose  is  strongly  dextrorotatory. 
According  to  the  latest  measurements  of  Schulze  §  [a]D  =  +  148.0. 
Lupeose  is  not  affected  by  boiling  solutions  of  dilute  alkalies  and  does  not 
reduce  Fehling's  solution.  Oxidation  with  nitric  acid  gives  a  large  yield 
of  mucic  acid.  Upon  boiling  with  dilute  hydrochloric  or  sulphuric  acid 
lupeose  is  hydrolyzed  into  a  mixture  consisting  of  d-galactose,  d-fructose 
and  d-glucose,  the  former  to  the  extent  of  about  50  per  cent.  This  would 
correspond  to  a  tetrasaccharide  made  up  of  2  molecules  of  d-galactose 
and  1  molecule  each  of  d-glucose  and  d-fructose;  additional  investigation 
is  required,  however,  before  the  composition  of  lupeose  can  be  expressed 
with  certainty. 

Verbascose.  —  This  sugar,  discovered  by  Bourquelot  and  Bridel  || 
in  the  roots  of  the  common  mullein  (Verbascum  Thapsus),  has  been 
classified  provisionally  as  a  tetrasaccharide. 

Preparation.  —  Fresh  mullein  roots  are  extracted  with  boiling  alco- 
hol. The  sugar  is  precipitated  from  the  concentrated  extract  by  barium 
hydroxide  solution;  the  insoluble  barium  compound  is  filtered  off,  de- 

*  Ber.,  43,  2230. 

f  Landw.  Vers.  Stationen,  9,  117;  14,  164. 

t  Schulze  and  Steiger,  Ber.,  19,  827;  20,  280,  Schulze  and  Winterstein,  Ber., 
25,  2213. 

§  Ber.,  43,  2233. 

II  Compt.  rend.  161,760. 


750  SUGAR  ANALYSIS 

composed  in  water  with  carbon  dioxide,  and  the  solution  of  sugar 
filtered;  any  excess  of  barium  is  removed  with  sulphuric  acid.  The 
filtered  solution  is  concentrated  and  treated  with  a  large  excess  of  95 
per  cent  alcohol  which  causes  a  precipitation  of  the  sugar.  The  latter 
is  filtered  off,  and  c(ried  in  vacuo  over  concentrated  sulphuric  acid.  The 
sugar  is  purified  by  dissolving  in  hot  methyl  alcohol  (diluted  one-fifth 
with  water),  filtering  and  then  adding  one-half  the  volume  of  absolute 
alcohol.  The  verbascose  crystallizes  upon  cooling. 

Properties.  —  Verbascose  is  obtained  as  small  needle-like  crystals 
of  sweetish  taste,  soluble  in  water,  but  almost  insoluble  in  strong  alcohol. 
The  crystals,  after  drying  in  vacuo  over  concentrated  sulphuric  acid, 
lose  2.37  per  cent  of  water  of  crystallization  at  100°  C.  The  sugar 
melts  at  219°  to  220°  C.  (Maquenne's  Block)  and  at  213°  C.  (capillary 
tube).  Verbascose  is  dextrorotatory,  [a]D  (for  the  sugar  dried  at  100°  C.) 
=  -f-  169.9,  and  does  not  reduce  boiling  Fehling's  solution;  it  is  only 
partially  hydrolyzed  by  invertase  and,  upon  oxidation  with  nitric  acid, 
yields  mucic  acid  equivalent  to  56.7  per  cent  galactose;  d-glucose  and 
d-fructose  are  obtained  as  other  products  of  hydrolysis.  Verbascose  is 
apparently  a  true  isomer  of  stachyose  from  which  it  differs  in  higher 
melting  point  and  in  higher  specific  rotation. 


CHAPTER  XXII 

THE  AMINO  SUGARS  AND  THE  CYCLOSES 

IN  addition  to  the  monosaccharides,  previously  described,  there  are 
a  number  of  closely  related  compounds  which  from  their  frequent  asso- 
ciation with  the  ordinary  sugars  and  their  similarity  in  properties  have 
more  than  a  theoretical  interest  for  the  analyst.  Only  two  classes  of 
substances  will  be  considered  in  this  connection,  the  amino  sugars  and 
the  cyclic  sugars;  in  the  description  of  these  only  such  compounds  will 
be  mentioned  as  may  be  met  with  in  the  investigation  of  plant  and 
animal  substances. 

THE  AMINO  SUGARS 

The  amino  sugars  have  considerable  theoretical  interest  as  they 
form  one  of  the  connecting  links  between  the  carbohydrates  and  the 
proteids.  Only  one  compound,  aminoglucose  or  d-glucosamine,  will  be 
described.  For  an  account  of  the  many  synthetic  amino  sugars  refer- 
ence should  be  made  to  the  special  works  upon  the  subject.* 

D-GLUCOSAMINE.  —  Chitosamine. 

CH2OH 

HOCH 


HOCH 
HCO 

A 


H 
HNH2 


CHO 

Occurrence.  —  d-Glucosamine  does  not  occur  in  nature,  so  far  as 
known,  in  the  free  condition;  it  is  formed,  however,  during  the  hy- 
drolysis of  many  nitrogenous  substances  of  animal  and  vegetable 
origin. 

Among  the  animal  substances  which  yield  glucosamine  upon  hy- 
drolysis the  most  important  are  the  mucins  or  mucoids  and  the  chitins. 
The  mucin  of  human  sputum  yields  upon  hydrolysis  with  hydrochloric 
acid  about  34  per  cent  of  the  weight  of  dry  substance  as  glucosamine 
*  For  a  full  description  and  bibliography  of  the  amino  sugars  and  carbohy- 
drates, see  article  by  Geza  Zemplen  in  the  Biochem.  Handlexikon,  p.  527. 

751 


752  SUGAR  ANALYSIS 

chloride;  mucins  from  other  products  of  the  body  also  yield  large  quanti- 
ties of  the  same  compound.  Among  the  mucoids  the  ovomucoid  of  eggs, 
the  chondromucoid  of  cartilage  and  the  mucoid  of  blood  serum  have 
been  examined  and  these  yield  in  some  cases  as  high  as  30  per  cent  glu- 
cosamine  chloride. 

Chitin.  —  The  material  which  yields  the  largest  amount  of  glucos- 
amine  upon  hydrolysis  is  chitin,*  a  nitrogenous  substance  found  in  the 
outer  covering  of  lobsters,  crabs,  scorpions,  spiders,  insects  and  other 
members  of  the  Arthropoda.  Chitin  is  also  found  widely  distributed  in 
the  vegetable  kingdom,  as  a  constituent  of  the  cellular  tissues  and  mem- 
branes of  the  lower  orders  of  plants,  such  as  lichens,  mushrooms,  moulds, 
fungi,  bacteria,  etc.  Chitin,  when  purified,  yields  over  80  per  cent  of 
its  weight  in  glucosamine  chloride. 

The  exact  chemical  nature  of  chitin  has  not  as  yet  been  determined; 
it  is  also  uncertain  whether  the  chitins  of  different  origins  are  identical 
in  composition  or  are  condensations  of  glucosamine  with  varying  com- 
plexity. Arakif  ascribed  to  the  chitin  of  lobster  shells  the  formula 
Ci8H3oN2Oi2.  Upon  heating  this  with  concentrated  potassium  hydroxide, 
acetic  acid  is  split  off  with  formation  of  chitosan.t 

Ci8H30N2Oi2  +  2  H20  =  2  CH3COOH  +  Ci4H26N2Oi0. 

Chitin  Acetic  acid  Chitosan. 

Chitosan  is  a  yellow  amorphous  substance  with  pronounced  basic 
properties;  upon  heating  with  concentrated  hydrochloric  acid  to  110°  C. 
it  is  rapidly  hydrolyzed,  yielding  acetic  acid  and  glucosamine  chloride. 

CH2OH 


C14H26N2Oi0  +  2  HC1  +  2  H2O  =  CH3COOH  +  2 

CH- 


(CHOH)s 

NH2HC1 


Chitosan  Acetic  acid  Glucosamine  chloride. 

According  to  Irvine  §  the  formula  of  chitin  is  C3oH50Oi9N4,  the  hy- 
drolysis with  hydrochloric  acid  proceeding  as  follows: 

CaoHwOwN*  +  7  H2O  +  4  HC1  =  4  C6H1305NHCl+3  CH3COOH 

Chitin  Glucosamine  chloride  Acetic  acid. 

Preparation  of  Glucosamine. — Glucosamine  chloride  is  most  easily 
prepared  from  lobster  shells;  the  latter  are  first  pulverized  and  then 
washed  in  cold  hydrochloric  acid  in  order  to  remove  mineral  matter.  The 
crude  chitin  thus  obtained  may  be  still  further  purified  by  warming 
with  dilute  alkalies  and  extracting  with  alcohol  and  ether.  The  ex- 

*  Discovered  by  Odier  in  1823  (Memoire,  Soc.  hist,  natur.  de  Paris,  1,  35). 

t  Z.  physiol.  Chem.,  20,  498. 

J  Hoppe-Seyler,  Ber.,  27,  3329;  28,  82. 

§  J.  Chem.  Soc.,  96,  564-570  (1909). 


THE  AMINO  SUGARS  AND  THE  CYCLOSES  753 

tracted  material  is  then  heated  to  boiling  with  concentrated  hydrochloric 
acid  until  solution  is  effected;  the  liquid  is  then  diluted,  decolorized  with 
bone  black,  filtered  and  evaporated  when  the  glucosamine  chloride  will 
separate  as  brilliant  shining  crystals.  The  compound  is  purified  by 
recrystallizing  from  80  per  cent  alcohol. 

Glucosamine  chloride  has  a  sweet  taste  with  a  bitter  after-flavor. 
Its  solutions  are  strongly  dextrorotatory,  showing  mutarotation;  [a]D 
after  solution  =  +  100  about  and  [0:]^  constant  =  +  72.5  (values  given 
range  from  +  70  to  +75). 

d-Glucosamine  is  liberated  from  its  chloride  by  decomposing  the 
latter  in  absolute  alcohol  with  diethylamine,  according  to  the  method 
of  Breuer,*  or  by  treatment  of  the  chloride  with  sodium  methylate  in 
absolute  methyl  alcohol  according  to  the  method  of  Lobry  de  Bruyn  and 
van  Ekenstein.f  The  presence  or  formation  of  water  during  the  process 
must  be  excluded. 

Properties. — Free  d-glucosamine  forms  a  fine  white  crystalline  com- 
pound melting  at  about  110°  C.  with  decomposition.  It  is  stable  in  a 
dry  atmosphere,  but  decomposes  in  presence  of  moisture  with  evolution 
of  ammonia.  It  is  easily  soluble  in  water,  forming  an  alkaline  solution; 
it  is  also  soluble  in  hot  ethyl  and  methyl  alcohols  but  insoluble  in  ether. 
d-Glucosamine  is  dextrorotatory,  [0:]^  =  +  44  (Lobry  de  Bruyn)  and 
+  47  to  +  50  (Breuer).  It  is  not  fermented  by  yeast  although  readily 
attacked  by  moulds  and  bacteria. 

Tests. — d-Glucosamine  or  its  chloride  reduces  Fehling's  solution  and 
other  metallic  salt  solutions  with  great  readiness,  acting  even  in  the  cold. 
Warming  with  sodium  hydroxide  causes  strong  evolution  of  ammonia 
with  rapid  darkening  of  the  solution  and  formation  of  caramel-like  odors. 
d-Glucosamine  upon  careful  oxidation  with  bromine  is  changed  to  d-glucos- 
aminic  acid  which  has  the  formula  CH2OH  •  (CHOH)3  •  CHNH2  •  COOH. 
Oxidation  with  nitric  acid  causes  a  splitting  off  of  the  NH2  group  with 
formation  of  isosaccharic  acid.  Sodium  amalgam  and  other  reducing 
agents  seem  to  have  no  action  upon  glucosamine.  The  ordinary  color 
reactions  of  the  aldose  and  ketose  sugars  also  fail  to  develop. 

d-Glucosamine  gives  a  large  number  of  derivatives  and  substitution 
products.  Heated  with  phenylhydrazine  the  NH2  group  is  split  off  and 
an  osazone  is  formed  which  is  identical  in  every  respect  with  that  of 
d-glucose  and  d-fructose.  This  reaction  serves  to  establish  the  con- 
figuration of  d-glucosamine. 

Synthesis  of  d-Glucosamine.  —  The  configuration  of  d-glucos- 
amine has  been  confirmed  by  its  synthesis  from  d-arabinose.  Fischer 
*  Ber.,  31,  2193.  t  Ber.,  31,  2476. 


754  SUGAR  ANALYSIS 


and  Leuchs*  by  treating  d-arabinose  with  ammonium  cyanide  obtained 
the  following  reaction: 

CH2OH  CH2OH 

HOCH  HOCH 

HOCH    +  NH4CN  =  HOCH        +  H2O 

HCOH  HCOH 

CHO  CHNH2 


. 

d-Arabinose  d-Glucosaminic  acid  nitrile. 

The  nitrile  upon  saponification  yields  d-glucosaminic  acid,  the  lac- 
tone  of  which  upon  reduction  is  converted  into  d-glucosamine. 

The  above  reaction  may  serve  as  a  general  example  for  the  synthesis 
of  amino  sugars. 

Chitose.  —  C6Hi005. 

Preparation.  —  d-Glucosamine  chloride,  when  dissolved  in  water 
and  shaken  up  in  the  cold  with  a  slight  excess  of  silver  nitrite,  loses  its 
NH2  group  and  by  a  process  of  inner  condensation  is  converted  into 
chitose. 

CH2OH  CH2OH 

CHOH  CH-CHOH 


HOH)2         +  AgNO2  =       O 

HNH2HC1  CH-CHOH 


AgCl  +  2  H20  +  N2 


k 

CHO  CHO 

d-Glucosamine  chloride  Chitose. 

Properties.  —  Chitose  has  been  obtained  only  as  a  colorless  dextro- 
rotatory non-fermentable  sirup,  all  attempts  to  crystallize  it  having 
thus  far  proved  unsuccessful.  The  above  constitution,  proposed  by 
Fischer  and  Andrese,f  is  based  upon  the  reactions  of  chitose  and  upon 
the  analysis  of  its  derivatives. 

Chitose  in  many  of  its  properties,  such  as  reducing  power,  forma- 
tion of  hydrazones,  oxime  reaction,  etc.,  behaves  as  an  ordinary  reduc- 
ing sugar.  On  the  other  hand,  in  its  failure  to  form  osazones,  chitose 
does  not  behave  in  a  manner  typical  of  the  normal  monosaccharides, 

and  this  is  supposed  to  be  due  to  the  absence  of  a  HCOH  group  in 
the  position  adjoining  the  CHO  radical. 

Chitose  was  first  observed  by  Berthelott  in  the  action  of  mineral 
acids  upon  chitin.  The  chitose  thus  obtained  seems  to  have  been  due, 
however,  to  the  decomposition  of  glucosamine. 

*  Ber.,  36,  3787;  36,  24.          f  Ber.,  36,  2587.          |  Compt.  rend.,  47,  227. 


THE  AMINO  SUGARS  AND  THE  CYCLOSES  755 

Reactions.  —  Chitose  upon  oxidation  with  bromine  is  converted  into 
chitonic  acid,  CeHioOe,  and  upon  oxidation  with  nitric  acid  into  isosac- 
charic  acid,  C6H807.  The  configuration  of  these  follows  from  that  of 
chitose  : 

CH2OH  COOH 


CH-CHOH  CH- 


/-CHOH 


v 
XCH-CHOH  XCH-CHOH 

COOH  COOH 

Chitonic  acid  Isosaccharic  acid. 

Chitonic  acid  was  obtained  by  Fischer  and  Tiemann*  as  a  sirup 
(W/>  =  +  44.5),  and  isosaccharic  acid  as  a  white  crystalline  compound 
melting  at  184°  to  185°  C.  ([a]D  =  +  48  about).  The  two  acids  do  not 
form  lactones  and  cannot  be  reduced  by  means  of  sodium  amalgam. 

Isosaccharic  acid  in  presence  of  dehydrating  agents  is  converted  into 
dehydromucic  acid  and  gives  the  characteristic  reaction  of  this  when 
heated  with  sulphuric  acid  and  isatin  (p.  781). 

Chitose,  chitonic  and  isosaccharic  acids  can  be  regarded  as  hydrated 
derivates  of  furfuran  which  has  the  formula 


t 

/C=C- 

0  I 

NC=C- 


Their  close  relationship  to  furfural  and  its  derivatives  is  referred  to 
elsewhere  (p.  782). 

THE  CYCLOSES 

The  cycloses  f  are  an  important  group  of  compounds,  widely  dis- 
tributed in  nature  and  forming  a  connecting  link  between  the  sugars 
and  the  aromatic  benzol-ring  derivatives.  The  cycloses  frequently 
occur  in  nature  associated  with  the  sugars  and  there  seems  to  be  an  in- 
timate physiological  connection  between  the  two  groups  of  substances; 
the  transformation  of  the  one  group  into  the  other  has  not,  however, 
been  accomplished  as  yet  in  the  laboratory.  Although  a  number  of 
the  cycloses  are  isomeric  with  several  of  the  sugars,  the  cycloses  are 
not  sugars  in  the  chemical  sense,  as  they  contain  no  aldehyde  or  ketone 
group  and  give  none  of  the  characteristic  sugar  reactions. 

*  Ber.,  27,  138. 

t  For  a  full  description  and  bibliography  of  the  cycloses  see  article  by  Viktor 
Grafe  in  the  Biochemisches  Handlexikon,  p.  551. 


756 


SUGAR  ANALYSIS 


The  cycloses  may  be  regarded  chemically  as  derivatives  of  hexa- 
methylene,  or  hexahydrobenzol,  which  is  a  cyclic  carbon  compound  of 
the  formula: 

H2 
C 

/     \ 
H2C  CH2 

H2C  CH2 

H2 

Betite,  C6H8(OH)4.  —  A  compound  answering  to  the  properties  of 
a  tetroxyhexamethylene  was  found  by  Lippmann*  in  the  end  prod- 
ucts of  beet  molasses  and  was  hence  given  the  name  of  betite. 

Betite  crystallizes  in  colorless  prisms  melting  at  224°  C.  It  is 
easily  soluble  in  water  and  is  slightly  dextrorotatory.  It  has  no  reduc- 
ing power,  is  not  attacked  by  boiling  alkalies  and  upon  oxidation  yields 
quinone. 

QUERCITE.  —  Acorn   sugar.      Oak  sugar. 

C6H7(OH)5. 


/ 


HO 
H 


\ 


HO 


OH 
H 


OH 


\      ;/ 
i\  / 

C 

/  \ 

HO         H 

Pentoxyhexamethylene 

Quercite,  which  is  isomeric  with  the  methylpentoses,  C6Hi205>  is 
widely  distributed  in  nature,  being  found  in  acorns,  cork,  bark  and  other 
tissues  of  the  oak.  Of  the  large  number  of  possible  isomeric  pentoxy- 
hexamethylenes  quercite  is  the  only  one  at  present  known. 

Quercite  was  discovered  by  Braconnot;f  it  is  best  prepared  by  ex- 
tracting finely  ground  acorns  with  cold  water.  The  filtered  extract  is 
evaporated  in  vacuum  at  40°  C.  and  any  sugars  which  are  present  de- 
stroyed by  fermentation  with  yeast;  the  solution  is  then  clarified  by 
means  of  lead  subacetate  to  remove  tannic  acid  and  other  impurities 

*  Ber.,  34,  1159.  f  Ann.  chim.  phys.  [3],  27,  392. 


THE  AMINO  SUGARS  AND  THE  CYCLOSES  757 

and  the  filtrate  freed  from  excess  of  lead  by  means  of  hydrogen  sulphide. 
The  clear  filtered  solution  upon  evaporation  gives  crystals  of  quercite 
which  are  purified  by  recrystallizing  from  alcohol. 

Properties.  —  Quercite  crystallizes  in  colorless  monoclinic  prisms 
which  melt  at  234°  C.,  dissolve  in  8  to  10  parts  of  water  and  have  a 
sweet  taste.  It  is  soluble  in  hot  alcohol  but  insoluble  in  ether.  Quer- 
cite is  dextrorotatory,  [0:]^  =  +  24.24.  It  is  not  fermented  by  yeast, 
although  certain  bacteria  are  able  to  effect  a  slow  decomposition. 

Tests.  —  Quercite  does  not  reduce.  Fehling's  solution  and  fails  to 
give  any  of  the  reactions  characteristic  of  the  sugars.  Hot  solutions  of 
the  alkalies  are  without  action.  Upon  heating  at  260°  to  290°  C.,  quer- 
cite is  decomposed  into  quinone,  C6H402,  hydroquinone,  C6H4(OH)2, 
pyrocatechin,  C6H4(OH)2,  and  pyrogallol,  C6H3(OH)3,  which  sublime 
with  other  benzol  derivatives.  A  similar  series  of  compounds  is  ob- 
tained upon  heating  with  concentrated  hydriodic  acid  or  fusing  with 
potassium  hydroxide. 

Quercite  having  5  OH  groups  yields  a  corresponding  number  of 
acetates  upon  heating  with  acetic  anhydride  at  temperatures  ranging 
from  100°  to  150°  C. 

The  INOSITES.  —  C6H6(OH)6. 

H         OH 
\  / 
C 

H    y  ^ 


C 
/  \ 

H        OH 

Hexoxyhexamethylene 

Isomeric  Forms.  —  The  inosites,  which  are  isomeric  with  the  hexoses, 
C6Hi206,  are  widely  distributed  in  both  the  vegetable  and  the  animal 
worlds.  Of  the  nine  possible  arrangements  of  the  H  and  OH  groups  of 
inosite  upon  the  two  sides  of  the  ring  plane  only  two  of  these  arrange- 
ments possess  molecular  assymetry  and  there  would,  therefore,  be  only 
two  optically  active  isomers,  corresponding  to  the  following  configurations : 
H  OH  OH  H 

™\OH 


H/  OH 


OH 


758  SUGAR  ANALYSIS 

The  two  optically  active  d-  and  1  inosites  corresponding  to  the  above 
configurations  occur  in  nature  as  their  methyl  esters  pinite  and  que- 
brachite  from  which  they  have  been  separated  by  treatment  with  hydri- 
odic  acid. 

A  peculiarity  of  the  inosites  is  that  none  of  their  carbon  atoms  is 
structurally  asymmetric,  two  bonds  of  each  C  atom  being  connected 
alike  with  reference  to  the  remainder  of  the  ring;  this  apparent  excep- 
tion to  the  theory  of  van't  Hoff  and  Le  Bel  disappears,  however,  if 
the  question  is  regarded  from  the  standpoint  of  molecular  assymmetry. 

d-Inosite,  CeH^Oe.  —  This  compound  has  not  been  found  as  yet 
free  in  nature;  its  methyl  ester,  however,  is  widely  distributed  as 
pinite,  and  d-inosite  is  obtained  directly  from  this  by  heating  with  con- 
centrated hydriodic  acid.  The  reaction  proceeds  quantitatively  as 
follows : 

C6H6(OH)5(OCH3)      +      HI    =    C6H6(OH)6  +    CH,I. 

Finite  Hydriodic  d-Inosite  Methyl  iodide, 

acid 

Properties.  —  d-Inosite  consists  of  small  colorless  octahedral  crystals 
which  melt  at  247°  to  248°  C.,  and  are  easily  soluble  in  water,  less  solu- 
ble in  alcohol,  but  insoluble  in  ether.  By  crystallizing  from  water  a 
hydrate  has  been  obtained  having  the  formula  C6Hi206  +  2  H20. 
d-Inosite  is  dextrorotatory  without  mutarotation,  [a]D  =  +  65 ;  it  is  not 
fermented  by  yeast,  and  does  not  reduce  Fehling's  solution. 

Tests.  —  All  of  the  inosites  upon  oxidation  with  nitric  acid  yield 
colored  oxyquinone  derivatives.  In  carrying  out  this  test  the  method 
of  Scherer*  is  generally  used.  A  small  quantity  of  the  material  to  be 
tested  is  treated  with  a  little  nitric  acid  and  evaporated  upon  the  water 
bath  almost  to  dryness ;  a  little  ammoniacal  barium  chloride  or  calcium 
chloride  solution  is  then  added  and  the  solution  again  evaporated.  If 
inosite  is  present  a  beautiful  rose  red  color  will  develop;  0.5  mg.  of  in- 
osite  may  be  detected  in  this  way.  Seidelf  has  modified  this  test  by 
using  ammoniacal  strontium  acetate  to  develop  the  color  and  in  this 
way  0.3  mg.  of  inosite  may  be  detected. 

d-Inosite  when  heated  to  boiling  with  an  excess  of  acetic  anhydride 
in  presence  of  a  little  zinc  chloride  is  converted  into  the  hexacetate 
C6H6(CH3COO)6,  which  is  obtained  as  an  amorphous  mass  insoluble  in 
water  but  soluble  in  alcohol  ([a]D  =  +  9.75). 

Pinite,  C6H6(OH)5(OCH3).  —  This,  the  methyl  ester  of  d-inosite, 
is  isomeric  with  the  methylhexose  sugars  and  is  found  widely  dis- 
tributed in  nature.  It  was  discovered  by  BerthelotJ  in  1856  in  the 

*  Ann.,  73,  322;  81,  375.  f  Chem.  Ztg.,  11,  676. 

|  Compt.  rend.,  41,  392. 


THE  AMINO  SUGARS  AND  THE  CYCLOSES        .       759 

resin  of  the  Pinus  lambertiana  of  California;  it  also  occurs  as  sennite* 
in  Senna  leaves,  as  matezitef  in  the  juice  of  the  Madagascar  rubber 
plant  (Mateza  roritina)  and  has  also  been  found  in  the  mother  liquors  t 
from  the  crystallization  of  coniferin.  The  identity  of  these  various 
methyl  esters  of  d-inosite  with  pinite  has  been  established  by  Combes,  § 
Wiley, ||  and  others.^ 

Pinite  forms  white  rhombic-hemihedral  crystals  melting  at  185°  to 
186°  C.,  and  subliming  without  decomposition  at  200°  C.  It  has  the 
same  degree  of  sweetness  as  cane  sugar,  is  easily  soluble  in  water,  less 
soluble  in  alcohol  and  insoluble  in  ether.  It  is  not  fermentable,  and 
does  not  reduce  Fehling  solution.  Pinite  is  dextrorotatory,  [a]D  =  +65.5. 

1-Inosite,  C6Hi206.  —  This  compound  has  been  found  as  yet 
only  in  the  form  of  its  methyl  ester,  quebrachite,  from  which  it  was 
obtained  by  Tanret  **  upon  heating  with  hydriodic  acid.  The  reaction 
is  the  same  as  that  given  for  pinite. 

Properties.  —  1-Inosite  crystallizes  from  alcohol  as  the  anhydride 
C6Hi2O6  in  the  form  of  colorless  prisms  melting  at  247°  C.  A  hydrate, 
C6Hi206  +  2  H2O,  has  been  obtained  by  crystallizing  from  water. 
1-Inosite  is  easily  soluble  in  water,  less  soluble  in  alcohol  but  insoluble 
in  ether.  It  is  levorotatory,  [a]D  =  —  65  for  the  anhydride  without  mu- 
tarotation,  is  unfermentable  and  does  not  reduce  Fehling's  solution. 

1-Inosite  gives  Scherer's  inosite  reaction  upon  heating  with  nitric  acid. 
With  acetic  anhydride  an  amorphous  hexacetate  is  formed;  the  com- 
pound is  levorotatory  ([a]D  =  —  10)  but  in  other  respects  behaves  the 
same  as  the  hexacetate  of  d-inosite. 

Quebrachite,  C6H6(OH)5(OCH3).  —  This,  the  methyl  ester  of 
1-inosite,  occurs  in  the  bark  of  the  Quebracho  tree.  It  crystallizes  in 
prisms  melting  at  186°  to  187°  C.;  the  crystals  are  very  sweet,  easily 
soluble  in  water,  less  soluble  in  alcohol  and  insoluble  in  ether.  Quebra- 
chite is  levorotatory,  [a]D  =  —  80;  this  figure,  though  of  opposite  sign, 
is  not  of  the  same  value  as  that  of  pinite  (+  65.5),  so  that  the  two 
compounds  are  not  optical  antipodes.  The  compound  is  not  attacked 
by  dilute  alkalies  or  acids;  heated  with  concentrated  nitric  acid  it  gives 
Scherer's  reaction.  Quebrachite  is  unfermentable  and  does  not  reduce 
Fehling's  solution. 

*  Dragendorff  and  Kubly,  Ztschr.  f.  Chemie  (1866),  411. 
t  Girard,  Compt.  rend.,  77,  995;  110,  84. 
t  Tiemann  and  Haarmann,  Ber.,  7,  609. 
§  Compt.  rend.,  110,  46. 
II  Amer.  Chem.  Jour.,  13,  228. 
f  See  Maquenne's  "  Les  Sucres,"  p.  209. 
**  Compt.  rend.,  109,  908. 


760  SUGAR  ANALYSIS 

d,  1-Inosite.  —  Racemic  inosite  was  obtained  by  Maquenne  and 
Tanret  *  by  dissolving  and  crystallizing  equal  parts  of  d-  and  1-inosite. 
The  anhydride  consists  of  colorless  crystals  melting  at  253°  C. ;  the  sub- 
stance behaves  as  a  true  racemic  combination  and  not  as  a  simple  mix- 
ture, d,  1-Inosite  is  optically  inactive ;  in  its  chemical  behavior  it  reacts 
the  same  as  either  d-  or  1-inosite.  It  is  not  fermented  by  yeast ;  it  has 
been  partially  resolved  by  Tanret  who  found  that  Aspergillus  niger 
at  low  temperatures  caused  the  inactive  solution  to  become  sensibly 
levorotatory. 

i-Inosite,  CeH^Oe  (Phaseomannite,  Nucite,  Dambose) .  Occurrence. 
—  Inactive  inosite,  also  called  anti-  or  mesoinosite,  is  the  only  inosite 
which  has  thus  far  been  found  free  in  nature.  It  was  discovered  by 
Schererf  in  1850  in  the  mother  liquors  from  a  preparation  of  creatine 
obtained  by  extracting  meat,  and  has  since  been  found  to  be  very 
widely  distributed  throughout  the  animal  and  vegetable  kingdoms.  It 
occurs  in  the  muscles,  kidneys,  liver,  lungs,  heart,  brain  and  other 
organs  of  the  body  and  has  also  been  found  in  the  urine  of  patients 
afflicted  with  Bright's  disease  and  diabetes,  and  also  frequently  in 
normal  urines.  The  occurrence  of  inosite  in  the  urine  is  sometimes 
termed  inosuria. 

In  the  vegetable  world  i-inosite  has  been  found  in  green  beans,  peas 
and  other  legumes,  in  the  cabbage,  in  the  leaves  of  asparagus,  the 
potato,  dandelion,  grape  vine,  oak,  ash  and  other  trees,  in  different 
mushrooms,  in  the  roots  of  many  plants  and  in  the  juices  of  grapes, 
blueberries  and  other  fruits. 

In  the  combined  form  i-inosite  occurs  as  its  methyl  esters  bornesite 
and  dambonite. 

Preparation.  —  i-Inosite  is  prepared  from  meat  by  first  extracting 
the  finely  cut  material  with  water.  The  aqueous  extract  is  then 
slightly  acidified  with  acetic  acid  and  boiled;  the  coagulated  albumin 
is  filtered  off  and  the  filtrate  clarified  with  normal  lead  acetate.  The 
solution  is  again  filtered  and  the  filtrate  heated  with  an  excess  of  lead 
subacetate  solution  and  allowed  to  stand  for  1  to  2  days.  The  basic 
lead-inosite  compound  is  filtered  off  and  decomposed  in  water  with 
hydrogen  sulphide.  The  filtrate  from  the  lead  sulphide  is  concentrated, 
treated  with  an  excess  of  hot  alcohol  and  the  solution  separated  from 
any  precipitated  impurities.  The  alcoholic  solution  upon  cooling  will 
usually  deposit  crystals  of  inosite;  if  no  crystals  form,  the  separation 
may  be  promoted  by  adding  ether  to  the  point  of  turbidity,  and  setting 

*  Compt.  rend.,  110,  86, 
t  Ann.,  73,  322. 


THE  AMINO  SUGARS  AND  THE  CYCLOSES  761 

the  solution  aside  in  a  cool  place.  The  compound  is  purified  by  re- 
crystallizing  from  alcohol. 

To  prepare  inosite  from  plant  materials  the  process  employed  by 
Maquenne*  for  its  extraction  from  walnut  leaves  may  be  employed. 
The  dried  finely  ground  leaves  are  extracted  repeatedly  with  5  to  6  parts 
of  boiling  water,  the  residue  pressed  out  and  the  brownish  colored  ex- 
tract treated  hot  with  concentrated  milk  of  lime  until  the  precipitate 
which  has  formed  settles  quickly.  The  solution  is  filtered  and  the  fil- 
trate treated  with  a  very  slight  excess  of  normal  lead  acetate.  The 
solution  is  again  filtered  and  the  inosite  precipitated  with  ammoniacal 
lead  subacetate  solution.  The  precipitate,  which  should  be  perfectly 
white,  is  filtered  off  and  then  decomposed  in  aqueous  suspension  with 
hydrogen  sulphide.  The  filtrate  from  the  lead  sulphide  precipitate  is 
evaporated  to  a  sirup;  the  latter  is  then  treated  while  still  warm  (about 
50°  C.)  with  7  to  8  per  cent  of  its  volume  of  concentrated  nitric  acid 
which  oxidizes  most  of  the  impurities  but  is  without  action  upon  the 
inosite.  (Excess  of  acid  and  high  temperature  must,  however,  be 
avoided.)  The  acid  solution  is  then  heated  for  a  few  minutes  upon 
the  water  bath  and  then  treated  with  4  to  5  volumes  of  strong  alcohol; 
after  cooling  1  volume  of  ether  is  added  when  the  inosite  will  begin  to 
crystallize.  After  24  hours  the  solution  is  decanted,  the  impure  ino- 
site washed  with  alcohol  and  then  recrystallized  from  acetic  acid.  To 
remove  the  last  traces  of  coloring  matter,  calcium  sulphate  and  other 
impurities,  the  inosite  is  dissolved  in  water  and  treated  with  a  slight 
excess  of  barium  hydroxide  solution.  The  solution  is  filtered,  the  ex- 
cess of  barium  removed  with  ammonium  carbonate  and  the  clear  filtrate 
evaporated  to  dryness.  The  residue  upon  recrystallizing  from  water 
gives  pure  inosite.  By  this  method  Maquenne  obtained  440  gms.  of 
inosite  from  150  kgs.  of  leaves,  a  yield  of  about  0.29  per  cent. 

Properties.  —  i-Inosite  crystallizes  from  alcohol  or  from  water  above 
a  temperature  of  50°  C.  as  the  anhydride  in  the  form  of  needles  melting 
at  224°  C.  Upon  crystallizing  from  water  below  a  temperature  of 
50°  C.,  the  hydrate  CeH^Oe  +  2  H20  is  obtained  in  the  form  of  large 
hexagonal  monoclinic  crystals  which  effloresce  rapidly  in  a  dry  atmos- 
phere. i-Inosite  has  a  sweet  taste,  is  very  soluble  in  water  (7.5  parts 
at  15°  C.  for  the  anhydride),  less  soluble  in  alcohol  and  insoluble  in 
ether.  It  is  optically  inactive  even  after  the  addition  of  borax;  its 
optical  neutrality  is  not  affected  by  the  attack  of  moulds  as  is  the  case 
with  d,  1-inosite.  It  is  not  fermented  by  yeast,  although  certain  bac- 
teria appear  to  cause  destructive  changes.  It  does  not  reduce  Fehling's 
*  "  Les  Sucres,"  p.  216. 


762  SUGAR  ANALYSIS 

reagent,  although  it  produces  a  metallic  mirror  with  ammoniacal  silver 
solution.  i-Inosite  gives  Scherer's  reaction,  described  under  d-inosite. 

Bornesite.  C6H6(OH)5(OCH3).  —  This,  the  monomethyl  ester  of 
i-inosite,  was  discovered  by  Girard*  in  crude  Borneo  caoutchouc;  it 
was  also  found  by  Flint  and  Tollensf  in  the  wash  waters  from  certain 
rubber  factories.  It  is  isomeric  with  pinite  and  quebrachite  and  crys- 
tallizes in  rhombic  prisms  melting  at  about  200°  C.  and  subliming  at 
205°  C.  It  is  easily  soluble  in  water,  but  less  soluble  in  alcohol.  It  is 
dextrorotatory,  [a]D  =  +  32  (Girard),  +  31.16  (Flint  and  Tollens);  it  is 
unfermentable  and  does  not  reduce  Fehling's  solution.  It  is  decom- 
posed J  by  heating  with  hydriodic  acid  into  methyl  iodide  and 
i-inosite. 

Dambonite,  CeHetOHWOCI^.  —  This,  the  dimethyl  ester  of 
i-inosite,  was  discovered  by  Girard  §  in  Gabon  rubber;  it  has  also  been 
found  in  the  latex  or  milky  caoutchouc  yielding  juice  of  the  Castilloa 
elastica.  Dambonite  crystallizes  in  white  rhombic  prisms  which  melt 
at  about  190°  to  195°  C.  and  sublime  between  200°  to  210°  C.  It  is 
sweet,  very  soluble  in  water  and  dilute  alcohol,  unfermentable,  optically 
inactive  and  does  not  reduce  Fehling's  solution.  Dambonite  forms 
with  potassium  iodide  a  double  salt  of  the  formula  C8Hi606KI.  Upon 
heating  with  hydriodic  acid  it  yields  methyl  iodide  and  i-inosite.  Hy- 
drolysis is  also  effected  upon  heating  with  concentrated  hydrochloric 
acid. 

Quercinite,  C6H6(OH)6.  —  This  compound  was  discovered  by  Vin- 
cent and  Delachanal  ||  in  the  mother  liquors  obtained  from  the  crystal- 
lization of  quercite.  Quercinite  crystallizes  from  cold  water  as  a 
hydrate,  the  crystals  of  which  effloresce  rapidly  upon  exposure  to  the 
air.  Crystallized  from  hot  water  the  anhydride  is  obtained  in  the 
form  of  rhombic  prisms  melting  at  340°  C.  The  anhydride  is  soluble 
in  66  parts  of  cold  water,  easily  soluble  in  hot  water,  insoluble  in  alcohol 
and  ether;  it  is  optically  inactive,  unfermentable  and  does  not  reduce 
Fehling's  solution.  Quercinite  gives  Scherer's  inosite  reaction,  and  in 
its  general  behavior  seems  to  belong  to  the  group  of  inactive  inosites 
of  which  there  are  seven  possible  stereo-isomers. 

Phytin.  —  Inosite  also  exists  in  nature  in  combination  with  phos- 
phoric acid  as  phytin,  the  principal  phosphorus  compound  of  vegetable 

*  Compt.  rend.,  73,  426;  77,  995. 

t  Ann.,  272,  288. 

J  Maquenne,  Ann.  chim.  phys.  [6],  12,  566. 

§  Compt.  rend.,  67,  820. 

II  Compt.  rend.,  104,  1855. 


THE  AMINO  SUGARS  AND  THE  CYCLOSES 


763 


seeds.  Phytin,  according  to  the  researches  of  Suzuki,  Yoshimura  and 
Takaishi,*  is  an  inosite-hexaphosphoric  acid  C6H6[OPO(OH)2]6  ,  which, 
by  the  action  of  a  special  enzyme  phytase,  is  hydrolyzed  into  inosite  and 
phosphoric  acid. 

6  H3P04. 


C6H6[OPO(OH)2] 

Phytin 


6  H20  =  C6Hi206 

Inoaite 


Phosphoric 
acid 


Bull.  College  of  Agric.,  Tokyo,  7,  495,  503  (1907), 


CHAPTER  XXIII 

THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 

THE  close  relationship  of  the  sugars  to  the  alcohols  upon  the  one  side 
and  to  the  monobasic  and  dibasic  acids  upon  the  other  has  already  been 
mentioned.  While  these  two  groups  of  substances  are  entirely  distinct 
from  the  sugars,  their  constant  association  with  the  sugars  in  nature 
and  their  great  importance  in  many  analytical  and  synthetical  oper- 
ations of  sugar  chemistry  are  of  sufficient  account  to  require  brief 
mention. 

THE  SUGAR  ALCOHOLS 

Of  some  thirty  known  sugar  alcohols  the  following  eight  have  been 
found  in  nature:  glycerol,  erythrite,  adonite,  sorbite,  mannite,  dulcite, 
perseite  and  volemite.  Reference  has  already  been  made  to  the 
occurrence  of  these. 

Synthesis  of  the  Sugar  Alcohols.  —  The  sugar  alcohols  are  gener- 
ally prepared  by  the  action  of  nascent  hydrogen  upon  an  aldose  or 
ketose  sugar.  The  reduction  is  best  accomplished  by  means  of  sodium 
amalgam.  The  process  of  Fischer*  is  as  follows:  a  10  per  cent  aqueous 
solution  of  the  sugar  is  treated  ice  cold  with  small  additions  of  sodium 
amalgam  (2  to  2|  per  cent  sodium  content)  until  the  reducing  power 
of  the  solution  has  almost  disappeared.  During  the  first  part  of  the 
operation  the  solution  is  kept  weakly  acid  with  constant  additions  of 
dilute  sulphuric  acid  in  order  to  prevent  molecular  transformation  of 
sugar  by  action  of  the  free  alkali;  in  the  last  stages  of  the  reduction 
the  solution  is  kept  faintly  alkaline.  After  reduction  the  solution  is 
neutralized,  evaporated  until  sodium  sulphate  begins  to  crystallize  and 
then  poured  into  8  volumes  of  absolute  alcohol.  The  alcoholic  solu- 
tion is  filtered  from  sodium  sulphate  and  evaporated  when  the  sugar 
alcohol  is  obtained  either  as  a  sirup  or  in  crystalline  form. 

Formation  of  Sugar  Alcohols  During  Fermentation.  —  The  sugar 
alcohols  are  also  formed  in  many  anaerobic  fermentations  through  a 
similar  process  of  reduction.  The  best-known  example  of  this  is  the 
so-called  mannitic  fermentation  which  takes  place  frequently  in  the 
juices  of  the  sugar  cane,  sugar  beet,  grapes,  apples  and  in  other  vege- 

*  "  Untersuchungen  uber  Kohlenhydrate  "  (1909),  pp.  186,  292,  473,  etc. 

764 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  765 

table  extracts.  The  sugar  is  changed  partly  to  mannite  and  partly  to 
the  mucilaginous  gum  dextran  (C6Hi0O5)n;  the  latter  can  be  precipi- 
tated by  means  of  alcohol  and  the  mannite  obtained  by  evaporation  of 
the  alcoholic  solution.  The  presence  of  mannite  in  wines,  musts,  vine- 
gars, sugar-house  products,  distillery  residues,  etc.,  is  due  largely  to  the 
result  of  such  fermentations. 

Properties  and  Reactions  of  the  Sugar  Alcohols.  —  The  sugar  alco- 
hols resemble  one  another  in  their  sweet  taste,  in  not  being  fermented  by 
yeast  and  in  the  complete  lack  of  the  aldehyde  or  ketone  properties 
(reduction  of  Fehling's  solution,  hydrazone  and  osazone  formation, 
color  reactions,  etc.),  characteristic  of  the  parent  sugar.  In  presence  of 
free  alkalies  the  sugar  alcohols  give  soluble  complex  substitution  prod- 
ucts with  many  of  the  heavy  metals;  for  this  reason  salts  of  copper,  etc., 
are  not  precipitated  by  alkaline  hydroxides  in  presence  of  glycerol, 
mannite  and  other  polyvalent  alcohols.  This  property,  however,  is 
not  a  characteristic  one,  being  also  shared  by  the  sugars  and  their  acid 
derivatives. 

Compounds  of  Sugar  Alcohols  and  Metals.  —  If  excess  of  alkali  be 
avoided,  the  metallic  substitution  products  of  the  sugar  alcohols  may 
be  obtained  in  some  cases  as  a  precipitate.  Mannite,  for  example,  can 
be  precipitated  from  solution  in  presence  of  copper  sulphate  by  adding 
ammonium  hydroxide  to  faintest  possible  excess.  The  blue  copper- 
mannite  compound  can  then  be  filtered  off;  it  is  practically  insoluble  in 
water,  but  is  soluble  in  excess  of  ammonia  from  which  solution  the 
mannite  can  be  regenerated  after  removing  the  copper  with  hydrogen 
sulphide.  This  process  due  to  Guignet  *  can  be  utilized  for  the  separation 
of  mannite  from  plant  juices. 

Reaction  of  Sugar  Alcohols  with  Borax.  —  The  behavior  of  many 
sugar  alcohols  with  borax  and  boric  acid  is  also  worthy  of  mention.  If 
a  little  borax  be  added  to  an  aqueous  solution  of  mannite,  arabite,  etc., 
the  solution  becomes  strongly  acid,  with  a  marked  increase  in  the  elec- 
trical conductivity.!  The  phenomenon  is  due  to  the  formation  of 
alcohol-boric  acid  complexes,  the  constitution  of  which  remains  in 
doubt.  The  acid  complex,  which  is  strong  enough  to  decompose  car- 
.bonates,  undergoes  dissociation  J  upon  dilution  with  water. 

Borax  and  boric  acid  also  have  the  peculiar  property  of  intensifying 
the  rotatory  power  §  of  solutions  of  the  sugar  alcohols  to  a  very  marked 

*  Compt.  rend.,  109,  528. 
f  Magnanini,  Gazetta  chim.  Ital.,  20,  428. 
}  Klein,  Bull.  soc.  chim.  [2],  29,  195,  198,  357. 
§  Vignon,  Compt.  rend.,  77,  1191;  78,  148. 


766  SUGAR  ANALYSIS 

degree,  the  result  no  doubt  of  the  higher  specific  rotation  of  the  boric  acid 
alcohol  complex.  Acid  molybdates  *  of  sodium  and  ammonium  produce 
the  same  effect  to  an  even  greater  extent;  so  also  the  tungstatef  and 
paratungstate  of  sodium.  Polarization  of  solutions  before  and  after  the 
addition  of  constant  quantities  of  borax  has  been  employed  for  esti- 
mating certain  sugar  alcohols,  as  mannite,  i  in  mixture  with  other  sub- 
stances. 

Table  CIII  gives  a  list  of  the  different  alcohols,  with  a  few  of  their 
properties,  which  are  obtained  by  reduction  of  the  different  mono- 
saccharides.  The  sugar  alcohols,  which  have  been  found  free  in 
nature,  are  marked  in  italics.  In  the  nomenclature  of  the  sugar 
alcohols  the  ending  -ite  §  is  usually  substituted  in  place  of  the  termina- 
tion -ose  of  the  sugar,  as  pentite,  hexite,  etc. 

It  will  be  noted  from  the  table  that  the  ketose  sugars,  erythrulose, 
fructose,  sorbose,  and  tagatose,  yield  two  isomeric  alcohols  upon  reduc- 
tion. This  necessarily  follows  from  the  configuration,  since  reduction  of 


C=O  group  will  give  both  HC( 


the  C  =  O  group  will  give  both  HCOH  and  HOCH  isomers. 

Reaction  of  Sugar  Alcohols  with  Aldehydes.  —  A  number  of  re- 
actions, which  have  been  employed  for  the  separation  and  identification 
of  the  sugar  alcohols,  should  be  mentioned.  Chief  among  these  are  the 
reactions  with  formaldehyde,  acetaldehyde  and  benzaldehyde  in  pres- 
ence of  strong  hydrochloric  or  sulphuric  acid  (50  per  cent)  with  forma- 
tion of  a  characteristic  group  of  compounds  known  as  acetals. 

Formats.  —  Mannite,  for  example,  when  heated  with  equal  parts  of 
40  per  cent  formaldehyde  and  concentrated  hydrochloric  acid  gives 
mannite  triformal,  ||  C6H806(CH2)3,  which  consists  of  white  needles,  only 
slightly  soluble  in  water  and  melting  at  227°  C. 

Acetals.  —  In  the  same  way,  by  heating  mannite  with  acetaldehyde  or 
paracetaldehyde  in  presence  of  concentrated  hydrochloric  acid  or  50  per 
cent  sulphuric  acid,  mannite  triacetal,  CeHsOe^H^a,  is  formed. 

Benzols.  —  Of  greater  value  than  the  formals  and  acetals  for  separa- 
tion and  identification  of  the  sugar  alcohols  are  the  benzals.  This  re- 

*  Gernez,  Compt.  rend.,  112,  1360. 

t  Klein,  Compt.  rend.,  89,  484. 

j  Muller,  Bull.  soc.  chim.  [3],  11,  329. 

§  Many  chemists  prefer  the  ending  -itol  in  place  of  -ite,  as  mannitol,  arabitol, 
perseitol,  etc.;  while  this  conforms  with  the  rule  that  all  alcohols  should  end  in  -ol 
the  author  has  preferred  the  older  and  simpler  terminology,  which  is  still  retained  by 
Fischer,  Tollens,  Lippmann,  Maquenne  and  other  leading  authorities, 

II  Tollens  and  Schulz,  Ber.,  27,  1892. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 


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768 


SUGAR  ANALYSIS 


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THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  769 

action,  which  is  due  to  Meunier,*  has  been  much  employed  by  Fischer. f 
The  alcohol,  in  concentrated  hydrochloric  acid  or  50  per  cent  sulphuric 
acid,  is  shaken  up  with  benzaldehyde  when  the  benzal  derivatives  of 
erythrite,  xylite,  mannite,  sorbite,  and  perseite  will  quickly  precipitate: 
the  separation  with  these  alcohols  is  almost  quantitative.  In  the  case 
of  glycerol,  arabite,  and  dulcite  the  benzal  derivatives  obtained  by  this 
method  remain  in  solution  so  that  no  separation  is  effected. 

As  to  the  constitution  of  the  benzals  obtained  by  the  method  just 
described  there  appears  to  be  no  uniformity.  Mannite,  for  example, 
combines  with  three  molecules  of  benzaldehyde;  erythrite,  xylite,  ado- 
nite,  sorbite,  and  perseite  with  two;  and  glucoheptite  with  only  one. 
This  peculiarity  is  probably  due  to  the  spatial  arrangement  of  the 
alcohol  groups  within  the  molecule,  although  no  satisfactory  theory  J 
has  as  yet  been  formulated.  As  in  the  case  of  the  formals  and  acetals 
the  reaction  probably  results  from  the  withdrawal  of  the  H  from  2 
hydroxyl  groups  of  the  sugar  alcohol  by  the  0  of  the  aldehyde.  The 
reaction,  for  example,  with  sorbite  would  be: 

C6H5  /    C6H5  \ 

CeH^Oo      +      2  O  :  C-H  =  C6H10O6\  :  C -H/2  +  2  H2O, 

Sorbite  Benzaldehyde  Sorbite-dibenzal  Water. 

but  which  of  the  hydroxyl  groups  of  the  sugar  alcohol  participate  in  the 
reaction  is  not  at  present  known. 

The  formulae  and  properties  of  the  more  important  benzal  deriva- 
tives of  the  sugar  alcohols  are  given  in  Table  CIV. 

The  benzals  upon  boiling  with  5  per  cent  sulphuric  acid  are  decom- 
posed into  benzaldehyde  and  the  free  alcohol.  The  process  of  decompo- 
sition is  much  facilitated  by  the  addition  of  a  little  free  benzaldehyde. 
In  a  few  cases,  as  with  mannite,  long  boiling  and  a  high  temperature  of 
heating  are  required  to  effect  complete  hydrolysis.  The  benzaldehyde 
can  be  removed  by  shaking  out  the  cold  acid  solution  with  ether  and  the 
sulphuric  acid  eliminated  by  neutralizing  with  barium  hydroxide  and 
filtering  off  the  barium  sulphate.  The  clear  filtrate  upon  evaporation 
will  then  yield  the  sugar  alcohol  either  as  a  sirup  or  in  the  crystalline 
form.  By  this  means  it  is  possible  to  effect  the  separation  of  different 
sugar  alcohols  from  plant  extracts,  juices,  etc. 

Sugar  alcohols  can  be  detected  in  the  presence  of  sugars  by  first 
heating  the  solution  with  dilute  hydrochloric  acid  to  invert  any  higher 
saccharides ;  the  sugars  are  then  precipitated  in  the  neutralized  solution 
as  osazones  by  means  of  phenylhydrazine.  After  filtering  off  the  osa- 

*  Compt.  rend.,  106,  1425,  1732;  107,  910;  108,  408.  t  Ber.,  27,  1524. 

t  See  Fischer's  discussion  upon  this  point,  Ber.,  27,  1524. 


770 


SUGAR  ANALYSIS 


zones,  the  filtrate  is  shaken  out  with  ether  to  remove  excess  of  phenyl- 
hydrazine  and  the  aqueous  solution  tested  for  sugar  alcohols  with 
benzaldehyde  in  the  manner  described. 

TABLE  CIV 

Giving  Formulae  and  Properties  of  Sugar  Alcohol  Benzols 


Alcohol. 

Formula. 

Appearance. 

Melting 
point, 
deg.  C. 

Solubility. 

Glycerol  -mono- 

C3H6O3 

:  CHC6H6 

Fine  white  needles. 

66 

Sol.  hot  water. 

benzal. 

Erythrite-di- 

C4He04 

(:CHC6H6)2 

Fine  white  needles. 

197-8 

Insol.  in  water. 

benzal. 

Arabite-mono- 

OsHioOji 

:  CHCeHs 

Fine  white  needles. 

150 

Sol.  hot  water. 

benzal. 

Xylite-  diben- 

C5H8O6 

(l  C-<HCy6-H.5)2 

Gelatinous  flakes. 

175 

Insol.  in  water. 

zal. 

Adonite-diben- 

C6H805 

(:CHC6H6)2 

Fine  white  needles. 

164-5 

Insol.  in  water. 

zal. 

Manni  te-tri- 

C6H806 

(:  CHCeH6)3 

Fine  white  needles. 

220 

Insol.  in  water. 

benzal. 

Talite-triben- 

C6H8O6 

(:  CHCeH6)3 

Fine  white  needles. 

206 

Insol.  in  water. 

zal. 

Sorbite-diben- 

„„! 

C6H1006  (:  CHC6H6)2 

(  a  Amorphous. 

200 

Slightly  sol.  in 
water. 

zai. 

f  ft  Crystalline. 

164 

Insol.  in  water. 

Dulcite-diben- 

C6H1006 

(:CHC6H6)2 

Fine  white  needles. 

215-20 

Sol.  hot  water. 

zal. 

Perseite-diben- 

C7H1207 

(:  CHC6H6)2 

Fine  white  needles. 

230-5 

Insol.  in  water. 

zal. 

Glucoheptite- 

CyHuO? 

:  CHCeHs 

Fine  white  needles. 

214 

Insol.  in  water. 

monobenzal. 

Oxidation  of  Sugar  Alcohols.  —  As  the  sugars  upon  reduction  yield 
alcohol  derivatives  so  the  latter  upon  gentle  oxidation  are  converted 
into  sugars.  The  two  processes  are  not  however  strictly  reversible  for 
while  glucose  upon  reduction  gives  the  alcohol  sorbite,  the  latter  upon 
oxidation  gives  a  mixture  of  glucose  and  sorbose.  In  fact  it  may  be 
stated  as  a  general  rule  that  the  sugar  alcohols  upon  weak  oxidation 
yield  both  an  aldose  and  a  ketose  sugar.  This  may  be  seen  from  the 
following  examples: 

Alcohol  Sugars  derived  by  oxidation. 

Aldose  Ketose 

Glycerol  =  d,l-Glycerose  +  Dioxyacetone 

i-Erythrite  =  d,l-Erythrose  +  d,l-Erythrulose 

d-Mannite  =  d-Mannose      +  d-Fructose 

d-Sorbite  =  d-Glucose        +  d-Sorbose 

Oxidation  of  Sugar  Alcohols  by  Chemical  Means.  —  One  method  of 
oxidation  frequently  used  by  Fischer  *  is  to  treat  the  alcohol  with  10 
*  "  Untersuchungen  iiber  Kohlenhydrate  "  (1909),  pp.  244,  294,  etc. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  771 

parts  nitric  acid  of  1.18  sp.  gr.  at  a  temperature  of  about  45°  C.  The 
liquid  soon  acquires  reducing  properties  and  when  this  has  reached  its 
maximum  the  solution  is  cooled,  neutralized,  and  the  sugar  precipitated 
as  hydrazone,  osazone,  or  examined  by  other  suitable  methods.  In 
place  of  nitric  acid  other  agents  may  be  used  for  oxidizing  the  sugar 
alcohols  to  sugars,  such,  for  example,  as  sodium  hypobromite,  weak  per- 
manganate, hydrogen  peroxide  in  presence  of  ferrous  sulphate,  and  lead 
peroxide  with  hydrochloric  acid. 

Oxidation  of  Sugar  Alcohols  by  Means  of  Bacteria.  —  The  oxidation 
of  the  sugar  alcohols  to  sugars  may  also  be  accomplished  by  biochemical 
means.  The  organism  most  used  for  this  purpose  is  the  Bacterium 
xylinum,  or  sorbose  bacterium,  the  action  of  which  upon  sugar  alcohols 
and  sugars  has  been  especially  studied  by  Bertrand.*  The  peculiarity 
of  the  oxidation  of  sugar  alcohols  by  Bacterium  xylinum  is  that  the 
sugars  formed  are  largely  if  not  entirely  ketoses.  The  following  ex- 
amples are  given  of  oxidation  of  sugar  alcohols  made  by  means  of  this 
organism: 

Glycerol  =  Dioxyacetone. 
i-Erythrite  =  Erythrulose. 
1-Arabite  =  Araboketose. 
d-Mannite  =  d-Fructose. 
d-Sorbite  =  d-Sorbose. 

Perseite  =  Heptoketose. 
Volemite  =  Heptoketose. 

All  the  sugar  alcohols,  however,  are  not  oxidized  by  Bacterium 
xylinum.  Dulcite  and  xylite,  for  example,  are  not  affected  by  this  or- 
ganism. A  curious  fact  noted  in  this  connection  is  that  oxidation  by 
Bacterium  xylinum  does  not  take  place  in  compounds  where  the  hy- 
droxyl  groups  in  the  second  and  third  position  lie  on  opposite  sides  of 
the  carbon  chain.  Thus  xylite  and  duleite  both  have  the  following 
configuration  in  common: 

HO-C-H       3 

H-C-OH    2 

CH2OH    1 

For  some  reason  not  understood  sugar  alcohols  having  the  above 
arrangement,  are  not  oxidized  by  Bacterium  xylinum. 

Sorbite,  mannite,  arabite  and  erythrite,  on  the  other  hand,  have  the 

*  Compt.  rend.,  126,  762,  894,  984;  130,  1330;  Bull.  soc.  chim.  [3],  16,  627;  19, 
347. 


772  SUGAR  ANALYSIS 

hydroxyl  groups  in  the  second  and  third  position  on  the  same  side  of 
the  carbon  chain  and  are  oxidized  by  Bacterium  xylinum  as  follows: 

3    H-C-OH  H-C-OH 

2    H-C-OH+O          =  C:O         +  H2O. 

1        CH2OH  CH2OH 

Alcohol  Ketose. 

Too  prolonged  or  too  violent  oxidation  of  the  sugar  alcohols  will 
lead  beyond  the  sugars  to  the  formation  of  sugar  acids,  the  description 
of  which  will  follow. 

THE  SUGAR  ACIDS 

The  sugar  acids  according  to  the  degree  of  oxidation  are  divided  into 
two  groups:  the  monobasic  and  the  dibasic  acids. 

THE   MONOBASIC   ACIDS   OF   THE   SUGARS 

Synthesis  of  the  Monobasic  Acids.  —  The  oxidation  of  sugars  to 
the  monobasic  acids  is  usually  accomplished  by  means  of  bromine  water. 
The  general  equation  for  the  reaction  with  an  aldose  sugar  is : 
CnH2nOn  +  2  Br  +  H2O  =  CnH2nOn+1  +       2  HBr. 

Aldose  Bromine  Aldonic  acid  Hydrobromic  acid. 

In  carrying  out  the  reaction  according  to  Fischer  *  1  part  of  sugar 
is  dissolved  in  5  parts  of  water  and  2  parts  of  bromine  added.  The 
solution  is  kept  cold  and  shaken  frequently  until  all  bromine  has  dis- 
solved. After  standing  at  room  temperature  1  to  3  days,  the  solution  is 
heated  to  expel  any  excess  of  bromine;  carbonate  of  lead  is  then  added  to 
neutralize  the  hydrobromic  acid  formed  in  the  reaction  and  the  filtered 
solution  evaporated  to  about  half  its  volume.  After  24  hours  the  lead 
bromide,  which  has  crystallized,  is  filtered  off  and  the  lead  remaining  in 
solution  precipitated  with  hydrogen  sulphide.  After  boiling  off  the 
hydrogen  sulphide  from  the  filtrate  the  last  traces  of  hydrobromic  acid 
are  removed  from  the  solution  by  shaking  with  silver  oxide,  and  any 
dissolved  silver  removed  from  the  filtrate  with  hydrogen  sulphide.  The 
solution  is  then  reboiled  to  expel  hydrogen  sulphide,  decolorized  if 
necessary  with  animal  charcoal  and  filtered  when  the  acid  can  either 
be  precipitated,  in  the  form  of  an  insoluble  salt  or  other  derivative,  or 
separated  as  a  crystalline  lactone  by  evaporation. 

The  method  just  described  for  oxidizing  sugars  to  their  monobasic 
acids  holds  true,  however,  only  for  the  aldose  sugars.  Ketose  sugars  are 
but  little  affected  by  bromine  water  at  ordinary  temperature  during  the 

*  Ber.,  22,  3218. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 


773 


+H20 


first  few  days.  Several  weeks'  contact,  however,  will  bring  about  slow 
oxidation,  with  a  breaking  up  of  the  molecule  into  a  mixture  of  acids  of 
lower  carbon  content.  /Lusfrr  £  f  4|  , 

Nomenclature.  —  In  the  nomenclature  of  the  monobasic  acids  de- 
rived from  the  sugars  the  ending  -onic  is  usually  substituted  for  the 
termination  -ose  of  the  sugar  as  xylonic,  gluconic,  pentonic,  hexonic, 
etc. 

Lactones  of  the  Monobasic  Acids.  —  Of  the  monobasic  acids  gly- 
collic  acid,  corresponding  to  a  diose  sugar,  is  obtained  in  the  form  of 
crystals  (melting  point  80°  C.)  and  gly eerie  acid,  corresponding  to  a 
triose  sugar,  as  a  thick  sirup.  The  higher  tetronic,  pentonic,  hexonic, 
heptonic,  octonic  and  nononic  acids  split  off  one  molecule  of  water  upon 
evaporation  and  crystallize  out  as  lactones.  The  formation  of  the 
lactone  of  a  hexonic  acid  is  represented  as  follows: 

CH2OH 

CHOH 
7  CHOjH  j 
ft CHOH  i  I 
a  CHOH 
OC-;OH  ! 

Hexonic  acid  Hexonic  acid  lactone 

In  the  above  reaction  the  splitting  off  of  water  and  the  linkage  by  the 
oxygen  ring  always  take  place  between  the  carbon  atom  of  the  terminal 
COOH  group  and  the  third  or  7  carbon  atom.  Glycollic  and  glyceric 
acids,  which  have  no  7  carbon  atom,  are  unable  to  form  lactones. 

The  lactones  of  the  monobasic  acids  are  well-defined  crystalline 
compounds  easily  soluble  in  water.  Freshly  prepared  aqueous  solu- 
tions of  the  lactones  'are  neutral  in  reaction,  but  on  standing  a  strong 
acidity  develops  owing  to  the  regeneration  of  the  carboxyl  group  by 
addition  of  water. 

The  sugar  monobasic  acids  and  their  lactones  are  optically  active. 
A  marked  difference,  however,  is  noticeable  between  the  specific  rota- 
tions of  the  acid  and  its  lactone,  and  with  the  transformation  of  the 
one  into  the  other,  by  the  addition  or  splitting  off  of  water,  changes  in 
rotation  take  place  which  resemble  the  mutarotation  of  sugars.  This 
is  seen  from  the  following  observations  made  upon  galactonic  acid  and 
its  lactone;  to  reduce  the  influence  of  lactone  formation  the  observations 
for  the  free  acid  were  made  upon  a  solution  prepared  by  decomposing  a 


774 


SUGAR  ANALYSIS 


solution  of  the  calcium  salt  with  the  equivalent  amount  of  oxalic  acid 
and  filtering. 


Galactonic  acid  *  from  calcium  salt 


10  minutes  after  solution 

5  hours  after  solution 

6  days  after  solution 
15  days  after  solution 
3  weeks  after  solution 


Gfllartonir  arid  t  lartone  I  immediately  after  solution 
Lralactomc  acid  T  lactone  s  severaj  days  after  solution 


-  10.56 

-  13.77 

-  39.24 

-  45.90 

-  46.82 

-  77.61 

-  67.89 

The  observations  show  a  slow  conversion  of  the  acid  into  the  lactone 
and  a  similar  conversion  of  the  lactone  into  the  acid;  after  a  longer  or 
shorter  period  of  time,  depending  upon  temperature  and  concentration, 
a  condition  of  equilibrium  is  reached  when  the  rotation  remains  constant. 

Relation  of  Configuration  to  the  Rotation  of  Lactones.  —  An  im- 
portant relation,  noted  by  Hudson, f  between  the  configuration  and 
rotation  of  the  lactones  of  the  sugar  acids,  is  that  all  dextrorotatory 
lactones  have  their  ring  linkages  upon  one  side  of  the  carbon  chain  and 
all  levorotatory  lactones  upon  the  opposite  side.  In  the  following 
table  the  position  of  the  lactone  ring,  with  reference  to  the  terminal 
CO  group  and  the  carbon  chain,  is  indicated  at  the  head  of  the  two 
classes  of  lactones. 


Dextrorotatory  lactones. 

Levorotatory  lactones. 

C    H 

7H-C  1 

fX.il 

ft    -C- 

0         | 
U-    a 
=0 

1       o 

o     —  C—        j 

1-Xy  Ionic 

+  83 

1-Arabonic 

-73.9 

d-Lyxonic 

+  82.4 

1-Ribonic 

-18.0 

d-Gluconic 

f  68.2 

Rhamnonic 

-39.0 

d-Mannonic 

+  53.8 

Isorhamnonic 

-62.0 

d-Gulonic 

+  56.1 

Rhodeonic 

-76.3 

a-Rhamnohexonic 

+  83.8 

d-Galactonic 

-77.6 

jS-Rhamnohexonic 
a-Rhamnoheptonic 
a-Glucooctonic 
/S-Glucooctonic 
a-Galaoctonic 

+  43.3 
+  55.6 
+  45.9 
+  23.6 
+  64.0 

a-Glucoheptonic 
/S-Glucoheptonic 
d-Mannoheptonic 
a-Galaheptonic 
Rhamnooctonic 

-55.3 

-67.7 
-74.2 
-52.3 

-50.8 

d-Mannooctonic 

-43.6 

Anderson  §   has  extended  the  above  list  and  shows  that  the  re- 
lationship discovered  by  Hudson  also  holds   for  the  lactones  of   the 


*  Schnelle  and  Tollens,  Ber.,  23,  2991. 
|  Ruff  and  Franz,  Ber.,  35,  948. 


J  J.  Am.  Chem.  Soc.,  32,  338. 
§  J.  Am.  Chem.  Soc.,  34,  51. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  775 

different  saccharinic  acids,  as  saccharin,  isosaccharin,  metasaccharin, 
etc.,  (see  pp.  587  and  604).  The  relationship  is  an  important  one,  since 
the  rotation  of  a  lactone  indicates  the  position  of  the  ring,  thus  estab- 
lishing the  configuration  for  the  y  position  of  the  acid  and  hence  also 
for  the  corresponding  sugar.  In  this  manner  Hudson  has  not  only 
verified  the  configurations  of  the  sugars  established  by  Fischer  from 
purely  chemical  data,  but  has  pointed  out  the  probable  structure  of  a 
number  of  sugars  whose  configurations  have  been  in  doubt. 

Molecular  Rearrangement  of  the  Sugar  Acids.  —  A  peculiarity  of 
many  sugar  acids  is  the  ease  with  which  they  undergo  molecular  change 
into  other  isomers  when  their  solutions  are  heated  at  high  temperature. 
The  simplest  instance  of  such  a  change  is  the  transformation  of  dextro- 
lactic  into  levo-lactic  acid  or  vice  versa,  the  reaction  as  in  all  such  cases 

being  a  reversible  one. 

CH3  CH3 

H-C-OH^±  HO-C-H 
HO-C=O          HO-C=O 

d- Lactic  acid  1-Lactic  acid 

The  lactones  do  not  appear  susceptible  to  this  kind  of  molecular 
rearrangement  and  to  prevent  their  formation  the  experiment  with 
acids,  which  yield  lactones,  is  carried  out  *  by  heating  the  aqueous  solu- 
tion at  130°  to  150°  C.  in  presence  of  pyridine  or  quinoline,  the  latter 
through  formation  of  salts  preventing  the  generation  of  lactones. 

The  part  of  the  molecule  which  is  affected  in  this  method  of  iso- 
merization  is  always  the  hydroxyl  adjoining  the  carboxyl  group,  the 
general  formula  for  the  reaction  being: 

H-C-OH  _>  HO-C-H 
0=C-OH          0=C-OH 

The  following  examples  are  given  of  monobasic  acids  which  have 
been  found  to  undergo  mutual  isomerization  by  the  method  of  Fischer 

just  described. 

1-Xylonic        <=*  d-Lyxonic 

1-Arabonic      <±  1-Ribonic 

d-Gluconic     +±  d-Mannonic 

1-Gluconic      +±  1-Mannonic 

d-Galactonic  <=±  d-Talonic 

1-Gulonic        <=±  1-Idonic 

The  same  reaction  is  also  obtained  between  the  a  and  0  isomers  of 
the  heptonic,  octonic  and  nononic  acids. 

*  Fischer,  Ber.,  27,  3189. 


776 


SUGAR  ANALYSIS 


Reduction  of  Lactories  to  Sugars.  —  It  has  not  been  found  possible 
to  reduce  the  monobasic  acids  in  aqueous  solution;  the  lactones*  how- 
ever, are  easily  reduced  in  aqueous  solution  by  means  of  sodium  amalgam 
first  to  sugars  and  after  prolonged  reduction  to  sugar  alcohols.  The 
reaction  for  a  hexonic  lactone  would  be: 

CH2OH  CH2OH 

CHOH  CHOH 


0 


HOH 

:H 

CHOH 
CHOH 

-io 

Hexonic  lactone 


nH 
HOH 
CHOH 
I CHOH 


or 


Hexoset 


CH2OH 
CHOH 
CHOH 
CHOH 
CHOH 
CHO 


The  reaction,  according  to  Fischer,  J  is  carried  out  by  treating  an  ice- 
cold  solution  of  the  lactone  in  10  parts  of  water  with  sodium  -amalgam 
(2J  per  cent  sodium),  the  mixture  being  always  kept  weakly  acid  with 
sulphuric  acid.  The  reaction  is  stopped  when  the  reducing  power  upon 
Fehling's  solution  has  reached  its  maximum  (usually  30  to  40  minutes). 
The  solution  is  then  neutralized,  decolorized  with  bone  black  and  evapo- 
rated to  crystallization  of  sodium  sulphate,  when  it  is  poured  into  20 
times  its  volume  of  hot  alcohol.  After  cooling,  the  alcoholic  solution  is 
filtered  from  sodium  sulphate  and  evaporated  to  a  sirup  from  which  the 
sugar  may  be  separated  as  hydrazone  or  other  compound  according  to 
conditions.  The  yield  of  sugar  is  40  to  60  per  cent  of  the  pure  lactone. 

Employment  of  Method  in  the  Synthesis  of  New  Sugars.  —  The  trans- 
formation of  the  monobasic  acids  of  known  sugars  into  new  isomers 
and  the  reduction  of  the  lactones  of  the  new  acid  by  the  process  just 
described  have  been  used  by  Fischer  with  great  success  in  the  synthesis  of 
many  new  sugars.  The  following  is  given  as  an  illustration  of  the  method : 


Monobasic  acid  (pro- 
Sugar,               duced  by  oxidizing 

New  monobasic  acid 
(produced  by  heating 

New  sugar 
(produced  by  reduction 

sugar  with  bromine). 

with  pyridine  to  140°). 

of  lactone  of  new  acid;. 

CH2OH 

CH2OH 

CH2OH 

CH2OH 

HOCH 

HOCH 

HOCH 

HOCH 

HCOH 

HCOH 

HCOH 

HCOH 

HOCH 

HOCH 

HCOH 

HCOH 

CHO 

COOH 

COOH 

CHO 

l-Xylose 

l-Xy  Ionic  acid 

d-Lyxonic  acid 

d-Lyxose 

*  Fischer,  Ber.,  22,  2204. 

t  The  sugars  are  regarded  by  many  chemists  as  having  a  lactonic  structure 
similar  to  the  form  shown  in  the  equation.  The  fact  that  only  lactones  are  reduced 
to  sugars  tends  to  support  this  view.  |  Ber.,  23,  930. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  777 

In  the  same  manner : 

1-Arabinose  =  1-arabonic  acid      =  1-ribonic  acid  =  1-ribose. 

Rhamnose     =  rhamnonic  acid     =  isorhamnonic  acid  =  isorhamnose 

d-Galactose  =  d-galactonic  acid  =  d-talonic  acid  =  d-talose. 

d-Gulose        =  d-gulonic  acid       =  d-idonic  acid  =  d-idose. 

a-Heptose     =  a-heptonic  acid     =  /8-heptonic  acid  =  £-heptose. 

a-Octose        =  a-octonic  acid       =  /3-octonic  acid  =  /3-octose. 

Hydrazide*  Reaction  of  the  Monobasic  Acids.  —  Among  the  most 
important  derivatives  of  the  sugar  acids,  for  purposes  of  identification 
and  separation,  are  the  phenylhydrazides.  All  of  the  acids  derived 
from  the  sugars  react  with  phenylhydrazine;  the  resulting  product, 
however,  is  entirely  different  in  chemical  properties  from  the  hydrazones 
and  osazones  of  the  sugars,  resembling  more  the  acid  amides.  The  re- 
action of  a  hexonic  acid  with  phenylhydrazine  is  given  as  illustration: 
CH2OH  CH2OH 

(CHOH)4  (CHOH)4 

-.     H    H  I     H    H 

O:C-jOH  +  H;-N-N-C6H5  =  O  rC-N-N-CgHs  +  H2O 

Hexonic  Acid  Phenylhydrazine  Hexonic  phenylhydrazide. 

The  reaction  is  carried  out  by  heating  a  solution  containing  1  part 
of  the  acid  in  10  parts  of  water  with  1  part  of  phenylhydrazine  and  1  part 
of  50  per  cent  acetic  acid  for  three-quarters  of  an  hour  upon  the  water 
bath.  The  solution  is  cooled,  the  precipitate  of  phenylhydrazide  filtered 
off,  washed  with  a  little  cold  water  and  recrystallized  from  hot  water 
using  a  little  animal  black.  The  hydrazides  thus  obtained  are  colorless 
crystalline  compounds,  the  melting  points  of  which  will  serve  in  many 
cases  for  purpose  of  identification. 

The  phenylhydrazides  are  decomposed  upon  heating  with  alkaline 
hydroxides,  with  formation  of  a  salt  of  the  acid  and  free  phenylhydra- 
zine. Barium  hydroxide  is  generally  used  for  this  purpose:  1  part  of 
hydrazide  is  treated  with  30  parts  of  hot  10  per  cent  barium  hydroxide 
solution,  boiled  one-half  hour  and  then  cooled.  The  free  phenylhydra- 
zine is  then  extracted  with  ether,  the  barium  precipitated  with  the  exact 
amount  of  sulphuric  acid  and  the  solution  filtered;  the  filtrate  upon 
evaporation  will  yield  the  lactone  of  the  acid. 

Salts  of  the  Monobasic  Acids.  —  The  monobasic  acid  derivatives 
of  the  sugars  give  a  large  number  of  salts  with  different  metals,  some 
of  which  have  been  used  for  purposes  of  identification.  Mention  has 
been  made  of  a  few  of  these,  in  so  far  as  they  pertain  to  the  identification 
of  sugars,  under  the  reactions  of  the  individual  sugars. 

*  Fischer  and  Passmore,  Ber.,  22,  2728. 


778  SUGAR  ANALYSIS 

The  salts  of  calcium,  barium,  cadmium,  and  lead  have  been  em- 
ployed in  some  cases  for  isolating  certain  of  the  acids.  The  cadmium 
and  lead  salts  (the  latter  usually  amorphous  flocculent  precipitates)  are 
decomposed  after  separation  with  hydrogen  sulphide  and  the  calcium 
and  barium  salts  with  the  equivalent  amounts  of  oxalic  or  sulphuric 
acid;  the  precipitates  are  filtered  off  and  the  liberated  acid  is  obtained 
by  concentrating  the  filtrate. 

A  number  of  the  monobasic  acids  give  characteristic  salts  with 
different  alkaloids,  as  strychnine,  brucine,  morphine,  and  the  various 
cinchona  bases.  The  utilization  of  these  salts  in  analyzing  racemic 
mixtures  of  sugar  acids  will  be  described  later  (p.  786). 

Oxidation  of  Monobasic  Acids  of  the  Sugars.  —  The  monobasic 
acid  derivatives  of  the  unsubstituted  aldose  sugars  are  converted  by 
oxidizing  agents  (as  nitric  acid,  1.2  sp.  gr.)  into  the  corresponding  dibasic 
acids;  the  substituted  monobasic  acids,  rhamnonic,  fuconic,  rhodeonic, 
methylhexonic,  etc.,  yield  dibasic  acids  of  one  less  carbon  atom  with  loss 
of  the  methyl  group. 


THE  DIBASIC  ACIDS   OF  THE   SUGARS 

Formation.  —  The  oxidation  of  sugars  to  their  dibasic  acids  is 
usually  performed  by  warming  the  sugar  with  30  per  cent  nitric  acid. 
The  reaction  only  holds  for  normal  unsubstituted  aldose  sugars,  the 
ketoses  being  all  degraded  into  lower  oxidation  products,  of  which 
oxalic  acid  is  usually  formed  in  largest  amount.  The  oxidation  of  an 
aldohexose  sugar  to  its  dibasic  acid  by  means  of  nitric  acid  proceeds 
as  follows: 

CH2OH  O:C-OH 

(CHOH)4  +  2  HNO3  =          (CHOH)4  -f  2  H2O  +  2  NO 
H-C:O  O:C-OH 

Nomenclature.  —  The  nomenclature  of  the  dibasic  acids  is  irregular. 
In  some  cases  where  there  is  a  genetic  relationship,  as  between  the 
sugars  glucose,  mannose,  and  idose,  and  their  dibasic  acids  saccharic, 
mannosaccharic,  and  idosaccharic,  a  certain  uniformity  exists;  so  also 
between  the  sugars  galactose  and  talose,  and  their  dibasic  acids  mucic 
and  talomucic.  The  family  to  which  each  acid  belongs  is  usually  in- 
dicated by  the  name  of  the  saturated  dibasic  fatty  acid  having  the 
same  number  of  carbon  atoms,  as:  malonic  (3  C  atoms),  succinic  (4), 
glutaric  (5),  adipic  (6),  pimelic  (7),  suberic  (8)  and  azelaic  (9). 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 


779 


Sugar. 

Dibasic  acid. 

Class. 

Formula. 

Class. 

Formula. 

Triose  

C3H6O3 

Oxymalonic*.  . 

C3H4O5 

Tetrose  

C4H8O4 

Dioxysuccinic.  . 

C4H6O6 

Pentose 

Trioxyglutaric 

C5H8O7 

Hexose 

C6H12O6 

Tetroxyadipic 

Heptose 

C7H14O7 

Pentoxypimelic.. 

C7H12O9 

Octose 

C8H16O8 

Hexoxysuberic. 

Nonose                  .    . 

C9H18O9 

Heptoxyazelaic  . 

C  H^V)1 

16      11 

Properties  of  the  Dibasic  Acid  Derivatives  of  Sugars.  —  The  pos- 
session of  an  additional  carboxyl  group  gives  the  dibasic  acids  of  the 
sugars  certain  properties  which  distinguish  them  from  the  monobasic 
acids.  Among  these  properties  may  be  mentioned,  (1)  The  formation 
of  lactone  acids  and  double  lactones;  (2)  The  formation  of  two  classes 
of  hydrazides,  the  single  and  double;  (3)  The  formation  of  several 
classes  of  salts,  the  acid,  neutral,  and  double. 

Lactone  Acids.  —  The  formation  of  lactones  is  not  so  general  with 
the  dibasic  as  with  the  monobasic  acids.  With  the  tetrose  derivatives 
the  7  position,  which  is  held  by  an  alcohol  group  in  the  monobasic 
acids,  is  occupied  by  one  of  the  carboxyl  groups  in  the  dibasic  acids 
(d-,  1-,  and  i-tartaric  acids)  so  that  lactone  formation  is  excluded. 
But  even  in  the  case  of  some  of  the  higher  derivatives,  as  of  arabinose, 
xylose,  and  galactose,  the  dibasic  acid  crystallizes  out  in  the  free  con- 
dition. Mucic  acid,  derived  from  galactose,  can  be  converted,  however, 
into  a  monolactone  by  long  boiling  with  water. 

The  lactones  of  the  dibasic  acids  are  in  nearly  all  cases  mono-  or 
acid  lactones  :  in  other  words  only  one  of  the  carboxyl  groups  is  affected, 
the  other  remaining  free  and  retaining  its  acid  properties.  The  mono- 
lactone of  saccharic  acid,  for  example,  can  be  represented  by  the 

formula 

0  =  C  -  1 

HOCH    I 
HOCH 


HOCH 
O  =  C-OH. 

*  The  prefix  oxy-  is  loosely  used  instead  of  hydroxy-.  According  to  the  nomen- 
clature of  the  Geneva  Congress,  which  is  but  little  followed,  the  dibasic  acid  of  a 
pentose  sugar  would  be  pentane-triol-dicarboxylic  acid;  of  a  hexose,  hexane-tetrol- 
dicarboxylic  acid;  of  a  heptose,  heptane-pentol-dicarboxylic  acid,  etc. 


780  SUGAR  ANALYSIS 

The  lactone  acids  are  nearly  all  crystalline  compounds,  easily  soluble 
in  water.  The  solution  of  a  lactone  acid,  neutralized  in  the  cold  with 
sodium  hydroxide,  quickly  becomes  acid  again  through  reconversion  of 
the  lactone  into  the  free  acid  group.  Stable  compounds  of  the  lactone 
acids  are  for  this  reason  unknown. 

Solutions  of  the  lactone  acids  in  water  undergo  spontaneously  a 
partial  change  into  the  dibasic  acid  with  establishment  of  a  condition  of 
equilibrium,  the  predominance  of  lactone  acid,  or  of  dibasic  acid,  depend- 
ing upon  the  temperature  and  concentration.  With  this  transformation 
changes  are  noted  in  the  rotation  of  the  solution.  In  the  case  of  saccharic 
acid  and  its  lactone  acid,  the  following  specific  rotations  were  noted. 

WD. 

Saccharic  acid,*  after  solution +    9.1 

Saccharic  acid,  constant  (29  days) -j-  22.7 

Saccharic  acid  monolactone,  after  solution +  37.9 

Saccharic  acid  monolactone,  constant  (56  days) +  22.5 

The  results  show  that  the  change  between  saccharic  acid  and  its 
lactone  is  a  reversible  one,  the  same  condition  of  equilibrium  being 
reached  whichever  compound  is  first  dissolved.  The  case  is  similar  to 
that  of  galactonic  acid  and  its  lactone  (p.  774). 

Double  Lactones.  —  With  the  dibasic  acids  derived  from  d-  and 
1-mannose,  the  peculiarity  of  double  lactone  f  formation  is  observed. 
These  very  characteristic  compounds  crystallize  out  with  2  molecules  of 
water,  which  can  be  eliminated  by  drying  over  concentrated  sulphuric 
acid.  Aqueous  solutions  of  the  double  lactones  are  at  first  neutral, 
but  become  acid  upon  standing;  the  aqueous  solutions  have  also. the 
peculiarity  of  strongly  reducing  Fehling's  solution,  this  being  probably 
due  to  an  aldehydic  rearrangement  of  the  dilactone  molecule  in  pres- 
ence of  free  alkalies. 

The  rotations  of  the  lactone  acids  and  double  lactones  agree  per- 
fectly with  Hudson's  hypothesis  (p.  774)  according  to  which  the  char- 
acter of  rotation  depends  upon  the  position  of  the  lactone  ring. 

The  structure  of  the  double  lactone  of  d-mannosaccharic  acid  is 
shown  as  follows: 


*  Tollens  and  Sohst,  Chem.  Ztg.,  11,  99,  1178j  Ann.,  246,  1. 
t  Kiliani,  Ber.,  20,  341;   Fischer,  Ber.,  24,  539. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  781 

The  property  of  undergoing  transformation  to  other  isomers  upon 
heating  with  pyridine  at  140°,  noted  for  the  monobasic  acids  (p.  775), 
also  exists  with  the  dibasic  acids.     Mucic  acid  has  been  converted  in  this 
way  by  Fischer  *  into  the  isomeric  compound  allomucic  acid. 
COOH  COOH 

HCOH  HOCH 

HOCH  HOCH 

HOCH  HOCH 

HCOH  HOCH 
COOH  COOH 

Mucic  acid  Allomucic  acid 

As  with  the  monobasic  acids  the  HCOH  groups  adjoining  COOH  radicals 
are  the  parts  of  the  molecule  affected  in  this  reaction. 

Dehydration  of  Dibasic  Acids  of  Hexoses.  —  A  noteworthy  char- 
acteristic of  the  dibasic  acids  of  the  hexoses  is  the  ease  with  which  they 
undergo  dehydration,  upon  heating  to  150°  C.  with  concentrated  hydro- 
chloric acid,  hydrobromic  acid,  sulphuric  acid  or  other  dehydrating 
agent,  with  formation  of  the  unsaturated  dehydromucic  acid.  The 
reaction  is  illustrated  graphically  as  follows: 

H  H  H  H 

:  HO  ic—       —  c  ion";    _  c 


/    \  /    \  /    \  /\ 

.      HOOC         O  fcT;       COOH          HOOC  O         COOH 

|"H"  H  I 

Hexose  dibasic  acid  Dehydromucic  acid  Water. 

Dehydromucic  Acid.—  The  best  dehydrating  agent  to  use  for  the  above 
reaction,  according  to  Fischer,*  is  a  mixture  of  hydrochloric  and  hydro- 
bromic acids.  Fischer  considers  the  dehydromucic  acid  reaction  the 
best  of  all  methods  for  detecting  a  dibasic  acid  of  the  hexose  type. 

Dehydromucic  acid  is  best  recognized  by  the  reaction  of  Tollens 
and  Yoderf:  2  to  5  mgs.  of  substance  are  carefully  heated  with  2  c.c. 
concentrated  sulphuric  acid  and  1  to  4  mgs.  of  isatin  at  145°  to  155°  C. 
When  the  test  is  made  with  pure  dehydromucic  acid  the  solution  will 
be  colored  a  strong  violet  blue;  with  the  dibasic  hexose  acids  (mucic, 
saccharic,  mannosaccharic,  etc.),  the  solution  takes  on  more  of  a  green 
color  and  shows  before  the  spectroscope  two  characteristic  absorption 
bands  near  the  a  and  (3  lines  of  strontium. 

*  Her.,  24,  2136.  t  Ber.,  34,  3448. 


782  SUGAR  ANALYSIS 

Dehydromucic  acid  upon  heating  splits  off  C02  and  yields  pyro- 
mucic  acid  which  is  the  acid  derivative  of  furfural  (p.  374). 

H      H  H      H 

C  -  C  C  -  C 


\  /  \  \  /  \ 

O      COOH  O        CHO 

Pyromucic  acid  Furfural 

Chitonic  and  Isosaccharic  Acids.  —  Resembling  dehydromucic  acid 
in  structure  are  the  saturated  monobasic  and  dibasic  acids  derived 
from  chitose,  which  is  probably  also  itself  a  saturated  furfuran  de- 
rivative. 

H      H  H      H  H      H 

HOC  -  COH  HOG  -  COH  HOC  -  COH 

HC       CH  HC       CH  HC       CH 

/\/\  /  \    /  \  /  \    /  \ 

HOH2C       O       CHO         HOH2C        O       COOH        HOOC       O        COOH 

Chitose  Chitonic  acid  Isosaccharic  acid 

Hydrazides  of  Dibasic  Acids.  —  The  dibasic  acids  of  the  sugars 
yield  hydrazides  the  same  as  the  monobasic  derivatives;  the  second 
carboxyl  group  enables  them  however  to  fix  an  additional  molecule  of 
phenylhydrazine.  Many  of  the  dibasic  acids  give,  in  fact,  two  classes 
of  compounds,  the  acid  and  double  hydrazides.  The  acid  hydrazides 
are  precipitated  usually  with  phenylhydrazine  in  the  cold  and  the  double 
hydrazides  by  heating.  The  following  formulae  illustrate  the  configu- 
ration of  the  acid  and  double  hydrazides: 

H    H 
COOH  OC-N-N-C6H6 

(CHOH)4  (CHOH)4 

I     H    H  |      H     H 

OC-N-N-C6H5  OC-N-N-C6H5 

Acid  phenyl-  Double   phenyl- 

hydrazide  hydrazide. 

The  acid  hydrazides  are  colorless  compounds  easily  soluble  in  hot 
water,  while  the  double  hydrazides  are  usually  of  a  pale  yellow  color  and 
only  slightly  soluble  in  hot  water. 

Reduction  of  Dibasic  Acids.  —  The  lactones  of  the  dibasic  acids 
are  reduced  by  sodium  amalgam,  following  the  same  method  described 
on  p.  776,  and  yield  in  succession  the  lactones  of  the  monobasic  acid, 
the  sugars  and  the  corresponding  alcohols. 

d-Glucuronic  Add.  —  An  interesting  intermediary  step  between  the 
dibasic  and  monobasic  acids,  noted  in  the  reduction  of  the  lactones  of 
saccharic  and  mucic  acids,  is  the  production  of  an  aldehyde  acid.  In 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 


783 


the  case  of  saccharic  acid  monolactone,  for  example,  Fischer  and  Piloty 
obtained  as  an  intermediary  reduction  product  d-glucuronic  acid. 


COOH 
CHOH 
)H 

CHOH 

O   I 
I   CHOH 

Uo 

Saccharic  acid  monolactone 


H2  = 


COOH 
CHOH 
CHOH 
CHOH 
CHOH 


mo 

d-Glucuronic  acid 


d-Glucuronic  acid  occurs  naturally  in  the  urine  and  yields  furfural 
upon  distillation  with  hydrochloric  acid;  its  properties,  reactions,  and 
close  relationship  to  the  pentoses  are  referred  to  elsewhere  (p.  375). 

The  successive  steps  in  the  reduction  of  different  lactones  of  the 
dibasic  acids  are  given  as  follows: 


Dibasic  acid  lactone. 

Aldehyde  acid. 

Monobasic  acid 
lactone. 

Sugar. 

Alcohol. 

Saccharic  acid 
Mannosaccharic  acid 
Mucic  acid 

d-Glucuronic 
? 

Galacturonic 

d-Gulonic 
d-Mannonic 
d,  1-Galactonic 

d-Gulose 
d-Mannose 
d,  1-Galactose 

Sorbite 
Mannite 
Dulcite 

Salts  of  the  Dibasic  Acids.  —  The  dibasic  acid  derivatives  of  the 
sugars  yield  a  large  variety  of  salts;  the  formation  of  acid  and  double 
salts  is  in  general  a  distinguishing  feature  of  the  dibasic  as  compared 
with  the  monobasic  acids. 

Many  of  the  dibasic  acids  give  insoluble  compounds  with  calcium,  lead 
and  other  metals,  and  some  of  these  (as  calcium  oxalate)  are  used  con- 
siderably for  purposes  of  separation  and  analysis.  The  calcium  salts  of 
the  higher  dibasic  acids  can  usually  be  precipitated  from  cold  aqueous 
solution;  after  filtering  and  dissolving  in  hot  water  the  calcium  can  be 
removed  by  treating  with  an  exactly  equivalent  quantity  of  oxalic  acid. 
The  calcium  oxalate  is  then  filtered  off  and  the  pure  acid  obtained  in  the 
filtrate.  The  isolation  of  the  acids  can  also  be  effected  by  means  of  the 
lead  salts;  the  latter  after  precipitation  are  filtered  off,  washed  and 
then  decomposed  in  aqueous  suspension  with  hydrogen  sulphide.  The 
lead  sulphide  is  filtered  off  and  the  acid  obtained  in  the  filtrate. 

Of  the  acid  salts  of  the  dibasic  acids  those  of  potassium  have  the 
greatest  importance.  Several  of  these,  as  the  acid  potassium  tartrate 
(cream  of  tartar)  and  acid  potassium  saccharate,  are  characterized  by 

*  Ber.,  24,  521. 


HOH 


784  SUGAR  ANALYSIS 

low  solubility  in  cold  water  and  this  property  is  made  use  of  in  the 
identification  of  these  acids. 

There  are  a  large  number  of  interesting  double  salts  of  the  dibasic 
acids  but  only  a  few  of  these  can  be  mentioned.  Several  dibasic  acids, 
as  tartaric,  saccharic  and  mucic,  give  double  compounds  with  potassium 
and  antimony  oxide.  Of  these  potassium  antimonyl  tartrate,  or  tartar 
emetic,  is  given  as  illustration: 

COOK 

J, 

i 

COO-Sb=O. 

Of  other  double  salts  the  sodium  ammonium  tartrates  have  a 
special  historical  interest,  since  it  was  owing  to  the  work  of  Pasteur 
upon  these  salts  that  the  science  of  molecular  asymmetry  and  the 
methods  for  analyzing  racemic  mixtures  had  their  first  beginning.  The 
problem  of  separating  the  dextro-  and  levo-rotatory  components  of  an 
optically  inactive  racemic  mixture  was  in  fact  first  solved  by  Pasteur; 
as  the  methods  established  by  him  are  still  the  ones  most  generally 
employed,  this  particular  branch  of  sugar  analysis  may  be  treated  best 
in  connection  with  a  review  of  Pasteur's  work  upon  tartaric  acid. 

THE  ANALYSIS  OF  RACEMIC  MIXTURES 

Tartaric  acid  may  be  said  to  exist  under  four  different  forms;  the 
structural  formulae  of  these  are  represented  as  follows: 

COOH     COOH      COOH        COOH     COOH 

HCOH    HOCH       HCOH        HCOH    HOCH 
HOCH      HCOH      HCOH       HOCH      HCOH 
COOH     COOH      COOH        COOH     COOH 

Dextro-  or  Levo-  or  Meso-  or  Racemic  or 

d-tartaric  acid       1-tartaric  acid  i-tartaric  acid  d,  1-tartaric  acid 

(inactive)  (inactive) . 

I  II  III  IV 

The  d-  and  1-components  of  a  racemic  *  mixture  usually  resemble  one 
another  in  melting  point,  solubility,  specific  gravity,  chemical  affinity, 
and  all  other  properties  except  specific  rotation;  the  racemic  substance 
itself  may  differ,  however,  from  its  components  in  crystalline  form, 
melting  point,  solubility,  and  other  characteristics.  In  other  words  a 
racemic  compound  may  behave  not  as  a  mixture,  but  as  a  simple  sub- 

The  word  racemic  is  derived  from  the  Latin  for  tartaric  acid,  acidum  racemi- 
cum,  where  the  phenomenon  was  first  noted. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS 


785 


stance;  it  is  this  peculiarity  which  renders  the  separation  of  the  two 
optically  active  antipodes  in  a  racemic  mixture  a  matter  of  such  diffi- 
culty. 

In  many  laboratory  operations  where  optically  active  substances 
are  formed,  the  d-  and  1-isomers  are  produced  in  equal  amounts;  many 
instances  of  optical  activity  escape  notice  for  this  very  reason.  The 
possibility  of  separating  an  optically  inactive  compound  into  two  opti- 
cally active  components  should  therefore  always  be  considered. 

Separation  of  Racemic  Mixtures  by  Differences  in  Crystalline  Form. 
—  It  was  observed  by  Pasteur*  in  1848  that  when  a  solution  of  racemic 


Fig.  200.  —  Showing  opposite  hemihedrism  of  crystals  of  the  sodium-ammonium  salts 
of  d-tartaric  and  1-tartaric  acids. 

acid  which  had  been  neutralized,  one-half  with  sodium  hydroxide  and 
one-half  with  ammonia,  was  allowed  to  evaporate  under  certain  condi- 
tions, separate  crystals  were  obtained  of  the  d-  and  1-  double  salts.  The 
two  classes  of  salts  were  similar  in  all  respects  except  in  the  position  of 
their  hemihedral  faces  (shown  in  black,  Fig.  200).  In  one  set  of  crystals, 
for  example,  the  hemihedral  faces  were  always  at  the  right  of  the  sur- 
faces d  and  e,  when  the  latter  were  uppermost,  and  in  the  other  set  of 
crystals  always  at  the  left.  The  relationship  between  the  two  crystal- 
line forms  was  exactly  like  that  between  one  crystal  and  its  mirror 
image,  where  one  form  cannot  be  brought  into  coincidence  with  the 
other  by  any  method  of  turning  the  crystal. 

By  dissolving  separately  the  two  sets  of  hemihedral  crystals,  Pasteur 
obtained  in  one  case  a  solution  which  rotated  the  plane  of  polarized 
light  to  the  right,  and  in  the  other  case  a  solution  which  rotated  the 
plane  of  polarized  light  to  the  left.  Separation  was  thus  effected  of 

*  For  a  full  account  of  Pasteur's  researches  upon  the  tartaric  acids  see  his 
"  Re"cherches  sur  la  dissymmetric  moleculaire  des  produits  organiques  naturels," 
Paris;  also  his  original  papers,  Compt.  rend.,  26,  535;  27,  401;  32,  110;  36,  180;  36, 
26;  37,  110,  162;  etc. 


786  SUGAR  ANALYSIS 

the  inactive  racemic  salt  into  its  two  optically  active  components.  The 
phenomenon  of  hemihedrism  was  explained  by  Pasteur  as  due  to  an 
asymmetric  arrangement  of  the  atoms  within  the  molecule,  the  group- 
ing in  one  compound  being  exactly  the  reverse  of  that  in  the  other. 

If  the  d,  1-sodium  ammonium  tartrate  crystallizes  out  at  a  high  tem- 
perature only  the  non-hemihedral  crystals  of  the  racemate  are  obtained. 
The  transition  point  between  separation  of  racemate  and  that  of  the 
hemihedral  crystals  of  d-  and  1-tartrate  is  28°  C. ;  and  it  is  only  under 
this  temperature  that  separation  of  the  two  salts  can  be  effected  by  the 
difference  in  crystalline  form. 

Separations  of  racemic  mixtures  into  their  optically  active  com- 
ponents by  differences  in  crystalline  form  have  been  made  upon  other 
sugar  derivatives.  The  optically  inactive  lactone  of  d,  1-gulonic  acid, 
for  example,  crystallizes,  according  to  Haushofer,*  in  rhombic  crystals 
with  hemihedral  faces;  by  selecting  the  forms  of  opposite  hemihedry 
the  d-  and  1-lactones  are  obtained  of  opposite  specific  rotation.  This 
means  of  separation  is  not,  however,  generally  applicable,  and  recourse 
is  usually  made  to  other  methods. 

Separation  of  Racemic  Mixtures  by  Combination  with  Other  Opti- 
cally Active  Compounds.  —  This  second  method  of  separating  racemic 
mixtures  is  also  due  to  Pasteur,  who  discovered  that  when  a  hot  aqueous 
solution  of  d,  1-tartaric  acid  was  saturated  with  equivalent  amounts  of 
different  cinchona  bases  the  quinine  and  quinicine  salts  of  d-tartaric 
acid  crystallized  out  before  the  corresponding  compounds  of  1-tartaric 
acid,  while  the  cinchonine  and  cinchonicine  salts  of  1-tartaric  acid 
separated  before  the  corresponding  compounds  of  d-tartaric  acid. 
This  method  of  separating  racemic  mixtures  has  been  greatly  extended 
since  the  time  of  Pasteur  and  has  been  applied  to  many  different  classes 
of  compounds.  In  many  operations  where  sugar  acids  are  formed, 
both  optical  antipodes  are  produced,  the  inactive  racemic  mixture  of 
the  d-  and  1-acids  behaving  very  much  as  a  simple  acid  and  yielding 
upon  evaporation  an  optically  inactive  lactone. 

The  salts  of  the  alkaloids  have  been  of  great  service  in  separating  the 
d-  and  1-components  of  different  inactive  sugar  acids.  The  strychnine 
salt  of  d-mannonic  acid,f  for  example,  is  soluble  in  hot  absolute  alcohol, 
while  the  strychnine  salt  of  1-mannonic  acid  is  insoluble.  If  the  latter  is 
filtered  off,  dissolved  in  water  and  treated  with  barium  hydroxide  solu- 
tion, the  strychnine  is  precipitated  and  a  soluble  barium  salt  of  1-man- 
nonic acid  formed.  The  solution  is  filtered,  shaken  out  with  ether  to 

*  Ber.,  24,  530;  26,  1027. 
t  Fischer,  Ber.,  23,  370. 


THE  SUGAR  ALCOHOLS  AND  SUGAR  ACIDS  787 

remove  any  remaining  strychnine  and  then  treated  with  sulphuric  acid 
in  exact  amount  to  precipitate  all  barium  sulphate.  The  latter  is  fil- 
tered off  and  the  filtrate  evaporated  when  the  1-mannonic  acid  will 
crystallize  out  as  a  lactone.  In  the  same  manner  d-galactonic  acid 
(strychnine  salt  of  low  solubility)  has  been  separated  from  1-galactonic 
acid. 

The  principal  alkaloids  used  for  separating  racemic  mixtures  of  acids 
are  the  cinchona  bases,  quinine,  quinidine,  cinchonine  and  cinchonid- 
ine;  the  strychnos  bases,  strychnine  and  brucine;  and  the  opium  base, 
morphine. 

The  principle  of  this  method  has  also  been  employed  in  separating 
racemic  mixtures  of  sugars  by  means  of  optically  active  hydrazines 
(p.  361). 

Separation  of  Racemic  Mixtures  by  Selective  Fermentation. 

This  third  method  of  separating  racemic  mixtures  is  also  due  to 
Pasteur  and  is  based  upon  the  difference  in  susceptibility  of  the  d-  and 
1-components  to  attack  by  different  ferments  and  moulds.  Pasteur 
noted  that  inactive  solutions  of  ammonia  d,  1-tartrate  after  inoculation 
with  spores  of  Penicillium  glaucum  (in  presence  of  slight  amounts  of 
mineral  salts  to  act  as  nutrients)  became  strongly  levorotatory.  This 
was  explained  by  the  fact  that  the  d-tartaric  acid  was  fermented  by 
the  mould,  the  1-tartaric  acid  remaining  unaffected. 

Pasteur's  third  method  of  resolving  racemic  compounds  has  also 
been  greatly  extended  and  has  been  employed  with  success  in  sepa- 
rating mixtures  of  d,  1-sugars  and  acids.  Thus  by  means  of  yeast 
Fischer  was  able  to  ferment  the  d-sugar  in  d,  1-glucose,  d,  1-mannose, 
d,  1-galactose  and  d,  1-fructose,  and  obtain  the  1-sugar  in  a  pure  con- 
dition. 

For  separating  the  sugar  acids,  Penicillium  glaucum,  first  used  by  Pas- 
teur, is  still  largely  employed.  Of  the  acids  fermented  by  this  mould, 
may  be  mentioned  d-tartaric,  d-glyceric,  d-mannonic,  and  d-glutaminic 
acids,  the  1-isomers  of  these  compounds  not  being  attacked.  The 
selective  influence  of  a  mould,  yeast,  or  other  organism  is  not  confined, 
however,  to  the  members  of  a  single  d-  or  1-series  as  might  be  inferred 
from  the  examples  mentioned.  Thus  with  the  ammonium  salt  of  d,  1- 
lactic  acid  (fermentation  lactic  acid),  the  1-lactic  acid  is  fermented  by 
Penicillium  glaucum  and  the  d-compound  left  behind  in  solution. 


APPENDIX  OF  SUGAR  TABLES 


INTRODUCTION 

THE  following  tables,  which  have  been  selected  to  accompany  various 
methods  described  in  the  author's  "  Handbook  of  Sugar  Analysis," 
have  been  grouped  together  for  convenience  as  a  separate  Appendix. 
This  arrangement  was  made  partly  to  prevent  breaking  the  continuity 
of  the  text  by  the  introduction  of  lengthy  tables  and  partly  to  permit 
the  publication  of  the  Appendix  as  a  separate  book  for  the  convenience 
of  those  who  have  occasion  to  make  use  of  special  tables  in  the  laboratory. 

Knowing  the  very  diverse  preferences  of  individual  sugar  chemists, 
the  author  has  made  a  rather  wide  selection  from  the  more  commonly 
used  copper  reduction  tables.  Limitations  of  space  have  obliged  him, 
however,  to  leave  out  many  tables  of  recognized  merit  and  this  must  be 
his  excuse  for  any  errors  of  omission. 


LIST  OF  TABLES 

TABLE  PAGE 

20° 

1.  Specific   Gravity  of  Sucrose  Solutions  at  ^5-  C.    (Kaiserliche  Normal- 

Eichungs-Kommission) 1 

2.  Temperature  Corrections  for  Changing  Percentages  of  Sugar  by  Specific 

Gravity  to  True  Values  at  20°  C 5 

1 7  'i0 

3.  Specific  Gravity  of  Sucrose   Solutions   at      '  0  C.  with  Corresponding 

1 1  .o 


Degrees  Brix  and  Baume", 


4.  Table  for  Correcting  Readings  of  Brix  Hydrometers  at  Different  Tempera- 

tures to  17.5°  C 16 

5.  Main's  Table  for  Determining  Water  in  Sugar  Solutions  by  Means  of  the 

Abbe  Refractometer  at  20°  C 17 

6.  Stanek's  Correction  Table  for  Determining  Water  in  Sugar  Solutions  by 

Means  of  the  Abbe  Refractometer  when  Readings  are  Made  at  Other 
Temperatures  than  20°  C 21 

7.  Geerligs's  Table  for  Determining  Dry  Substance  in  Sugar  House  Products 

by  the  Abbe  Refractometer  at  28°  C 22 

8.  Hiibener's  Table  for  Determining  Percentages  by  Weight  of  Sucrose  in 

Sugar  Solutions  from  Readings  of  the  Zeiss  Immersion  Refractometer      24 

9.  Kruis's  Table  for  Determining  Glucose  by  Reischauer's  Method 27 

10.  Allihn's  Table  for  Determining  Glucose 30 

11.  Pfliiger's  Table  for  Determining  Glucose 33 

12.  Koch  and  Ruhsam's  Table  for  Determining  Glucose  in  Tanning  Materials  35 

13.  Meissl's  Table  for  Determining  Invert  Sugar 38 

14.  Wein's  Table  for  Determining  Maltose 40 

15.  Soxhlet  and  Wein's  Table  for  Determining  Lactose 42 

16.  Woy's  Table  for  Determining  Glucose,  Fructose,  Invert  Sugar,  Lactose 

and  Maltose  by  Kjeldahl's  Method 44 

17.  Brown,  Morris  and  Millar's  Table  for  Determining  Glucose,  Fructose  and 

Invert  Sugar 62 

18.  Defren's  Table  for  Determining  Glucose,  Maltose  and  Lactose 63 

19.  Munson  and  Walker's  Table  for  Determining  Glucose,  Invert  Sugar  Alone, 

Invert  Sugar  in  the  Presence  of  Sucrose  (0.4  gram  and  2  grams  Total 

Sugar),  Lactose  and  Maltose 66 

vii 


viii  SUGAR  TABLES 

TABLE  PAGE 

20.  Bertrand's  Table  for   Determining   Invert   Sugar,    Glucose,    Galactose, 

Maltose  and  Lactose 79 

21.  Herzf eld's  Table  for  Determining  Invert  Sugar  in  Raw  Sugars  (Invert 

Sugar  not  to  Exceed  1.5%) 81 

22.  Krober's  Table  for  Determining  Pentoses  and  Pentosans 83 

23.  Tollens,  Ellet  and  Mayer's  Table  for  Determining  Methylpentoses  and 

Methylpentosans 89 

24.  Formulae,  Descriptions,  Melting  Points  and  Solubilities  of  the  Principal 

Hydrazones  and  Osazones  of  the  Sugars 90 

25.  Reciprocals  of  Numbers  from  1  to  100 101 


SUGAR   TABLES 


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SUGAR   TABLES 


TABLE*  2. 

TEMPERATURE  CORRECTIONS  FOR  CHANGING  PERCENTAGES  OF  SUGAR  BY 
SPECIFIC  GRAVITY  TO  TRUE  VALUES  AT  20° C. 


Observed  per  cent  of  sugar. 

ture. 
Degrees 

0 

5 

10 

15 

20 

25 

30 

35 

40 

45 

50 

55 

60 

70 

Centigrade. 

Correction  to  be  subtracted  from  observed  per  cent. 

0 

0.30 

0.49 

0.65 

0.77 

0.89 

0.99 

1.08 

Lie 

1.24 

1.31 

1.37 

1.41 

1.44 

1.49 

5 

0.36 

0.47 

0.56 

0.65 

0.73 

0.80 

0.86 

0.91 

0.97 

1.01 

1.05 

1.08 

1.10 

1.14 

10 

0.32 

0.38 

0.43 

0.48 

0.52 

0.57 

0.60 

0.64 

0.67 

0.70 

0.72 

0.74 

0.75 

0.77 

11 

0.31 

0.35 

0.40 

0.44 

0.48 

0.51 

0.55 

0.58 

0.60 

0.63 

0.65 

0.66 

0.68 

0.70 

12 

0.29 

0.32 

0.36 

0.40 

0.43 

0.46 

0.50 

0.52 

0.54 

0.56 

0.58 

0.59 

0.60 

0.62 

13 

0.26 

0.29 

0.32 

0.35 

0.38 

0.41 

0.44 

0.46 

0.48 

0.49 

0.51 

0.52 

0.53 

0.55 

14 

0.24 

0.26 

0.29 

0.31 

0.34 

0.36 

0.38 

0.40 

0.41 

0.42 

0.44 

0.45 

0.46 

0.47 

15 

0.20 

0.22 

0.24 

0.26 

0.28 

0.30 

0.32 

0.33 

0.34 

0.36 

0.36 

0.37 

0.38 

0.39 

16 

0.17 

0.18 

0.20 

0.22 

0.23 

0.25 

0.26 

0.27 

0.28 

0.28 

0.29 

0.30 

0.31 

0.32 

17 

0.13 

0.14 

0.15 

0.16 

0.18 

0.19 

0.20 

0.20 

0.21 

0.21 

0.22 

0.23 

0.23 

0.24 

18 

0.09 

0.10 

0.10 

0.11 

0.12 

0.13 

0.13 

0.14 

0.14 

0.14 

0.15 

0.15 

0.15 

0.16 

19 

0.05 

0.05 

0.05 

0.06 

0.06 

0.06 

0.07 

0.07 

0.07 

0.07 

0.08 

0.08 

0.08 

0.08 

Correction  to  be  added  to  observed  per  cent. 


21 

0.04 

0.05 

0.06 

0.06 

0.06 

0.07 

0.07 

0.07 

0.07 

0.08 

0.08 

0.08 

0.08 

0.09 

22 

0.10 

0.10 

0.11 

0.12 

0.12 

0.13 

0.14 

0.14 

0.15 

0.15 

0.16 

0.16 

0.16 

0.16 

23 

0.16 

0.16 

0.17 

0.17 

0.19 

0.20 

0.21 

0.21 

0.22 

0.23 

0.24 

0.24 

0.24 

0.24 

24 

0.21 

0.22 

0.23 

0.24 

0.26 

0.27 

0.28 

0.29 

0.30 

0.31 

0.32 

0.32 

0.32 

0.32 

25 

0.27 

0.28 

0.30 

0.31 

0.32 

0.34 

0.35 

0.36 

0.38 

0.38 

0.39 

0.39 

0.40 

0.39 

26 

0.33 

0.34 

0.36 

0.37 

0.40 

0.40 

0.42 

0.44 

0.46 

0.47 

0.47 

0.48 

0.48 

0.48 

27 

0.40 

0.41 

0.42 

0.44 

0.46 

0.48 

0.50 

0.52 

0.54 

0.54 

0.55 

0.56 

0.56 

0.56 

28 

0.46 

0.47 

0.49 

0.51 

0.54 

0.56 

0.58 

0.60 

0.61 

0.62 

0.63 

0.64 

0.64 

0.64 

29 

0.54 

0.55 

0.56 

0.59 

0.61 

0.63 

0.66 

0.68 

0.70 

0.70 

0.71 

0.72 

0.72 

0.72 

30 

0.61 

0.62 

0.63 

0.66 

0.68 

0.71 

0.73 

0.76 

0.78 

0.78 

0.79 

0.80 

0.80 

0.81 

35 

0.99 

1.01 

1.02 

1.06 

1.10 

1.13 

1.16 

1.18 

1.20 

1.21 

1.22 

1.22 

1.23 

1.22 

40 

1.42 

1.45 

1.47 

1.51 

1.54 

1.57 

1.60 

1.62 

1.64 

1.65 

1.65 

1.65 

1.66 

1.65 

45 

1.91 

1.94 

1.96 

2.00 

2.03 

2.05 

2.07 

2.09 

2.10 

2.10 

2.10 

2.10 

2.10 

2.08 

50 

2.46 

2.48 

2.50 

2.53 

2.56 

2.57 

2.58 

2.59 

2.59 

2.58 

2.58 

2.57 

2.56 

2.52 

55 

3.05 

3.07 

3.09 

3.12 

3.12 

3.12 

3.12 

3.11 

3.10 

3.08 

3.07 

3.053.03 

2.97 

60 

3.69 

3.72 

3.73 

3.73 

3.72 

3.70 

3.67 

3.65 

3.62 

3.60 

3.57 

3.543.50 

3.43 

*  Taken  from  Circular  19,  1909,  U.  S.  Bureau  of  Standards.  The  data  of  the  Kaiserliche  Normal 
Eichungs-Kommission  were  used  in  making  the  calculations,  the  specific  gravity  instrument  being  assumed 
to  be  of  Jena  16in  glass.  On  account  of  the  differences  in  cubical  expansion  of  glass  the  corrections  must  be 
used  with  caution  for  temperatures  much  different  from  20°  C.  See  also  "  Handbook,"  page  31. 


6  SUGAR  TABLES 

TABLE*  3. 
SPECIFIC   GRAVITY   OF  SUCROSE   SOLUTIONS  AT 


17.5° 


17.5° 
DEGREES  BRIX  AND  BAUME 


C.  WITH   CORRESPONDING 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baum6. 

New. 

Old. 

New. 

Old. 

0.0 

1.00000 

0.0 

0.0 

4.8 

1.01890 

2.7 

2.7 

0.1 

1.00038 

0.1 

0.1 

4.9 

1.01930 

2.8 

2.7 

0.2 

1.00077 

0.1 

0.1 

5.0 

1.01970 

2.8 

2.8 

0.3 

1.00116 

0.2 

0.2 

5.1 

1.02010 

2.9 

2.8 

0.4 

1.00155 

0.2 

0.2 

5.2 

1.02051 

2.95 

2.9 

0.5 

1.00193 

0.3 

0.3 

5.3 

1.02091 

3.0 

2.9 

0.6 

1.00232 

0.3 

0.3 

5.4 

1.02131 

3.1 

3.0 

0.7 

1.00271 

0.4 

0.4 

5.5 

1.02171 

3.1 

3.0 

0.8 

1.00310 

0.45 

0.4 

5.6 

1.02211 

3.2 

3.1 

0.9 

1.00349 

0.5 

0.5 

5.7 

1.02252 

3.2 

3.2 

1.0 

1.00388 

0.6 

0.55 

5.8 

1.02292 

3.3 

3.2 

.1 

1.00427 

0.6 

0.6 

5.9 

1.02333 

3.35 

3.3 

.2 

1.00466 

0.7 

0.7 

6.0 

1.02373 

3.4 

3.3 

.3 

.00505 

0.7 

0.7 

6.1 

1.02413 

3.5 

3.4 

.4 

.00544 

0.8 

0.8 

6.2 

1.02454 

3.5 

3.4 

.5 

.00583 

0.85 

0.8 

6.3 

1.02494 

3.6 

3.5 

.6 

.00622 

0.9 

0.9 

6.4 

1.02535 

3.6 

3.6 

1.7 

.00662 

1.0 

0.9 

6.5 

1.02575 

3.7 

3.6 

1.8 

.00701 

1.0 

.0 

6.6 

1.02616 

3.7 

3.7 

1.9 

.00740 

1.1 

.05 

6.7 

1.02657 

3.8 

3.7 

2.0 

1.00779 

1.1 

.1 

6.8 

1.02697 

3.9 

3.8 

2.1 

1.00818 

1.2 

.2 

6.9 

1.02738 

3.9 

3.8 

2.2 

1.00858 

.2 

.2 

7.0 

1.02779 

4.0 

3.9 

2.3 

1.00897 

.3 

.3 

7.1 

1.02819 

4.0 

3.9 

2.4 

1.00936 

.4 

.3 

7.2 

1.02860 

4.1 

4.0 

2.5 

1.00976 

.4 

.4 

7.3 

1.02901 

4.1 

4.1 

2.6 

1.01015 

.5 

.4 

7.4 

1.02942 

4.2 

4.1 

2.7 

1.01055 

.5 

1.5 

7.5 

1.02983 

4.25 

4.2 

2.8 

1.01094 

.6 

1.55 

7.6 

1.03024 

4.3 

4.2 

2.9 

1.01134 

.6 

1.6 

7.7 

1.03064 

4.4 

4.3 

3.0 

1.01173 

.7 

1.7 

7.8 

1.03105 

4.4 

4.3 

3.1 

1.01213 

.8 

1.7 

7.9 

1.03146 

4.5 

4.4 

3.2 

1.01252 

.8 

1.8 

8.0 

1.03187 

4.5 

4.4 

3.3 

1.01292 

.9 

1.8 

8.1 

1.03228 

4.6 

4.5 

3.4 

1.01332 

1.9 

1.9 

8.2 

1.03270 

4.6 

4.6 

3.5 

1.01371 

2.0 

1.9 

8.3 

1,03311 

4.7 

4.6 

3.6 

.01411 

2.0 

2.0 

8.4 

1.03352 

4.8 

4.7 

3.7 

.01451 

2.1 

2.0 

8.5 

1.03393 

4.8 

4.7 

3.8 

.01491 

2.2 

2.1 

8.6 

1.03434 

4.9 

4.8 

3.9 

.01531 

2.2 

2.2 

8.7 

1.03475 

4.9 

4.8 

4.0 

.01570 

2.3 

2.2 

8.8 

1.03517 

5.0 

4.9 

4.1 

1.01610 

2.3 

2.3 

8.9 

1.03558 

5.0 

4.9 

4.2 

1.01650 

2.4 

2.3 

9.0 

1.03599 

5.1 

5.0 

4.3 

1.01690 

2.4 

2.4 

9.1 

1.03640 

5.2 

5.05 

4.4 

1.01730 

2.5 

2.4 

9.2 

1.03682 

5.2 

5.1 

4.5 

1.01770 

2.55 

2.5 

9.3 

1.03723 

5.3 

5.2 

4.6 

1.01810 

2.6 

2.6 

9.4 

1.03765 

5.3 

5.2 

4.7 

1.01850 

2.7 

2.6 

9.5 

1.03806 

5.4 

5.3 

See  "  Handbook,"  pages  29  and  48. 


SUGAR   TABLES 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Erix. 

Specific 
gravity. 

Degrees  Baum6. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baum6. 

New. 

Old. 

New. 

Old. 

9.6 

1.03848 

5.4 

5.3 

14.8 

1.06047 

8.4 

8.2 

9.7 

1.03889 

5.5 

5.4 

14.9 

1.06090 

8.4 

8.3 

9.8 

1.03931 

5.55 

5.4 

15.0 

1.06133 

8.5 

8.3 

9.9 

1.03972 

5.6 

5.5 

15.1 

1.06176 

8.5 

8.4 

10  0 

1.04014 

5.7 

5.55 

15.2 

1.06219 

8.55 

8.4 

10.1 

1.04055 

5.7 

5.6 

15.3 

1.06262 

8.6 

8.5 

10.2 

1.04097 

5.8 

5.7 

15.4 

1.06306 

8.7 

8.5 

10.3 

1.04139 

5.8 

5.7 

15.5 

1.06349 

8.8 

8.6 

10.4 

1.04180 

5.9 

5.8 

15.6 

1.06392 

8.8 

8.65 

10.5 

1.04222 

5.9 

5.8 

15.7 

1.06436 

8.9 

8.7 

10.6 

.04264 

6.0 

5.9 

15.8 

1.06479 

8.9 

8.8 

10.7 

.04306 

6.1 

5.9 

15.9 

1.06522 

9.0 

8.8 

10.8 

.04348 

6.1 

6.0 

16.0 

.06566 

9.0 

8.9 

10.9 

.04390 

6.2 

6.05 

16.1 

.06609 

9.1 

8.9 

11.0 

.04431 

6.2 

6.1 

16.2 

.06653 

9.2 

9.0 

11.1 

.04473 

6.3 

6.2 

16.3 

.06696 

9.2 

9.0 

11.2 

.04515 

6.3 

6.2 

16.4 

.06740 

9.3 

9.1 

11.3 

.04557 

6.4 

6.3 

16.5 

.06783 

9.3 

9.1 

11.4 

.04599 

6.5 

6.3 

16.6 

.06827 

9.4 

9.2 

11.5 

.04641 

6.5 

6.4 

16.7 

.06871 

9.4 

9.25 

11.6 

.04683 

6.6 

6.4 

16.8 

.06914 

9.5 

9.3 

11.7 

.04726 

6.6 

6.5 

16.9 

.06958 

9.5 

9.4 

11.8 

1.04768 

6.7 

6.55 

17.0 

1.07002 

9.6 

9.4 

11.9 

1.04810 

6.7 

6.6 

17.1 

1.07046 

9.7 

9.5 

12  0 

1.04852 

6.8 

6.7 

17.2 

1.07090 

9.7 

9.5 

12.1 

1.04894 

6.8 

6.7 

17.3 

1.07133 

9.8 

9.6 

12.2 

1.04937 

6.9 

6.8 

17.4 

1.07177 

9.8 

9.6 

12.3 

1.04979 

7.0 

6.8 

17.5 

1.07221 

9.9 

9.7 

12.4 

1.05021 

7.0 

6.9 

17.6 

1.07265 

9.9 

9.75 

12.5 

1.05064 

7.1 

6.9 

17.7 

1.07309 

10.0 

9.8 

12.6 

1.05106 

7.1 

7.0 

17.8 

1.07353 

10.0 

9.9 

12.7 

1.05149 

7.2 

7.05 

17.9 

1.07397 

10.1 

9.9 

12.8 

1.05191 

7.2 

7.1 

18.0 

1.07441 

10.1 

10.0 

12.9 

1.05233 

7.3 

7.2 

18.1 

1.07485 

10.2 

10.0 

13  0 

1.05276 

7.4 

7.2 

18.2 

1.07530 

10.3 

10.1 

13.1 

1.05318 

7.4 

7.3 

18.3 

1.07574 

10.3 

10.1 

13.2 

.05361 

7.5 

7.3 

18.4 

1.07618 

10.4 

10.2 

13.3 

.05404 

7.5 

7.4 

18.5 

1.07662 

10.4 

10.2 

13.4 

.05446 

7.6 

7.4 

18.6 

1.07706 

10.5 

10.3 

13.5 

.05489 

7.6 

7.5 

18.7 

1.07751 

10.5 

10.35 

13.6 

.05532 

7.7 

7.5 

18.8 

1.07795 

10.6 

10.4 

13.7 

.05574 

7.75 

7.6 

18.9 

1.07839 

10.6 

10.5 

13.8 

.05617 

7.8 

7.65 

19  0 

1.07884 

10.7 

10.5 

13.9 

.05660 

7.9 

7.7 

19.1 

1.07928 

10.8 

10.6 

14.0 

.05703 

7.9 

7.8 

19.2 

1.07973 

10.8 

10.6 

14.1 

.05746 

8.0 

7.8 

19.3 

1.08017 

10.9 

10.7 

14.2 

1.05789 

8.0 

7.9 

19.4 

1.08062 

10.9 

10.7 

14.3 

1.05831 

8.1 

7.9 

19.5 

1.08106 

11.0 

10.8 

14.4 

1.05874 

8.1 

8.0 

19.6 

1.08151 

11.1 

10.85 

14.5 

1.05917 

8.2 

8.0 

19.7 

1.08196 

11.1 

10.9 

14.6 

1.05960 

8.3 

8.1 

19.8 

1.08240 

11.2 

11.0 

14.7 

1.06003 

8.3 

8.15 

19.9 

1.08285 

11.2 

11.0 

8 


SUGAR  TABLES 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume1. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

New. 

Old. 

New. 

Old. 

20.0 

1.08329 

11.3 

11.1 

25.2 

1  .  10700 

14.2 

13.9 

20.1 

1.08374 

11.3 

11.1 

25.3 

1.10746 

14.2 

14.0 

20.2 

1.08419 

11.4 

11.2 

25.4 

1.10793 

14.3 

14.0 

20.3 

1.08464 

11.5 

11.2 

25.5 

.10839 

14.3 

14.1 

20.4 

1.08509 

11.5 

11.3 

25.6 

.10886 

14.4 

14.1 

20.5 

1.08553 

11.6 

11.3 

25.7 

.  10932 

14.5 

14.2 

20.6 

.08599 

11.6 

11.4 

25.8 

.  10979 

14.5 

14.2 

20.7 

.08643 

11.7 

11.45 

25.9 

.11026 

14.6 

14.3 

20.8 

.08688 

11.7 

11.5 

26.0 

.11072 

14.6 

14.35 

20.9 

.08733 

11.8 

11.6 

26.1 

.11119 

14.7 

14.4 

21  0 

.08778 

11.8 

11.6 

26.2 

.11166 

14.7 

14.5 

21.1 

.08824 

11.9 

11.7 

26.3 

.11213 

14.8 

14.5 

21.2 

.08869 

11.95 

11.7 

26.4 

.11259 

14.85 

14.6 

21.3 

1.08914 

12.0 

11.8 

26.5 

.11306 

14.9 

14.6 

21.4 

1.08959 

12.0 

11.8 

26.6 

.11353 

15.0 

14.7 

21.5 

1.09004 

12.1 

11.9 

26.7 

.11400 

15.0 

14.7 

21.6 

1.09049 

12.1 

11.95 

26.8 

.11447 

15.1 

14.8 

21.7 

1.09095 

12.2 

12.0 

26.9 

.11494 

15.1 

14.8 

21.8 

1.09140 

.     12.3 

12.05 

27.0 

.11541 

15.2 

14.9 

21.9 

1.09185 

12.3 

12.1 

27.1 

.11588 

15.2 

14.9 

22  0 

1.09231 

12.4 

12.2 

27.2 

.11635 

15.3 

15.0 

22.1 

1.09276 

12.5 

12.2 

27.3 

.11682 

15.3 

15.1 

22.2 

1.09321 

12.5 

12.3 

27.4 

.11729 

15.4 

15.1 

22.3 

1.09367 

12.6 

12.3 

27.5 

.11776 

15.5 

15.2 

22.4 

1.09412 

12.6 

12.4 

27.6 

.11824 

15.5 

15.2 

22.5 

1.09458 

12.7 

12.4 

27.7 

.11871 

15.6 

15.3 

22.6 

1.09503 

12.7 

12.5 

27.8 

.11918 

15.6 

15.3 

22.7 

1.09549 

12.8 

12.55 

27.9 

.11965 

15.7 

15.4 

22.8 

1.09595 

12.85 

12.6 

28.0 

.12013 

15.7 

15.4 

22.9 

1.09640 

12.9 

12.7 

28.1 

.  12060 

15.8 

15.5 

23  0 

1.09686 

13.0 

12.7 

28.2 

.12107 

15.8 

15.55 

23.1 

1.09732 

13.0 

12.8 

28.3 

.  12155 

15.9 

15.6 

23.2 

1.09777 

13.1 

12.8 

28.4 

.12202 

16.0 

15.7 

23.3 

1.09823 

13.1 

12.9 

28.5 

.  12250 

16.0 

15.7 

23.4 

1.09869 

13.2 

12.9 

28.6 

.12297 

16.1 

15.8 

23.5 

1.09915 

13.2 

13.0 

28.7 

.  12345 

16.1 

15.8 

23.6 

1.09961 

13.3 

13.0 

28.8 

.12393 

16.2 

15.9 

23.7 

1.10007 

13.3 

13.1 

28.9 

.  12440 

16.2 

15.9 

23.8 

1.10053 

13.4 

13.15 

29.0 

.12488 

16.3 

16.0 

23.9 

.10099 

13.5 

13.2 

29.1 

.12536 

16.3 

16.0 

240 

.  10145 

13.5 

13.3 

29.2 

.12583 

16.4 

16.1 

24.1 

.10191 

13.6 

13.3 

29.3 

.  12631 

16.5 

16.1 

24.2 

.10237 

13.6 

13.4 

29.4 

.  12679 

16.5 

16.2 

24.3 

.10283 

13.7 

13.4 

29.5 

.  12727 

16.6 

16.25 

24.4 

.  10329 

13.7 

13.5 

29.6 

.12775 

16.6 

16.3 

24.5 

.10375 

13.8 

13.5 

29.7 

.12823 

16.7 

16.4 

24.6 

.10421 

13.8 

13.6 

29.8 

1.12871 

16.7 

16.4 

24.7 

.10468 

13.9 

13.6 

29.9 

1  .  12919 

16.8 

16.5 

24.8 

.  10514 

14.0 

13.7 

30  0 

1  .  12967 

16.8 

16.5 

24.9 

1.10560 

14.0 

13.75 

30.1 

1.13015 

16.9 

16.6 

25  0 

1  .  10607 

14.1 

13.8 

30.2 

1.13063 

16.95 

16.6 

25.1 

1  .  10653 

14.1 

13.9 

30.3 

1.13111 

17.0 

16.7 

SUGAR    TABLES 


9 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by  • 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

New. 

Old. 

New. 

Old. 

30.4 

.  13159 

17.1 

16.7 

35.6 

1.15710 

19.9 

19.55 

30.5 

.  13207 

17.1 

16.8 

35.7 

1.15760 

20.0 

19.6 

30.6 

.  13255 

17.2 

16.85 

35.8 

1.15810 

20.0 

19.65 

30.7 

.13304 

17.2 

16.9 

35.9 

1.15861 

20.1 

19.7 

30.8 

.13352 

17.3 

17.0 

36  0 

1.15911 

20.1 

19.8 

30.9 

.13400 

17.3 

17.0 

36.1 

1  .  15961 

20.2 

19.8 

31.0 

.13449 

17.4 

17.1 

36.2 

1.16011 

20.25 

19.9 

31.1 

.  13497 

17.45 

17.1 

36.3 

1.16061 

20.3 

19.9 

31.2 

1.13545 

17.5 

17.2 

36.4 

1.16111 

20.4 

20.0 

31.3 

1  .  13594 

17.6 

17.2 

36.5 

1.16162 

20.4 

20.0 

31.4 

1.13642 

17.6 

17.3 

36.6 

1  .  16212 

20.5 

20.1 

31.5 

1.13691 

17.7 

17.3 

36.7 

1  .  16262 

20.5 

20.1 

31.6 

1.13740 

17.7 

17.4 

36.8 

1  .  16313 

20.6 

20.2 

31.7 

1.13788 

17.8 

17.4 

36.9 

1.16363 

20.6 

20.2 

31.8 

1.13837 

17.8 

17.5 

37  0 

1.16413 

20.7 

20.3 

31.9 

1.13885 

17.9 

17.55 

37.1 

1.16464 

20.7 

20.35 

32.0 

1.13934 

17.95 

17.6 

37.2 

1.16514- 

20.8 

20.4 

32.1 

1  .  13983 

18.0 

17.7 

37.3 

1.16565 

20.9 

20.5 

32.2 

1  .  14032 

18.0 

17.7 

37.4 

.16616 

20.9 

20.5 

32.3 

1  .  14081 

18.1 

17.8 

37.5 

.16666 

21.0 

20.6 

32.4 

1.14129 

18.2 

17.8 

37.6 

.16717 

21.0 

20.6 

32.5 

1.14178 

18.2 

17.9 

37.7 

.16768 

21.1 

20.7 

32.6 

1.14227 

18.3 

17.9 

37.8 

.16818 

21.1 

20.7 

32.7 

1.14276 

18.3 

18.0 

37.9 

.16869 

21.2 

20.8 

32.8 

1  .  14325 

18.4 

18.0 

38  0 

.  16920 

21.2 

20.8 

32.9 

1  .  14374 

18.4 

18.1 

38.1 

.16971 

21.3 

20.9 

33  0 

1  .  14423 

18.5 

18.15 

38.2 

.17022 

21.35 

20.9 

33.1 

1.14472 

18.55 

18.2 

38.3 

.17072 

21.4 

21.0 

33.2 

1.14521 

18.6 

18.25 

38.4 

.  17123 

21.5 

21.05 

33.3 

1.14570 

18.7 

18.3 

38.5 

.  17174 

21.5 

21.1 

33.4 

1  .  14620 

18.7 

18.4 

38.6 

.  17225 

21.6 

21.15 

33.5 

1.14669 

18.8 

18.4 

38.7 

.17276 

21.6 

21.2 

33.6 

1  .  14718 

18.8 

18.5 

38.8 

.17327 

21.7 

21.3 

33.7 

1.14767 

18.9 

18.5 

38.9 

1.17379 

21.7 

21.3 

33.8 

1.14817 

18.9 

18.6 

39.0 

1  .  17430 

21.8 

21.4 

33.9 

1.14866 

19.0 

18.6 

39.1 

1  .  17481 

21.8 

21.4 

34  0 

1.14915 

19.05 

18.7 

39.2 

.17532 

21.9 

21.5 

34.1 

1.14965 

19.1 

18.7 

39.3 

.17583 

21.9 

21.5 

34.2 

1.15014 

19.2 

18.8 

39.4 

.17635 

22.0 

21.6 

34.3 

1.15064 

19.2 

18.85 

39.5 

.  17686 

22.05 

21.6 

34.4 

1.15113 

19.3 

18.9 

39.6 

.  17737 

22.1 

21.7 

34.5 

1  .  15163 

19.3 

18.95 

39.7 

.17789 

22.2 

21.7 

34.6 

1.15213 

19.4 

19.0 

39.8 

.17840 

22.2 

21.8 

34.7 

1.15262 

19.4 

19.1 

39.9 

.  17892 

22.3 

21.85 

34.8 

1.15312 

19.5 

19.1 

40.0 

.17943 

22.3 

21.9 

34.9 

1.15362 

19.5 

19.2 

40.1 

.17995 

22.4 

22.0 

35.0 

1.15411 

19.6 

19.2 

40.2 

.18046 

22.4 

22.0 

35.1 

1  .  15461 

19.65 

19.3 

40.3 

.18098 

22.5 

22.1 

35.2 

1.15511 

19.7 

19.3 

40.4 

.  18150 

22.5 

22.1 

35.3 

1.15561 

19.8 

19.4 

40.5 

.18201 

22.6 

22.2 

35.4 

1.15611 

19.8 

19.4 

40.6 

.  18253 

22.6 

22.2 

35.5 

1  .  15661 

19.9 

19.5 

40.7 

.18305 

22.7 

22.3 

10 


SUGAR  TABLES 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baum6. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baum£. 

New. 

Old. 

New. 

Old. 

40.8 

1.18357 

22.8 

22.3 

46.0 

1.21100 

25.6 

25.1 

40.9 

1.18408 

22.8 

22.4 

46.1 

1.21154 

25.6 

25.1 

410 

1.18460 

22.9 

22.4 

46.2 

1.21208 

25.7 

25.2 

41.1 

1.18512 

22.9 

22.5 

46.3 

1.21261 

25.7 

25.2 

41.2 

1.18564 

23.0 

22.5 

46.4 

1.21315 

25.8 

25.3 

41.3 

1.18616 

23.0 

22.6 

46.5 

1.21369 

25.8 

25.35 

41.4 

.18668 

23.1 

22.65 

46.6 

1.21423 

25.9 

25.4 

41.5 

.  18720 

23.1 

22.7 

46.7 

1.21477 

25.95 

25.45 

41.6 

.  18772 

23.2 

22.75 

46.8 

1.21531 

26.0 

25.5 

41.7 

.18824 

23.25 

22.8 

46.9 

1.21585 

26.1 

25.6 

41.8 

.18877 

23.3 

22.9 

47.0 

1.21639 

26.1 

25.6 

41.9 

.18929 

23.4 

22.9 

47.1 

1.21693 

26.2 

25.7 

42  0 

1.18981 

23.4 

23.0 

47.2 

1.21747 

26.2 

25.7 

42.1 

1.19033 

23.5 

23.0 

47.3 

1.21802 

26.3 

25.8 

42.2 

1  .  19086 

23.5 

23.1 

47.4 

1.21856 

26.3 

25.8 

42.3 

1.19138 

23.6 

23.1 

47.5 

1.21910 

26.4 

25.9 

42.4 

1.19190 

23.6 

23.2 

47.6 

1.21964 

26.4 

25.9 

42.5 

1.19243 

23.7 

23.2 

47.7 

.22019 

26.5 

26.0 

42.6 

1.19295 

23.7 

23.3 

47.8 

.22073 

26.5 

26.0 

42.7 

1.19348 

23.8 

23.3 

47.9 

.22127 

26.6 

26.1 

42.8 

1.19400 

23.8 

23.4 

48.0 

.22182 

26.6 

26.1 

42.9 

1.19453 

23.9 

23.45 

48.1 

.22236 

26.7 

26.2 

43.0 

1.19505 

23.95 

23.5 

48.2 

.22291 

26.75 

26.2 

43.1 

1.19558 

24.0 

23.55 

48.3 

.22345 

26.8 

26.3 

43.2 

1.19611 

24.1 

23.6 

48.4 

1.22400 

26.9 

26.35 

43.3 

1.19663 

24.1 

23.7 

48.5 

1.22455 

26.9 

26.4 

43.4 

1  .  19716 

24.2 

23.7 

48.6. 

1.22509 

27.0 

26.45 

43.5 

1.19769 

24.2 

23.8 

48.7 

1.22564 

27.0 

26.5 

43.6 

1.19822 

24.3 

23.8 

48.8 

1.22619 

27.1 

26.6 

43.7 

1.19875 

24.3 

23.9 

48.9 

1.22673 

27.1 

26.6 

43.8 

1.19927 

24.4 

23.9 

49.0 

1.22728 

27.2 

26.7 

43.9 

1  .  19980 

24.4 

24.0 

49.1 

1.22783 

27.2 

26.7 

44.0 

1.20033 

24.5 

24.0 

49.2 

.22838 

27.3 

26.8 

44.1 

1.20086 

24.55 

24.1 

49.3 

.22893 

27.3 

26.8 

44.2 

1.20139 

24.6 

24.1 

49.4 

.22948 

27.4 

26.9 

44.3 

1.20192 

24.65 

24.2 

49.5 

.23003 

27.4 

26.9 

44.4 

1.20245 

24.7 

24.2 

49.6 

.23058 

27.5 

27.0 

44.5 

1.20299 

24.8 

24.3 

49.7 

.23113 

27.6 

27.0 

44.6 

1.20352 

24.8 

24.35 

49.8 

.23168 

27.6 

27.1 

44.7 

1.20405 

24.9 

24.4 

49.9 

.23223 

27.7 

.27.1 

44.8 

1.20458 

24.9 

24.45 

50.0 

.23278 

27.7 

27.2 

44.9 

1.20512 

25.0 

24.5 

50.1 

.23334 

27.8 

27.2 

45.0 

.20565 

25.0 

24.6 

50.2 

1.23389 

27.8 

27.3 

45.1 

.20618 

25.1 

24.6 

50.3 

1.23444 

27.9 

27.3 

45.2 

.20672 

25.1 

24.7 

50.4 

1.23499 

27.9 

27.4 

45.3 

.20725 

25.2 

24.7 

50.5 

1.23555 

28.0 

27.45 

45.4 

.20779 

25.2 

24.8 

50.6 

1.23610 

28.0 

27.5 

45.5 

.20832 

25.3 

24.8 

50.7 

1.23666 

28.1 

27.55 

45.6 

.20886 

25.4 

24.9 

50.8 

1.23721 

28.1 

27.6 

45.7 

.20939 

25.4 

24.9 

50.9 

1.23777 

28.2 

27.7 

45.8 

.20993 

25.5 

25.0 

51.0 

1.23832 

28.2 

27.7 

45.9 

1.21046 

25.5 

25.0 

51.1 

1.23888 

28.3 

27.8 

SUGAR   TABLES 


11 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baum6. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific       , 
gravity. 

Degrees  Baum6. 
1 

New. 

Old. 

New. 

Old. 

51.2 

1.23943 

28.35 

27.8 

56.4 

.26889 

31.1 

30.5 

51.3 

1.23999 

28.4 

27.9 

56.5 

.26946 

31.2 

30.6 

51.4 

1.24055 

28.5 

27.9 

56.6 

.27004 

31.2 

30.6 

51.5 

1.24111 

28.5 

28.0 

56.7 

.27062 

31.3 

30.7 

51.6 

1.24166 

28.6 

28.0 

56.8 

.27120 

31.3 

30.7 

51.7 

1.24222 

28.6 

28.1 

56.9 

.27177 

31.4 

30.8 

51.8 

1.24278 

28.7 

28.1 

57.0 

.27235 

31.4 

30.8 

51.9 

1.24334 

28.7 

28.2 

57.1 

.27293 

31.5 

30.9 

52  0 

1.24390 

28.8 

28.2 

57.2 

.27351 

31.5 

30.9 

52.1 

1.24446 

28.8 

28.3 

57.3 

.27409 

31.6 

31.0 

52.2 

1.24502 

28.9 

28.3 

57.4 

.27464 

31.6 

31.0 

52.3 

1.24558 

28.9 

28.4 

57.5 

1.27525 

31.7 

31.1 

52.4 

1.24614 

29.0 

28.4 

57.6 

1.27583 

31.7 

31.1 

52.5 

1.24670 

29.0 

28.5 

57.7 

1.27641 

31.8 

31.2 

52.6 

1.24726 

29.1 

28.5 

57.8 

1.27699 

31.8 

31.2 

52.7 

.24782 

29.15 

28.6 

57.9 

1.27758 

31.9 

31.3 

52.8 

.24839 

29.2 

28.65 

58.0 

1.27816 

31.9 

31.3 

52.9 

.24895 

29.2 

28.7 

58.1 

1.27874 

32.0 

31.4 

53.0 

.24951 

29.3 

28.75 

58.2 

1.27932 

32.0 

31.4 

53.1 

.25008 

29.4 

28.8 

58.3 

1.27991 

32.1 

31.5 

53.2 

.25064 

29.4 

28.85 

58.4 

1.28049 

32.15 

31.5 

53.3 

.25120 

29.5 

28.9 

58.5 

1.28107 

32.2 

31.6 

53.4 

.25177 

29.5 

28.9 

58.6 

1.28166 

32.3 

31.6 

53.5 

.25233 

29.6 

29.0 

58.7 

1.28224 

32.3 

31.7 

53.6 

.25290 

29.6 

29.1 

58.8 

1.28283 

32.4 

31.7 

53.7 

.25347 

29.7 

29.1 

58.9 

1.28342 

32.4 

31.8 

53.8 

.25403 

29.7 

29.2 

59.0 

1.28400 

32.5 

31.85 

53.9 

.25460 

29.8 

29.2 

59.1 

1.28459 

32.5 

31.9 

54.0 

.25517 

29.8 

29.3 

59.2 

1.28518 

32.6 

31.95 

54.1 

.25573 

29.9 

29.3 

59.3 

1.28576 

32.6 

32.0 

54.2 

.25630           29.9 

29  4 

59.4 

1.28635 

32.7 

32.05 

54.3 

.25687           30.0 

29.4 

59.5 

1.28694 

32.7 

32.1 

54.4 

.25744           30.05 

29.5 

59.6 

1.28753 

32.8 

32.15 

54.5 

.25801           30.1 

29.5 

59.7 

1.28812 

32.8 

32.2 

54.6 

.25857 

30.2 

29.6 

59.8 

1.28871 

32.9 

32.3 

54.7 

1.25914 

30.2 

29.6 

59.9 

1.28930 

32.9 

32.3 

54.8 

1.25971 

30.3 

29.7 

60.0 

1.28989 

33.0 

32.4 

54.9 

1.26028 

30.3 

29.7 

60.1 

1.29048 

33.0 

32.4 

55.0 

1.26086 

30.4 

29.8 

60.2 

1.29107 

33.1 

32.5 

55.1 

1.26143 

30.4 

29.8 

60.3 

1.29166 

33.1 

32.5 

55.2 

1.26200 

30.5 

29.9 

60.4 

1.29225 

33.2 

32.6 

55.3 

1.26257 

30.5 

29.9 

60.5 

1.29284 

33.2 

32.6 

55.4 

1.26314 

30.6 

30.0 

60.6 

1.29343 

33.3 

32.7 

55.5 

1.26372 

30.6 

30.05 

60.7 

1.29403 

33.35 

32.7 

55.6 

1.26429 

30.7 

30.1 

60.8 

1.29462 

33.4 

32.8 

55.7 

1.26486 

30.7 

30.15 

60.9 

1.29521 

33.45 

32.8 

55.8 

1.26544 

30.8 

30.2 

61.0 

1.29581 

33.5 

32.9 

55.9 

1.26601 

30.8 

30.25 

61.1 

1.29640 

33.6 

32.9 

66.0 

1.26658 

30.9 

30.3 

61.2 

1.29700 

33.6 

33.0 

56.1 

1.26716 

30.9 

30.4 

61.3 

1.29759 

33.7 

33.0 

56.2 

1.26773 

31.0 

30.4 

61-.  4 

1.29819 

33.7 

33.1 

56.3 

1.26831 

31.05 

30.5 

61.5 

1.29878 

33.8 

33.1 

12 


SUGAR  TABLES 


TABLE   3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

New. 

Old. 

New. 

Old. 

61.6 

1.29938 

33.8 

33.2 

66.8 

1.33093 

36.5 

35.8 

61.7 

1.29998 

33.9 

33.2 

66.9 

1.33155 

36.5 

35.9 

61.8 

1.30057 

33.9 

33.8 

67  0 

1.33217 

36.6 

35.9 

61.9 

1.30117 

34.0 

33.3 

67.1 

1.33278 

36.6 

36.0 

62.0 

1.30177 

34.0 

33.4 

67.2 

1.33340 

36.7 

36.0 

62.1 

1.30237 

34.1 

33.4 

67.3 

1.33402 

36.75 

36.1 

62.2 

1.30297 

34.1 

33.5 

67.4 

1.33464 

36.8 

36.1 

62.3 

1.30356 

34.2 

33.5 

67.5  • 

1.33526 

36.85 

36.2 

62.4 

1.30416 

34.2 

33.6 

67.6 

1.33588 

36.9 

36.2 

62.5 

1.30476 

34.3 

33.6 

67.7 

1.33650 

36.95 

36.3 

62.6 

1.30536 

34.3 

33.7 

67.8 

1.33712 

37.0 

36.3 

62.7 

1.30596 

34.4 

33.7 

67.9 

1.33774 

37.0 

36.4 

62.8 

1.30657 

34.4 

33.8 

68.0 

1.33836 

37.1 

36.4 

62.9 

1.30717 

34.5 

33.8 

68.1 

1.33899 

37.1 

36.5 

63  0 

1.30777 

34.5 

33.9 

68.2 

1.33981 

37.2 

36.5 

63.1 

1.30837 

34.6 

33.9 

68.3 

1.34023 

37.3 

36.6 

63.2 

1.30897 

34.6 

34.0 

68.4 

1.34085 

37.3 

36.6 

63.3 

1.30958 

34.7 

34.0 

68.5 

1.34148 

37.4 

36.7 

63.4 

1.31018 

34.7 

34.1 

68.6 

1.34210 

37.4 

36.7 

63.5 

1.31078 

34.8 

34.1 

68.7 

1.34273 

37.5 

36.8 

63.6 

1.31139 

34.85 

34.2 

68.8 

1.34335 

37.5 

36.8 

63.7 

1.31199 

34.9 

34.2 

68.9 

1.34398 

37.6 

36.9 

63.8 

1.31260 

34.95 

34.3 

69.0 

1.34460 

37.6 

36.9 

63.9 

1.31320 

35.0 

34.3 

69.1 

1.34523 

37.7 

37.0 

64.0 

1.31381 

35.1 

34.4 

69.2 

1.34585 

37.7 

37.0 

64.1 

1.31442 

35.1 

34.4 

69.3 

1.34648 

37.8 

37.1 

64.2 

1.31502 

35.2 

34.5 

69.4 

1.34711 

37.8 

37.1 

64.3 

1.31563 

35.2 

34.5 

69.5 

1.34774 

37.9 

37.2 

64.4 

1.31624 

35.3 

34.6 

69.6 

1.34836 

37.9 

37.2 

64.5 

1.31684 

35.3 

34.6 

69.7 

1.34899 

38.0 

37.3 

64.6 

1.31745 

35.4 

34.7 

69.8 

1.34962 

38.0 

37.3 

64.7 

1.31806 

35.4 

34.7 

69.9 

1.35025 

38.1 

37.4 

64.8 

1.31867 

35.5 

34.8 

70  0 

1.35088 

38.1 

37.4 

64.9 

.31928 

35.5 

34.8 

70.1 

1.35151 

38.2 

37.5 

65.0 

.31989 

35.6 

34.9 

70.2 

1.35214 

38.2 

37.5 

65.1 

.32050 

35.6 

34.95 

70.3 

1.35277 

38.3 

37.6 

65.2 

.32111 

35.7 

35.0 

70.4 

1.35340 

38.3 

37.6 

65.3 

.32172 

35.7 

35.05 

70.5 

1.35403 

38.4 

37.7 

65.4 

.32233 

35.8 

35.1 

70.6 

1.35466 

38.4 

37.7 

65.5 

.32294 

35.8 

35.15 

70.7 

1.35530 

38.5 

37.8 

65.6 

.32355 

35.9 

35.2 

70.8 

1.35593 

38.5 

37.8 

65.7 

.32417 

35.9 

35.25 

70.9 

1.35656 

38.6 

37.9 

65.8 

.32478 

36.0 

35.3 

71.0 

1.35720 

38.6 

37.9 

65.9 

.32539 

36.0 

35.35 

71.1 

1.35783 

38.7 

37.9 

66.0 

.32601 

36.1 

35.4 

71.2 

1.35847 

38.7 

38.0 

66.1 

.32662 

36.1 

35.5 

71.3 

1.35910 

38.8 

38.0 

66.2 

1.32724 

36.2 

35.5 

71.4 

1.35974 

38.8 

38.1 

66.3 

1.32785 

36.2 

35.6 

71.5 

1.36037 

38.9 

38.1 

66.4 

1.32847 

36.3 

35.6 

71.6 

1.36101 

38.9 

38.2 

66.5 

1.32908 

36.3 

35.7 

71.7 

1.36164 

39.0 

38.2 

66.6 

1.32970 

36.4 

35.7 

71.8 

1.36228 

39.0 

38.3 

66.7 

1.33031 

36.4 

35.8 

71.9 

1.36292 

39.1 

38.3 

SUGAR    TABLES 


13 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume. 

New. 

Old. 

New. 

Old. 

72  0 

1.36355 

39.1 

38.4 

77.2 

1.39726 

41.7 

40  9 

72.1 

.36419 

39.2 

38.4 

77.3 

1.39792 

41.8 

41.0 

72.2 

.36483 

39.2 

38.5 

77.4 

.39858 

41.8 

41.0 

72.3 

.36547 

39.3 

38.5 

77.5 

.39924 

41.9 

41.1 

72.4 

.36611 

39.3 

38.6 

77.6 

.39990 

41.9 

41.1 

72.5 

.36675 

39.4 

38.6 

77.7 

.40056 

42.0 

41.2 

72.6 

1.36739 

39.4 

38.7 

77.8 

.40122 

42.0 

41.2 

72.7 

1.36803 

39.5 

38.7 

77.9 

.40188 

42.1 

41.3 

72.8 

1.36867 

39.5 

38.8 

78.0 

.40254 

42.1 

41.3 

72.9 

1.36931 

39.6 

38.8 

78.1 

.40321 

42.2 

41.4 

73.0 

1.36995 

39.6 

38.9 

78.2 

.40387 

42.2 

41.4 

73.1 

1.37059 

39.7 

38.9 

78.3 

.40453 

42.3 

41.5 

73.2 

1.37124 

39.7 

39.0 

78.4 

.40520 

42.3 

41.5 

73.3 

.37188 

39.8 

39.0 

78.5 

.40586 

42.4 

41.6 

73.4 

.37252 

39.8 

39.1 

78.6 

.40652 

42.4 

41.6 

73.5 

.37317 

39.9 

39.1 

78.7 

.40719 

42.5 

41.7 

73.6 

.37381 

39.9 

39.2 

78.8 

.40785 

42.5 

41.7 

73.7 

.37446 

40.0 

39.2 

78.9 

.40852 

42.6 

41.8 

73.8 

1.37510 

40.0 

39.3 

79  0 

.40918 

42.6 

41.8 

73.9 

1.37575 

40.1 

39.3 

79.1 

.40985 

42.7 

41.9 

74  0 

1.37639 

40.1 

39.4 

79.2 

.41052 

42.7 

41.9 

74.1 

'     1.37704 

40.2 

39.4 

79.3 

.41118 

42.8 

42.0 

74.2 

.37768 

40.2 

39.5 

79.4 

.41185 

42.8 

42.0 

74.3 

.37833 

40.3 

39.5 

79.5 

.41252 

42.9 

42.1 

74.4 

.37898 

40.3 

39.6 

79.6 

.41318 

42.9 

42.1 

74.5 

.37962 

40.4 

39.6 

79.7 

.41385 

43.0 

42.1 

74.6 

.38027 

40.4 

39.7 

79.8 

.41452 

43.0 

42.2 

74.7 

.38092 

40.5 

39.7 

79.9 

.41519 

43.1 

42.2 

74.8 

.38157 

40.5 

39.8 

80  0 

1.41586 

43.1 

42.3 

74.9 

.38222 

40.6 

39.8 

80.1 

1.41653 

43.2 

42.3 

75.0 

.38287 

40.6 

39.9 

80.2 

1.41720 

43.2 

42.4 

75.1 

.38352 

40.7 

39.9 

80.3 

1.41787 

43.2 

42.4 

75.2 

.38417 

40.7 

40.0 

80.4 

1.41854 

43.3 

42.5 

75.3 

.38482 

40.8 

40.0 

80.5 

1.41921 

43.3 

42.5 

75.4 

.38547 

40.8 

40.1 

80.6 

1.41989 

43.4 

42.6 

75.5 

.38612 

40.9 

40.1 

80.7 

1.42056 

43.45 

42.6 

75.6 

.38677 

40.9 

40.2 

80.8 

1.42123 

43.5 

42.7 

75.7 

.38743 

41.0 

40.2 

80.9 

1.42190 

43.55 

42.7 

75.8 

.38808 

41.0 

40.3 

81.0 

1.42258 

43.6 

42.8 

75.9 

.38873 

41.1 

40.3 

81.1 

1.42325 

43.65 

42.8 

76  0 

.38939 

41.1 

40.4 

.81.2 

1.42393 

43.7 

42.9 

76.1 

.39004 

41.2 

40.4 

81.3 

1.42460 

43.7 

42.9 

76.2 

.39070 

41.2 

40.5 

81.4 

1.42528 

43.8 

43.0 

76.3 

.39135 

41.3 

40.5 

81.5 

1.42595 

43.8 

43.0 

76.4 

.39201 

41.3 

40.6 

81.6 

1.42663 

43.9 

43.1 

76.5 

1.39266 

41.4 

40.6 

81.7 

1.42731 

43.9 

43.1 

76.6 

1.39332 

41.4 

40.7 

81.8 

1.42798 

44.0 

43.2 

76.7 

1.39397 

41.5 

40.7 

81.9 

1.42866 

44.0 

43.2 

76.8 

1.39463 

41.5 

40.8 

82  0 

1.42934 

44.1 

43.2 

76.9 

1.39529 

41.6 

40.8 

82.1 

1.43002 

44.1 

43.3 

77.0 

1.39595 

41.6 

40.8 

82.2 

1.43070 

44.2 

43.3 

77.1 

1.39660 

41.7 

40.9 

82.3 

1.43137 

44.2 

43.4 

14 


SUGAR  TABLES 


TABLE  3.     (Continued.) 


Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baume\ 

Per  cent 
sucrose  by 
weight  or 
degrees 
Brix. 

Specific 
gravity. 

Degrees  Baum6. 

New. 

Old. 

New. 

Old. 

82.4 

1.43205 

44.3 

43.4 

87.6 

1.46794 

46.8 

45.9 

82.5 

1.43273 

44.3 

43.5 

87.7 

1.46864 

46.8 

45.9 

82.6 

1.43341 

44.4 

43.5 

87.8 

1.46934 

46.9 

46.0 

82.7 

1.43409 

44.4 

43.6 

87.9 

1.47004 

46.9 

46.0 

82.8 

1.43478 

44.5 

43.6 

88.0 

1.47074 

47.0 

46.1 

82.9 

.43546 

44.5 

43.7 

88.1 

1.47145 

47.0 

46.1 

83.0 

.43614 

44.6 

43.7 

88.2 

1.47215 

47.1 

46.2 

83.1 

.43682 

44.6 

43.8 

88.3 

1.47285 

47.1 

46.2 

83.2 

.43750 

44.7 

43.8 

88.4 

1.47356 

47.2 

46.3 

83.3 

.43819 

44.7 

43.9 

88.5 

1.47426 

47.2 

46.3 

83.4 

.43887 

44.8 

43.9 

88.6 

1.47496 

47.3 

46.4 

83.5 

.43955 

44.8 

44.0 

88.7 

1.47567 

47.3 

46.4 

83.6 

1.44024 

44.9 

44.0 

88.8 

1.47637 

47.4 

46.5 

83.7 

1.44092 

44.9 

44.1 

88.9 

1.47708 

47.4 

46.5 

83.8 

1.44161 

45.0 

44.1 

89.0 

1.47778 

47.45 

46.5 

83.9 

1.44229 

45.0 

44.2 

89.1 

1.47849 

47.5 

46.6 

84.0 

1.44298 

45.1 

44.2 

89.2 

1.47920 

47.55 

46.6 

84.1 

.44367 

45.1 

44.2 

89.3 

1.47991 

47.6 

46.7 

84.2 

.44435 

45.15 

44.3 

89.4 

1.48061 

47.6 

46.7 

84.3 

.44504 

45.2 

44.3 

89.5 

1.48132 

47.7 

46.8 

84.4 

.44573 

45.25 

44.4 

89.6 

1.48203 

47.7 

46.8 

84;5 

.44641 

45.3 

44.4 

89.7 

1.48274 

47.8 

46.9 

84.6 

.44710 

45.35 

44.5 

89.8 

1.48345 

47.8 

46.9 

84.7 

1.44779 

45.4 

44.5 

89.9 

1.48416 

47.9 

47.0 

84.8 

1.44848 

45.4 

44.6 

90.0 

1.48486 

47.9 

47.0 

84.9 

1.44917 

45.5 

44.6 

90.1 

1.48558 

48.0 

47.1 

85.0 

1.44986 

45.5 

44.7 

90.2 

1.48629 

48.0 

47.1 

85.1 

1.45055 

45.6 

44.7 

90.3 

1.48700 

48.1 

47.2 

85.2 

.45124 

45.6 

44.8 

-      90.4 

1.48771 

48.1 

47.2 

85.3 

.45193 

45.7 

44.8 

90.5 

1.48842 

48.2 

47.2 

85.4 

.45262 

45.7 

44.9 

90.6 

1.48913 

48.2 

47.3 

85.5 

.45331 

45.8 

44.9 

90.7 

1.48985 

48.3 

47.3 

85.6 

.45401 

45.8 

45.0 

90.8 

1.49056 

48.3 

47.4 

85.7 

.45470 

45.9 

45.0 

90.9 

.49127 

48.35 

47.4 

85.8 

.45539 

45.9 

45.0 

91.0 

.49199 

48.4 

47.5 

85.9 

.45609 

46.0 

45.1 

91.1 

.49270 

48.45 

47.5 

86.0 

.45678 

46.0 

45.1 

91.2 

.49342 

48.5 

47.6 

86.1 

.45748 

46.1 

45.2 

91.3 

.49413 

48.5 

47.6 

86.2 

.45817 

46.1 

45.2 

91.4 

.49485 

48.6 

47.7 

86.3 

.45887 

46.2 

45.3 

91.5 

.49556 

48.6 

47.7 

86.4 

.45956 

46.2 

45.3 

91.6 

.49628 

48.7 

47.8 

86.5 

.46026 

46.3 

45.4 

91.7 

.49700 

48.7 

47.8 

86.6 

.46095 

46.3 

45.4 

91.8 

.49771 

48.8 

47.8 

86.7 

.46165 

46.35 

45.5 

91.9 

1.49843 

48.8 

47.9 

86.8 

.46235 

46.4 

45.5 

92.0 

1.49915 

48.9 

47.9 

86.9 

.46304 

46.45 

45.6 

92.1 

1.49987 

48.9 

48.0 

87.0 

.46374 

46.5 

45.6 

92.2 

1.50058 

49.0 

48.0 

87.1 

.46444 

46.55 

45.7 

92.3 

1.50130 

49.0 

48.1 

87.2 

.46514 

46.6 

45.7 

92.4 

1.50202 

49.05 

48.1 

87.3 

.46584 

46.65 

45.8 

92.5 

1.50274 

49.1 

48.2 

87.4 

1.46654 

46.7 

45.8 

92.6 

1.50346 

49.15 

48.2 

87.5 

1.46724 

46.7 

45.8 

92.7 

1.50419 

49.2 

48.3 

SUGAR   TABLES 


15 


TABLE  3.     (Concluded.) 


Per  cent 
sucrose  by 
weight  or 

Specific 
gravity. 

Degrees  Baiiine". 

Per  cent 
sucrose  by 
weight  or 

Specific 
gravity. 

Degrees  Baum6. 

GCgr66S 

Brix. 

New. 

Old. 

degrees 
Brix. 

New. 

Old. 

92.8 

1.50491 

49.25 

48.3 

94  0 

1.51359 

49.8 

48.8 

92.9 

1.50563 

49.3 

48.3 

94.1 

1.51431 

49.85 

48.9 

93.0 

1.50635 

49.3 

48.4 

94.2 

1.51504 

49.9 

48.9 

93.1 

1.50707 

49.4 

48.4 

94.3 

1.51577 

49.9 

49.0 

93.2 

1.50779 

49.4 

48.5 

94.4 

1.51649 

50.0 

49.0 

93.3 

1.50852 

49.5 

48.5 

94.5 

1.51722 

50.0 

49.1 

93.4 

1.50924 

49.5 

48.6 

94.6 

1.51795 

50.1 

49.1 

93.5 

1.50996 

49.6 

48.6 

94.7 

1.51868 

50.1 

49.2 

93.6 

1.51069 

49.6 

48.7 

94.8 

1.51941 

50.2 

49.2 

93.7 

1.51141 

49.7 

48.7 

94.9 

1.52014 

50.2 

49.3 

93.8 

1.51214 

49.7 

48.8 

95.0 

1.52087 

50.3 

49.3 

93.9 

1.51286 

49.8 

48.8 

16 


SUGAR  TABLES 


TABLE*  4. 

TABLE  FOR  CORRECTING  READINGS  OF  BRIX  HYDROMETERS  AT  DIFFERENT 
TEMPERATURES  TO  17.5°C. 


Degrees  Brix  of  solution. 

Tempera- 
ture. 

0 

5 

10 

15 

20 

25 

30 

35 

40 

50 

60 

70 

75 

Degrees 

Centigrade. 

Corrections  to  be  subtracted  from  degrees  Brix. 

0° 

0.17 

0.30 

0.41 

0.52 

0.62 

0.72 

0.82 

0.92 

0.98 

1.11 

1.22 

1.25 

1.29 

5 

0.23 

0.30 

0.37 

0.44 

0.52 

0.59 

0.65 

0.72 

0.75 

0.80 

0.88 

0.91 

0.94 

10 

0.20 

0.26 

0.29 

0.33 

0.36 

0.39 

0.42 

0.45 

0.48 

0.50 

0.54 

0.58 

0.61 

11 

0.18 

0.23 

0.26 

0.28 

0.31 

0.34 

0.36 

0.39 

0.41 

0.43 

0.47 

0.50 

0.53 

12 

0.16 

0.20 

0.22 

0.24 

0.26 

0.29 

0.31 

0.33 

0.34 

0.36 

0.40 

0.42 

0.46 

13 

0.14 

0.18 

0.19 

0.21 

0.22 

0.24 

0.26 

0.27 

0.28 

0.29 

0.33 

0.35 

0.39 

14 

0.12 

0.15 

0.16 

0.17 

0.18 

0.19 

0.21 

0.22 

0.22 

0.23 

0.26 

0.28 

0.32 

15 

0.09 

0.11 

0.12 

0.14 

0.14 

0.15 

0.16 

0.17 

0.16 

0.17 

0.19 

0.21 

0.25 

16 

0.06 

0.07 

0.08 

0.09 

0.10 

0.10 

0.11 

0.12 

0.12 

0.12 

0.14 

0.16 

0.18 

17 

0.02 

0.02 

0.03 

0.03 

0.03 

0.04 

0.04 

0.04 

0.04 

0.04 

0.05 

0.05 

0.06 

Corrections  to  be  added  to  degrees  Brix. 


18 

0.02 

0.03 

0.03 

0.03 

0.03 

0.03 

0.03 

0.03 

0.03 

0.03 

0.03 

0.03 

0.02 

19 

0.06 

0.08 

0.08 

0.09 

0.09 

0.10 

0.10 

0.10 

0.10 

0.10 

0.100.08 

0.06 

20 

0.11 

0.14 

0.15 

0.17 

0.17 

0.18 

0.18 

0.18 

0.19 

0.19 

0.180.15 

0.11 

21 

0.16 

0.20 

0.22 

0.24 

0.24 

0.25 

0.25 

0.25 

0.26 

0.26 

0.25 

0.22 

0.18 

22 

0.21 

0.26 

0.29 

0.31 

0.31 

0.32 

0.32 

0.32 

0.33 

0.34 

0.32 

0.29 

0.25 

23 

0.27 

0.32 

0.35 

0.37 

0.38 

0.39 

0.39 

0.39 

0.40 

0.42 

0.39 

0.36 

0.33 

24 

0.32 

0.38 

0.41 

0.43 

0.44 

0.46 

0.46 

0.47 

0.47 

0.50 

0.46 

0.430.40 

25 

0.37 

0.44 

0.47 

0.49 

0.51 

0.53 

0.54 

0.55 

0.55 

0,£8 

0.54 

0.510.48 

26 

0.43 

0.50 

0.54 

0.56 

0.58 

0.60 

0.61 

0.62 

0.62 

0.66 

0.62 

0.58 

0.55 

27 

0.49 

0.57 

0.61 

0.63 

0.65 

0.68 

0.68 

0.69 

0.70 

0.74 

0.70 

0.65 

0.62 

28 

0.56 

0.64 

0.68 

0.70 

0.72 

0.76 

0.76 

0.78 

0.78 

0.82 

0.78 

0.72 

0.70 

29 

0.63 

0.71 

0.75 

0.78 

0.79 

0.84 

0.84 

0.86 

0.86 

0.90 

0.86 

0.80 

0.78 

30 

0.70 

0.78 

0.82 

0.87 

0.87 

0.92 

0.92 

0.94 

0.94 

0.98 

0.94 

0.88 

0.86 

35 

1.10 

1.17 

1.22 

1.24 

1.30 

1.32 

1.33 

1.35 

1.36 

1.39 

1.34 

1.27 

1.25 

40 

1.50 

1.61 

1.67 

1.71 

1.73 

1.79 

1.79 

1.80 

1.82 

1.83 

1.78 

1.69 

1.65 

50 

2.65 

2.71 

2.74 

2.78 

2.80 

2.80 

2.80 

2.80 

2.79 

2.70 

2.56 

2.51 

60 

3.87 

3.88 

3.88 

3.88 

3.88 

3.88 

3.88 

3.90 

3.82 

3.70 

3.43 

3.41 

70 

5.17 

5.18 

5.20 

5.14 

5.13 

5.10 

5.08 

5.06 

4.90 

4.724.47 

4.35 

80 

6  62 

6  59 

6.54 

6  46 

6  38 

6  30 

6  26 

6.06 

5.82's  sn 

5  33 

90 

8.26 

8.16 

8^06 

7^97 

7'.83 

7^71 

7^58 

7^30 

6.96 

6^58 

6.37 

100 

.... 

10.01 

9.87 

9.72 

9.56 

9.39 

9.21 

9.03 

8.64 

8.22 

7.76 

7.42 

*  See  "Handbook,"  page  31. 


SUGAR   TABLES 


17 


TABLE*  5. 

MAIN'S  TABLE  FOR  DETERMINING  WATER  IN  SUGAR  SOLUTIONS  BY  MEANS  OF 
THE  ABBE  REFRACTOMETER. 


Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

1.3330 

Per  cent. 
100 

.3397 

Per  cent. 
95.2 

1.3469 

Per  cent. 

90.4 

1.3545 

Per  cent. 

•     85.6 

.3331 

99.9 

.3399 

95.1 

1.3471 

90.3 

1.3546 

85.5 

.3333 

99.8 

.3400 

95 

1.3472 

90.2 

1.3548 

85.4 

.3334 

99.7 

.3402 

94.9 

1.3474 

90.1 

1.3549 

85.3 

.3336 

99.6 

.3403 

94.8 

1.3475 

90 

1.3551 

85.2 

.3337 

99.5 

.3405 

94.7 

1.3477 

89.9 

1.3552 

85.1 

.3338 

99.4 

.3406 

94.6 

1.3478 

89.8 

1.3554 

85 

.3340 

99.3 

.3408 

94.5 

1.3480 

89.7 

1.3556 

84.9 

.3341 

99.2 

.3409 

94.4 

1.3481 

89.6  . 

1.3557 

84.8 

.3343 

99.1 

1.3411 

94.3 

1.3483 

89.5 

1.3559 

84.7 

.3344 

99 

1.3412 

94.2 

1.3484 

89.4 

1.3561 

84.6 

.3345 

98.9 

1.3414 

94.1 

1.3486 

89.3 

1.3562 

84.5 

.3347 

98.8 

1.3415 

94 

1.3488 

89.2 

1.3564 

84.4 

.3348 

98.7 

1.3417 

93.9 

1.3489 

89.1 

1.3566 

84.3 

.3350 

98.6 

1.3418 

93.8 

1.3491 

89 

1.3567 

84.2 

.3351 

98.5 

1.3420 

93.7 

1.3492 

88.9 

.3569 

84.1 

.3352 

98.4 

1.3421 

93.6 

1.3494 

88.8 

.3571 

84 

.3354 

98.3 

1.3423 

93.5 

1.3496 

88.7 

.3572 

83.9 

.3355 

98.2 

1.3424 

93.4 

1.3497 

88.6 

.3574 

83.8 

.3357 

98.1 

1.3426 

93.3 

1.3499 

88.5 

.3576 

83.7 

.3358 

98 

1.3427 

93.2 

1.3500 

88.4 

.3577 

83.6 

.3359 

97.9 

1.3429 

93.1 

1.3502 

88.3 

1.3579 

83.5 

.3361 

97.8 

1.3430 

93 

1.3503 

88.2 

1.3581 

83.4 

.3362 

97.7 

1.3432 

92.9 

1.3505 

88.1 

1.3582 

83.3 

.3364 

97.6 

1.3433 

92.8 

1.3507 

88 

1.3584 

83.2 

1.3365 

97.5 

1.3435 

92.7 

1.3508 

87.9 

1.3586 

83.1 

1.3366 

97.4 

1.3436 

92.6 

1.3510 

87.8 

1.3587 

83 

1.3368 

97.3 

1.3438 

92.5 

1.3511 

87.7 

1.3589 

82.9 

1.3369 

97.2 

1.3439 

92.4 

1.3513 

87.6 

1.3591 

82.8 

1.3371 

97.1 

1.3441 

92.3 

1.3515 

87.5 

1.3592 

82.7 

1.3372 

97 

1.3442 

92.2 

~  1.3516 

87.4 

1.3594 

82.6 

1.3373 

96.9 

1.3444 

92.1 

1.3518 

87.3 

1.3596 

82.5 

1.3375 

96.8 

1.3445 

92 

1.3519 

87.2 

1.3597 

82.4 

1.3376 

96.7 

1.3447 

91.9 

1.3521 

87.1 

1.3599 

82.3 

1.3378 

96.6 

1.3448 

91.8 

1.3522 

87 

1.3600 

82.2 

1.3379 

96.5 

1.3450 

91.7 

1.3524 

86.9 

.3602 

82.1 

1.3380 

96.4 

1.3451 

91.6 

.3526 

86.8 

.3604 

82 

1.3382 

96.3 

1.3453 

91.5 

.3527 

86.7 

.3605 

81.9 

1.3383 

96.2 

1.3454 

91.4 

.3529 

86.6 

.3607 

81.8 

1.3385 

96.1 

1.3456 

91.3 

.3530 

86.5 

.3609 

81.7 

.3386 

96 

1.3457 

91.2 

.3532 

86.4 

.3610 

81.6 

.3387 

95.9 

1.3459 

91.1 

.3533 

86.3 

.3612 

81.5 

.3389 

95.8 

1.3460 

91 

.3535 

86.2 

.3614 

81.4 

.3390 

95.7 

1.3462 

90.9 

.3537 

86.1 

.3615 

81.3 

.3392 

95.6 

1.3463 

90.8 

.3538 

86 

.3617 

81.2 

.3393 

95.5 

1.3465 

90.7 

.3540 

85.9 

.3619 

81.1 

.3394 

95.4 

1.3466 

90.6 

.3541 

85.8 

1.3620 

81 

.3396 

95.3 

1.3468 

90.5 

1.3543 

85.7 

1.3622 

80.9 

*  See  "  Handbook,"  page  64. 


18 


SUGAR  TABLES 


TABLE  5.     (Continued.) 


Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 

20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Per  cent. 

Per  cent. 

Per  cent. 

Per  cent. 

.3624 

80.8 

1.3709 

75.7 

1.3799 

70.6 

1.3893 

65.5 

.3625 

80.7 

1.3711 

75.6 

1.3801 

70.5 

1.3895 

65.4 

.3627  ' 

80.6 

1.3713 

75.5 

1.3803 

70.4 

1.3896 

65.3 

.3629 

80.5 

1.3714 

75.4 

1.3805 

70.3 

1.3898 

65.2 

.3630 

80.4 

1.3716 

75.3 

1.3806 

70.2 

1.3900 

65.1 

.3632 

80.3 

1.3718 

75.2 

1.3808 

70.1 

1.3902 

65 

.3634 

80.2 

1.3719 

75.1 

1.3810 

70 

1.3904 

64.9 

.3635 

80.1 

1.3721 

75 

.3812 

69.9 

1.3906 

64.8 

.3637 

80 

1.3723 

74.9 

.3814 

69.8 

.3908 

64.7 

.3639 

79.9 

1.3725 

74.8 

.3816 

69.7 

.3910 

64.6 

.3640 

79.8 

1.3726 

74.7 

.3817 

69.6 

.3912 

64.5 

.3642 

79.7 

1.3728 

74.6 

.3819 

69.5 

.3913 

64.4 

.3644 

79.6 

.3730 

74.5 

.3821 

69.4 

.3915 

64.3 

.3645 

79.5 

.3732 

74.4 

.3823 

69.3 

.3917 

64.2 

.3647 

79.4 

.3733 

74.3 

.3825 

69.2 

.3919 

64.1 

.3649 

79.3 

.3735 

74.2 

.3827 

69.1 

.3921 

64 

1.3650 

79.2 

.3737 

74.1 

.3828 

69 

.3923 

63.9 

1.3652 

79.1 

.3739 

74 

.3830 

68.9 

3925 

63.8 

1.3654 

79 

.3741 

73.9 

.3832 

68.8 

.3927 

63.7 

1.3655 

78.9 

.3742 

73.8 

.3834 

68.7 

.3929 

63.6 

1.3657 

78.8 

.3744 

73.7 

.3836 

68.6 

.3931 

63.5 

1.3659 

78.7 

.3746 

73.6 

.3838 

68.5 

.3932 

63.4 

1.3661 

78.6 

.3748 

73.5 

.3839 

68.4 

.3934 

63.3 

1.3662 

78.5 

.3749 

73.4 

.3841 

68.3 

.3936 

63.2 

1.3664 

78.4 

.3751 

73.3 

.3843 

68.2 

.3938 

63.1 

1.3666 

78.3 

.3753 

73.2 

.3845 

68.1 

.3940 

63 

1.3667 

78.2 

.3755 

73.1 

.3847 

68 

.3942 

62.9 

1.3669 

78.1 

.3757 

73 

.3849 

67.9 

.3944 

62.8 

1.3671 

78 

.3758 

72.9 

.3850 

67.8 

.3946 

62.7 

.3672 

77.9 

.3760 

72.8 

.3852 

67.7 

.3948 

62.6 

.3674 

77.8 

.3762 

72.7 

.3854 

67.6 

.3950 

62.5 

.3676 

'77.7 

.3764 

72.6 

.3856 

67.5 

.3951 

62.4 

.3677 

77.6 

.3766 

72.5 

.3858 

67.4 

.3953 

62.3 

.3679 

77.5 

.3767 

72.4 

.3860 

67.3 

.3955 

62.2 

.3681 

77.4 

.3769 

72.3 

.3862 

67.2 

.3957 

62.1 

.3682 

77.3 

.3771 

72.2 

.3863 

67.1 

.3959 

62 

.3684 

77.2 

.3773 

72.1 

.3865 

67 

.3961 

61.9 

1.3686 

77.1 

1.3774 

72 

.3867 

66.9 

1.3963 

61.8 

1.3687 

77 

1.3776 

71.9 

.3869 

66.8 

1.3965 

61.7 

1.3689 

76.9 

1.3778 

71.8 

.3871 

66.7 

1.3967 

61.6 

.3691 

76.8 

1.3780 

71.7 

.3873 

66.6 

1.3969 

61.5 

.3692 

76.7 

1.3782 

71.6 

1.3874 

66.5 

1.3970 

61.4 

.3694 

76.6 

1.3783 

71.5 

1.3876 

66.4 

1.3972 

61.3 

.3696 

76.5 

1.3785 

71.4 

1.3878 

66.3 

.3974 

61.2 

.3697 

76.4 

.3787 

71.3 

1.3880 

66.2 

.3976 

61.1 

.3699 

76.3 

.3789 

71.2 

1.3882 

66.1 

.3978 

61 

3701 

76.2 

.3790 

71.1 

1.3884 

66 

.3980 

60.9 

.3703 

76.1 

.3792 

71 

1.3885 

65.9 

.3982 

60.8 

.3704 

76 

.3794 

70.9 

1.3887 

65.8 

.3984 

60.7 

.3706 

75.9 

.3796 

70.8 

1.3889 

65.7 

.3986 

60.6 

.3708 

75.8 

.3798 

70.7 

1.3891 

65.6 

.3988 

60.5 

SUGAR   TABLES 


19 


TABLE  5.     (Continued.) 


Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Refractive 
.  index  at 

20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

1.3989 

Per  cent. 

60.4 

1.4089 

Per  cent. 
55.3 

1.4197 

Per  cent. 
50.2 

1.4302 

Per  cent. 
45.1 

1.3991 

60.3 

1.4091 

55.2 

1.4199 

50.1 

1.4304 

45 

1.3993 

60.2 

1.4093 

55.1 

1.4201 

50 

1.4306 

44.9 

1.3995 

60.1 

1.4095 

55 

1.4203 

49.9 

1.4309 

44.8 

1.3997 

60 

1.4097 

54.9 

1.4205 

49.8 

1.4311 

44.7 

1.3999 

59.9 

1.4099 

54.8 

1.4207 

49.7 

1.4313 

44.6 

1.4001 

59.8 

1.4101 

54.7 

1.4209 

49.6 

1.4316 

44.5 

1.4003 

59.7 

1.4103 

54.6 

1.4211 

49.5 

1.4318 

44.4 

1.4005 

59.6 

1.4106 

54.5 

1.4213 

49.4 

1.4320 

44.3 

1.4007 

59.5 

1.4108 

54.4 

.4215 

49.3 

1.4322 

44.2 

1.4009 

59.4 

1.4110 

54.3 

.4217 

49.2 

1.4325 

44.1 

1.4011 

59.3 

1.4112 

54.2 

.4220 

49.1 

1.4327 

44 

1.4013 

59.2 

1.4114 

54.1 

.4222 

49 

1.4329 

43.9 

1.4015 

59.1 

1.4116 

54 

.4224 

48.9 

1.4332 

43.8 

1.4017 

59 

1.4118 

53.9 

.4226 

48.8 

1.4334 

43.7 

1.4019 

58.9 

1.4120 

53.8 

.4228 

48.7 

1.4336 

43.6 

1.4021 

58.8 

1.4123 

53.7 

1.4230 

48.6 

1.4339 

43.5 

1.4022 

58.7 

1.4125 

53.6 

1.4232 

48.5 

1.4341 

43.4 

1.4024 

58.6 

1.4127 

53.5 

1.4234 

48.4 

1.4343 

43.3 

1.4026 

58.5 

1.4129 

53.4 

1.4236 

48.3 

1.4345 

43.2 

1.4028 

58.4 

1.4131 

53.3 

1.4238 

48.2 

1.4348 

43.1 

1.4030 

58.3 

1.4133 

53.2 

1.4240 

48.1 

1.4350 

43 

1.4032 

58.2 

1.4135 

53.1 

1.4242 

48 

1.4352 

42.9 

1.4034 

58.1 

.4137 

53 

1.4244 

47.9 

1.4355 

42.8 

1.4036 

58 

.4140 

52.9 

1.4246 

47.8 

1.4357 

42.7 

1.4038 

57.  ^ 

.4142 

52.8 

1.4248 

47.7 

1.4359 

42.6 

1.4040 

57.8 

.4144 

52.7 

1.4250 

47.6 

1.4362 

42.5 

1.4042 

57.7 

.4146 

52.6 

1.4253 

47.5 

1.4364 

42.4 

1.4044 

57.6 

.4148 

52.5 

1.4255 

47.4 

1.4366 

42.3 

1.4046 

57.5 

.4150 

52.4 

1.4257 

47.3 

1.4368 

42.2 

1.4048 

57.4 

1.4152 

52.3 

1.4259 

47.2 

1.4371 

42.1 

1.4050 

57.3 

1.4154 

52.2 

1.4261 

47.1 

1.4373 

42 

1.4052 

57.2 

1.4156 

52.1 

1.4263 

47 

1.4375 

41.9 

1.4054 

57.1 

1.4159 

52 

1.4265 

46.9 

1.4378 

41.8 

1.4056 

57 

1.4161 

51.9 

1.4267 

46.8 

1.4380 

41.7 

1.4058 

56.9 

1.4163 

51.8 

1.4269 

46.7 

1.4382 

41.6 

1.4060 

56.8 

1.4165 

51.7 

1.4271 

46.6 

1.4385 

41.5 

1.4062 

56.7 

1.4167 

51.6 

1.4273 

46.5 

1.4387 

41.4 

1.4064 

56.6 

1.4169 

51.5 

1.4275 

46.4 

1.4389 

41.3 

1.4066 

56.5 

4171 

51.4 

1.4277 

46.3 

1.4391  , 

41.2 

1.4068 

56.4 

.4173 

51.3 

1.4279 

46.2 

1.4394 

41.1 

1.4070 

56.3 

.4176 

51.2 

1.4281 

46.1 

1.4396 

41 

1.4071 

56.2 

.4178 

51.1 

1.4283 

46 

1.4398 

40.9 

1.4073 

56.1 

.4180 

51 

1.4285 

45.9 

1.4401 

40.8 

1.4075 

56 

.4182 

50.9 

1.4288 

45.8 

1.4403 

40.7 

1.4077 

55.9 

.4184 

50.8 

1.4290 

45.7 

1.4405 

40.6 

1.4079 

55.8 

.4186 

50.7 

1.4292 

45.6 

1.4408 

40.5 

1.4081 

55.7 

.4188 

50.6 

1.4294 

45.5 

1.4410 

40.4 

1.4083 

55.6 

.4190 

50.5 

1.4296 

45.4 

1.4412 

40.3 

1.4085 

55.5 

1.4193 

50.4 

1.4298 

45.3 

1.4414 

40.2 

1.4087 

55.4 

1.4195 

50.3 

1.4300 

45.2 

1.4417 

40.1 

20 


SUGAR  TABLES 


TABLE  5.     (Continued.} 


Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 

20°  C. 

Water. 

Refractive 
index  at 

20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

1.4419 

Per  cent. 
40 

1.4537 

Per  cent. 
34.9 

1.4656 

Per  cent. 

29.8 

.4782 

Per  cent. 

24.7 

.4421 

39.9 

1.4540 

34.8 

.4658 

29.7 

.4784 

24.6 

.4424 

39.8 

1.4542 

34.7 

.4661 

29.6 

.4787 

24.5 

.4426 

39.7 

1.4544 

34.6 

.4663 

29.5 

.4789 

24.4 

.4428 

39.6 

1.4547 

34.5 

.4666 

29.4 

.4792 

24.3 

.4431 

39.5 

1.4549 

34.4 

.4668 

29.3 

.4794 

24.2 

.4433 

39.4 

1.4551 

34.3 

.4671 

29.2 

.4797 

24.1 

.4435 

39.3 

1.4554 

34.2 

.4673 

29.1 

.4799 

24 

1.4438 

39.2 

1.4556 

34.1 

.4676 

29 

1.4802 

23.9 

1.4440 

39.1 

1.4558 

34 

.4678 

28.9 

1.4804 

23.8 

1.4442 

39 

1.4561 

33.9 

.4681 

28.8 

1.4807 

23.7 

.4445 

38.9 

1.4563 

33.8 

.4683 

28.7 

1.4810 

23.6 

.4447 

38.8 

1.4565 

33.7 

.4685 

28.6 

1.4812 

23.5 

.4449 

38.7 

1.4567 

33.6 

1.4688 

28.5 

1.4815 

23.4 

.4451 

38.6 

1.4570 

33.5 

1.4690 

28.4 

1.4817 

23.3 

.4454 

38.5 

1.4572 

33.4 

1.4693 

28.3 

1.4820 

23.2 

.4456 

38.4 

1.4574 

33.3 

1.4695 

28.2 

.4822 

23.1 

.4458 

38.3 

1.4577 

33.2 

1.4698 

28.1 

.4825 

23 

.4461 

38.2 

1.4579 

33.1 

1.4700 

28 

.4827 

22.9 

.4463 

38.1 

1.4581 

33 

1.4703 

27.9 

.4830 

22.8 

.4465 

38 

1.4584 

32.9 

1.4705 

27.8 

.4832 

22.7 

.4468 

37.9 

1.4586 

32.8 

1.4708 

27.7 

.4835 

22.6 

.4470 

37.8 

1.4588 

32.7 

1  .4710 

27.6 

.4838 

22.5 

.4472 

37.7 

1.4591 

32.6 

1.4713 

27.5 

.4840 

22.4 

1.4475 

37.6 

1.4593 

32.5 

1.4715 

27.4 

.4843 

22.3 

1.4477 

37.5 

1.4595 

32.4 

1.4717 

27.3 

.4845 

22.2 

1.4479 

37.4 

1.4598 

32.3 

1.4720 

27.2 

.4848 

22.1 

.4482 

37.3 

1.4600 

32.2 

1.4722 

27.1 

1.4850 

22 

.4484 

57.2 

1.4602 

32.1' 

1.4725 

27 

1.4853 

21.9 

.4486 

37.1 

1.4605 

32 

1.4727 

26.9 

1.4855 

21.8 

.4489 

37 

1.4607 

31.9 

1.4730 

26.8 

1.4858 

21.7 

.4491 

36.9 

1.4609 

31.8 

1.4732 

26.7 

1.4860 

21.6 

.4493 

36.8 

1.4612 

31.7 

1.4735 

26.6 

.4863 

21.5 

.4496 

36.7 

1.4614 

31.6 

1.4737 

26.5 

.4865 

21.4 

.4498 

36.6 

1.4616 

31.5 

1.4740 

26.4 

.4868 

21.3 

4500 

36.5 

1.4619 

31.4 

1.4742 

26.3 

.4871 

21.2 

.4503 

36.4 

1.4621 

31.3 

1.4744 

26.2 

.4873 

21.1 

.4505 

36.3 

1.4623 

31.2 

1.4747 

26.1 

.4876 

21 

.4507 

36.2 

1.4625 

31.1 

1.4749 

26 

.4878 

20.9 

.4509 

36.1 

1.4628 

31 

1.4752 

25.9 

.4881 

20.8 

.4512 

36 

1.4630 

30.9 

1.4754 

25.8 

.4883 

20.7 

.4514 

35.9 

1.4632 

30.8 

1.4757 

25.7 

.4886 

20.6 

.4516 

35.8 

1.4635 

30.7 

1.4759 

25.6 

.4888 

20.5 

.4519 

35.7 

1.4637 

30.6 

1.4762 

25.5 

.4891 

20.4 

.4521 

35.6 

1.4639 

30.5 

1.4764 

25.4 

.4893 

20.3 

.4523 

35.5 

1.4642 

30.4 

1.4767 

25.3 

.4896 

20.2 

.4526 

35.4 

1.4644 

30.3 

1.4769 

25.2 

1.4898 

20.1 

.4528 

35.3 

1.4646 

30.2 

1.4772 

25.1 

1.4901 

20 

.4530 

35.2 

1.4649 

30.1 

1.4774 

25 

1.4904 

19.9 

.4533 

35.1 

1.4651 

30       • 

1.4777 

24.9 

1.4906 

19.8 

1.4535 

35 

1.4653 

29.9 

1.4779 

24.8 

1.4909 

19.7 

SUGAR  TABLES 
TABLE  5.     (Concluded.") 


21 


Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 
20°  C. 

Water. 

Refractive 
index  at 

20°  C. 

Water. 

1.4912 

Per  cent. 
19.6 

1.4943 

Per  cent. 
18.4 

1.4975 

Per  cent. 

17.2 

.5007 

Per  cent. 
16 

1.4914 

19.5 

1.4946 

18.3 

1.4978 

17.1 

.5009 

15.9 

1.4917 

19.4 

1.4949 

18.2 

1.4980 

17 

.5012 

15.8 

1.4919 

19.3 

1.4951 

18.1 

1.4983 

16.9 

.5015 

15.7 

1.4922 

19.2 

1.4954 

18 

1.4985 

16.8 

.5017 

15.6 

1.4925 

19.1 

1.4956 

17.9 

1.4988 

16.7 

.5020 

15.5 

1.4927 

19 

1.4959 

17.8 

1.4991 

16.6 

.5022 

15.4 

1.4930 

18.9 

1.4962 

17.7 

1.4993 

16.5 

.5025 

15.3 

1.4933 

18.8 

1.4964 

17.6 

1.4996 

16.4 

.5028 

15.2 

1.4935 

18.7 

1.4967 

17.5 

1.4999 

16.3 

.5030 

15.1 

1.4938 

18.6 

1.4970 

17.4 

1.6001 

16.2 

.5033 

15 

1.4941 

18.5 

1.4972 

17.3 

1.5004 

16.1 

TABLE*  6. 

STANEK'S  CORRECTION  TABLE. 

For  Determining  Water  in  Sugar  Solutions  by  Means  of  the  Abbe  Refractometer  when 
Readings  are  Made  at  Other  Temperatures  than  20°  C. 


Water, 
per  cent. 

95 

90 

85 

80 

70 

60 

50 

40 

30 

25 

Water, 
per  cent. 

Tem- 

Tem- 

perature 

To  be  added  to  the  per  cent  of  water. 

perature 

15 

0.25 

0.27 

0.31 

0.31 

0.34 

0.35 

0.36 

0.37 

0.36 

0.36 

15 

16 

0.21 

0.23 

0.26 

0.27 

0.29 

0.31 

0.31 

0.32 

0.31 

0.29 

16 

17 

0.16 

0.18 

0.20 

0.20 

0.22 

0.23 

0.23 

0.23 

0.20 

0.17 

17 

18 

0.11 

0.12 

0.14 

0.14 

0.15 

0.16 

0.16 

0.15 

0.12 

0.09 

18 

19 

0.06 

0.07 

0.08 

0.08 

0.08 

0.09 

0.09 

0.08 

0.07 

0.05 

19 

Tem- 
perature 

To  be  subtracted  from  the  per  cent  of  water. 

Tem- 
perature 

21 

0.06 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

21 

22 

0.12 

0.14 

0.14 

0.14 

0.14 

0.14 

0.15 

0.14 

0.14 

0.14 

22 

23 

0.18 

0.20 

0.20 

0.21 

0.21 

0.21 

0.23 

0.21 

0.22 

0.22 

23 

24 

0.24 

0.26 

0.26 

0.27 

0.28 

0.28 

0.30 

0.28 

0.29 

0.29 

24 

25 

0.30 

0.32 

0.32 

0.34 

0.36 

0.36 

0.38 

0.36 

0.36 

0.37 

25 

26 

0.36 

0.39 

0.39 

0.41 

0.43 

0.43 

0.46 

0.44 

0.43 

0.44 

26 

27 

0.43 

0.46 

0.46 

0.48 

0.50 

0.51 

0.55 

0.62 

0.50 

0.51 

27 

28 

0.50 

0.53 

0.53 

0.55 

0.58 

0.59 

0.63 

0.70 

0.57 

0.59 

28 

29 

0.57 

0.60 

0.61 

0.62 

0.66 

0.67 

0.71 

0.78 

0.65 

0.67 

29 

30 

0.64 

0.67 

0.70 

0.71 

0.74 

0.75 

0.80 

0.86 

0.73 

0.75 

30 

Water, 
per  cent. 

95 

90 

85 

80 

70 

60 

50 

40 

30 

25 

Water, 
ser  cent. 

*  See  "Handbook,"  page  64. 


22 


SUGAR  TABLES 


TABLE*  7. 

GEERLIGS'S  TABLE  FOR  DETERMINING  DRY  SUBSTANCE  IN  SUGAR-HOUSE  PRODUCTS. 
By  the  Abbe  Refractometer,  at  28°  C. 


R6fr£ic~ 

*i 

Refrac- 

fri 

T3  | 

tive 

11 

Decimals. 

tive 

ll 

Decimals. 

Index. 

3  oo 

& 

Index. 

Sj 

*8 

1.3335 

1 

0.0001  =  0.05 

0.0010=0.75 

.4104 

46 

0.0005=0.25 

0.0016=0.8 

1.3349 

2 

0.0002=0.1 

0.0011=0.8 

.4124 

47 

0.0006=0.3 

0.0017=0.85 

1.3364 

3 

0.0003=0.2 

0.0012  =  0.8 

.4145 

48 

0.0007=0.35 

0.0018  =  0.9 

1.3379 

4 

0.0004=0.25 

0.0013=0.85 

.4166 

49 

0.0008=0.4 

0.0019  =  0.95 

1.3394 

5 

0.0005=0.3 

0.0014=0.9 

.4186 

50 

0.0009  =  0.45 

0.0020  =  1.0 

1.3409 

6 

0.0006=0.4 

0.0015  =  1.0 

.4207 

51 

0.0010=0.5 

0.0021  =  1.0 

1.3424 

7 

0.0007=0.5 

.4228 

52 

0  0011=0.55 

1.3439 

8 

0.0008=0.6 

.4249 

53 

1.3454 

9 

0.0009=0.7 

.4270 

54 

1OJAQ 

in 

.  O^bOiJ 

1U 

J.9Q9 

KK 

Onom  —0  o^ 

Onnio_f|    CK 

1.3484 

11 

0.0001  =  0.05 

.  '±£\)£ 

.4314 

OO 

56 

.  UUUl  —  U  .  UO 

0.0002  =  0.1 

.  UU  I  o  —  U  .  OO 

0.0014  =  0.6 

1.3500 

12 

0.0002  =  0.1 

.4337 

57 

0.0003=0.1 

0.0015=0.65 

1.3516 

13 

0.0003=0.2 

.4359 

58 

0.0004=0.15 

0.0016=0.7 

1.3530 

14 

0.0004=0.25 

.4382 

59 

0.0005  =  0.2 

0.0017  =  0.75 

1.3546 

15 

0.0005=0.3 

.4405 

60 

0.0006  =  0.25 

0.0018  =  0.8 

1.3562 

16 

0.0006=0.4 

.4428 

61 

0.0007  =  0.3 

0.0019=0.85 

.3578 

17 

0.0007=0.45 

.4451 

62 

0.0008  =  0.35 

0.0020  =  0.9 

.3594 

18 

0.0008=0.5 

.4474 

63 

0.0009=0.4 

0.0021  =  0.9 

.3611 

19 

0.0009=0.6 

.4497 

64 

0.0010=0.45 

0.0022  =  0.95 

.3627 

20 

0.0010=0.65 

.4520 

65 

0.0011=0.5 

0.0023  =  1.0 

.3644 

21 

0.0011=0.7 

.4543 

66 

0.0012  =  0.5 

0.0024  =  1.0 

.3661 

22 

0.0012=0.75 

.4567 

67 

.3678 

23 

0.0013=0.8 

.4591 

68 

.3695 

24 

0.0014=0.85 

.4615 

69 

.3712 

25 

0.0015=0.9 

.4639 

70 

.3729 

26 

0.0016=0.95 

.4663 

71 

J.RS7 

79 

3746 

27 

0.0001=0.05 

0  0012     0  fi 

.  4Ooi 

tA 

^3764 

28 

o!o002  =  o'l 

U  .  \J\J  JL£        \J  .  U 

0.0013  =  0.65 

.4711 

73 

0.0001  =  0.0 

0.0015  =  0.55 

.3782 

29 

0.0003  =  0.15 

0.0014  =  0.7 

.4736 

74 

0.0002=0.05 

0.0016=0,6 

.3800 

30 

0.0004  =  0.2 

0.0015  =  0.75 

.4761 

75 

0.0003  =  0.1 

0.0017  =  0.65 

.3818 

31 

0.0005  =  0.25 

0.0016  =  0.8 

.4786 

76 

0.0004  =  0.15 

0.0018  =  0.65 

1.3836 

32 

0.0006  =  0.3 

0.0017=0.85 

.4811 

77 

0.0005  =  0.2 

0.0019  =  0.7 

1.3854 

33 

0.0007=0.35 

0.0018  =  0.9 

.4836 

78 

0.0006  =  0.2 

0.0020  =  0.75 

1.3872 

34 

0.0008  =  0.4 

0.0019=0.95 

.4862 

79 

0.0007  =  0.25 

0.0021  =  0.8 

1.3890 

35 

0.0009=0.45 

0.0020  =  1.0 

.4888 

80 

0.0008  =  0.3 

0.0022  =  0.8 

1.3909 

36 

0.0010=0.5 

0.0021  =  1.0 

.4914 

81 

0.0009  =  0.35 

0.0023  =  0.85 

.3928 

37 

0.0011=0.55 

.4940 

82 

0.0010=0.35 

0.0024  =  0.9 

.3947 

38 

.4966 

83 

0.0011=0.4 

0.0025=0.9 

.3966 

39 

.4992 

84 

0.0012  =  0.45 

0.0026=0.95 

.3984 

40 

.5019 

85 

0.0013  =  0.5 

0.0027  =  1.0 

.4003 

41 

.5046 

r/yro 

86 

07 

0.0014=0.5 

0.0028  =  1.0 

1.4023 

42 

0.0001  =  0.05 

0.0012=0.6 

.  OU/O 

.5100 

of 

88 

1.4043 

43 

0.0002  =  0.1 

0.0013=0.65 

.5127 

89 

1.4063 

44 

0.0003=0.15 

0.0014=0.7 

.5155 

90 

1.4083 

45 

0.0004=0.2 

0.0015=0.75 

*  See  "  Handbook  "  page  65. 


SUGAR  TABLES 


23 


TABLE  7.     (Concluded.) 
CORRECTIONS  FOR  TEMPERATURE. 


Dry  substance. 

Temper- 

ature 

of  the 

0 

5 

10 

15 

20 

25 

30 

40 

50 

60 

70 

80 

90 

prisms 
in°C. 

Subtract. 

20 

0.53 

0.54 

0.55 

0.56 

0.57 

0.58 

0.60 

0.62 

0.64 

0.62 

0.61 

0.60 

0.58 

21 

0.46 

0.47 

0.48 

0.49 

0.50 

0.51 

0.52 

0.54 

0.56 

0.54 

0  53 

0  52 

0  50 

22 

0.40 

0.41 

0.42 

0.42 

0.43 

0.44 

0.45 

0.47 

0.48 

0.47 

0.46 

0.45 

0.44 

23 

0.33 

0.33 

0.34 

0.35 

0.36 

0.37 

0.38 

0.39 

0.40 

0.39 

0.38 

0.38 

0.38 

24 

0.26 

0.26 

0.27 

0.28 

0.28 

0.29 

0.30 

0.31 

0.32 

0.31 

0.31 

0.30 

0.30 

25 

0.20 

0.20 

0.21 

0.21 

0.22 

0.22 

0.23 

0.23 

0.24 

0.23 

0.23 

0.23 

0.22 

26 

0.12 

0.12 

0.13 

0.14 

0.14 

0.14 

0.15 

0.15 

0.16 

0.16 

0.16 

0.15 

0.14 

27 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.08 

0.08 

0.08 

0.08 

0.08 

0.08 

0.07 

Add. 

29 

0.07 

0.07 

0.07 

0.07 

0.07 

0.07 

0.08 

0.08 

0.08 

0.08 

0.08 

0.08 

0.07 

30 

0.12 

0.12 

0.13 

0.14 

0.14 

0.14 

0.15 

0.15 

0.16 

0.16 

0.16 

0.15 

0.14 

31 

0.20 

0.20 

0.21 

0.21 

0.22 

0.22 

0.23 

0.23 

0.24 

0.23 

0.23 

0.23 

0.22 

32 

0.26 

0.26 

0.27 

0.28 

0.28 

0.29 

0.30 

0.31 

0.32 

0.31 

0.31 

0.30 

0.30 

33 

0.33 

0.33 

0.34 

0.35 

0.36 

0.37 

0.38 

0.39 

0.40 

0.39 

0.38 

0.38 

0.38 

34 

0.40 

0.41 

0.42 

0.42 

0.43 

0.44 

0.45 

0.47 

0.48 

0.47 

0.46 

0.45 

0.44 

35 

0.46 

0.47 

0.48 

0.49 

0.50 

0.51 

0.52 

0.54 

0.56 

0.54 

0.53 

0.52 

0.50 

24 


SUGAR  TABLES 


TABLE*  8. 

HUBENER'S   TABLE   FOR  DETERMINING   PERCENTAGES   BY    WEIGHT   OP   SUCROSE 

IN   SUGAR  SOLUTIONS  FROM   READINGS   OF  THE  ZEISS   IMMERSION 

REFRACTOMETER. 


ijj 

•ofe 

"o  ® 

ofe' 

•3S 

•ss 

11 

.if 

|| 

jfg 

|| 

Ml 

ll 

ll 

^0 

-gg 

2  « 

c§ 

•si 

ll 

c§ 

ll 

•s* 

ll 

c  § 

I1 

SI 

I1 

V 

2 

I" 

|l 
OD 

ps™ 

I1 

1" 

l:f 

I3 

I1 

ls§ 

15.0 

0.00 

21  0 

1  58 

27.0 

3.16 

33.0 

4.74 

39.0 

6  31 

45  0 

7.84 

51.0 

9  32 

0  03 

.61 

.1 

.19 

.1 

.77 

.1 

.33 

.1 

.87 

.1 

.34 

'.2 

0.05 

'.2 

.64 

.2 

.21 

.2 

.79 

.2 

.36 

.2 

.90 

.2 

.36 

3 

0  08 

.3 

.66 

.3 

.24 

.3 

.82 

.3 

.39 

.3 

.92 

.3 

.39 

.4 

0.11 

.4 

.69 

.4 

.26 

.4 

.84 

.4 

.41 

.4 

.95 

.4 

.41 

.5 

0.13 

.5 

.71 

.5 

.29 

.5 

.87 

.5 

.43 

.5 

.97 

.5 

.44 

.6 

0.16 

.6 

.74 

.6 

.32 

.6 

.90 

.6 

.46 

.6 

8.00 

.6 

.46 

.7 

0.19 

.7 

.77 

.7 

.34 

.7 

.92 

.7 

.49 

.7 

.03 

.7 

.49 

8 

0  21 

.8 

.79 

.8 

.37 

.8 

.95 

.8 

.51 

.8 

.05 

.8 

.51 

.9 

0.24 

.9 

.82 

.9 

.40 

.9 

.98 

.9 

.54 

.9 

.07 

.9 

.53 

16.0 

0.26 

22.0 

.84 

28.0 

.42 

34  0 

5.00 

40.0 

.56 

46.0 

.10 

52.0 

.56 

.1 

0.29 

.1 

.87 

.1 

.45 

.1 

.03 

.1 

.59 

.1 

.12 

.1 

.58 

.2 

0.32 

.2 

.90 

.2 

.48 

.2 

.05 

.2 

.61 

.2 

.15 

.2 

.60 

.3 

0.34 

.3 

.92 

.3 

.50 

.3 

.08 

.3 

.64 

.3 

.17 

.3 

.63 

.4 

0.37 

.4 

.95 

.4 

.53 

.4 

.11 

.4 

.66 

.4 

.19 

.4 

.66 

.5 

0.40 

.5 

.98 

.5 

.56 

.5 

.13 

.5 

.69 

.5 

.22 

.5 

.68 

.6 

0.42 

.6 

2  00 

.6 

.58 

.6 

.16 

.6 

.72 

.6 

.24 

.6 

.70 

.7 

0.45 

.7 

.03 

.7 

.61 

.7 

.19 

.7 

.74 

.7 

.27 

.7 

.73 

.8 

0.48 

.8 

.05 

.8 

.64 

.8 

.21 

.8 

.77 

.8 

.29 

.8 

.75 

.9 

0.50 

.9 

.08 

.9 

66 

.9 

.24 

.9 

.79 

.9 

.32 

.9 

.78 

17.0 

0.53 

23  0 

.11 

29  0 

.69 

35.0 

.26 

41.0 

.82 

47.0 

.34 

53.0 

.80 

.1 

0.56 

.13 

.1 

.71 

.1 

.29 

.1 

.84 

j 

.36 

1 

.83 

.2 

0.58 

'.2 

.16 

.2 

.74 

.2 

.32 

.2 

.87 

'.2 

.39 

'.2 

.85 

.3 

0.61 

.3 

.19 

.3 

.77 

.3 

.34 

.3 

.90 

.3 

.41 

.3 

.88 

.4 

0.64 

.4 

.21 

.4 

.79 

.4 

.37 

.4 

.92 

.4 

.44 

.4 

.90 

.5 

0.66 

.5 

.24 

.5 

.82 

.5 

.40 

.5 

.95 

.5 

.46 

.5 

.92 

.6 

0.69 

.6 

.26 

.6 

.54 

.6 

.42 

.6 

.97 

.6 

.49 

.6 

.95 

.7 

0.71 

.7 

.29 

.7 

.87 

.7 

.45 

.7 

7  00 

.7 

.51 

.7 

.97 

.8 

0.74 

.8 

.32 

.8 

.90 

.8 

.48 

.8 

.03 

.8 

.53 

.8 

10.00 

.9 

0.77 

.9 

.34 

.9 

.92 

.9 

.50 

.9 

.05 

.9 

.56 

.9 

.03 

18.0 

0.79 

24  0 

.37 

30.0 

.95 

36  0 

.53 

42  0 

.08 

48  0 

.58 

54  0 

.05 

.1 

0.82  | 

.1 

.40  | 

.1 

.98 

.1 

.56 

.1 

.10 

.60 

.1 

.07 

.2 

0.84 

.2 

.42 

.2 

4  00 

.2 

.58 

.2 

.13 

'.2 

.63 

.2 

.10 

.3 

0.87 

.3 

.45 

.3 

.03 

.3 

.61 

.3 

.15 

.3 

.66 

.3 

.12 

.4 

0.90 

.4 

.48 

.4 

.05 

.4 

.64 

.4 

.18 

.4 

.68 

.4 

.15 

.5 

0.92 

.5 

.50 

.5 

.08 

.5 

.66 

.5 

.20 

.5 

.70 

.5 

.17 

.6 

0.95 

.6 

.53 

.6 

.11 

.6 

.69 

.6 

.23 

.6 

.73 

.6 

.19 

.7 

0.98 

.7 

.56 

.7 

.13 

.7 

.71 

.7 

.26 

.7 

.75 

.7 

.22 

.8 

1.00 

.8 

.58 

.8 

.16 

.8 

.74 

.8 

.28 

.8 

.78 

.8 

.24 

.9 

.03 

.9 

.61 

.9 

.19 

.9 

.77 

.9 

.31 

.9 

.80 

.9 

.27 

19.0 

.05 

25  0 

.64 

31.0 

.21 

37  0 

.79 

43.0 

.33 

490 

.83 

55  0 

.29 

.1 

.08 

.  1 

.66 

.1 

.24 

.1 

.82 

.1 

.36 

.1 

.85 

.1 

.32 

.2 

.11 

.2 

.69 

.2 

.26 

.2 

.84 

.2 

.39 

.2 

.88 

.2 

.34 

.3 

.13 

.3 

.71 

.3 

.29 

.3 

.87 

.3 

.41 

.3 

.90 

.3 

.36 

.4 

.16 

.4 

.74 

.4 

.32 

.4 

.90 

.4 

.43 

.4 

.92 

.4 

.39 

.5 

.19 

.5 

.77 

.5 

.34 

.5 

.92 

.5 

.46 

.5 

.95 

.5 

.41 

.6 

.21 

.6 

.79 

.6 

.37 

.6 

.95 

.6 

.49 

.6 

.97 

.6 

.44 

.7 

.24 

.7 

.82 

.7 

.39 

.7 

.98 

.7 

.51 

.7 

900 

.7 

.46 

.8 

.26 

.8 

.84 

.8 

.42 

.8 

600 

.8 

.54 

.8 

.03 

.8 

.49 

.9 

.29 

.9 

.87 

.9 

.45 

.9 

.03 

.9 

.56 

.9 

.05 

.9 

.51 

20.0 

.32 

26.0 

.90 

32.0 

.48 

38.0 

.05 

44  0 

.59 

50  0 

.07 

56  0 

.53 

.1 

.34 

1 

.92 

.1 

.50 

.1 

.08 

.1 

.61 

.1 

.10 

.1 

.56 

.2 

.37 

'.2 

.95 

.2 

.53 

.2 

.10 

.2 

.64 

.2 

.12 

.2 

.58 

.3 

.40 

.3 

.98 

.3 

.56 

.3 

.13 

.3 

.66 

.3 

.15 

.3 

.60 

.4 

.42 

.4 

3.00 

.4 

.58 

.4 

.15 

.4 

.69 

.4 

.17 

.4 

.63 

.5 

.45 

.5 

.03 

.5 

.61 

.5 

.17 

.5 

.72 

.5 

.19 

.5 

.66 

.6 

.48 

.6 

.05 

.6 

.64 

.6 

.20 

.6 

.74 

.6 

.22 

.6 

.68 

.7 

.50 

.7 

.08 

.7 

.66 

.7 

.23 

.7 

.77 

.7 

.24 

.7 

.70 

.8 

.53 

.8 

.11 

.8 

.69 

.8 

.26 

.8 

79 

.8 

.27 

.8 

.73 

.9 

.56 

.9 

.13 

.9 

.71 

.9 

.28 

.9 

.82 

.9 

.29 

.9 

.75 

*  See  "  Handbook,"  page  74. 


SUGAR  TABLES 


25 


TABLE  8.     (Continued.) 


•sti 

•Sg 

o| 

o| 

1$ 

•8J 

•ofc 

I| 

• 

If 

60  0) 

|1 

|8 

If 

M-g 

!| 

Per  cent 
sucrose 

j| 

Per  cent 
sucrose 

o  *"* 

Per  cent 
sucrose 

P 

Per  cent 
sucrose 

P 

Per  cent 
sucrose 

jl 
d5 

P 

I1 

if 

57.0 

10  78 

63.0 

12.23 

69  0 

13.61 

75.0 

14.98 

81.0 

16.31 

87.0 

17.66 

93.0 

18.95 

.1 

.80 

1 

.25 

.1 

.63 

.1 

15  00 

.1 

.33 

.68 

.1 

.97 

.2 

.83 

'.2 

.28 

.2 

.66 

.2 

.03 

.2 

.35 

'.2 

.71 

.2 

19  00 

.3 

.85 

.3 

.30 

.3 

.68 

.3 

.05 

.3 

.38 

.3 

.73 

.3 

.02 

.4 

.88 

.4 

.32 

.4 

.70 

.4 

.07 

.4 

.40 

.4 

.75 

.4 

.04 

.5 

.90 

.5 

.35 

.5 

.73 

.5 

.09 

.5 

.42 

.5 

.77 

.5 

.06 

.6 

.92 

.6 

.37 

.6 

.75 

.6 

.11 

.6 

.44 

.6 

.79 

.6 

.08 

.7 

.95 

.7 

.39 

.7 

.77 

.7 

.13 

.7 

.47 

.7 

.82 

.7 

.10 

.8 

.97 

.8 

.42 

.8 

.79 

.8 

.16 

.8 

.49 

.8 

.84 

.8 

.13 

.9 

11  00 

.9 

.44 

.9 

.82 

.9 

.18 

.9 

.51 

.9 

.86 

.9 

.15 

58  0 

.03 

64.0 

.46 

70.0 

.84 

76.0 

.20 

82.0 

.54 

88.0 

.89 

94.0 

.17 

.1 

.05 

_  1 

.49 

.1 

.87 

.1 

.22 

.1 

.56 

.1 

.91 

.1 

.19 

.2 

.07 

'.2 

.51 

.2 

.89 

.2 

.24 

.2 

.59 

.2 

.93 

.2 

.21 

.3 

.10 

.3 

.53 

.3 

.92 

.3 

.26 

.3 

.61 

.3 

.95 

.3 

.23 

.4 

.12 

.4 

.56 

.4 

.94 

.4 

.28 

.4 

.63 

.4 

.98 

.4 

.25 

5 

.15 

.5 

.58 

.5 

.96 

.5 

.30 

.5 

.65 

.5 

18.00 

.5 

.27 

.6 

.17 

.6 

.60 

.6 

.98 

.6 

.32 

.6 

.68 

.6 

.02 

.6 

.29 

.7 

.19 

.7 

.63 

.7 

14  00 

.7 

.34 

.7 

.70 

.7 

.04 

.7 

.31 

.8 

.22 

.8 

.65 

.8 

.03 

.8 

.36 

.8 

.72 

.8 

.06 

.8 

.34 

.9 

.24 

.9 

.67 

.9 

.05 

.9 

.38 

.9 

.74 

.9 

.08 

.9 

.36 

59  0 

.27 

65.0 

.69 

71.0 

.07 

77.0 

.40 

83.0 

.76 

89.0 

.10 

95  0 

.38 

1 

.29 

1 

:72 

.1 

.09 

.1 

.42 

.1 

.79 

1 

.13 

1 

.40 

.'2 

.32 

'.2 

.74 

.2 

.11 

.2 

.44 

.2 

.81 

'.2 

.15 

'.2 

.42 

.3 

.34 

.3 

.76 

.3 

.14 

.3 

.47 

.3 

.83 

.3 

.17 

.3 

.44 

.4 

.36 

.4 

.79 

.4 

.16 

.4 

.49 

.4 

.85 

.4 

.19 

.4 

.47 

.5 

.39 

.5 

.81 

.5 

.18 

.5 

.51 

.5 

.88 

.5 

.21 

.5 

.49 

.6 

.41 

.6 

.83 

.6 

.20 

.6 

.54 

.6 

.90 

.6 

.23 

.6 

.51 

.7 

.44 

.7 

.86 

.7 

.23 

.7 

.56 

.7 

.92 

.7 

.25 

.7 

.53 

.8 

.46 

.8 

.88 

.8 

.25 

.8 

.59 

.8 

.95 

.8 

.27 

.8 

.55 

.9 

.49 

.9 

.90 

.9 

.27 

.9 

.61 

.9 

.97 

.9 

.29 

.9 

.57 

60.0 

.51 

66  0 

.93 

72.0 

.29 

78  0 

.63 

84.0 

17.00 

90.0 

.31 

96.0 

.59 

.1 

.53 

.1 

.95 

.1 

.32 

.1 

.65 

.1 

.02 

.1 

.34 

.61 

.2 

.56 

.2 

.97 

.2 

.34 

.2 

.68 

.2 

.04 

.2 

.36 

'.2 

.63 

.3 

.58 

.3 

13  00 

.3 

.36 

.3 

.70 

.3 

.07 

.3 

.38 

.3 

.66 

.4 

.60 

.4 

.03 

.4 

.38 

.4 

.72 

.4 

.09 

.4 

.40 

.4 

fJ8 

.5 

.63 

.5 

.05 

.5 

.40 

.5 

.74 

.5 

.11 

.5 

.42 

.5 

'.70 

.6 

.66 

.6 

.07 

.6 

.43 

.6 

.76 

.6 

.13 

.6 

.44 

.6 

.72 

.7 

.68 

.7 

.09 

.7 

.45 

.7 

.79 

.7 

.15 

.7 

.47 

.7 

.74 

.8 

.70 

.8 

.11 

.8 

.48 

.8 

.81 

.8 

.18 

.8 

.49 

.8 

.76 

.9 

.73 

.9 

.14 

.9 

.50 

.9 

.83 

.9 

.20 

.9 

.51 

.9 

.78 

61.0 

.75 

67.0 

.16 

73.0 

.52 

79.0 

.85 

85.0 

.22 

91.0 

.53 

97.0 

.80 

.78 

.1 

.18 

.54 

.1 

.88 

.1 

.24 

.55 

.1 

.82 

'.2 

.80 

.2 

.20 

'.2 

.57 

.2 

.90 

.2 

.27 

'.2 

.57 

.2 

.85 

.3 

.83 

.3 

.23 

.3 

.59 

.3 

.92 

.3 

.29 

.3 

.59 

.3 

.87 

.4 

.85 

.4 

.25 

.4 

.61 

.4 

.95 

.4 

.31 

.4 

.61 

.4 

,89 

.5 

.88 

.5 

.27 

.5 

.63 

.5 

.97 

.5 

.33 

.5 

.63 

.5 

.91 

.6 

.90 

.6 

.29 

.6 

.66 

.6 

16.00 

.6 

.35 

.6 

.66 

.6 

.93 

.7 

.92 

.7 

.32 

.7 

.68 

.7 

.03 

.7 

.38 

.7 

.68 

.7 

.95 

.8 

.95 

.8 

.34 

.8 

.70 

.8 

.05 

.8 

.40 

.8 

.70 

.8 

.97 

.9 

.97 

.9 

.36 

.9 

.73 

.9 

.07 

.9 

.42 

.9 

.72 

.9 

20  00 

62.0 

12  00 

68  0 

.38 

74.0 

.75 

80  0 

.09 

86  0 

.44 

92  0 

.74 

98  0 

.02 

.03 

.1 

.40 

.1 

.77 

.1 

.11 

.1 

.47 

1 

.76 

.1 

.04 

'.2 

.05 

.2 

.43 

.2 

.79 

.2 

.13 

.2 

.49 

'.2 

.78 

.2 

.06 

.3 

.07 

.3 

.45 

.3 

.82 

.3 

.16 

.3 

.51 

.3 

.80 

.3 

.08 

.4 

.09 

.4 

.48 

.4 

.84 

.4 

.18 

.4 

.53 

.4 

.82 

.4 

.10 

.5 

.12 

.5 

.50 

.5 

.87 

.5 

.20 

.5 

.55 

.5 

.85 

.5 

.13 

.6 

.14 

.6 

.52 

.6 

.89 

.6 

.22 

.6 

.58 

.6 

.87 

.6 

.15 

.7 

.16 

.7 

-54 

.7 

.92 

.7 

.24 

.7 

.60 

.7 

.89 

.7 

.17 

.8 

.18 

.8 

.57 

.8 

.94 

.8 

.27 

.8 

.62 

.8 

.91 

.8 

.19 

.9 

.21 

.9 

.59 

.9 

.96 

.9 

.29 

.9 

.64 

.9 

.93 

.9 

.21 

26 


SUGAR  TABLES 
TABLE  8.  (Concluded). 


99  0 


20.23 

.25 
.27 
.29 
.31 
.34 
.36 
.38 
.40 
.42 


100.0 

.1 

.2 
.3 
.4 
.5 
.6 
.7 
.8 
.9 


20  44 

.47 
.49 
.51 
.53 
.55 
.57 
.59 
.61 


101.0 

.1 
.2 
.3 
.4 
.5 
.6 
.7 


20  66 
.68 
.70 
.72 
.74 
.76 
.78 
.80 
.82 
.85 


102.0 

.1 
.2 


20.87 

.89 
.91 
.93 
.95 
.97 

21  00 
.02 
.04 


103.0 

.1 

.2 
.3 
.4 
.5 
.6 
.7 


21.08 

.10 
.13 
.15 
.17 
.19 
.21 
.23 
.25 
.27 


104.0 

.1 
.2 


21.29 

.31 
.34 
.36 
.38 
.40 
.42 
.44 
.47 
.49 


105  0 
1 

2 
3 

4 
5 
6 

7 


.9 
106.0 


21  51 
.53 
.55 
.57 
.59 
.61 
.63 
.66 
.68 
.70 

21.71 


SUGAR  TABLES 


27 


TABLE*  9. 
KRUIS'S  TABLE  FOR  DETERMINING  GLUCOSE  BY  REISCHAUER'S  METHOD. 


Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

c.c. 

1.00 

nags. 

5.57 

c.c. 
1.53 

nigs. 

8.20 

c.c 

2.06 

mgs. 

10.64 

c.c. 

2.59 

mgs. 

13.06 

1.01 

5.64 

1.54 

8.24 

2.07 

10.68 

2.60 

13.11 

1.02 

5.81 

1.55 

8.29 

2.08 

10.73 

2.61 

13.16 

1.03 

5.85 

1.56 

8.34 

2.09 

10.77 

2.62 

13.20 

1.04 

5.90 

1.57 

8.38 

2.10 

10.82 

2.63 

13.25 

1.05 

5.94 

1.58 

8.43 

2.11 

10.87 

2.64 

13.29 

1.06 

5.99 

1.59 

8.48 

2.12 

10.91 

2.65 

13.34 

1.07 

6.04 

1.60 

8.52 

2.13 

10.96 

2.66 

13.39 

1.08 

6.08 

1.61 

8.57 

2.14 

11.00 

2.67 

13.43 

1.09 

6.13 

1.62 

8.62 

2.15 

11.04 

2.68 

13.48 

1,10 

6.18 

1.63 

8.66 

2.16 

11.09 

2.69 

13.52 

.11 

6.22 

1.64 

8.71 

2.17 

11.14 

2.70 

13.57 

.12 

6.27 

1.65 

8.76 

2.18 

11.18 

2.71 

13.62 

.13 

6.32 

1.66 

8.80 

2.19 

11.23 

2.72 

13.66 

.14 

6.36 

1.67 

8.85 

2  20 

11.28 

2.73 

13.71 

.15 

6.41 

.68 

8.89 

2.21 

11.32 

2.74 

13.76 

.16 

6.46 

.69 

8.94 

2.22 

11.37 

2.75 

13.80 

.17 

6.51 

.70 

8.99 

2.23 

11.41 

2.76 

13.85 

.18 

6.55 

.71 

9.03 

2.24 

11.46 

2.77 

13.89 

.19 

6.60 

.72 

9.08 

2.25 

11.50 

2.78 

13.94 

20 

6.65 

.73 

9.13 

2.26 

11.55 

2.79 

13.99 

1.21 

6.69 

.74 

9.17 

2.27 

11.60 

2.80 

14.03 

1.22 

6.74 

.75 

9.22 

2.28 

11.64 

2.81 

14.08 

1.23 

6.79 

.76 

9.26 

2.29 

11.69 

2.82 

14.12 

1.24 

6.84 

.77 

9.31 

2.30 

11.73 

2.83 

14.17 

1.25 

6.88 

.78 

9.36 

2.31 

11.78 

2.84 

14.22 

1.26 

6.93 

1.79 

9.40 

2.32 

11.82 

2.85 

14.26 

1.27 

6.98 

1.80 

9.45 

2.33 

11.87 

2.86 

14.31 

1.28 

7.02 

1.81 

9.49 

2.34 

11.92 

2.87 

14.35 

1.29 

7.07 

1.82 

9.54 

2.35 

12.96 

2.88 

14.40 

1.30 

7.12 

1.83 

9.59 

2.36 

12.00 

2.89 

14.45 

1.31 

7.17 

1.84 

9.63 

2.37 

12.05 

2.90 

14.49 

.32 

7.21 

1.85 

9.68 

2.38 

12.10 

2.91 

14.54 

.33 

7.26 

1.86 

9.72 

2.39 

12.14 

2.92 

14.58 

.34 

7.31 

1.87 

9.77 

2.40 

12.19 

2.93 

14.63 

.35 

7.35 

1.88 

9.81 

2.41 

12.24 

2.94 

14.68 

.36 

7.40 

1.89 

9.86 

2.42 

12.28 

2.95 

14.72 

.37 

7.45 

1.90 

9.91 

2.43 

12.33 

2.96 

14.77 

.38 

7.49 

1.91 

9.95 

2.44 

12.37 

2.97 

14.81 

.39 

7.54 

1.92 

10.00 

2.45 

12.42 

2.98 

14.86 

.40 

7.59 

1.93 

10.04 

2.46 

12.47 

2.99 

14.91 

.41 

7.64 

1.94 

10.09 

2.47 

12.51 

3.00 

14.95 

.42 

7.68 

1.95 

10.13 

2.48 

12.56 

3.01 

15.00 

.43 

7.73 

1.96 

10.18 

2.49 

12.60 

3.02 

15.04 

.44 

7.77 

1.97 

10.23 

2.50 

12.65 

3.03 

15.09 

.45 

7.82 

1.98 

10.27 

2.51 

12.69 

3.04 

15.14 

.46 

7.87 

1.99 

10.32 

2.52 

12.74 

3.05 

15.18 

.47 

7.92 

2.00 

10.36 

2.53 

12.79 

3.06 

15.23 

.48 

7.96 

2.01 

10.41 

2.54 

12.83 

3.07 

15.27 

1.49 

8.01 

2.02 

10.45 

2.55 

12.88 

3.08 

15.32 

1.60 

8.06 

2.03 

10.50 

2.56 

12.92 

3.09 

15.37 

1.51 

8.10 

2.04 

10.55 

2.57 

12.97 

3.10 

15.41 

1.52 

8.15 

2.05 

10.59 

2.58 

13.02 

3.11 

15.46 

*  See  "  Handbook,"  page  398. 


28 


SUGAR  TABLES 


TABLE  9.     (Continued.) 


Fe'iling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

c.c. 

3.12 

mgs. 

15.50 

c.c. 
3.65 

mgs. 

17.95 

c.c. 

4.18 

mgs. 
20.41 

c.c. 

4.71 

mgs. 

22.90 

3.13 

15.55 

3.66 

17.99 

4.19 

20.46 

4.72 

22.94 

3.14 

15.60 

3.67 

18.04 

4.20 

20.51 

4.73 

22.99 

3.15 

15.64 

3.68 

18.09 

4.21 

20.55 

4.74 

23.04 

3.16 

15.69 

3.69 

18.13 

4.22 

20.60 

4.75 

23.09 

3.17 

15.73 

3.70. 

18.18 

4.23 

20.65 

4.76 

23.13 

3.18 

15.78 

3.71 

18.23 

4.24 

20.69 

4.77 

23.18 

3.19 

15.83 

3.72 

18.27 

4.25 

20.74 

4.78 

23.23 

3.20 

15.87 

3.73 

18.32 

4.26 

20.79 

4.79 

23.28 

3.21 

15.92 

3.74 

18.37 

4.27 

20.83 

4.80 

23.32 

3.22 

15.96 

3.75 

18.41 

4.28 

20.88 

4.81 

23.37 

3.23 

16.01 

3.76 

18.46 

4.29 

20.93 

4.82 

23.42 

3.24 

16.06 

3.77 

18.50 

4.30 

20.98 

4.83 

23.46 

3.25 

16.10 

3.78 

18.55, 

4.31 

21.02 

4.84 

23.51 

3.26 

16.15 

3.79 

18.60 

4.32 

21.07 

4.85 

23.56 

3.27 

16.19 

3.80 

18.64 

4.33 

21.12 

4.86 

23.60 

3.28 

16.24 

3.81 

18.69 

4.34 

21.16 

4.87 

23.65 

3.29 

16.29 

3.82 

18.73 

4.35 

21.21 

4.88 

23.70 

3  30 

16.33 

3.83 

18.78 

4.36 

21.26 

4.89 

23.74 

3.31 

16.38 

3.84 

18.83 

4.37 

21.30 

4.90 

23.79 

3.32 

16.43 

3.85 

18.88 

4.38 

21.35 

4.91 

23.84 

3.33 

16.47 

3.86 

18.92 

4.39 

21.40 

4.92 

23.89 

3.34 

16.52 

3.87 

18.97 

4.40 

21.44 

4.93 

23.93 

3.35 

16.56 

3.88 

19.02 

4.41 

21.49 

4.94 

23.98 

3.36 

16.61 

3.89 

19.06 

4.42 

21.54 

4.95 

24.03 

3.37 

16.66 

3.90 

19.11 

4.43 

21.58 

4.96 

24.07 

3.38 

16.70 

3.91 

19.15 

4.44 

21.63 

4.97 

24.12 

3.39 

16.75 

3.92 

19.20 

4.45 

21.68 

4.98 

24.17 

3  40 

16.79 

3.93 

19.25 

4.46 

21.73 

4.99 

24.22 

3.41 

16.84 

3.94 

19.29 

4.47 

21.77 

5.00 

24.26 

3.42 

16.89 

3.95 

19.34 

4.48 

21.82 

5.01 

24.31 

3.43 

16.93 

3.96 

19.39 

4.49 

21.87 

5.02 

24.36 

3.44 

16.98 

3.97 

19.43 

4.50 

21.91 

5.03 

24.40 

3.45 

17.02 

3.98 

19.48 

4.51 

21.96 

5.04 

24.45 

3.46 

17.07 

3.99 

19.53 

4.52 

22.01 

5.05 

24.50 

3.47 

17.12 

4.00 

19.57 

4.53 

22.05 

5.06 

24.55 

3.48 

17.16 

4.01 

19.62 

4.54 

22.10 

5.07 

24.59 

3.49 

17.21 

4.02 

19.67 

4.55 

22.  14 

5.08 

24.64 

3  50 

17.26 

4.03 

19.71 

4.56 

22.19 

5.09 

24.69 

3.51 

17.30 

4.04 

19.76 

4.57 

22.24 

5.10 

24.73 

3.52 

17.35 

4.05 

19.80 

4.58 

22.29 

5.11 

24.78 

3.53 

17.39 

4.06 

19.85 

4.59 

22.34 

5.12 

24.83 

3.54 

17.44 

4.07 

19.90 

4.60 

22.38 

5.13 

24.88 

3.55 

17.49 

4.08 

19.95 

4.61 

22.43 

5.14 

24.92 

3.56 

17.53 

4.09 

19.99 

4.62 

22.48 

5.15 

24.97 

3.57 

17.58 

4.10 

20.04 

4.63 

22.52 

5.16 

25.02 

3.58 

17.62 

4  11 

20.09 

4.64 

22.57 

5.17 

25.06 

3.59 

17.67 

4.12 

20.13 

4.65 

22.62 

5.18 

25.11 

3  60 

17.72 

4.13 

20.18 

4.66 

22.66 

5.19 

25.16 

3.61 

17.76 

4.14 

20.23 

4.67 

22.71 

5.20 

25.20 

3.62 

17.81 

4.15 

20.27 

4.68 

22.76 

5.21 

25.25 

3.63 

17.86 

4.16 

20.32 

4.69 

22.80 

5.22 

25.30 

3.64 

17.90 

4.17 

20.37 

4.70 

22.85 

5.23 

25.34 

SUGAR  TABLES 


29 


TABLE  9.     (Concluded.) 


Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

Fehling's 
solution. 

Glucose. 

c.c. 

5.24 

mgs. 

25.39 

c.c. 
5.44 

mgs. 

26.34 

c.c. 

5.64 

mgs. 

27.28 

c.c. 

5.84 

mgs. 
28.22 

5.25 

25.44 

5.45 

26.38 

5.65 

27.32 

5.85 

28.26 

5.26 

25.49 

5.46 

26.43 

5.66 

27.37 

5.86 

28.31 

5.27 

25.53 

5.47 

26.48 

5.67 

27.42 

5.87 

28.36 

5.28 

25.58 

5.48 

26.52 

5.68 

27.47 

5.88 

28.41 

5.29 

25.63 

5.49 

26.57 

5.69 

27.51 

5.89 

28.46 

5.30 

25.68 

5.50 

26.62 

5.70 

27.56 

5  90 

28.50 

5.31 

25.72 

5.51 

26.66 

5.71 

27.61 

5.91 

28.55 

5.32 

25.77 

5.52 

26.72 

5.72 

27.65 

5.92 

28.60 

5.33 

25.82 

5.53 

26.76 

5.73 

27.70 

5.93 

28.64 

5.34 

25.86 

5.54 

26.81 

5.74 

27.75 

5.94 

28.69 

5.35 

25.91 

5.55 

26.85 

5.75 

27.80 

5.95 

28.74 

5.36 

25.96 

5.56 

26.90 

5.76 

27.84 

5.96 

28.79 

5.37 

26.00 

5.57 

26.95 

5.77 

27.89 

5.97 

28.83 

5.38 

26.05 

5.58 

26.99 

5.78 

27.90 

5.98 

28.88 

5.39 

26.10 

5.59 

27.04 

5.79 

27.98 

5.99 

28.93 

5.40 

26.15 

5.60 

27.09 

5.80 

28.03 

6.00 

28.97 

5.41 

26.19 

5.61 

27.14 

5.81 

28.08 

5.42 

26.24 

5.62 

27.19 

5.82 

28.13 

5.43 

26.29 

5.63 

27.23 

5.83 

28.17 

30 


SUGAR  TABLES 


TABLE*  10. 
ALLIHN'S  TABLE  FOR  DETERMINING  GLUCOSE. 


Cop- 
t&i 

Cuprous 
oxide. 
(CujO). 

Glucose. 

Copper. 

(Cu). 

Cuprous 
oxide. 
(Cu20). 

Glucose. 

Copper. 

(Cu). 

Cuprous 
oxide. 
(Cu2O). 

Glucose. 

Copper. 
(Cu.) 

Cuprous 
oxide. 

(Cu20). 

Glucose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

11 

12.4 

6.6 

51 

57.4 

26.4 

91 

102.4 

46.4 

131 

147.5 

66.7 

12 

13.5 

7.1 

52 

58.5 

26.9 

92 

103.6 

46.9 

132 

148.6 

67.2 

13 

14.6 

7.6 

53 

59.7 

27.4 

93 

104.7 

47.4 

133 

149.7 

67.7 

14 

15.8 

8.1 

54 

60.8 

27.9 

94 

105.8 

47.9 

134 

150.9 

68.2 

15 

16.9 

8.6 

55 

61.9 

28.4 

95 

107.0 

48.4 

135 

152.0 

68.8 

16 

18.0 

9.0 

56 

63.0 

28.8 

96 

108.1 

48.9 

136 

153.1 

69.3 

17 

19.1 

9.5 

57 

64.2 

29.3 

97 

109.2 

49.4 

137 

154.2 

69.8 

18 

20.3 

10.0 

58 

65.3 

29.8 

98 

110.3 

49.9 

138 

155.4 

70.3 

19 

21.4 

10.5 

59 

66.4 

30.3 

99 

111.5 

50.4 

139 

156.5 

70.8 

20 

22.5 

11.0 

60 

67.6 

30.8 

100 

112.6 

50.9 

140 

157.6 

71.3 

21 

23.6 

11.5 

61 

68.7 

31.3 

101 

113.7 

51.4 

141 

158.7 

71.8 

22 

24.8 

12.0 

62 

69.8 

31.8 

102 

114.8 

51.9 

142 

159.9 

72.3 

23 

25.9 

12.5 

63 

70.9 

32.3 

103 

116.0 

52.4 

143 

161.0 

72.9 

24 

27.0 

13.0 

64 

72.1 

32.8 

104 

117.1 

52.9 

144 

162.1 

73.4 

25 

28.1 

13.5 

65 

73.2 

33.3 

105 

118.2 

53.5 

145 

163.2 

73.9 

26 

29.3 

14.0 

66 

74.3 

33.8 

106 

119.3 

54.0 

146 

164.4 

74.4 

27 

30.4 

14.5 

67 

75.4 

34.3 

107 

120.5 

54.5 

147 

165.5 

74.9 

28 

31.5 

15.0 

68 

76.6 

34.8 

108 

121.6 

55.0 

148 

166.6 

75.5 

29 

32.7 

15.5 

69 

77.7 

35.3 

109 

122.7 

55.5 

149 

167.7 

76.0 

30 

33.8 

16.0 

70 

78.8 

35.8 

110 

123.8 

56.0 

150 

168.9 

76.5 

31 

34.9 

16.5 

71 

79.9 

36.3 

111 

125.0 

56.5 

151 

170.0 

77.0 

32 

36.0 

17.0 

72 

81.1 

36.8 

112 

126.1 

57.0 

152 

171.1 

77.5 

33 

37.2 

17.5 

73 

82.2 

37.3 

113 

127.2 

57.5 

153 

172.3 

78.1 

34 

38.3 

18.0 

74 

83.3 

37.8 

114 

128.3 

58.0 

154 

173.4 

78.6 

35 

39.4 

18.5 

75 

84.4 

38.3 

115 

129.6 

58.6 

155 

174.5 

79.1 

36 

40.5 

18.9 

76 

85.6 

38.8 

116 

130.6 

59.1 

156 

175.6 

79.6 

37 

41.7 

19.4 

77 

86.7 

39.3 

117 

131.7 

59.6 

157 

176.8 

80.1 

38 

42.8 

19.9 

78 

87.8 

39.8 

118 

132.8 

60.1 

158 

177.9 

80.7 

39 

43.9 

20.4 

79 

88.9 

40.3 

119 

134.0 

60.6 

159 

179.0 

81.2 

40 

45.0 

20.9 

80 

90.1 

40.8 

120 

135.1 

61.1 

160 

180.1 

81.7 

41 

46.2 

21.4 

81 

91.2 

41.3 

121 

136.2 

61.6 

161 

181.3 

82.2 

42 

47.  a 

21.9 

82 

92.3 

41.8 

122 

137.4 

62.1 

162 

182.4 

82.7 

43 

48.4 

22.4 

83 

93.4 

42.3 

123 

138.5 

62.6 

163 

183.5 

83.3 

,44 

49.5 

22.9 

84 

94.6 

42.8 

124 

139.6 

63.1 

164 

184.6 

83.8 

45 

50.7 

23.4 

85 

95.7 

43.4 

125 

140.7 

63.7 

165 

185.8 

84.3 

46 

51.8 

23.9 

86 

96.8 

43.9 

126 

141.9 

64.2 

166 

186.9 

84.8 

47 

52.9 

24.4 

87 

97.9 

44.4 

127 

143.0 

64.7 

167 

188.0 

85.3 

48 

54.0 

24.9 

88 

99.1 

44.9 

128 

144.1 

65.2 

168 

189.1 

85.9 

49 

55.2 

25.4 

89 

100.2 

45.4 

129 

145.2 

65.7 

169 

190.3 

86.4 

50 

56.3 

25.9 

90 

101.3 

45.9 

130 

146.4 

66.2 

170 

191.4 

86.9 

*  See  "  Handbook,"  page  403. 


SUGAR  TABLES 


31 


TABLE   10.     (Continued.) 


Copper 

(Cu). 

Cuprous 
oxide. 
(Cu20). 

Glucose 

Copper. 

(Cu). 

Cuprous 
oxide. 

(Cu2O). 

Glucose. 

Copper. 

(Cu). 

Cuprous 
oxide. 

(Cu20). 

Glucose. 

Copper. 

(Cu). 

Cuprous 
oxide. 
(Cu20). 

Glucose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

171 

192.5 

87.4 

216 

243.2 

111.1 

261 

293.8 

135.1 

306 

344.5 

159.8 

172 

193.6 

87.9 

217 

244.3 

111.6 

262 

295.0 

135.7 

307 

345.6 

160.4 

173 

194.8 

88.5 

218 

245.4 

112.1 

263 

296.1 

136.2 

308 

346.8 

160.9 

174 

195.9 

89.0 

219 

246.6 

112.7 

264 

297.2 

136.8 

309 

347.9 

161.5 

175 

197.0 

89.5 

220 

247.7 

113.2 

265 

298.3 

137.3 

310 

349.0 

162.0 

176 

198.1 

90.0 

221 

248.7 

113.7 

266 

299.5 

137.8 

311 

350.1 

162.6 

177 

199.3 

90.5 

222 

249.9 

114.3 

267 

300.6 

138.4 

312 

351.3 

163.1 

178 

200.4 

91.1 

223 

251.0 

114.8 

268 

301.7 

138.9 

313 

352.4 

163.7 

179 

201.5 

91.6 

224 

252.4 

115.3 

269 

302.8 

139.5 

314 

353.5 

164.2 

180 

202.6 

92.1 

225 

253.3 

115.9 

270 

304.0 

140.0 

315 

354.6 

164.8 

181 

203.8 

92.6 

226 

254.4 

116.4 

271 

305.1 

140.6 

316 

355.8 

165.3 

182 

204.9 

93.1 

227 

255.6 

116.9 

272 

306.2 

141.1 

317 

356.9 

165.9 

183 

206.0 

93.7 

228 

256.7 

117.4 

273 

307.3 

141.7 

318 

358.0 

166.4 

184 

207.1 

94.2 

229 

257.8 

118.0 

274 

308.5 

142.2 

319 

359.1 

167.0 

185 

208.3 

94.7 

230 

258.9 

118.5 

275 

309.6 

142.8 

320 

360.3 

167.5 

186 

209.4 

95.2 

231 

260.1 

119.0 

276 

310.7 

143.3 

321 

361.4 

168.1 

187 

210.5 

95.7 

232 

261.2 

119.6 

277 

311.9 

143.9 

322 

362.5 

168.6 

188 

211.7 

96.3 

233 

262.3 

120.1 

278 

313.0 

144.4 

323 

363.7 

169.2 

189 

212.8 

96.8 

234 

263.4 

120.7 

279 

314.1 

145.0 

324 

364.8 

169.7 

190 

213.9 

97.3 

235 

264.6 

121.2 

280 

315.2 

145.5 

325 

365.9 

170.3 

191 

215.0 

97.8 

236 

265.7 

121.7 

281 

316.4 

146.1 

326 

367.0 

170.9 

192 

216.2 

98.4 

237 

266.8 

122.3 

282 

317.5 

146.6 

327 

368.2 

171.4 

193 

217.3 

98.9 

238 

268.0 

122.8 

283 

318.6 

147.2 

328 

369.3 

172.0 

194 

218.4 

99.4 

239 

269.1 

123.4 

284 

319.7 

147.7 

329 

370.4 

172.5 

195 

219.5 

100.0 

240 

270.2 

123.9 

285 

320.9 

148.3 

330 

371.5 

173.1 

196 

220.7 

100.5 

241 

271.3 

124.4 

286 

322.0 

148.8 

331 

372.7 

173.7 

197 

221.8 

101.0 

242 

272.5 

125.0 

287 

323.1 

149.4 

332 

373.8 

174.2 

198 

222.9 

101.5 

243 

273.6 

125.5 

288 

324.2 

149.9 

333 

374.9 

174.8 

199 

224.0 

102.0 

244 

274.7 

126.0 

289 

325.4 

150.5 

334 

376.0 

175.3 

200 

225.2 

102.6 

245 

275.8 

126.6 

290 

326.5 

151.0 

335 

377.2 

175.9 

201 

226.3 

103.1 

246 

277.0 

127.1 

291 

327.4 

151.6 

336 

378.3 

176.5 

202 

227.4 

103.7 

247 

278.1 

127.6 

292 

328.7 

152.1 

337 

379.4 

177.0 

203 

228.5 

104.2 

248 

279.2 

128.1 

293 

329.9 

152.7 

338 

380.5 

177.6 

204 

229.7 

104.7 

249 

280.3 

128.7 

294 

331.0 

153.2 

339 

381.7 

178.1 

205 

230.8 

105.3 

250 

281.5 

129.2 

295 

332.1 

153.8 

340 

382.8 

178.7 

206 

231.9 

105.8 

251 

282.6 

129.7 

296 

333.3 

154.3 

341 

383.9 

179.3 

207 

233.0 

106.3 

252 

283.7 

130.3 

297 

334.4 

154.9 

342 

385.0 

179.8 

208 

234.2 

106.8 

253 

284.8 

130.8 

298 

335.5 

155.4 

343 

386.2 

180.4 

209 

235.3 

107.4 

254 

286.0 

131.4 

299 

336.6 

156.0 

344 

387.3 

180.9 

210 

236.4 

107.9 

255 

287.1 

131.9 

300 

337.8 

156.5 

345 

388.4 

181.5 

211 

237.6 

108.4 

256 

288.2 

132.4 

301 

338.9 

157.1 

346 

389.6 

182.1 

212 

238.7 

109.0 

257 

289.3 

133.0 

302 

340.0 

157.6 

347 

390.7 

182.6 

213 

239.8 

109.5 

258 

290.5 

133.5 

303 

341.1 

158.2 

348 

391.8 

183.2 

214 

240.9 

110.0 

259 

291.6 

134.1 

304 

342.3 

158.7 

349 

392.9 

183.7 

215 

242.1 

110.6 

260 

292.7 

134.6 

305 

343.4 

159.3 

350 

394.0 

184.3 

32 


SUGAR  TABLES 


TABLE   10.     (Concluded.) 


Ogpe, 

Cuprous 
oxide. 
(Cu20). 

Glucose. 

Copper. 
(Cu.) 

Cuprous 
oxide. 
(Cu20). 

Glucose. 

Ogpe, 

Cuprous 
oxide. 

(Cu20). 

Glucose. 

Copper. 

(Cu). 

Cuprous 
oxide. 
(Cu2O). 

Glucose. 

mgs. 

mgs. 

mga. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

351 

395.2 

184:9 

380 

427.8 

201.4 

408 

459.4 

217.5 

436 

490.9 

233.9 

352 

396.3 

185.4 

381 

429.0 

202.0 

409 

460.5 

218.1 

437 

492.0 

234.5 

353 

397.4 

186.0 

382 

430.1 

202.5 

410 

461.6 

218.7 

438 

493.1 

235.1 

354 

398.6 

186.6 

383 

431.2 

203.1 

411 

462.7 

219.3 

439 

494.3 

235.7 

355 

399.7 

187.2 

384 

432.3 

203.7 

412 

463.8 

219.9 

440 

495.4 

236.3 

356 

400.8 

187.7 

385 

433.5 

204.3 

413 

465.0 

220.4 

441 

496.5 

236.9 

357 

401.9 

188.3 

386 

434.6 

204.8 

414 

466.1 

221.0 

442 

497.6 

237.5 

358 

403.1 

188.9 

387 

435.7 

205.4 

415 

467.2 

221.6 

443 

498.8 

238.1 

359 

404.2 

189.4 

388 

436.8 

206.0 

416 

468.4 

222.2 

444 

499.9 

238.7 

360 

405.3 

190.0 

389 

438.0 

206.5 

417 

469.5 

222.8 

445 

501.0 

239.3 

361 

406.4 

190.6 

390 

439.1 

207.1 

418 

470.6 

223.3 

446 

502.1 

239.8 

362 

407.6 

191.1 

391 

440.2 

207.7 

419 

471.8 

223.9 

447 

503.2 

240.4 

363 

408.7 

191.7 

392 

441.3 

208.3 

420 

472.9 

224.5 

448 

504.4 

241.0 

364 

409.8 

192.3 

393 

442.4 

208.8 

421 

474.0 

225.1 

449 

505.5 

241.6 

365 

410.9 

192.9 

394 

443.6 

209.4 

422 

475.6 

225.7 

450 

506.6 

242.2 

366 

412..  1 

193.4 

395 

444.7 

210.0 

423 

476.2 

226.3 

451 

507.8 

242.8 

367 

413.2 

194.0 

396 

445.9 

210.6 

424 

477.4 

226.9 

452 

508.9 

243.4 

368 

414.3 

194.6 

397 

447.0 

211.2 

425 

478.5 

227.5 

453 

510.0 

244.0 

369 

415.4 

195.1 

398 

448.1 

211.7 

426 

479.6 

228.0 

454 

511.1 

244.6 

370 

416.6 

195.7 

399 

449.2 

212.3 

427 

480.7 

228.6 

455 

512.3 

245.2 

371 

417.7 

196.3 

400 

450.3 

212.9 

428 

481.9 

229.2 

456 

513.4 

245.7 

372 

418.8 

196.8 

401 

451.5 

213.5 

429 

483.0 

229.8 

457 

514.5 

246.3 

373 

420.0 

197.4 

402 

452.6 

214.1 

430 

484.1 

230.4 

458 

515.6 

246.9 

374 

421.1 

198.0 

403 

453.7 

214.6 

431 

485.3 

231.0 

459 

516.8 

247.5 

375 

422.2 

198.6 

404 

454.8 

215.2 

432 

486.4 

231.6 

460 

517.9 

248.1 

376 

423.3 

199.1 

405 

456.0 

215.8 

433 

487.5 

232.2 

461 

519.0 

248.7 

377 

424.5 

199.7 

406 

457.1 

216.4 

434 

488.6 

232.8 

462 

520.1 

249.3 

378 

425.6 

200.3 

407 

458.2 

217.0 

435 

489.7 

233.4 

463 

521.3 

249.9 

379 

426.7 

200.8 

SUGAR   TABLES 


33 


TABLE*  11. 
PFLUGERS  TABLE  FOR  DETERMINING  GLUCOSE. 


Glu- 
cose. 

c(°cpuT- 

Cuprous 
oxide. 
(Cu,O). 

Glu- 
cose. 

Copper. 

(Cu). 

Cuprous 
oxide. 

(Cu20). 

Glu- 
cose. 

°Br 

Cuprous 
oxide. 

(Cu20). 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

12 

32.8 

36.8 

64 

139.4 

157.0 

116 

244.0 

274.7 

13 

34.9 

39.2 

65 

141.4 

159.3 

117 

246.0 

276.9 

14 

37.0 

41.6 

66 

143.4 

161.6 

118 

248.0 

279.2 

15 

39.1 

43.9 

67 

145.5 

163.9 

119 

250.0 

281.4 

16 

41.2 

46.3 

68 

147.5 

166.2 

120 

252.0 

283.6 

17 

43.3 

48.7 

69 

149.6 

168.5 

121 

253.9 

285.9 

18 

45.4 

51.0 

70 

151.6 

170.8 

122 

255.9 

288.1 

19 

47.5 

53.4 

71 

153.6 

173.0 

123 

257.8 

290.3 

20 

49.6 

55.8 

72 

155.7 

175.3 

124 

259.8 

292.6 

21 

51.7 

58.1 

73 

157.7 

177.6 

125 

261.8 

294.8 

22 

53.8 

60.5 

74 

159.8 

179.9 

126 

263.7 

296.9 

23 

55.9 

62.9 

75 

161.8 

182.2 

127 

265.6 

299.0 

24 

58.0 

65.2 

76 

163.8 

184.5 

128 

267.5 

301.2 

25 

60.1 

67.6 

77 

165.8 

186.7 

129 

269.3 

303.3 

26 

62.1 

69.9 

78 

167.9 

189.0 

130 

271.2 

305.4 

27 

64.2 

72.2 

79 

169.9 

191.3 

131 

273.1 

307.5 

28 

66.2 

74.5 

80 

171.9 

193.6 

132 

275.0 

309.6 

29 

68.2 

76.8 

81 

173.9 

195.8 

133 

276.9 

311.8 

.  30 

70.2 

79.1 

82 

175.9 

198.1 

134 

278.8 

313.9 

31 

72.3 

81.3 

83 

178.0 

200.4 

135 

280.6 

316.0 

32 

74.3 

83.6 

84 

180.0 

202.6 

136 

282.5 

318.1 

33 

76.3 

85.9 

85 

182.0 

204.9 

137 

284.4 

320.2 

34 

78.4 

88.2 

86 

184.0 

207.2 

138 

286.3 

322.4 

35 

80.4 

90.5 

87 

186.0 

209.5 

139 

288.2 

324.5 

36 

82.4 

92.8 

88 

188.1 

211.7 

140 

290.1 

326.6 

37 

84.4 

95.1 

89 

190.1 

214.0 

141 

291.9 

328.7 

38 

86.5 

97.4 

90 

192.1 

216.3 

142 

293.8 

330.8 

39 

88.5 

99.7 

91 

194.1 

218.6 

143 

295.7 

333.0 

40 

90.5 

101.9 

92 

196.1 

220.8 

144 

297.6 

335.1 

41 

92.6 

104.2 

93 

198.2 

223.1 

145 

299.5 

337.2 

42 

94.6 

106.5 

94 

200.2 

225.4 

146 

301.4 

339.3 

43 

96.6 

108.8 

95 

202.2 

227.6 

147 

303.2 

341.4 

44 

98.6 

111.1 

96 

204.2 

229.9 

148 

305.1 

343.6 

45 

100.7 

113.4 

97 

206.2 

232.2 

149 

307.0 

345.7 

46 

102.7 

115.7 

98 

208.3 

234.5 

150 

308.9 

347.8 

47 

104.7 

118.0 

99 

210.3 

236.7 

151 

310.7 

349.8 

48 

106.7 

120.2 

100 

212.3 

239.0 

152 

312.4 

351.8 

49 

108.8 

122.5 

101 

214.3 

241.2 

153 

314.2 

353.8 

50 

110.8 

124.8 

102 

216.3 

243.5 

154 

315.9 

355.7 

51 

112.8 

127.1 

103 

218.2 

245.7 

155 

317.7 

357.7 

52 

114.9 

129.4 

104 

220.2 

247.9 

156 

319.5 

359.7 

53 

116.9 

131.7 

105 

222.2 

250.2 

157 

321.2 

361.7 

54 

119.0 

134.0 

106 

224.2 

252.4 

158 

323.0 

363.7 

55 

121.0 

136.3 

107 

226.2 

254.6 

159 

324.7 

365.7 

56 

123.0 

138.6 

108 

228.1 

256.8 

160 

326.5 

367.7 

57 

125.1 

140.9 

109 

230.1 

259.1 

161 

328.3 

369.6 

58 

127.1 

143.2 

110 

232.1 

261.3 

162 

330.0 

371.6 

59 

129.2 

145.5 

111 

234.1 

263.6 

163 

331.8 

373.6 

60 

131.2 

147.8 

112 

236.1 

265.8 

164 

333.5 

375.6 

61 

133.2 

150.1 

113 

238.0 

268.0 

165 

335.3 

377.6 

62 

135.3 

152.4 

114 

240.0 

270.2 

166 

337.1 

379.6 

63 

137.3 

154.7 

115 

242.0 

272.5 

167 

338.8 

381.6 

*  See  "  Handbook,"  page  419.* 


34 


SUGAR  TABLES 


TABLE  11.     (Concluded.) 


Glu- 
cose. 

Copper. 

(Cu). 

Cuprous 
oxide. 
(Cu2O). 

Glu- 
cose. 

Copper. 
(Cu). 

Cuprous 
oxide. 
(Cu2O). 

Glu- 
cose. 

c(°cpuT- 

Cuprous 
oxide. 
(Cu20). 

mgs. 

168 

mgs. 

340.6 

mgs. 

383.5 

mgs. 

196 

mgs. 

387.8 

mgs. 

436.8 

mgs. 

224 

mgs. 

432.2 

mgs. 

487.0 

169 

342.3 

385.5 

197 

389.5 

438.7 

225 

433.8 

488.8 

170 

344.1 

387.5 

198 

391.2 

440.6 

226 

435.3 

490.4 

171 

345.9 

389.5 

199 

392.8 

442.4 

227 

436.7 

492.1 

172 

347.6 

391.5 

200 

394.5 

444.3 

228 

438.1 

493.7 

173 

349.4 

393.5 

201 

396.1 

446.1 

229 

439.6 

495.3 

174 

351.1 

395.5 

202 

397.6 

447.9 

230 

441.1 

497.0 

175 

352.9 

397.5 

203 

399.2 

449.6 

231 

442.6 

498.6 

176 

354.6 

399.3 

204 

400.8 

451.4 

1     232 

444.0 

500.3 

177 

356.2 

401.2 

205 

402.4 

453.2 

233 

445.5 

501.9 

178 

357.9 

403.1 

206 

403.9 

455.0 

234 

446.9 

503.5 

179 

359.6 

404.9 

207 

405.5 

456.8 

235 

448.4 

505.2 

180 

361.2 

406.8 

208 

407.1 

458.5 

236 

449.9 

506.8 

181 

362.9 

408.7 

209 

408.6 

460.3 

237 

451.3 

508.4 

182 

364.5 

410.6 

210 

410.2 

462.1 

238 

452.8 

510.1 

183 

366.2 

412.4 

211 

411.8 

463.9 

239 

454.2 

511.7 

184 

367.9 

414.3 

212 

413.4 

465.7 

240 

455.7 

513.3 

185 

369.5 

416.2 

213 

414.9 

467.4 

241 

457.2 

515.0 

186 

371.2 

418.1 

214 

416.5 

469.2 

242 

458.6 

516.6 

187 

372.9 

419.9 

215 

418.1 

471.0 

243 

460.1 

518.2 

188 

374.5 

421.8 

216 

419.7 

472.8 

244 

461.5 

519.9 

189 

376.2 

423.7 

217 

421.2 

474.6 

245 

463.0 

521.5 

190 

377.9 

425.6 

218 

422.8 

476.3 

246 

464.5 

523.6 

191 

379.5 

427.4 

219 

424.4 

478.1 

247 

465.9 

524.8 

192 

381.2 

429.3 

220 

425.9 

479.9 

248 

467.4 

526.4 

193 

382.9 

431.2 

221 

427.5 

481.7 

249 

468.8 

528.1 

194 

384.5 

433.1 

222 

429.1 

483.5 

250 

470.3 

529.7 

195 

386.2 

434.9 

223 

430.7 

485.2 

SUGAR  TABLES 


35 


TABLE*   12. 
KOCH  AND  RUHSAM'S  TABLE  FOR  DETERMINING  GLUCOSE  IN  TANNING  MATERIALS. 


Copper. 

(Cu). 

Glucose. 

Cog.. 

Glucose. 

°3SS!- 

Glucose. 

c(°cpuT- 

Glucose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

1 

0.4 

53 

22.8 

105 

49.5 

157 

75.5 

2 

0.8 

54 

23.3 

106 

50.0 

158 

76.0 

3 

1.2 

55 

23.9 

107 

50.5 

159 

76.5 

4 

1.6 

56 

24.4 

108 

51.0 

160 

77.0 

5 

2.0 

57 

24.9 

109 

51.6 

161 

77.5 

6 

2.5 

58 

25.4 

110 

52.1 

162 

78.0 

7 

2.9 

59 

25.9 

111 

52.6 

163 

78.5 

8 

3.3 

60 

26.4 

112 

53.1 

164 

79.0 

9 

3.7 

61 

26.9 

113 

53.6 

165 

79.5 

10 

4.1 

62 

27.4 

114 

54.1 

166 

80.0 

11 

4.5 

63 

28.0 

115 

54.6 

167 

80.5 

12 

4.9 

64 

28.5 

116 

55.1 

168 

81.0 

13 

5.3 

65 

29.0 

117 

55.7 

169 

81.4 

14 

5.7 

66 

29.5 

118 

56.2 

170 

81.9 

15 

6.1 

67 

30.0 

119 

56.7 

171 

82.4 

16 

6.5 

68 

30.5 

120 

57.2 

172 

82.9 

17 

7.0 

69 

31.0 

121 

57.7 

173 

83.4 

18 

7.4 

70 

31.6 

122 

58.2 

174 

83.9 

19 

7.8 

71 

32.1 

123 

58.7 

175 

84.4 

20 

8.2 

72 

32.6 

124 

59.2 

176 

84.9 

21 

8.6 

73 

33.1 

125 

59.7 

177 

85.4 

22 

9.0 

74 

33.6 

126 

60.2 

178 

85.9 

23 

9.4 

75 

34.1 

127 

60.7 

179 

86.4 

24 

9.9 

76 

34.6 

128 

61.2 

180 

86.9 

25 

10.3 

77 

35.1 

129 

61.7 

181 

87.4 

26 

10.7 

78 

35.7 

130 

62.2 

182 

87.9 

27 

11.1 

79 

36.2 

131 

62.6 

183 

88.4 

28 

11.6 

80 

36.7 

132 

63.1 

184 

88.9 

29 

12.0 

81 

37.2 

133 

63.6 

185 

89.4 

30 

12.4 

82 

37.7 

134 

64.1 

186 

89.9 

31 

12.9 

83 

38.2 

135 

64.6 

187 

90.4 

32 

13.3 

84 

38.7 

136 

65.1 

188 

90.9 

33 

13.7 

85 

39.2 

137 

65.6 

189 

91.3 

34 

14.1 

86 

39.8 

138 

66.1 

190 

91.8 

35 

14.6 

87 

40.3 

139 

66.6 

191 

92.3 

36 

15.0 

88 

40.8 

140 

67.1 

192 

92.8 

37 

15.4 

89 

41.2 

141 

67.6 

193 

93.3 

38 

15.9 

90 

41.8 

142 

68.1 

194 

93.8 

39 

16.3 

91 

42.3 

143 

68.6 

195 

94.3 

40 

16.7 

92 

42.8 

144 

69.1 

196 

94.8 

41 

17.2 

93 

43.3 

145 

69.6 

197 

95.3 

42 

17.6 

94 

43.9 

146 

70.1 

198 

95.8 

43 

18.0 

95 

44.4 

147 

70.6 

199 

96.3 

44 

18.4 

96 

44.9 

148 

71.1 

200 

96.8 

45 

18.9 

97 

45.4 

149 

71.5 

201 

97.3 

46 

19.3 

98 

45.9 

150 

72.0 

202 

97.8 

47 

19.7 

99 

46.4 

151 

72.5 

203 

98.3 

48 

20.2 

100 

46.9 

152 

73.0 

204 

98.8 

49 

20.7 

101 

47.5 

153 

73.5 

205 

99.3 

50 

21.3 

102 

48.0 

154 

74.0 

206 

99.8 

51 

21.8 

103 

48.5 

155 

74.5 

207 

100.3 

52 

22.3 

104 

49.0 

156 

75.0 

208 

100.8 

*  See  "  Handbook,  "  page  420. 


36 


SUGAR  TABLES 
TABLE   12.     (Continued.) 


Copper. 

(Cu). 

Glucose. 

Copper. 

Glucose. 

Copper. 

(Cu). 

Glucose. 

Copper. 

(Cu). 

Glucose. 

mga. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

209 

101.4 

263 

129.5 

317 

158.1 

371 

188.3 

210 

101.9 

264 

130.1 

318 

158.7 

372 

188.8 

211 

102.4 

265 

130.6 

319 

159.2 

373 

189.4 

212 

102.9 

266 

131.1 

320 

159.8 

374 

190.0 

213 

103.5 

267 

131.6 

321 

160.3 

375 

190.6 

214 

104.0 

268 

132.2 

322 

160.9 

376 

191.1 

215 

104.5 

269 

132.7 

323 

161.4 

377 

191.7 

216 

105.0 

270 

133.2 

324 

162.0 

378 

192.3 

217 

105.5 

271 

133.7 

325 

162.5 

379 

192.8 

218 

106.0 

272 

134.2 

326 

163.0 

380 

193.4 

219 

106.6 

273 

134.7 

327 

163.6 

381 

194.0 

220 

107.1 

274 

135.5 

328 

164.1 

382 

194.6 

221 

107.6 

275 

135.8 

329 

164.7 

383 

195.2 

222 

108.1 

276 

136.3 

330 

165.2 

384 

195.7 

223 

108.7 

277 

136.8 

331 

165.8 

385 

196.3 

224 

109.2 

278 

137.4 

332 

166.3 

386 

196.9 

225 

109.7 

279 

137.9 

333 

166.9 

387 

197.5 

226 

110.2 

280 

138.4 

334 

167.4 

388 

198.0 

227 

110.7 

281 

139.0 

335 

167.9 

389 

198.6 

228 

111.2 

282 

139.5 

336 

168.4 

390 

199.2 

229 

111.8 

283 

140.0 

337 

169.0 

391 

199.8 

230 

112.3 

284 

140.5 

338 

169.5 

392 

200.3 

231 

112.8 

285 

141.1 

339 

170.1 

393 

200.9 

232 

113.3 

286 

141.6 

340 

170.6 

394 

201.5 

233 

113.8 

287 

142.1 

341 

171.2 

395 

202.1 

234 

114.4 

288 

142.6 

342 

171.7 

396 

202.7 

235 

114.9 

289 

143.2 

343 

172.2 

397 

203.3 

236 

115.4 

290 

143.7 

344 

172.8 

398 

203.8 

237 

115.9 

291 

144.2 

345 

173.3 

399 

204.4 

238 

116.4 

292 

144.7 

346 

173.9 

400 

205.0 

239 

117.0 

293 

145.3 

347 

174.5 

401 

205.6 

240 

117.5 

294 

145.8 

348 

175.0 

402 

206.2 

241 

118.0 

295 

146.3 

349 

175.6 

403 

206.8 

242 

118.5 

296 

146.9 

350 

176.2 

404 

207.3 

243 

119.0 

297 

147.4 

351 

176.8 

405 

207.9 

244 

119.5 

298 

147.9 

352 

177.3 

406 

208.5 

245 

120.1 

299 

148.4 

353 

177.9 

407 

209.1 

246 

120.6 

300 

149.0 

354 

178.5 

408 

209.7 

247 

121.1 

301 

149.5 

355 

179.1 

409 

210.3 

248 

121.6 

302 

150.1 

356 

179.6 

410 

210.8 

249 

122.1 

303 

150.6 

357 

180.2 

411 

211.4 

250 

122.7 

304 

151.1 

358 

180.8 

412 

212.0 

251 

123.2 

305 

151.7 

359 

181.4 

413 

212.6 

252 

123.7 

306 

152.2 

360 

181.9 

414 

213.2 

253 

124.2 

307 

152.8 

361 

182.5 

415 

213.8 

254 

124.8 

308 

153.3 

362 

183.1 

416 

214.4 

255 

125.3 

309 

153.9 

363 

183.7 

417 

214.9 

256 

125.8 

310 

154.4 

364 

184.2 

418 

215.5 

257 

126.3 

311 

155.0 

365 

184.8 

419 

216.1 

258 

126.9 

312 

155.5 

366 

185.4 

420 

216.7 

259 

127.5 

313 

156.0 

367 

186.0 

421 

217.3 

260 

128.0 

314 

156.5 

368 

186.5 

422 

217.9 

261 

128.5 

315 

157.1 

369 

187.1 

423 

218.4 

262 

129.0 

316 

157.6 

370 

187.7 

424 

219.0 

SUGAR  TABLES 


37 


TABLE  12.     (Concluded.) 


Copper. 
(Cu). 

Glucose. 

Copper. 

Glucose. 

?cT' 

Glucose. 

Copper. 

(Cu). 

Glucose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

425 

219.6 

438 

227.8 

451 

236.6 

464 

245.3 

426 

220.2 

439 

228.5 

452 

237.2 

465 

246.0 

427 

220.8 

440 

229.1 

453 

237.9 

466 

246.7 

428 

221.4 

441 

229.8 

454 

238.6 

467 

247.4 

429 

221.9 

442 

230.5 

455 

239.3 

468 

248.0 

430 

222.5 

443 

231.2 

456 

239.9 

469 

248.7 

431 

223.1 

444 

231.8 

457 

240.6 

470 

249.4 

432 

223.7 

445 

232.5 

458 

241.3 

471 

250.1 

433 

224.4 

446 

233.2 

459 

242.0 

472 

250.8 

434 

225.1 

447 

233.9 

460 

242.6 

473 

251.4 

435 

225.8 

448 

234.5 

461 

243.3 

474 

252.1 

436 

226.4 

449 

235.2 

462 

244.0 

475 

252.8 

437 

227.1 

450 

235.9 

463 

244.7 

476 

253.5 

38 


SUGAR  TABLES 


TABLE*  13. 
MEISSL'S  TABLE  FOB  DETERMINING  INVERT  SUGAR. 


Copper. 

(Cu). 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

•    mgs. 

90 

mgs. 

46.9 

mgs. 

135 

mgs. 
70.8 

mgs. 
180 

mgs. 

95.2 

mgs. 

225 

mgs. 

120.4 

91 

47.4 

136 

71.3 

181 

95.7 

226 

120.9 

92 

47.9 

137 

71.9 

182 

96.2 

227 

121.5 

93 

48.4 

138 

72.4 

183 

96.8 

228 

122.1 

94 

48.9 

139 

72.9 

184 

97.3 

229 

122.6 

95 

49.5 

140 

73.5 

185 

97.8 

230 

123.2 

96 

50.0 

141 

74.0 

186 

98.4 

231 

123.8 

97 

50.5 

142 

74.5 

187 

99.0 

232 

124.3 

98 

51.1 

143 

75.1 

188 

99.5 

233 

124.9 

99 

51.6 

144 

75.6 

189 

100.1 

234 

125.5 

100 

52.1 

145 

76.1 

190 

100.6 

235 

126.0 

101 

52.7 

146 

76.7 

191 

101.2 

236 

126.6 

102 

53.2 

147 

77.2 

192 

101.7 

237 

127.2 

103 

53.7 

148 

77.8 

193 

102.3 

238 

127.8 

104 

54.3 

149 

78.3 

194 

102.9 

239 

128.3 

105 

54.8 

150 

78.9 

195 

103.4 

240 

128.9 

106 

55.3 

151 

79.4 

196 

104.0 

241 

129.5 

107 

55.9 

152 

80.0 

197 

104.6 

242 

130.0 

108 

56.4 

153 

80.5 

198 

105.1 

243 

130.6 

109 

56.9 

154 

81.0 

199 

105.7 

244 

131.2 

110 

57.5 

155 

81.6 

200 

106.3 

245 

131.8 

111 

58.0 

156 

82.1 

201 

106.8 

246 

132.3 

112 

58.5 

157 

82.7 

202 

107.4 

247 

132.9 

113 

59.1 

158 

83.2 

203 

107.9 

248 

133.5 

114 

59.6 

159 

83.8 

204 

108.5 

249 

134.1 

115 

60.1 

160 

84.3 

205 

109.1 

250 

134.6 

116 

60.7 

161 

84.8 

206 

109.6 

251 

135.2 

117 

61.2 

162 

85.4 

207 

110.2 

252 

135.8 

118 

61.7 

163 

85.9 

208 

110.8 

253 

136.3 

119 

62.3 

164 

86.5 

209 

111.3 

254 

136.9 

120 

62.8 

165 

87.0 

210 

111.9 

255 

137.5 

121 

63.3 

166 

87.6 

211 

112.5 

256 

138.1 

122 

63.9 

167 

88.1 

212 

113.0 

257 

138.6 

123 

64.4 

168 

88.6 

213 

113.6 

258 

139.2 

124 

64.9 

169 

89.2 

214 

114.2 

259 

139.8 

125 

65.5 

170 

89.7 

215 

114.7 

260 

140.4 

126 

66.0 

171 

90.3 

216 

115.3 

261 

140.9 

127 

66.5 

172 

90.8 

217 

115.8 

262 

141.5 

128 

67.1 

173 

91.4 

218 

116.4 

263 

142.1 

129 

67.6 

174 

91.9 

219 

117.0 

264 

142.7 

130 

68.1 

175 

92.4 

220 

117.5 

265 

143.2 

131 

68.7 

176 

93.0 

221 

118.1 

266 

143.8 

132 

69.2 

177 

93.5 

222 

118.7 

267 

144.4 

133 

69.7 

178 

94.1 

223 

119.2 

268 

144.9 

134 

70.3 

179 

94.6 

224 

119.8 

269 

145.5 

*  See  "  Handbook,"  page  423. 


SUGAR  TABLES 
TABLE  13.     (Concluded.) 


39 


Copper. 
(Cu). 

Invert 
sugar. 

Copper. 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

mgs. 

mgs. 

mgs. 

nigs. 

mgs. 

mgs. 

mgs. 

mgs. 

270 

146.1 

310 

169.7 

350 

193.8 

390 

218.7 

271 

146.7 

311 

170.3 

351 

194.4 

391 

219.3 

272 

147.2 

312 

170.9 

352 

195.0 

392 

219.9 

273 

147.8 

313 

171.5 

353 

195.6 

393 

220.5 

274 

148.4 

314 

172.1 

354 

196.2 

394 

221.2 

275 

149.0 

315 

172.7 

355 

196.8 

395 

221.8 

276 

149.5 

316 

173.3 

356 

197.4 

396 

222.4 

277 

150.1 

317 

173.9 

357 

198.0 

397 

223.1 

278 

150.7 

318 

174.5 

358 

198.6 

398 

223.7 

279 

151.3 

319 

175.1 

359 

199.2 

399 

224.3 

280 

151.9 

320 

175.6 

360 

199.8 

400 

224.9 

281 

152.5 

321 

176.2 

361 

200.4 

401 

225.7 

282 

153.1 

322 

176.8 

362 

201.1 

402 

226.4 

283 

153.7 

323 

177.4 

363 

201.7 

403 

227.1 

284 

154.3 

324 

178.0 

364 

202.3 

404 

227.8 

285 

154.9 

325 

178.6 

365 

203.0 

405 

228.6 

286 

155.5 

326 

179.2 

366 

203.6 

406 

229.3 

287 

156.1 

327 

179.8 

367 

204.2 

407 

230.0 

288 

156.7 

328 

180.4 

368 

204.8 

408 

230.7 

289 

157.2 

329 

181.0 

369 

205.5 

409 

231.4 

290 

157.8 

330 

181.6 

370 

206.1 

410 

232.1 

291 

158.4 

331 

182.2 

371 

206.7 

411 

232.8 

292 

159.0 

332 

182.8 

372 

207.3 

412 

233.5 

293 

159.6 

333 

183.5 

373 

208.0 

413 

234.3 

294 

160.2 

334 

184.1 

374 

208.6 

414 

235.0 

295 

160.8 

335 

184.7 

375 

209.2 

415 

235.7 

296 

161.4 

336 

185.4 

376 

209.9 

416 

236.4 

297 

162.0 

337 

186.0 

377 

210.5 

417 

237.1 

298 

162.6 

338 

186.6 

378 

211.1 

418 

237.8 

299 

163.2 

339 

187.2 

379 

211.7 

419 

238.5 

300 

163.8 

340 

187.8 

380 

212.4 

420 

239.2 

301 

164.4 

341 

188.4 

381 

213.0 

421 

239.9 

302 

165.0 

342 

189.0 

382 

213.6 

422 

240.6 

303 

165.6 

343 

189.6 

383 

214.3 

423 

241.3 

304 

166.2 

344 

190.2 

384 

214.9 

424 

242.0 

305 

166.8 

345 

190.8 

385 

215.5 

425 

242.7 

306 

167.3 

346 

191.4 

386 

216.1 

426 

243.4 

307 

167.9 

347 

192.0 

387 

216.8 

427 

244.1 

308 

168.5 

348 

192.6 

388 

217.4 

428 

244.9 

309 

169.1 

349 

193.2 

389 

218.0 

429 

245.6 

430 

246.3 

40 


SUGAR  TABLES 


TABLE*  14. 
WEIN'S  TABLE  FOR  DETERMINING  MALTOSE. 


Cop- 
(Cu). 

Cu- 
prous 
oxide 
(Cu20). 

Mal- 
tose. 

Copper 

(Cu). 

Cu- 
prous 
oxide 

(Cu2O). 

Mal- 
tose. 

%T 

Cu- 
prous 
oxide 

(Cu20). 

Mal- 
tose. 

C('&T 

Cu- 
prous 
oxide 

(Cu2O). 

Mal- 
tose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

31 

34.9 

26.1 

76 

85.6 

65.4 

121 

136.2 

105.3 

166 

186.9 

145.8 

32 

36.0 

27.0 

77 

86.7 

66.2 

122 

137.4 

106.2 

167 

188.0 

146.7 

33 

37.2 

27.9 

78 

87.8 

67.1 

123 

138.5 

107.1 

168 

189.1 

147.6 

34 

38.3 

28.7 

79 

88.9 

68.0 

124 

139.6 

108.0 

169 

190.3 

148.5 

35 

39.4 

29.6 

80 

90.1 

68.9 

125 

140.7 

108.9 

170 

191.4 

149.4 

36 

40.5 

30.5 

81 

91.2 

69.7 

126 

141.9 

109.8 

171 

192.5 

150.3 

37 

41.7 

31.3 

82 

92.3 

70.6 

127 

143.0 

110.7 

172 

193.6 

151.2 

38 

42.8 

32.2 

83 

93.4 

71.5 

128 

144.1 

111.6 

173 

194.8 

152.0 

39 

43.9 

33.1 

84 

94.6 

72.4 

129 

145.2 

112.5 

174 

195.9 

152.9 

40 

45.0 

33.9 

85 

95.7 

73.2 

130 

146.4 

113.4 

175 

197.0 

153.8 

41 

46.2 

34.8 

86 

96.8 

74.1 

131 

147.5 

114.3 

176 

198.1 

154.7 

42 

47.3 

35.7 

87 

97.9 

75.0 

132 

148.6 

115.2 

177 

199.3 

155.6 

43 

48.4 

36.5 

88 

99.1 

75.9 

133 

149.7 

116.1 

178 

200.4 

156.5 

44 

49.5 

37.4 

89 

100.2 

76.8 

134 

150.9 

117.0 

179 

201.5 

157.4 

45 

50.7 

38.3 

90 

101.3 

77.7 

135 

152.0 

117.9 

180 

202.6 

158.3 

46 

51.8 

39.1 

91 

102.4 

78.6 

136 

153.1 

118.8 

181 

203.8 

159.2 

47 

52.9 

40.0 

92 

103.6 

79.5 

137 

154.2 

119.7 

182 

204.9 

160.1 

48 

54.0 

40.9 

93 

104.7 

80.3 

138 

155.4 

120.6 

183 

206.0 

160.9 

49 

55.2 

41.8 

94 

105.8 

81.2 

139 

156.5 

121.5 

184 

207.1 

161.8 

50 

56.3 

42.6 

95 

107.0 

82.1 

140 

157.6 

122.4 

185 

208.3 

162.7 

51 

57.4 

43.5 

96 

108.1 

83.0 

141 

158.7 

123.3 

186 

209.4 

163.6 

52 

58.5 

44.4 

97 

109.2 

83.9 

142 

159.9 

124.2 

187 

210.5 

164.5 

53 

59.7 

45.2 

98 

110.3 

84.8 

143 

161.0 

125.1 

188 

211.7 

165.4 

54 

60.8 

46.1 

99 

111.5 

85.7 

144 

162.1 

126.0 

189 

212.8 

166.3 

55 

61.9 

47.0 

100 

112.6 

86.6 

145 

163.2 

126.9 

190 

213.9 

167.2 

56 

63.0 

47.8 

101 

113.7 

87.5 

146 

164.4 

127.8 

191 

215.0 

168.1 

57 

64.2 

48.7 

102 

114.8 

88.4 

147 

165.5 

128.7 

192 

216.2 

169.0 

58 

65.3 

49.6 

103 

116.0 

89.2 

148 

166.6 

129.6 

193 

217.3 

169.8 

59 

66.4 

50.4 

104 

117.1 

90.1 

149 

167.7 

130.5 

194 

218.4 

170.7 

60 

67.6 

51.3 

105 

118.2 

91.0 

150 

168.9 

131.4 

195 

219.5 

171.6 

61 

68.7 

52.2 

106 

119.3 

91.9 

151 

170.0 

132.3 

196 

220.7 

172.5 

62 

69.8 

53.1 

107 

120.5 

92.8 

152 

171.1 

133.2 

197 

221.8 

173.4 

63 

70.9 

53.9 

108 

121.6 

93.7 

153 

172.3 

134.1 

198 

222.9 

174.3 

64 

72.1 

54.8 

109 

122.7 

94.6 

154 

173.4 

135.0 

199 

224.0 

175.2 

65 

73.2 

55.7 

110 

123.8 

95.5 

155 

174.5 

135.9 

200 

225.2 

176.1 

66 

74.3 

56.6 

111 

125.0 

96.4 

156 

175.6 

136.8 

201 

226.3 

177.0 

67 

75.4 

57.4 

112 

126.1 

97.3 

157 

176.8 

137.7 

202 

227.4 

177.9 

68 

76.6 

58.3 

113 

127.2 

98.1 

158 

177.9 

138.6 

203 

228.5 

178.7 

69 

77.7 

59.2 

114 

128.3 

99.0 

159 

179.0 

139.5 

204 

229.7 

179.6 

70 

78.8 

60.1 

115 

129.6 

99.9 

160 

180.1 

140.4 

205 

230.8    180.5 

71 

79.9 

61.0 

116 

130.6 

100.8 

161 

181.3 

141.3 

206 

231.9 

181.4 

72 

81.1 

61.8 

117 

131.7 

101.7 

162 

182.4 

142.2 

207 

233.0 

182.3 

73 

82.2 

62.7 

118 

132.8 

102.6 

163 

183.5 

143.1 

208 

234.  2    183.2 

74 

83.3 

63.6 

119 

134.0 

103.5 

164 

184.6 

144.0 

209 

235.3:  184.1 

75 

84.4 

64.5 

120 

135.1 

104.4 

165 

185.8 

144.9 

210 

236.4    185.0 

*  See  "  Handbook,'"page  423. 


SUGAR  TABLES 
TABLE  14.     (Concluded.) 


41 


Cop- 
(Qu). 

Cu- 
prous, 
oxide 
(Cu,0). 

Mal- 
tose. 

Copper 

(Cu). 

Cu- 
prous 
oxide 
(Cu,O). 

Mal- 
tose. 

C(cT 

Cu- 
prous 
oxide 

(Cu20). 

Mal- 
tose. 

Copper 

(Cu). 

Cu- 
prous 
oxide 
(Cu2O). 

Mal- 
tose. 

mgs. 

211 

mgs. 

237.6 

mgs. 

185.9 

mgs. 
236 

mgs. 

265.7 

mgs. 

208.3 

mgs. 
261 

mgs. 

293.8 

mgs. 

230.7 

mgs. 

286 

mgs. 

322.0 

mgs. 

253.1 

212 

238.7 

186.8 

237 

266.8 

209.1 

262 

295.0 

231.6 

287 

323.1 

254.0 

213 

239.8 

187.7 

238 

268.0 

210.0 

263 

296.1 

232.5 

288 

324.2 

254.9 

214 

240.9 

188.6 

239 

269.1 

210.9 

264 

297.2 

233.4 

289 

325.4 

255.8 

215 

242.1 

189.5 

240 

270.2 

211.8 

265 

298.3 

234.3 

290 

326.5 

256.6 

216 

243.2 

190.4 

241 

271.3 

212.7 

266 

299.5 

235.2 

291 

327.4 

257.5 

217 

244.3 

191.2 

242 

272.5 

213.6 

267 

300.6 

236.1 

292 

328.7 

258.4 

218 

245.4 

192.1 

243 

273.6 

214.5 

268 

301.7 

237.0 

293 

329.9 

259.3 

219 

246.6 

193.0 

244 

274.7 

215.4 

269 

302.8 

237.9 

294 

331.0 

260.2 

220 

247.7 

193.9 

245 

275.8 

216.3 

270 

304.0 

238.8 

295 

332.1 

261.1 

221 

248.7 

194.8 

246 

277.0 

217.2 

271 

305.1 

239.7 

296 

333.2 

262.0 

222 

249.9 

195.7 

247 

278.1 

218.1 

272 

306.2 

240.6 

297 

334.4 

262.8 

223 

251.0 

196.6 

248 

279.2 

219.0 

273 

307.3 

241.5 

298 

335.5 

263.7 

224 

252.4 

197.5 

249 

280.3 

219.9 

274 

308.5 

242.4 

299 

336.6 

264.6 

225 

253.3 

198.4 

250 

281.5 

220.8 

275 

309.6 

243.3 

300 

337.8 

265.5 

226 

254.4 

199.3 

251 

282.6 

221.7 

276 

310.7 

244.2 

227 

255.6 

200.2 

252 

283.7 

222.6 

277 

311.9 

245.1 

228 

256.7 

201.1 

253 

284.8 

223.5 

278 

313.0 

246.0 

229 

257.8 

202.0 

254 

286.0 

224.4 

279 

314.1 

246.9 

230 

258.9 

202.9 

255 

287.1 

225.3 

280 

315.2 

247.8 

231 

260.1 

203.8 

256 

288.2 

226.2 

281 

316.4 

248.7 

232 

261.2 

204.7 

257 

289.3 

227.1 

282 

317.5 

249.6 

- 

233 

262.3 

205.6 

258 

290.5 

228.0 

283 

318.6 

250.4 

234 

263.4 

206.5 

259 

291.6 

228.9 

284 

319.7 

251.3 

235 

264.6 

207.4 

260 

292.7 

229.8 

285 

320.9 

252.2 

42 


SUGAR  TABLES 


TABLE*  15. 

SOXHLET   AND    WEIN'S   TABLE    FOR    DETERMINING    LACTOSE. 


<&T 

Lactose. 

^uT 

Lactose. 

Copper 
(Cu). 

Lactose. 

Copper 

(Cu). 

Lactose. 

?cT 

Lactose. 

mgs. 

mgs. 

mgs. 

mgs. 

ings. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

100 

71.6 

145 

105.1 

190 

139.3 

235 

173.1 

280 

208.3 

101 

72.4 

146 

105.8 

191 

140.0 

236 

173.9 

281 

209.1 

102 

73.1 

147 

106.6 

192 

140.8 

237 

174.6 

282 

209.9 

103 

73.8 

148 

107.3 

193 

141.6 

238 

175.4 

283 

210.7 

104 

74.6 

149 

108.1 

194 

142.3 

239 

176.2 

284 

211.5 

105 

75.3 

150 

108.8 

195 

143.1 

240 

176.9 

285 

212.3 

106 

76.1 

151 

109.6 

196 

143.9 

241 

177.7 

286 

213.1 

107 

76.8 

152 

110.3 

197 

144.6 

242 

178.5 

!     287 

213.9 

108 

77.6 

153 

111.1 

198 

145.4 

243 

179.3 

1     288 

214.7 

109 

78.3 

154 

111.9 

199 

146.2 

244 

180.1 

289 

215.5 

110 

79.0 

155 

112.6 

200 

146.9 

245 

180.8 

290 

216.3 

111 

79.8 

156 

113.4 

201 

147.7 

246 

181.6 

291 

217.1 

112 

80.5 

157 

114.1 

202 

148.5 

247 

182.4 

292 

217.9 

113 

81.3 

158 

114.9 

203 

149.2 

248 

183.2 

293 

218.7 

114 

82.0 

159 

115.6 

204 

150.0 

249 

184.0 

294 

219.5 

115 

82.7 

160 

116.4 

205 

150.7 

250 

184.8 

295 

220.3 

116 

83.5 

161 

117.1 

206 

151.5 

251 

185.5 

296 

221.1 

117 

84.2 

162 

117.9 

207 

152.2 

252 

186.3 

297 

221.9 

118 

85.0 

163 

118.6 

208 

153.0 

253 

187.1 

298 

222.7 

119 

85.7 

164 

119.4 

209 

153.7 

254 

187.9 

299 

223.5 

120 

86.4 

165 

120.2 

210 

154.5 

255 

188.7 

300 

224.4 

121 

87.2 

166 

120.9 

211 

155.2 

256 

189.4 

301 

225.2 

122 

87.9 

167 

121.7 

212 

156.0 

257 

190.2 

302 

225.9 

123 

88.7 

168 

122.4 

213 

156.7 

258 

191.0 

303 

226.7 

124 

89.4 

169 

123.2 

214 

157.5 

259 

191.8 

304 

227.5 

125 

90.1 

170 

123.9 

215 

158.2 

260 

192.5 

305 

228.3 

126 

90.9 

171 

124.7 

216 

159.0 

261 

193.3 

306 

229.1 

127 

91.6 

172 

125.5 

217 

159.7 

262 

194.1 

307 

229.8 

128 

92.4 

173 

126.2 

218 

160.4 

263 

194.9 

308 

230.6 

129 

93.1 

174 

127.0 

219 

161.2 

264 

195.7 

309 

231.4 

130 

93.8 

175 

127.8 

220 

161.9 

265 

196.4 

310 

232.2 

131 

94.6 

176 

128.5 

221 

162.7 

266 

197.2 

311 

232.9 

132 

95.3 

177 

129.3 

222 

163.4 

267 

198.0 

312 

233.7 

133 

96.1 

178 

130.1 

223 

164.2 

268 

198.8 

313 

234.5 

134 

96.9 

179 

130.8 

224 

164.9 

269 

199.5 

314 

235.3 

135 

97.6 

180 

131.6 

225 

165.7 

270 

200.3 

315 

236.1 

136 

98.3 

181 

132.4 

226 

166.4 

271 

201.1 

316 

236.8 

137 

99.1 

182 

133.1 

227 

167.2 

272 

201.9 

317 

237.6 

138 

99.8 

183 

133.9 

228 

167.9 

273 

202.7 

318 

238.4 

139 

100.5 

184 

134.7 

229 

168.6 

274 

203.5 

319 

239.2 

140 

101.3 

185 

135.4 

230 

169.4 

275 

204.3 

320 

240.0 

141 

102.0 

186 

136.2 

231 

170.1 

276 

205.1 

321 

240.7 

142 

102.8 

187 

137.0 

232 

170.9 

277 

205.9 

322 

241.5 

143 

103.5 

188 

137.7 

233 

171.6 

278 

206.7 

323 

242.3 

144 

104.3 

189 

138.5 

234 

172.4 

279 

207.5 

324 

243.1 

*  See  "  Handbook,"  page  424. 


SUGAR  TABLES 


43 


TABLE  15.     (Concluded.) 


c(cpr 

Lactose. 

Copper. 
(Cu). 

Lactose. 

C(°cpuT- 

Lactose. 

c(°cpur 

Lactose. 

Copper. 
(Cu). 

Lactose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

325 

243.9 

341 

256.5 

356 

268.8 

371 

281.4 

386 

294.2 

326 

244.6 

342 

257.4 

357 

269.6 

372 

282.2 

387 

295.1 

327 

245.4 

343 

258.2 

358 

270.4 

373 

283.1 

388 

296.0 

328 

246.2 

344 

259.0 

359 

271.2 

374 

283.9 

389 

296.8 

329 

247.0 

345 

259.8 

360 

272.1 

375 

284.8 

390 

297.7 

330 

247.7 

346 

260.6 

361 

272.9 

376 

285.7 

391 

298.5 

331 

248.5 

347 

261.4 

362 

273.7 

377 

286.5 

392 

299.4 

332 

249.2 

348 

262.3 

363 

274.5 

378 

287.4 

393 

300.3 

333 

250.0 

349 

263.1 

364 

275.3 

379 

288.2 

394 

301.1 

334 

250.8 

350 

263.9 

365 

276.2 

380 

289.1 

395 

302.0 

335 

251.6 

351 

264.7 

366 

277.1 

381 

289.9 

396 

302.8 

336 

252.5 

352 

265.5 

367 

277.9 

382 

290.8 

397 

303.7 

337 

253.3 

353 

266.3 

368 

278.8 

383 

291.7 

398 

304.6 

338 

254.1 

354 

267.2 

369 

279.6 

384 

292.5 

399 

305.4 

339 

254.9 

355 

268.0 

370 

280.5 

385 

293.4 

400 

306.3 

340 

255.7 

44 


SUGAR  TABLES 


TABLE*  16. 

WOY'S  TABLE  FOR  DETERMINING  GLUCOSE,  FRUCTOSE,  INVERT  SUGAR, 

LACTOSE  AND  MALTOSE  BY  KJELDAHL'S  METHOD. 

15  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12H22On+H2O 

Maltose 
Ci2H22Ou 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs 

mgs. 

mgs. 

5 

4.0 

1.7 

2.1 

2.0 

2.0 

2.8 

3.0 

6 

4.8 

2.1 

2.5 

2.4 

2.4 

3.3 

3.6 

7 

5.6 

2.5 

2.9 

2.8 

2.8 

3.8 

4.2 

8 

6.4 

2.9 

3.3 

3.2 

3.2 

4.3 

4.8 

9 

7.2 

3.2 

3.7 

3.6 

3.6 

4.8 

5.4 

10 

8.0 

3.5 

4.1 

4.0 

4.0 

5.4 

6.0 

11 

8.8 

3.9 

4.5 

4.4 

4.4 

5.9 

6.6 

12 

9.6 

4.2 

5.0 

4.9 

4.9 

6.4 

7.2 

13 

10.4 

4.6 

5.4 

5.3 

5.2 

7.0 

7.8 

14 

.11.2 

5.0 

5.8 

5.7 

5.7 

7.5 

8.4 

15 

12.0 

5.4 

6.2 

6.1 

6.1 

8.1 

9.0 

16 

12.8 

5.7 

6.6 

6.4 

6.5 

8.7 

9.6 

17 

13.6 

6.1. 

7.0 

6.8 

6.9 

9.2 

10.2 

18 

14.4 

6.5 

7.4 

7.2 

7.3 

9.8 

10.8 

19 

15.2 

6.8 

7.9 

7.6 

7.7 

10.3 

11.4 

20 

16.0 

7.2 

8.3 

8.0 

8.1 

10.8 

12.0 

21 

16.8 

7.6 

8.7 

8.4 

8.6 

11.4 

12.6 

22 

17.6 

7.9 

9.2 

8.8 

9.0 

11.9 

13.2 

23 

18.4 

8.3 

9.6 

9.2 

9.4 

12.5 

13.8 

24 

19.2 

8.7 

10.0 

9.6 

9.8 

13.0 

14.5 

25 

20.0 

9.0 

10.4 

10.0 

10.2 

13.6 

15.1 

26 

20.8 

9.4 

10.8 

10.4 

10.6 

14.2 

15.7 

27 

21.6 

9.8 

11.3 

10.8 

11.1 

14.7 

16.3 

28 

22.4 

10.1 

11.7 

11.2 

11.5 

15.2 

16.9 

29 

23.2 

10.5 

12.1 

11.6 

11.9 

15.8 

17.5 

30 

24.0 

10.9 

12.5 

12.0 

12.3 

16.4 

18.1 

31 

24.8 

11.2 

13.0 

12.4 

12.8 

17.0 

18.8 

32 

25.6 

11.6 

13.4 

12.8 

13.2 

17.5 

19.4 

33 

26.4 

12.0 

13.8 

13.2 

13.6 

18.0 

20.0 

34 

27.2 

12.4 

14.2 

13.6 

14.0 

18.6 

20.6 

35 

28.0 

12.8 

14.7 

14.0 

14.4 

19.1 

21.2 

36 

28.7 

13.2 

15.1 

14.4 

14.9 

19.7 

21.8 

37 

29.5 

13.5 

15.5 

14.8 

15.3 

20.2 

22.4 

38 

30.3 

13.9 

16.0 

15.2 

15.7 

20.7 

23.1 

39 

31.1 

14.3 

16.4 

15.5 

16.1 

21.3 

23.7 

40 

31.9 

14.6 

16.8 

16.0 

16.5 

21.8 

24.3 

41 

32.7 

15.0 

17.3 

16.4 

16.9 

22.4 

24.9 

42 

33.5 

15.4 

17.7 

16.8 

17.4 

22.9 

25.5 

43 

34.3 

15.8 

18.1 

17.2 

17.8 

23.5 

26.1 

44 

35.1 

16.1 

18.5 

17.6 

18.2 

24.1 

26.7 

45 

35.9 

16.5 

18.9 

18.0 

18.6 

24.7 

27.4 

46 

36.7 

17.0 

19.4 

18.5 

19.1 

25.3 

28.1 

47 

37.5 

17.4 

19.8 

18.9 

19.6 

25.9 

28.7 

48 

38.3 

17.8 

20.3 

19.3 

20.0 

26.4 

29.3 

49 

39.1 

18.2 

20.9 

19.7 

20.5 

27.0 

30.0 

*  See  "  Handbook,"  page  424. 


SUGAR  TABLES 


45 


TABLE   16.     (Continued.) 
15  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

c(0cT 

Glucose. 

Fructose. 

Invert, 
sugar. 

Galactose. 

Lactose 
CizH^On+HjO 

Maltose 
CuHaOu 

mgs. 

50 

mgs. 

39.9 

mgs. 

18.6 

mgs. 

21.2 

mgs. 

20.2 

mgs. 
20.9 

mgs. 

27.6 

mgs. 

30.7 

51 

40.7 

19.0 

21.6 

20.6 

21.3 

28.1 

31.3 

52 

41.5 

19.4 

22.0 

21.0 

21.8 

28.7 

31.9 

53 

42.3 

,     19.8 

22.5 

21.4 

22.2 

29.3 

32.5 

54 

43.1 

20.2 

22.9 

21.8 

22.7 

29.9 

33.2 

55 

43.9 

20.6 

23.4 

22.3 

23.2 

30.5 

33.9 

56 

44.7 

21.0 

23.8 

22.7 

23.6 

31.1 

34.5 

57 

45.5 

21.4 

24.2 

23.1 

24.0 

31.7 

35.1 

58 

46.3 

21.8 

24.7 

23.5 

24.5 

32.2 

35.7 

59 

47.1 

22.2 

25.2 

24.0 

24.9 

32.8 

36.4 

60 

47.9 

22.7 

25.6 

24.4 

25.4 

33.4 

37.1 

61 

48.7 

23.1 

26.0 

24.9 

25.9 

34.0 

37.7 

62 

49.5 

23.5 

26.5 

25.3 

26.3 

34.6 

38.3 

63 

50.3 

23.9 

27.0 

25.7 

26.8 

35.1 

39.0 

64 

51.1 

24.3 

27.4 

26.1 

27.2 

35.7 

39.6 

65 

51.9 

24.7 

27.9 

26.6 

27.7 

36.4 

40.3 

66 

52.7 

25.1 

28.3 

27.0 

28.1 

36.9 

40.9 

67 

53.5 

25.5 

28.7 

27.4 

28.6 

37.5 

41.5 

68 

54.3 

25.9 

29.1 

'  27.8 

29.0 

38.1 

42.2 

69 

55.1 

26.3 

29.6 

28.2 

29.5 

38.7 

42.9 

70 

55.9 

26.8 

30.1 

28.7 

30.0 

39.3 

43.6 

71 

56.7 

27.2 

30.5 

29.1 

30.4 

39.8 

44.2 

72 

57.5 

27.6 

31.0 

29.6 

30.9 

40.4 

44.8 

73 

58.3 

28.0 

31.4 

30.0 

31.4 

40.9 

45.4 

74 

59.1 

28.5 

31.9 

30.5 

31.8 

41.6 

46.1 

75 

59.9 

28.9 

32.4 

30.9 

32.3 

42.2 

46.9 

76 

60.7 

29.3 

32.9 

31.3 

32.7 

42.8 

47.5 

77 

61.5 

29.7 

33.2 

31.7 

33.2 

43.4 

48.1 

78 

62.3 

30.2 

33.7 

32.2 

33.7 

43.9 

48.7 

79 

63.1 

30.6 

34.2 

32.7 

34.2 

44.6 

49.4 

80 

63.9 

31.0 

34.7 

33.1 

34.7 

45.2 

50.2 

81 

64.7 

31.4 

35.1 

33.5 

35.1 

45.8 

50.8 

82 

65.5 

31.9 

35.5 

34.0 

35.6 

46.4 

51.4 

83 

66.3 

32.3 

36.0 

34.5 

36.1 

47.0 

52.1 

84 

67.1 

32.8 

36.5 

34.9 

36.6 

47.6 

52.8 

85 

67.9 

33.2 

37.0 

35.4 

37.1 

48.2 

53.5 

86 

68.7 

33.6 

37.4 

35.8 

37.5 

48.8 

54.1 

87 

69.5 

34.1 

37.9 

36.3 

38.0 

49.4 

54.8 

88 

70.3 

34.5 

38.3 

36.7 

38.5 

50.0 

55.4 

89 

71.1 

35.0 

38.8 

37.2 

39.0 

50.6 

56.1 

90 

71.9 

35.4 

39.3 

37.6 

39.5 

51.3 

56.9 

91 

72.7 

35.8 

39.7 

38.1 

39.9 

51.8 

57.5 

92 

73.5 

36.3 

40.2 

38.5 

40.4 

52.4 

58.2 

93 

74.3 

36.8 

40.7 

39.0 

40.9 

53.0 

58.8 

94 

75.1 

37.3 

41.2 

39.5 

41.4 

53.7 

59.5 

95 

75.9 

37.7 

41.7 

39.9 

42.0 

54.4 

60.3 

96 

76.7 

38.1 

42.0 

40.3 

42.4 

54.9 

60.9 

97 

77.5 

38.6 

42.5 

40.8 

42.9 

55.6 

61.6 

98 

78.3 

39.1 

43.0 

41.3 

43.4 

56.1 

62.4 

99 

79.1 

39.5 

43.5 

41.8 

43.9 

56.8 

63.0 

46 


SUGAR  TABLES 


TABLE  16.     (Continued.) 
15  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12H22On+H20 

Maltose 

Ci2H22On 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

100 

79.9 

40.0 

44.0 

42.3 

44.4 

5775 

63.8 

101 

80.7 

40.4 

44.4 

42.7 

44.8 

58.1 

64.4 

102 

81.5 

40.9 

44.9 

43.1 

45.3 

58.7 

65.0 

103 

82.3 

41.4 

45.4 

43.7 

45.8 

59.3 

65.7 

104 

83.1 

41.9 

45.9 

44.2 

46.5 

60.0 

66.5 

105 

83.9 

42.4 

46.4 

44.7 

47.0 

60.7 

67.2 

106 

84.7 

42.8 

46.8 

45.1 

47.4 

61.3 

67.8 

107 

85.5 

43.3 

47.3 

45.6 

47.8 

61.9 

68.5 

108 

86.3 

43.8 

47.8 

46.1 

48.5 

62.4 

69.2 

109 

87.1 

44.3 

48.3 

46.6 

49.0 

63.1 

69.9 

110 

87.8 

44.7 

48.7 

47.0 

49.5 

63.6 

70.5 

111 

88.6 

45.1 

49.2 

47.5 

50.0 

64.3 

71.2 

112 

89.4 

45.6 

49.7 

48.0 

50.5 

65.0 

72.0 

113 

90.2 

46.1 

50.1 

48.4 

50.9 

65.6 

72.6 

114 

91.0 

46.6 

50.6 

48.9 

51.5 

66.2 

73.3 

115 

91.8 

47.1 

51.2 

49.4 

52.1 

66.8 

74.0 

116 

92.6 

47.6 

51.7 

49.9 

52.6 

67.5 

74.7 

117 

93.4 

48.1 

52.1 

50.4 

53.1 

68.1 

75.5 

118 

94.2 

48.6 

52.6 

50.9 

53.6 

68.8 

76.2 

119 

95.0 

49.1 

53.1 

51.4 

54.2 

69.5 

76.9 

120 

95.8 

49.6 

53.6 

51.9 

54.7 

69.1 

77.6 

121 

96.6 

50.1 

54.1 

52.4 

55.2 

70.8 

78.3 

122 

97.4 

50.6 

54.6 

52.9 

55.7 

71.4 

79.0 

123 

98.2 

51.1 

55.1 

53.4 

56.3 

72.1 

79.7 

124 

99.0 

51.6 

55.6 

53.9 

56.8 

72.7 

80.4 

125 

99.8 

52.2 

56.1 

54.4 

57.4 

73.4 

81.2 

126 

100.6 

52.7 

56.6 

54.9 

57.9 

74.0 

81.8 

127 

101.4 

53.2 

57.0 

55.4 

58.5 

74.7 

82.6 

128 

102.2 

53.7 

57.5 

55.9 

59.0 

75.4 

83.4 

129 

103.0 

54.2 

58.1 

56.4 

59.6 

76.0 

84.1 

130 

103.8 

54.8 

58.6 

57.0 

60.2 

76.7 

84.9 

131 

104.6 

55.3 

59.1 

57.5 

60.7 

77.3 

85.5 

132 

105.4 

55.8 

59.6 

58.0 

61.3 

78.0 

86.3 

133 

106.2 

56.3 

60.0 

58.4 

61.8 

78.7 

87.0 

134 

107.0 

56.9 

60.6 

59.0 

62.4 

79.3 

87.7 

135 

107.8 

57.5 

61.1 

59.6 

63.0 

79.9 

88.4 

136 

108.6 

58.0 

61.6 

60.1 

63.5 

80.6 

89.0 

137 

109.4 

58.5 

62.1 

60.6 

64.0 

81.3 

89.8 

138 

110.2 

59.0 

62.6 

61.1 

64.5 

82.0 

90.6 

139 

111.0 

59.6 

63.1 

61.6 

65.2 

82.7 

91.4 

140 

111.8 

60.2 

63.7 

62.2 

65.8 

83.3 

92.1 

141 

112.6 

60.7 

64.2 

62.7 

66.3 

84.0 

92.8 

142 

113.4 

61.3 

64.7 

63.3 

66.9 

84.7 

93.6 

143 

114.2 

61.8 

65.1 

63.7 

67.5 

85.4 

94.4 

144 

115.0 

62.4 

65.7 

64.3 

68.1 

86.1 

95.1 

145 

115.8 

63.0 

66.2 

64.9 

68.7 

86.7 

95.9 

146 

116.6 

63.5 

66.7 

65.4 

69.2 

87.4 

96.6 

147 

117.4 

64.1 

67.3 

66.0 

69.8 

88.1 

97.4 

148 

118.2 

64.7 

67.8 

66.5 

70.4 

88.8 

98.1 

149 

119.0 

65.3 

68.3 

67.1 

71.0 

89.5 

98.9 

SUGAR  TABLES 


47 


TABLE   16.     (Continued.} 
15  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12H22On+H2O 

Maltose 
CuHadi 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mga. 

mgs. 

150 

119.8 

65.8 

68.9 

67.7 

71.6 

90.1 

99.6 

151 

120.6 

66.5 

69.4 

68.2 

72.1 

90.8 

100.4 

152 

121.4 

67.1 

70.0 

68.9 

72.9 

91.5 

101.2 

153 

122.2 

67.6 

70.4 

69.3 

73.4 

92.3 

101.9 

154 

123.0 

68.3 

70.9 

69.9 

74.0 

93.0 

102.7 

155 

123.8 

68.9 

71.5 

70.5 

74.7 

93.7 

103.4 

156 

124.6 

69.5 

72.0 

71.0 

75.3 

94.4 

104.2 

157 

125.4 

70.1 

72.6 

71.6 

75.9 

95.1 

105.0 

158 

126.2 

70.7 

73.0 

72.1 

76.4 

95.8 

105.7 

159 

127.0 

71.3 

73.6 

72.7 

77.1 

96.5 

106.5 

160 

127.8 

72.0 

74.2 

73.4 

77.7 

97.2 

107.2 

30  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 
(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12H22On+H20 

Maltose 
C12H220U 

mgs. 

.mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

50 

39.9 

17.7 

19.8 

19.1 

19.8 

26.6 

30.8 

51 

40.7 

18.1 

20.2 

19.4 

20.2 

27.2 

31.5 

52 

41.5 

18.5 

20.6 

19.8 

20.7 

27.8 

32.1 

53 

42.3 

18.8 

21.0 

20.2 

21.1 

28.3 

32.7 

54 

43.1 

19.2 

21.4 

20.6 

21.5 

28.9 

33.4 

55 

43.9 

19.6 

21.8 

21.0 

21.9 

29.4 

34.0 

56 

44.7 

20.0 

22.2 

21.4 

22.3 

30.0 

34.7 

57 

45.5 

20.3 

22.7 

21.8 

22.7 

30.5 

35.3 

58 

46.3 

20.7 

23.1 

22.1 

23.1 

31.0 

35.8 

59 

47.1 

21.1 

23.5 

22.6 

23.5 

31.6 

36.5 

60 

47.9 

21.5 

23.9 

23.0 

23.9 

32.1 

37.1 

61 

48.7 

21.8 

24.3 

23.3 

24.3 

32.7 

37.8 

62 

49.5 

22.2 

24.7 

23.7 

24.7 

33.3 

38.4 

63 

50.3 

22.5 

25.1 

24.1 

25.2 

33.8 

38.9 

64 

51.1 

22.9 

25.5 

24.5 

25.6 

34.3 

39.6 

65 

51.9 

23.3 

25.9 

24.9 

26.0 

34.9 

40.3 

66 

52.7 

23.7 

26.3 

25.3 

26.4 

35.5 

41.0 

67 

53.5 

24.0 

26.8 

25.7 

26.8 

36.1 

41.6 

68 

54.3 

24.4 

27.2 

26.1 

27.2 

36.6 

42.2 

69 

55.1 

24.8 

27.6 

26.4 

27.6 

37.2 

42.9 

70 

55.9 

25.2 

28.0 

26.9 

28.1 

37.7 

43.5 

71 

56.7 

25.6 

28.4 

27.3 

28.5 

38.3 

44.2 

72 

57.5 

25.9 

28.8 

27.6 

28.9 

38.9 

44.8 

73 

58.3 

26.3 

29.2 

28.0 

29.3 

39.4 

45.4 

74 

59.1 

26.7 

29.6 

28.4 

29.6 

40.0 

46.1 

75 

59.9 

27.0 

30.1 

28.8 

30.1 

40.5 

46.7 

76 

60.7 

27.4 

30.5 

29.2 

30.5 

41.1 

47.3 

77 

61.5 

27.8 

30.9 

29.6 

30.9 

41.7 

48.0 

78 

62.3 

28.2 

31.3 

30.0 

31.4 

42.2 

48.6 

79 

63.1 

28.5 

31.7 

30.4 

31.8 

42.8 

49.3 

48 


SUGAR  TABLES 


TABLE   16.     (Continued.) 
30  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 
(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose. 
C12H220U+H20 

Maltose 
C12H22On 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

80 

63.9 

28.9 

32.1 

30.8 

32.2 

43.3 

49.9 

81 

64.7 

29.3 

32.5 

31.2 

32.6 

43.9 

50.6 

82 

65.5 

29.7 

32.9 

31.6 

33.0 

44.5 

51.2 

83 

66.3 

30.1 

33.4 

32.0 

33.5 

45.0 

51.8 

84 

67.1 

30.4 

33.8 

32.4 

33.9 

45.6 

52.5 

85 

67.9 

30.8 

34.2 

32.8 

34.3 

46.1 

53.1 

86 

68.7 

31.2 

34.6 

33.2 

34.9 

46.7 

53.8 

87 

69.5 

31.6 

35.0 

33.6 

35.1 

47.3 

54.4 

88 

70.3 

32.0 

35.4 

34.0 

35.6 

47.8 

55.0 

89 

71.1 

32.3 

35.9 

34.4 

36.0 

48.4 

55.7 

90 

71.9 

32.7 

36.3 

34.8 

36.4 

48.9 

56.3 

91 

72.7 

33.1 

36.7 

35*2 

36.8 

49.5 

57.0 

92 

73.5 

33.5 

37.1 

35.6 

37.2 

50.1 

57.7 

:       93 

74.3 

33.9 

37.6 

36.0 

37.7 

50.6 

58.3 

94 

75.1 

34.3 

38.0 

36.4 

38.1 

51.2 

59.0 

95 

75.9 

34.6 

38.4 

36.8 

38.5 

51.7 

59.6 

96 

76.7 

35.0 

38.8 

37.2 

38.9 

52.3 

60.3 

(      97 

77.5 

35.4 

39.3 

37.6 

39.4 

52.9 

60.9 

98 

78.3 

35.8 

39.7 

38.0 

39.8 

53.4 

61.5 

99 

79.1 

36.2 

40.1 

38.4 

40.2 

54.0 

62.2 

100 

79.9 

36.6 

40.5 

38.8 

40.7 

54.5 

62.9 

101 

80.7 

37.0 

40.9 

39.2 

41.1 

55.1 

63.6 

102 

81.5 

37.4 

41.4 

39.7 

41.5 

55.7 

64.2 

103 

82.3 

37.7 

41.8 

40.2 

41.9 

56.2 

64.8 

104 

83.1 

38.1 

42.2 

40.5 

42.4 

56.8 

65.4 

105 

83.9 

38.5 

42.7 

40.9 

42.8 

57.4 

66.1 

106 

84.7 

38.9 

43.1 

41.3 

43.2 

58.0 

66.8 

107 

85.5 

39.3 

43.5 

41.7 

43.6 

58.6 

67.5 

108 

86.3 

39.7 

44.0 

42.1 

44.1 

59.1 

68.1 

109 

87.1 

40.1 

44.4 

42.5 

44.5 

59.7 

68.8 

110 

87.8 

40.4 

44.7 

42.8 

44.8 

60.2 

69.3 

111 

88.6 

40.7 

45.2 

43.2 

45.3 

60.8 

70.0 

112 

89.4 

41.1 

45.6 

43.6 

45.8 

61.4 

70.8 

113 

90.2 

41.5 

46.0 

44.0 

46.1 

61.9 

71.4 

114 

91.0 

41.9 

46.5 

44.4 

•46.6 

62.5 

72.0 

115 

91.8 

42.3 

46.9 

44.9 

47.0 

63.1 

72.7 

116 

92.6 

42.7 

47.2 

45.3 

47.4 

63.7 

73.3 

117 

93.4 

43.1 

47.7 

45.7 

47.9 

64.3 

74.0 

118 

94.2 

43.5 

48.2 

46.1 

48.3 

64.8 

74.6 

119 

95.0 

43.9 

48.6 

46.5 

48.7 

65.4 

75.3 

120 

95.8 

44.3 

49.0 

46.9 

49.2 

66.0 

75.9 

121 

96.6 

44.7 

49.5 

47.4 

49.6 

66.5 

76.7 

122 

97.4 

45.1 

49.9 

47.8 

50.0 

67.1 

77.3 

123 

98.2 

45.5 

50.3 

48.2 

50.5 

67.7 

78.0 

124 

99.0 

45.9 

50.8 

48.6 

50.9 

68.3 

78.6 

125 

99.8 

46.3 

51.2 

49.0 

51.4 

68.9 

79.3 

126 

100.6 

46.7 

51.7 

49.5 

51.8 

69.4 

80.0 

127 

101.4 

47.1 

52.1 

49.9 

52.2 

70.0 

80.6 

128 

102.2 

47.5 

52.5 

50.3 

52.7 

70.6 

81.3 

129 

103.0 

47.9 

53.0 

50.7 

53.1 

71.2 

81.9 

SUGAR   TABLES 


49 


TABLE  16.     (Continued.) 
30  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

c(°cpr 

Glucose. 

Fructose. 

Invert, 
sugar. 

Galactose 

Lactose 
CuHsAj+HjO 

Maltose 
CuH^O,, 

mgs. 

130 

mgs. 

103.8 

mgs. 
48.3 

mgs. 

53.4 

mgs. 

51.1 

mgs. 

53.6 

mgs. 

71.9 

mgs. 

82.7 

131 

104.6 

48.7 

53.9 

51.6 

54.0 

72.4 

83.3 

132 

105.4 

49.1 

54.3 

52.0 

54.4 

73.0 

83.9 

133 

106.2 

49.5 

54.7 

52.4 

54.9 

73.6 

84.6 

134 

107.0 

49.9 

55.2 

52.8 

55.3 

74.3 

85.2 

135 

107.8 

50.3 

55.6 

53.2 

55.8 

74.8 

86.0 

136 

108.6 

50.7 

56.1 

53.7 

56.2 

75.4 

86.6 

137 

109.4 

51.2 

56.5 

54.1 

56.6 

76.0 

87.2 

138 

110.2 

51.5 

56.9 

54.5 

57.1 

76.6 

87.8 

139 

111.0 

51.9 

57.4 

54.9 

57.5 

77.1 

88.6 

140 

111.8 

52.4 

57.9. 

55.4 

58.0 

77.8 

89.3 

141 

112.6 

52.8 

58.3 

55.8 

58.5 

78.3 

89.9 

142 

113.4 

53.2 

58.7 

56.2 

58.9 

78.9 

90.6 

143 

114.2 

53.6 

59.2 

56.7 

59.3 

79.5 

91.3 

144 

115.0 

54.0 

59.6 

57.1 

59.8 

80.1 

91.9 

145 

115.8 

54.4 

60.1 

57.5 

60.2 

80.7 

92.6 

146 

116.6 

54.8 

60.5 

57.9 

60.6 

81.3 

93.3 

147 

117.4 

55.2 

60.9 

58.3 

61.1 

81.9 

94.0 

148 

118.2 

55.6 

61.4 

58.8 

61.6 

82.5 

94.7 

149 

119.0 

56.0 

61.8 

59.2 

62.0 

83.1 

95.3 

150 

119.8 

56.5 

62.3 

59.7 

62.5 

83.7 

95.9 

151 

120.6 

56.9 

62.8 

60.1 

62.9 

84.3 

96.6 

152 

121.4 

57.3 

63.2 

60.5 

63.3 

84.9 

97.3 

153 

122.2 

57.7 

63.6 

60.9 

63.8 

85.5 

98.0 

154 

123.0 

58.1 

64.1 

61.4 

64.3 

86.1 

98.7 

155 

123.8 

58.5 

64.5 

61.8 

64.7 

86.7 

99.3 

156 

124.6 

59.0 

65.0 

62.3 

65.2 

87.3 

99.9 

157 

125.4 

59.4 

65.4 

62.7 

65.6 

87.9 

100.7 

158 

126.2 

59.8 

65.9 

63.1 

66.1 

88.5 

101.5 

159 

127.0 

60.2 

66.3 

63.5 

66.5 

89.1 

102.1 

160 

127.8 

60.6 

66.8 

64.0 

67.0 

89.7 

102.8 

161 

128.6 

61.0 

67.3 

64.4 

67.5 

90.3 

103.5 

162 

129.4 

61.4 

67.7 

64.8 

67.9 

90.9 

104.2 

163 

130.2 

61.9 

68.1 

65.2 

68.4 

91.5 

104.9 

164 

131.0 

62.3 

68.6 

65.7 

68.8 

92.1 

105.5 

165 

131.8 

62.7 

69.1 

66.2 

69.3 

92.7 

106.2 

166 

132.6 

63.2 

69.6 

66.7 

69.8 

93.2 

107.0 

167 

133.4 

63.6 

70.0 

67.1 

70.2 

93.9 

107.6 

168 

134.2 

64.0 

70.4 

67.5 

70.7 

94.5 

108.3 

169 

135.0 

64.4 

70.9 

67.9 

71.1 

95.1 

109.0 

170 

135.8 

64.8 

71.4 

68.4 

71.6 

95.8 

109.7 

171 

136.6 

65.3 

71.8 

68.8 

72.1 

96.3 

110.3 

172 

137.4 

65.7 

72.2 

69.2 

72.5 

96.9 

111.1 

173 

138.2 

66.1 

72.7 

69.7 

73.0 

97.5 

111.8 

174 

139.0 

66.6 

73.2 

70.2 

73.4 

98.1 

112.4 

175 

139.8 

67.0 

73.6 

70.6 

74.0 

98.8 

113.1 

176 

140.6 

67.4 

74.1 

71.0 

74.4 

99.4 

113.8 

177 

141.4 

67.8 

74.5 

71.4 

74.9 

100.0 

114.5 

178 

142.2 

68.3 

75.0 

71.9 

.  75.3 

100.6 

115.2 

179 

143.0 

68.7 

75.5 

72.4 

75.8 

101.2 

115.9 

50 


SUGAR  TABLES 


TABLE   16.     (Continued.) 
30  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

c(°cTr 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
CuHadu+HjO 

Maltose 
C12H22On 

mgs. 

mga. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

180 

143.8 

69.1 

76.0 

72.8 

76.3 

101.8 

116.5 

181 

144.6 

69.6 

76.4 

73.3 

76.7 

102.4 

117.2 

182 

145.4 

70.0 

76.8 

73.7 

77.1 

103.0 

118.0 

183 

-146.2 

70.4 

77.3 

74.1 

77.6 

103.6 

118.7 

184 

147.0 

70.9 

77.8 

74.6 

78.1 

104.2 

119.3 

185 

147.7 

71.3 

78.2 

75.0 

78.5 

104.8 

119.9 

186 

148.5 

71.7 

78.7 

75.5 

79.0 

105.4 

120.7 

187 

149.3 

72.2 

79.2 

76.0 

79.5 

105.9 

121.3 

188 

150.1 

72.6 

79.7 

76.4 

80.0 

106.6 

122.0 

189 

150.9 

73.0 

80.1 

76.8 

80.5 

107.3 

122.8 

190 

151.7 

73.4 

80.5 

77.2 

80.9 

107.9 

123.4 

191 

152.5 

73.9 

81.0 

77.7 

81.4 

108.5 

124.2 

192 

153.3 

74.3 

81.5 

78.2 

81.8 

109.0 

124.8 

193 

154.1 

74.8 

82.0 

78.7 

82.3 

109.7 

125.5 

194 

154.9 

75.2 

82.5 

79.1 

82.8 

110.3 

126.2 

195 

155.7 

75.6 

82.9 

79.5 

83.2 

111.0 

126.9 

196 

156.5 

76.1 

83.4 

80.0 

83.7 

111.6 

127.7 

197 

157.3 

76.6 

83.9 

80.5 

84.2 

112.2 

128.4 

198 

158.1 

77.0 

84.4 

81.0 

84.7 

112.8 

129.1 

199 

158.9 

77.5 

84.9 

81.5 

85.2 

113.4 

129.8 

200 

159.7 

77.9 

85.3 

81.9 

85.6 

114.1 

130.5 

201 

160.5 

78.3 

85.8 

82.3 

86.1 

114.7 

131.2 

202 

161.3 

78.8 

86.3 

82.8 

86.6 

115.3 

131.9 

203 

162.1 

79.3 

86.8 

83.3 

87.1 

116.0 

132.6 

204 

162.9 

79.7 

87.3 

83.8 

.87.6 

116.5 

133.3 

205 

163.7 

80.1 

87.7 

84.2 

88.0 

117.3 

134.0 

206 

164.5 

80.6 

88.2 

84.7 

88.5 

117.9 

134.8 

207 

165.3 

81.0 

88.7 

85.1 

89.0 

118.5 

135.4 

208 

166.1 

81.5 

89.2 

85.6 

89.5 

119.1 

136.1 

209 

166.9 

82.0 

89.7 

86.1 

90.0 

119.7 

136.8 

210 

167.7 

82.4 

90.1 

86.5 

90.5 

120.4 

137.5 

211 

168.5 

82.8 

90.6 

87.0 

91.0 

121.0 

138.3 

212 

169.3 

83.3 

91.1 

87.5 

91.5 

121.6 

138.9 

213 

170.1 

83.8 

91.6 

88.0 

92.0 

122.3 

139.7 

214 

170.9 

84.2 

92.1 

88.4 

92.5 

122.9 

140.3 

215 

171.7 

84.6 

92.5 

88.8 

92.9 

123.6 

141.1 

216 

172.5 

85.1 

93.0 

89.3 

93.4 

124.2 

141.9 

217 

173.3 

85.6 

93.5 

89.8 

93.9 

124.8 

142.5 

218 

174.1 

86.1 

94.0 

90.3 

94.4 

125.5 

143.3 

219 

174.9 

86.5 

94.5 

90.8 

94.9 

126.2 

144.0 

220 

175.7 

86.9 

94.9 

91.2 

95.3 

126.9 

144.7 

221 

176.5 

87.4 

95.5 

91.7 

95.8 

127.5 

145.5 

222 

177.3 

87.9 

96.0 

92.2 

96.4 

128.1 

146.1 

223 

178.1 

88.4 

96.5 

92.7 

96.9 

128.8 

146.9 

224 

178.9 

88.8 

97.0 

93.2 

97.4 

129.4 

147.6 

225 

179.7 

89.2 

97.4 

93.6 

97.8 

130.1 

148.3 

226 

180.5 

89.7 

97.9 

94.1 

98.3 

130.7 

149.1 

227 

181.3 

90.2 

98.5 

94.6 

98.8 

131.3 

149.7 

228 

182.1 

90.7 

99.0 

95.1 

99.4 

132.0 

150.5 

229 

182.9 

91.2 

99.5 

95.6 

99.9 

132.6 

151.2 

SUGAR  TABLES 


51 


TABLE   16.     (Continued.) 
30  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12H22On+H20 

Maltose 
Ci2H22On 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

230 

183.7 

91.6 

99.9 

96.0 

100.3 

133.3 

151.9 

231 

184.5 

92.1 

100.4 

96.5 

100.8 

133.9 

152.7 

232 

185.3 

92.6 

101.0 

97.1 

101.3 

134.6 

153.3 

233 

186.1 

93.1 

101.5 

97.6 

101.9 

135.3 

154.1 

234 

186.9 

93.5 

102.0 

98.1 

102.4 

135.9 

154.8 

235 

187.7 

93.9 

102.5 

98.5 

102.8 

136.6 

155.5 

236 

188.5 

94.5 

103.0 

99.0 

103.3 

137.2 

156.3 

237 

189.3 

94.9 

103.5 

99.5 

103.8 

137.8 

156.9 

238 

190.1 

95.4 

104.0 

100.0 

104.4 

138.5 

157.7 

239 

190.9 

95.9 

104.5 

100.5 

104.9 

139.1 

158.5 

240 

191.7 

96.3 

105.0 

100.9 

105.3 

139.8 

159.2 

241 

192.5 

96.8 

105.5 

101.4 

105.8 

140.5 

160.0 

242 

193.3 

97.3 

106.0 

101.9 

106.4 

141.1 

160.6 

243 

194.1 

97.8 

106.5 

102.4 

106.9 

141.8 

161.4 

244 

194.9 

98.3 

107.1 

103.0 

107.4 

142.5 

162.1 

245 

195.7 

98.7 

107.5 

103.4 

107.9 

143.2 

162.8 

246 

196.5 

99.2 

107.9 

103.9 

108.4 

143.8 

163.6 

247 

197.3 

99.7 

108.5 

104.4 

108.9 

144.4 

164.2 

248 

198.1 

100.2 

109.0 

104.9 

109.5 

145.1 

165.1 

249 

198.9 

100.7 

109.6 

105.4 

110.0 

145.8 

165.8 

250 

199.7 

101.1 

110.0 

105.8 

110.5 

146.5 

166.5 

251 

200.5 

101.7 

110.5 

106.3 

110.9 

147.1 

167.3 

252 

201.3 

102.2 

111.0 

106.9 

111.5 

147.7 

167.9 

253 

202.1 

102.7 

111.6 

107.4 

112.0 

148.5 

168.8 

254 

202.9 

103.2 

112.1 

107.9 

112.6 

149.1 

169.5 

255 

203.6 

103.6 

112.5 

108.3 

113.0 

149.7 

170.1 

256 

204.4 

104.0 

113.0 

108.8 

113.5 

150.4 

170.9 

257 

205.2 

104.5 

113.5 

109.3 

114.0 

151.1 

171.7 

258 

206.0 

105.0 

114.1 

109.8 

114.5 

151.7 

172.4 

259 

206.8 

105.6 

114.6 

110.4 

115.1 

152.3 

173.1 

260 

207.6 

106.1 

115.1 

110.9 

115.6 

153.0 

173.8 

261 

208.4 

106.5 

115.6 

111.3 

116.1 

153.7 

174.6 

262 

209.2 

107.0 

116.1 

111.8 

116.6 

154.4 

175.4 

263 

210.0 

107.5 

116.7 

112.4 

117.1 

155.0 

176.1 

264 

210.8 

108.1 

117.2 

112.9 

117.7 

155.7 

176.8 

265 

211.6 

108.6 

117.7 

113.4 

118.2 

156.4 

177.5 

266 

212.4 

109.0 

118.2 

113.9 

118.8 

157.1 

178.4 

267 

213.2 

109.5 

118.7 

114.4 

119.2 

157.8 

179.1 

268 

214.0 

110.1 

119.2 

114.9 

119.8 

158.4 

179.8 

269 

214.8 

110.6 

119.8 

115.5 

120.3 

159.1 

180.6 

270 

215.6 

111.1 

120.3 

116.0 

120.8 

159.8 

181.3 

271 

216.4 

111.5 

120.7 

116.4 

121.4 

160.5 

182.1 

272 

217.2 

112.1 

121.3 

117.0 

121.9 

161.2 

182.9 

273 

218.0 

112.6 

121.9 

117.5 

122  A 

161.8 

183.6 

274 

218.8 

113.2 

122.4 

118.1 

123.0 

162.5 

184.4 

275 

219.6 

113.7 

122.9 

118.6 

123.5 

163.2 

185.1 

276 

220.4 

114.1 

123.4 

119.0 

124.1 

163.9 

185.9 

277 

221.2 

114.6 

124.0 

119.6 

124.5 

164.6 

186.7 

278 

222.0 

115.2 

124.6 

120.2 

125.1 

165.2 

187.4 

279 

222.8 

115.7 

125.1     |     120.7 

125.7 

165.9 

188.2 

52 


SUGAR  TABLES 


TABLE   16.     (Continued.) 
30  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

C(85T 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12H220U+H20 

Maltose 
C12H220U 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

280 

223.6 

116.2 

125.6 

121.2 

126.2 

166.6 

188.9 

281 

224.4 

116.7 

126.1 

121.7 

126.8 

167.4 

189.7 

282 

225.2 

117.2 

126.7 

122.2 

127.3 

168.1 

190.5 

283 

226.0 

117.8 

127.2 

122.8 

127.8 

168.7 

191.2 

284 

226.8 

118.3 

127.8 

123.3 

128.4 

169.4 

192.0 

285 

227.6 

118.8 

128.3 

123.8 

128.9 

170.1 

192.7 

286 

228.4 

119.3 

128.8 

124.3 

129.5 

170.9 

193.5 

287 

229.2 

119.8 

129.4 

124.9 

130.0 

171.5 

194.3 

288 

230.0 

120.4 

130.0 

125.5 

130.5 

172.2 

195.1 

289 

230.8 

121.0 

130.5 

126.0 

131.1 

172.9 

195.8 

290 

231.6 

121.5 

131.0 

126.5 

131.6 

173.6 

196.5 

291 

232.4 

122.0 

131.5 

127.0 

132.2 

174.4 

197.4 

292 

233.2 

122.5 

132.1 

127.6 

132.7 

175.0 

198.1 

293 

234.0 

123.1 

132.7 

128.2 

133.3 

175.7 

198.9 

294 

234.8 

123.7 

133.3 

128.8 

133.9 

176.4 

199.7 

295 

235.6 

124.2 

133.8 

129.3 

134.4 

177.1 

200.4 

296 

236.4 

124.6 

134.3 

129.7 

135.0 

177.9 

201.2 

297 

237.2 

125.2 

134.9 

130.3 

135.5 

178.6 

202.0 

298 

238.0 

125.8 

135.5 

130.9 

136.1 

179.2 

202.7 

299 

238.8 

126.4 

136.0 

131.5 

136.7 

179.9 

203.5 

300 

239.6 

126.9 

136.5 

132.0 

137.2 

180.6 

204.2 

301 

240.4 

127.3 

137.0 

132.4 

137.8 

181.4 

205.1 

302 

241.2 

127.9 

137.6 

133.0 

138.3 

182.1 

205.8 

303 

242.0 

128.5 

138.2 

133.6 

138.9 

182.8 

206.6 

304 

242.8 

129.1 

138.8 

134.2 

139.5 

183.5 

207.4 

305 

243.6 

129.6 

139.3 

134.7 

140.0 

184.2 

208.1 

306 

244.4 

130.1 

139.8 

135.2 

140.6 

185.0 

208.9 

307 

245.2 

130.7 

140.4 

135.8 

141.1 

185.7 

209.7 

308 

246.0 

131.3 

141.0 

136.4 

141.7 

186.3 

210.5 

309 

246.8 

131.9 

141.6 

137.0 

142.3 

187.0 

211.3 

310 

247.6 

132.4 

142.1 

137.5 

142.8 

187.7 

212.0 

311 

248.4 

132.9 

142.6 

138.0 

143.4 

188.5 

212.8 

312 

249.2 

133.5 

143.2 

138.6 

143.9 

189.2 

213.6 

313 

250.0 

134.1 

143.8 

139.2 

144.5 

189.9 

214.4 

314 

250.8 

134.7 

144.4 

139.8 

145.1 

190.6 

215.2 

315 

251.6 

135.2 

144.9 

140.3 

145.6 

191.3 

215.9 

316 

252.4 

135.7 

145.4 

140.8 

146.3 

192.1 

216.8 

317 

253.2 

136.3 

146.1 

141.5 

146.8 

192.8 

217.6 

318 

254.0 

136.9 

146.7 

142.1 

147.4 

193.5 

218.3 

319 

254.8 

137.5 

147.3 

142.7 

148.0 

194.3 

219.1 

320 

255.6 

138.0 

147.8 

143.2 

148.5 

195.0 

219.8 

321 

256.4 

138.5 

148.3 

143.7 

149.2 

195.8 

220.7 

322 

257.2 

139.2 

148.9 

144.3 

149.7 

196.5 

221.5 

323 

258.0 

139.8 

149.5 

144.9 

150.3 

197.2 

222.3 

324 

258.8 

140.4 

150.1 

145.5 

150.9 

197.9 

223.1 

325 

259.6 

140.9 

150.6 

146.0 

151.4 

198.6 

223.8 

326 

260.4 

141.4 

151.1 

146.5 

152.1 

199.4 

224.7 

327 

261.2 

142.1 

151.7 

147.2 

152.6 

200.1 

225.5 

328 

262.0 

142.7 

152.3 

147.8 

153.2 

200.8 

226.3 

SUGAR   TABLES 


53 


TABLE  16.    (Continued.) 
50  c.c.  Fehl ing's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 
(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose. 
C^H^On+HjO 

Maltose 
C12H22On 

nigs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs.    • 

126 

100.6 

44.9 

49.4 

47.5 

49.8 

71.8 

83.4 

127 

101.4 

45.3 

49.8 

47.9 

50.2 

72.4 

84.0 

128 

102.2 

45.7 

50.3 

48.3 

50.6 

73.0 

84.6 

129 

103.0 

46.1 

50.7 

48.7 

51.0 

73.6 

85.4 

130 

103.8 

46.4 

51.1 

49.1 

51.4 

74.2 

86.0 

131 

104.6 

46.8 

51.5 

49.5 

51.8 

74.7 

86.7 

132 

105.4 

47.2 

51.9 

49.9 

52.2 

75.4 

87.4 

133 

106.2 

47.6 

52.3 

50.3 

52.6 

75.9 

88.0 

134 

107.0 

48.0 

52.7 

50.7 

53.1 

76.5 

88.8 

135 

107.8 

48.3 

53.1 

51.1 

53.5 

77.1 

89.4 

136 

108.6 

48.7 

53.5 

51.5 

53.9 

77.7 

90.1 

137 

109.4 

49.1 

54.0 

51.9 

54.3 

78.3 

90.8 

138 

110.2 

49.5 

54.4 

52.3 

54.7 

78.8 

91.4 

139 

111.0 

49  .-8 

54.8 

52.6 

55.1 

79.4 

92.2 

140 

111.8 

50.2 

55.2 

53.0 

55.6 

80.1 

92.8 

141 

112.6 

50.6 

55.6 

53.4 

56.0 

80.6 

93.5 

142 

113.4 

51.0 

56.0 

53.8 

56.4 

81.2 

94.2 

143 

114.2 

51.3 

56.4 

54.2 

56.8 

81.8 

94.8 

144 

115.0 

51.7 

56.8 

54.6 

57.2 

82.4 

95.6 

145 

115.8 

52.1 

57.3 

55.0 

57.6 

83.0 

96.2 

146 

116.6 

52.5 

57.7 

55.4 

58.0 

83.6 

96.9 

147 

117.4 

52.9 

58.1 

55.8 

58.5 

84.2 

97.6 

148 

118.2 

53.2 

58.5 

56.2 

58.9 

84.7 

98.2 

149 

119.0 

53.6 

58.9 

56.6 

59.3 

85.4 

99.0 

150 

119.8 

54.0 

59.3 

57.0 

59.7 

86.0 

99.6 

151 

120.6 

54.4 

59.7 

57.4 

60.1 

86.5 

100.3 

152 

121.4 

54.8 

60.1 

57.8 

60.5 

87.1 

101.0 

153 

122.2 

55.1 

60.6 

58.2 

61.0 

87.7 

101.7 

154 

123.0 

55.5 

61.0 

58.6 

61.4 

88.3 

102.4 

155 

123.8 

55.9 

61.4 

59.0 

61.8 

89.0 

103.1 

156 

124.6 

56.3 

61.8 

59.4 

62.2 

89.5 

103.8 

157 

125.4 

56.7 

62.2 

59.8 

62.6 

90.1 

104.4 

158 

126.2 

57.0 

62.6 

60.1 

63.0 

90.6 

105.1 

159 

127.0 

57.4 

63.1 

60.5 

63.5 

91.3 

105.8 

160 

127.8 

57.8 

63.5 

60.9 

63.9 

91.9 

106.5 

161 

128.6 

58.2 

63.9 

61.3 

64.3 

92.5 

107.2 

162 

129.4 

58.6 

64.3 

61.7 

64.7 

93.1 

107.9 

163 

130.2 

58.9 

64.7 

62.1 

65.1 

93.6 

108.5 

164 

131.0 

59.3 

65.2 

62.5 

65.6 

94.2 

109.3 

165 

131.8 

59.7 

65.6 

62.9 

66.0 

94.9 

109.9 

166 

132.6 

60.1 

66.0 

63.3 

66.4 

95.4 

110.6 

167 

133.4 

60.5 

66.4 

63.7 

66.8 

96.0 

111.3 

168 

134.2 

60.9 

66.8 

64.1 

67.3 

96.6 

112.0 

169 

135.0 

61.2 

67.2 

64.5 

67.7 

97.2 

112.6 

170 

135.8 

61.6 

67.7 

64.9 

68.1 

97.8 

113.4 

171 

136.6 

62.0 

68.1 

65.3 

68.5 

98.4 

114.1 

172 

137.4 

62.4 

68.5 

65.7 

68.9 

99.0 

114.7 

173 

138.2 

62.8 

68.9 

66.1 

69.4 

99.5 

115.4 

174 

139.0 

63.2 

69.3 

66.5 

69.8 

100.2 

116.2 

54 


SUGAR  TABLES 


TABLE   16.     (Continued.) 
50  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert, 
sugar. 

Galactose. 

Lactose 
CwHaOu+HjO 

Maltose 
C,,HaOu 

'    mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

175 

139.8 

63.6 

69.7 

66.9 

70.2 

100.8 

116.8 

176 

140.6 

63.9 

70.2 

67.3 

70.6 

101.4 

117.5 

177 

141.4 

64.3 

70.6 

67.7 

71.1 

102.0 

118.2 

178 

142.2 

64.7 

71.0 

68.1 

71.5 

102.5 

118.8 

179 

143.0 

65.1 

71.4 

68.5 

71.9 

103.2 

119.6 

180 

143.8 

65.5 

71.9 

69.0 

72.3 

103.8 

120.3 

181 

144.6 

65.9 

72.3 

69.4 

72.8 

104.4 

121.0 

182 

145.4 

66.3 

72.6 

.  69.8 

73.2 

105.0 

121.7 

183 

146.2 

66.7 

73.1 

70.2 

73.6 

105.5 

122.3 

184 

147.0 

67.1 

73.6 

70.6 

74.0 

106.2 

123.1 

185 

147.7 

67.4 

74.0 

71.0 

74.4 

106.7 

123.7 

186 

148.5 

67.8 

74.4 

71.4 

74.9 

107.3 

124.4 

187 

149.3 

68.2 

74.8 

71.8 

75.3 

107.9 

125.1 

188 

150.1 

68.6 

75.3 

72.2 

75.7 

108.5 

125.8 

189 

150.9 

69.0 

75.7 

72.6 

76.2 

109.1 

126.4 

190 

151.7 

69.4 

76.1 

73.0 

76.6 

109.7 

127.1 

191 

152.5 

69.8 

76.5 

73.4 

77.0 

110.3 

127.8 

192 

153.3 

70.2 

77.0 

73.8 

77.4 

110.9 

128.5 

193 

154.1 

70.6 

77.4 

74.3 

77.9 

111.5 

129.2 

194 

154.9 

71.0 

77.8 

74.7 

78.3 

112.1 

129.9 

195 

155.7 

71.4 

78.1 

75.1 

78.7 

112.7 

130.6 

196 

156.5 

71.8 

78.6 

75.5 

79.2 

113.3 

131.3 

197 

157.3 

72.1 

79.1 

75.9 

79.6 

113.9 

132.0 

198 

158.1 

72.5 

79.5 

76.3 

80.0 

114.5 

132.7 

199 

158.9 

72.9 

79.9 

76.7 

80.5 

115.1 

133.3 

200 

159.7 

73.3 

80.3 

77.1 

80.9 

115.7 

134.0 

201 

160.5 

73.7 

80.8 

77.5 

81.3 

116.3 

134.8 

202 

161.3 

74.1 

81.2 

77.9 

81.7 

116.8 

135.5 

203 

162.1 

74.5 

81.6 

78.3 

82.2 

117.5 

136.1 

204 

162.9 

74.9 

82.1 

78.8 

82.6 

118.1 

136.8 

205 

163.7 

75.3 

82.5 

79.2 

83.0 

118.7 

137.5 

206 

164.5 

75.7 

82.9 

79.6 

83.5 

119.3 

138.3 

207 

165.3 

76.1 

83.4 

80.0 

83.9 

119.9 

139.0 

208 

166.1 

76.5 

83.8 

80.4 

84.3 

120.5 

139.6 

209 

166.9 

76.9 

84.2 

80.8 

84r.8 

121.1 

140.3 

210 

167.7 

77.3 

84.6 

81.2 

85.2 

121.7 

141.0 

211 

168.5 

77.7 

85.1 

81.7 

85.6 

122.3 

141.7 

212 

169.3 

78.1 

85.5 

82.1 

86.1 

122.9 

142.4 

213 

170.1 

78.5 

86.0 

82.5 

86.5 

123.5 

143.1 

214 

170.9 

78.9 

86.4 

82.9 

87.0 

124.1 

143.8 

215 

171.7 

79.3 

86.8 

83.3 

87.4 

124.7 

144.5 

216 

172.5 

79.7 

87.2 

83.7 

87.8 

125.3 

145.2 

217 

173.3 

80.1 

87.7 

84.2 

88.2 

125.9 

145.9 

218 

174.1 

80.5 

88.1 

84.6 

88.7 

126.5 

146.6 

219 

174.9 

80.9 

88.6 

85.0 

89.1 

127.1 

147.3 

220 

175.7 

81.3 

89.0 

85.4 

89.5 

127.7 

148.0 

221 

176.5 

81.7 

89.4 

85.8 

90.0 

128.3 

148.8 

222 

177.3 

82.1 

89.8 

86.4 

90.4 

128.9 

149.5 

223 

178.1 

82.5 

90.3 

86.7 

90.9 

129.5 

150.1 

SUGAR  TABLES 


55 


TABLE  16.     (Continued.) 
50  c.c.  Fehling's  Solution. 


Cnpric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C^H^On+H^O 

Maltose 
Ci2H22On 

ings 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

224 

178.9 

82.9 

90.7 

87.1 

91.3 

130.1 

150.8 

225 

179.7 

83.3 

91.1 

87.5 

91.7 

130.7 

151.5 

226 

180.5 

83.7 

91.6 

87.9 

92.2 

131.3 

152.3 

227 

181.3 

84.1 

92.0 

88.3 

92.6 

131.9 

153.0 

228 

182.1 

84.5 

92.5 

88.8 

93.1 

132.5 

153.6 

229 

182.9 

84.9 

92.9 

89.2 

93.5 

133.1 

154.3 

230 

183.7 

85.3 

93.3 

89.6 

93.9 

133.7 

155.0 

231 

184.5 

85.7 

93.8 

90.0 

94.4 

134.3 

155.8 

232 

185.3 

86.1 

94.2 

90.4 

94.8 

134.9 

156.5 

233 

186.1 

86.5 

94.7 

90.9 

95.3 

135.5 

157.2 

234 

186.9 

86.9 

95.1 

91.3 

95.7 

136.1 

157.8 

235 

187.7 

87.3 

95.5 

91.7 

96.1 

136.7 

158.5 

236 

188.5 

87.7 

96.0 

92.1 

96.6 

137.3 

159.3 

237 

189.3 

88.1 

96.4 

92.6 

97.0 

137.9 

160.0 

238 

190.1 

88.5 

96.9 

93.0 

97.5 

138.6 

160.7 

239 

190.9 

88.9 

97.3 

93.4 

97.9 

139.2 

161.4 

240 

191.7 

89.3 

97.7 

93.8 

98.3 

139.8 

162.1 

241 

192.5 

89.6 

98.1 

94.2 

98.7 

140.4 

162.8 

242 

193.3 

90.2 

98.6 

94.7 

99.2 

141.0 

163.5 

243 

194.1 

90.6 

99.1 

95.1 

99.7 

141.6 

164.2 

244 

194.9 

91.0 

99.5 

95.5 

100.2 

142.2 

164.9 

245 

195.7 

91.4 

99.9 

95.9 

100.6 

142.8 

165.6 

246 

196.5 

91.8 

100.4 

96.4 

101.1 

143.4 

166.3 

247 

197.3 

92.2 

100.8 

96.8 

101.5 

144.0 

167.0 

248 

198.1 

92.6 

101.3 

97.2 

101.9 

144.6 

167.7 

249 

198.9 

93.0 

101.7 

97.6 

102.2 

145.4 

168.4 

250 

199.7 

93.4 

102.1 

98.0 

102.6 

145.9 

169.1 

251 

200.5 

93.8 

102.6 

98.5 

103.2 

146.5 

169.8 

252 

201.3 

94.3 

103.0 

98.9 

103.7 

147.1 

170.6 

253 

202.1 

94.7 

103.5 

99.4 

104.2 

147.7 

171.3 

254 

202.9 

95.1 

103.9 

99.8 

104.6 

148.3 

172.0 

255 

203.6 

95.4 

104.3 

100.1 

105.0 

148.9 

172.6 

256 

204.4 

95.8 

104.7 

100.5 

105.4 

149.5 

173.3 

257 

205.2 

96.2 

105.1 

100.9 

105.8 

150.1 

174.0 

258 

206.0 

96.6 

105.6 

101.4 

106.3 

150.7 

174.7 

259 

206.8 

97.1 

106.1 

101.9 

106.8 

151.3 

175.4 

260 

207.6 

97.5 

106.5 

102.3 

107.2 

152.0 

176.1 

261 

208.4 

97.9 

106.9 

102.7 

107.6 

152.6 

176.9 

262 

209.2 

98.3 

107.4 

103.1 

108.1 

153.2 

177.6 

263 

210.0 

98.7 

107.9 

103.6 

108.5 

153.8 

178.3 

264 

210.8 

99.1 

108.3 

104.0 

109.0 

154.4 

179.0 

265 

211.6 

99.5 

108.7 

104.4 

109.4 

155.0 

179.7 

266 

212  A 

99.9 

109.2 

104.8 

109.9 

155.6 

180.4 

267 

213.2 

100.4 

109.6 

105.3 

110.3 

156.3 

181.2 

268 

214.0 

100.8 

110.1 

105.7 

110.8 

156.9 

181.9 

269 

214.8 

101.2 

110.6 

106.2 

111.3 

157.5 

182.6 

270 

215.6 

101.6 

111.0 

106.6 

111.7 

158.1 

183.3 

271 

216.4 

102.0 

111.4 

107.0 

112.1 

158.7 

184.0 

272 

217.2 

102.5 

111.9 

107.5 

112.6 

159.4 

184.7 

56 


SUGAR  TABLES 


TABLE  16.     (Continued.) 
50  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

c(°cpur 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C^H^On+H^ 

Maltose 
C12H220U 

nigs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

273 

218.0 

102.9 

112.3 

107.9 

113.1 

160.0 

185.4 

274 

218.8 

103.3 

112.8 

108.3 

113.5 

160.5 

186.1 

275 

219.6 

103.7 

113.2 

108.7 

113.9 

161.2 

186.8 

276 

220.4 

104.1 

113.7 

109.2 

114.4 

161.8 

187.6 

277 

221.2 

104.5 

114.1 

109.6 

114.9 

162.5 

188.3 

278 

222.0 

105.0 

114.6 

110.1 

115.3 

163.1 

189.0 

279 

222.8 

105.4 

115.1 

110.5 

115.8 

163.6 

189.7 

280 

223.6 

105.8 

115.5 

110.9 

116.2 

164.3 

190.4 

281 

224.4 

106.2 

115.9 

111.3 

116.7 

164.9 

191.2 

282 

225.2 

106.7 

116.4 

111.8 

117.1 

165.6 

191.9 

283 

226.0 

107.1 

116.9 

112.3 

117.6 

166.2 

192.6 

284 

226.8 

107.5 

117.4 

112.7 

118.1 

166.8 

193.3 

285 

227.6 

107.9 

117.8 

113.1 

118.5 

167.4 

194.0 

286 

228.4 

108.3 

118.2 

113.5 

118.9 

168.0 

194.8 

287 

229.2 

108.8 

118.7 

114.0 

119.4 

168.7 

195.5 

288 

230.0 

109.2 

119.2 

114.5 

119.9 

169.3 

196.2 

289 

230.8 

109.6 

119.6 

114.9 

120.4 

169.9 

196.9 

290 

231.6 

110.1 

120.1 

115.4 

120.8 

170.6 

197.6 

291 

232.4 

110.5 

120.5 

115.8 

121.2 

171.2 

198.4 

292 

233.2 

110.9 

121.0 

116.2 

121.7 

171.8 

199.1 

293 

234.0 

111.3 

121.4 

116.6 

122.2 

172.4 

199.8 

294 

234.8 

111.8 

121.9 

117.1 

122.7 

173.0 

200.5 

295 

235.6 

112.2 

122.4 

117.6 

123.1 

173.7 

201.2 

296 

236.4 

112.6 

122.8 

118.0 

123.5 

174.3 

202.0 

297 

237.2 

113.0 

123.3 

118.4 

124.0 

174.9 

202.7 

298 

238.0 

113.5 

123.7 

118.9 

124.5 

175.5 

203.4 

299 

238.8 

113.9 

124.2 

119.3 

125.0 

176.1 

204.1 

300 

239.6 

114.3 

124.7 

119.8 

125.5 

176.8 

204.8 

301 

240.4 

114.7 

125.1 

120.2 

125.9 

177.4 

205.6 

302 

241.2 

115.2 

125.5 

120.6 

126.3 

178.1 

206.3 

303 

242.0 

115.6 

126.0 

121.1 

126.8 

178.7 

207.0 

304 

242.8 

116.1 

126.5 

121.6 

127.3 

179.2 

207.7 

305 

243.6 

116.5 

127.0 

122.0 

127.8 

179.9 

208.4 

306 

244.4 

116.9 

127.4 

122.4 

128.2 

180.5 

209.2 

307 

245.2 

117.3 

127.9 

122.9 

128.7 

181.2 

209.9 

308 

246.0 

117.8 

128.3 

123.3 

129.1 

181.8 

210.6 

309 

246.8 

118.2 

128.8 

123.8 

129.6 

182.4 

211.3 

310 

247.6 

118.6 

129.2 

124.2 

130.0 

183.0 

212.0 

311 

248.4 

119.1 

129.7 

124.7 

130.5 

183.6 

212.8 

312 

249.2 

119.5 

130.2 

125.1 

131.0 

184.3 

213.6 

313 

250.0 

119.9 

130.7 

125.6 

131.5 

184.9 

214.3 

314 

250.8 

120.4 

131.2 

126.1 

132.0 

185.5 

215.0 

315 

251.6 

120.8 

131.6 

126.5 

132.4 

186.2 

215.7 

316 

252.4 

121.2 

132.0 

126.9 

132.9 

186.8 

216.5 

317 

253.2 

121.7 

132.5 

127.4 

133.3 

187.4 

217.2 

318 

254.0 

122.1 

133.0 

127.8 

133.8 

188.0 

217.9 

319 

254.8 

122.6 

133.5 

128.3 

134.3 

188.6 

218.6 

320 

255.6 

123.0 

133.9 

128.7 

134.7 

189.3 

219.3 

321 

256.4 

123.4 

134.4 

129.2 

135.2 

189.9 

220.1 

322 

257.2 

123.9 

134.8 

129.6 

135.7 

190.6 

220.8 

SUGAR  TABLES 


57 


TABLE  16.     (Continued.) 
50  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

CSer 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
CwHaOu+Btf) 

Maltose 
C12H22On 

323' 

nags. 

258.0 

mgs. 

124.3 

nags. 

135.3 

rags. 

130.1 

mgs. 

136.2 

mgs. 
191.2 

mgs. 

221.5 

324 

258.8 

124.8 

135.8 

130.6 

136.7 

191.7 

222.2 

325 

259.6 

125.2 

136.2 

131.0 

137.1 

192.4 

222.9 

326 

260.4 

125.6 

136.7 

131.4 

137.6 

193.0 

223.7 

327 

261.2 

126.1 

137.2 

131.9 

138.1 

193.7 

224.5 

328 

262.0 

126.5 

137.7 

132.4 

138.6 

194.3 

225.2 

329 

262.7 

126.9 

138.1 

132.8 

139.0 

194.9 

225.8 

330 

263.5 

127.4 

138.6 

133.3 

139.4 

195.5 

226.6 

331 

264.3 

127.8 

139.0 

133.7 

139.9 

196.1 

227.3 

332 

265.1 

128.3 

139.5 

134.2 

140.4 

196.8 

228.0 

333 

265.9 

128.7 

140.0 

134.6 

140.9 

197.3 

228.7 

334 

266.7 

129.1 

140.4 

135.0 

141.3 

198.0 

229.4 

335 

267.5 

129.6 

140.9 

135.5 

141.8 

198.6 

230.6 

336 

268.3 

130.1 

141.4 

136.0 

142.3 

199.2 

231.0 

337 

269.1 

130.5 

141.9 

136.5 

142.8 

199.9 

231.7 

338 

269.9 

131.0 

142.4 

137.0 

143.3 

200.5 

232.4 

339 

270.7 

131.4 

142.8 

137.4 

143.7 

201.1 

233.1 

340 

271.5 

131.8 

143.3 

137.8 

144.2 

201.8 

233.9 

341 

272.3 

132.3 

143.8 

138.3 

144.7 

202.4 

234.6 

342 

273.1 

132.7 

144.3 

138.8 

145.2 

203.1 

235.3 

343 

273.9 

133.2 

144.8 

139.3 

145.7 

203.7 

236.1 

344 

274.7 

133.6 

145.2 

139.7 

146.1 

204.3 

236.8 

345 

275.5 

134.1 

145.7 

140.2 

146.6 

205.0 

237.6 

346 

276.3 

134.5 

146.2 

140.6 

147.1 

205.6 

238.3 

347 

277.1 

135.0 

146.7 

141.1 

147.6 

206.3 

239.0 

348 

277.9         135.5 

147.1 

141.6 

148.1 

206.9 

239.7 

349 

278.7 

135.9 

147.5 

142.0 

148.5 

207.6 

240.4 

350 

279.5 

136.3 

148.0 

142.4 

149.0 

208.2 

241.3 

351 

280.3 

136.8 

148.5 

142.9 

149.5 

208.8 

242.0 

352 

281.1 

137.3 

149.0 

143.4 

150.0 

209.5 

242.7 

353 

281.9 

137.7 

149.5 

143.9 

150.5 

210.1 

243.4 

354 

282.7 

138.1 

149.9 

144.3 

150.9 

210.8 

244.1 

355 

283.5 

138.6 

150.4 

144.8 

151.4 

211.4 

245.0 

356 

284.3 

139.1 

150.9 

145.3 

151.9 

212.0 

245.7 

357 

285.1 

139.5 

151.4 

145.7 

152.5 

212.7 

246.4 

358 

285.9 

140.0 

151.9 

146.2 

153.0 

213.3 

247.1 

359 

286.7 

140.4 

152.3 

146.6 

153.4 

214.0 

247.8 

360 

287.5 

140.9 

152.8 

147.1 

153.9 

214.6 

248.7 

361 

288.3 

141.3 

153.3 

147.6 

154.4 

215.2 

249.4 

362 

289.1 

141.8 

153.8 

148.1 

154.9 

215.9 

250.1 

363 

289.9 

142.3 

154.3 

148.6 

155.4 

216.5 

250.9 

364 

290.7 

142.7 

154.7 

149.0 

155.8 

217.2 

251.6 

365 

291.5 

143.2 

155.2 

149.5 

156.3 

217.8 

252.4 

366 

292.3 

143.6 

155.8 

150.0 

156.8 

218.4 

253.1 

367 

293.1 

144.1 

156.3 

150.5 

157.3 

219.1 

253.8 

368 

293.9 

144.6 

156.8 

151.0 

157.8 

219.7 

254.6 

369 

294.7 

145.0         157.2 

151.4         158.2 

220.4 

255.3 

58 


SUGAR  TABLES 


TABLE  16.     (Continued.} 
50  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 

sugar. 

Galactose 

Lactose. 
C12H22On+H20 

Maltose 
Ci2H22On 

nigs. 

mgs. 

nags. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

370 

295.5 

145.4 

157.7 

151.8 

158.8 

221.0 

256.1 

371 

296.3 

145.9 

158.2 

152.3 

159.3 

221.6 

256.8 

372 

297.1 

146.4 

158.7 

152.8 

159.8 

222.3 

257.6 

373 

297.9 

146.9 

159.2 

153.3 

160.3 

222.9 

258.3 

374 

298.7 

147.3 

159.6 

153.7 

160.7 

223.6 

259.0 

375 

299.5 

147.8 

160.1 

154.2 

161.2 

224.2 

259.8 

376 

300.3 

148.2 

160.6 

154.7 

161.7 

224.8 

260.5 

377 

301.1 

148.7 

161.1 

155.2 

162.3 

225.5 

261.3 

378 

301.9 

149.2 

161.7 

155.7 

162.8 

226.1 

262.0 

379 

302.7 

149.6 

162.1 

156.1 

163.2 

226.8 

262.7 

380 

303.5 

150.1 

162.6 

156.6 

163.7 

227.4 

263.5 

381 

304.3 

150.6 

163.1 

157.1 

164.2 

228.0 

264.3 

382 

305.1 

151.0 

163.6 

157.6 

164.7 

228.8 

265.0 

383 

305.9 

151.5 

164.1 

158.1 

165.3 

229.4 

265.7 

384 

306.7 

151.9 

164.5 

158.5 

165.7 

230.1 

266.4 

385 

307.5 

152.4 

165.1 

159.0 

166.2 

230.7 

267.3 

386 

308.3 

152.9 

165.6 

159.5 

166.7 

231.3 

268.0 

387 

309.1 

153.4 

166.1 

160.0 

167.2 

232.0 

268.7 

388 

309.9 

153.9 

166.6 

160.5 

167.7 

232.6 

269.5 

389 

310.7 

154.3 

167.0 

160.9 

168.1 

233.3 

270.2 

390 

311.5 

154.8 

167.5 

161.4 

168.7 

233.9 

271.0 

391 

312.3 

155.3 

168.0 

161.9 

169.2 

234.5 

271.8 

392 

313.1 

155.7 

168.6 

162.4 

169.7 

235.2 

272.5 

393 

313.9 

156.2 

169.1 

162.9 

170.2 

235.8 

273.2 

394 

314.7 

156.6 

169.5 

163.3 

170.6 

236.5 

274.0 

395 

315.5 

157.1 

170.0 

163.8 

171.2 

237.2 

274.8 

396 

316.3 

157.6 

170.5 

164.3 

171.7 

237.8 

275.5 

397 

317.0 

158.0 

170.9 

164.7 

172.1 

238.4 

276.2 

398 

317.8 

158.5 

171.5 

165.3 

172.6 

239.0 

276.9 

399 

318.6 

159.0 

172.0 

165.8 

173.1 

239.7 

277.6 

400 

319.4 

159.4 

172.4 

166.2 

173.6 

240.3 

278.4 

401 

320.2 

159.9 

172.9 

166.7 

174.1 

241.0 

279.2 

402 

321.0 

160.4 

173.4 

167.2 

174.6 

241.6 

279.9 

403 

321.8 

160.9 

174.0 

167.7 

175.2 

242.2 

280.7 

404 

322.6 

161.4 

174.5 

168.2 

175.7 

242.9 

281.4 

405 

323.4 

161.8 

174.9 

168.6 

176.2 

243.6 

282.2 

406 

324.2 

162.3 

175.4 

169.1 

176.6 

244.3 

282.9 

407 

325.0 

162.8 

176.0 

169.7 

177.2 

244.9 

283.7 

408 

325.8 

163.3 

176.5 

170.2 

177.7 

245.5 

284.4 

409 

326.6 

163.8 

177.0 

170.7 

178.2 

246.2 

285.2 

410 

327.4 

164.2 

177.5 

171.1 

178.7 

246.9 

286.0 

411 

328.2 

164.7 

178.0 

171.6 

179.2 

247.6 

286.7 

412 

329.0 

165.2 

178.5 

172.1 

179.7 

248.2 

287.5 

413 

329.8 

165.7 

179.0 

172.6 

180.2 

248.8 

288.2 

414 

330.6 

166.2 

179.5 

173.1 

180.7 

249.5 

289.0 

415 

331.4 

166.6 

180.0 

173.6 

181.2 

250.1 

289.8 

416 

332.2 

167.1 

180.5 

174.1 

181.7 

250.8 

290.5 

417 

333.0 

167.6 

181.0 

174.6 

182.3 

251.5 

291.3 

418 

333.8 

168.1 

181.6 

175.1 

182.8 

252.1 

292.0 

419 

334.6 

168.6 

182.1 

175.6 

183.3 

252.8 

292.8 

SUGAR   TABLES 


59 


TABLE  16.     (Continued.) 
50  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert, 
sugar. 

Galactose. 

Lactose 
CuH^On+H^ 

Maltose 
CuH^On 

mgs. 

420 

mgs. 

335.4 

mgs. 

169.1 

mgs. 

182.5 

mgs. 

176.1 

mgs. 

183.8 

mgs. 

253.4 

mgs. 

293.6 

421 

336.2 

169.6 

183.0 

176.6 

184.3 

254.1 

294.3 

422 

337.0 

170.1 

183.6 

177.1 

184.8 

254.7 

295.1 

423 

337.8 

170.6 

184.1 

177.6 

185.4 

255.4 

295.8 

424 

338.6 

171.1 

184.6 

178.1 

185.9 

256.1 

296.6 

425 

339.4 

171.5 

185.0 

178.6 

186.4 

256.7 

297.4 

426 

340.2 

172.0 

185.6 

179.1 

186.9 

257.4 

298.1 

427 

341.0 

172.5 

186.1 

179.6 

187.4 

258.0 

298.9 

428 

341.8 

173.1 

186.6 

180.1 

188.0 

258.6 

299.6 

429 

342.6 

173.6 

187.1 

180.6 

188.5 

259.3 

300.4 

430 

343.4 

174.0 

187.6 

181.1 

189.0 

260.0 

301.2 

431 

344.2 

174.5 

188.1 

181.6 

189.5 

260.7 

301.9 

432 

345.0 

175.0 

188.7 

182.1 

190.0 

261.3 

302.7 

433 

345.8 

175.5 

189.2 

182.6 

190.6 

261.9 

303.4 

434 

346.6 

176.0 

189.7 

183.1 

191.1 

262.6 

304.2 

435 

347.4 

176.5 

190.2 

183.6 

191.6 

263.3 

305.0 

436 

348.2 

177.0 

190.7 

184.1 

192.1 

264.0 

305.7 

437 

349.0 

177.5 

191.3 

184.7 

192.6 

264.6 

306.5 

438 

349.8 

178.0 

191.8 

185.2 

193.2 

265.2 

307.3 

439 

350.6 

178.5 

192.3 

185.7 

193.7 

265.9 

308.0 

440 

351.4 

179.0 

192.8 

186.2 

194.2 

266.6 

308.8 

141 

352.2 

179.5 

193.3 

186.7 

194.7 

267.3 

309.5 

442 

353.0 

180.0 

193.8 

187.2 

195.2 

267.9 

310.3 

443 

353.8 

180.5 

194.4 

187.7 

195.8 

268.5 

311.1 

444 

354.6 

181.0 

194.9 

188.2 

196.3 

269.2 

311.8 

445 

355.4 

181.5 

195.4 

188.7 

196.8 

269.9 

312.6 

446 

356.2 

182.0 

195.9 

189  2 

197.3 

270.6 

313.5 

447 

357.0 

182.5 

196.4 

189.7 

197.9 

271.2 

314.2 

448 

357.8 

183.1 

197.0 

190.3 

198.4 

271.8 

315.0 

449 

358.6 

183.6 

197.5 

190.8 

198.9 

272.5 

315.7 

450 

359.4 

184.0 

198.0 

191.3 

199.4 

273.2 

316.5 

451 

360.2 

184.5 

198.5 

191.8 

199.9 

273.9 

317.2 

452 

361.0 

185.1 

199.0 

192.3 

200.5 

274.5 

318.0 

453 

361.8 

185.6 

199.6 

192.9 

201.1 

275.2 

318.8 

454 

362.6 

186.1 

200.1 

193.4 

201.6 

275.9 

319.6 

455 

363.4 

186.6 

200.7 

193.9 

202.1 

276.6 

320.3 

456 

364.2 

187.1 

201.1 

194.4 

202.6 

277.3 

321.1 

457 

365.0 

187.6 

201.7 

194.9 

203.3 

277.9 

321.9 

458 

365.8 

188.2 

202.3 

195.5 

203.7 

278.5 

322.6 

459 

366.6 

188.7 

202.8 

196.0 

204.2 

279.2 

323.4 

460 

367.4 

189.1 

203.3 

196.5 

204.8 

279.9 

324.2 

461 

368.2 

189.6 

203.8 

197.0 

205.3 

280.6 

325.0 

462 

369.0 

190.2 

204.3 

197.5 

205.8 

281.3 

325.7 

463 

369.8 

190.7 

204.9 

198.1 

206.4 

281.9 

326.5 

464 

370.6 

191.2 

205.4 

198.6 

206.9 

282.6 

327.3 

465 

371.4 

191.7 

206.0 

199.2 

207.5 

283.3 

328  :i 

466 

372.2 

192.2 

206.4 

199.6 

208.0 

284.0 

328.8 

467 

373.0 

192.8 

207.0 

200.2 

208.5 

284.6 

329.6 

468 

373.7 

193.2 

207.5 

200.6 

209.0 

285.2 

330.3 

469 

374.5 

193.8 

208.1 

201.2 

209.6 

285.9 

331.1 

60 


SUGAR  TABLES 


TABLE   16.     (Continued.) 
50  c.c.  Fehling's  Solution. 


Cupric 
oxide 
(CuO). 

c(°cpr 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
C12HM0U+H20 

Maltose 
C^H^On 

nigs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

470 

375.3 

194.3 

208.5 

201.7 

210.1 

286.5 

331.8 

471 

376.1 

194.8 

209.1 

202.2 

210.7 

287.2 

332.6 

472 

376.9 

195.3 

209.6 

202.7 

211.1 

287.9 

333.4 

473 

377.7 

195.8 

210.2 

203.2 

211.7 

288.6 

334.1 

474 

378.5 

196.4 

210.7 

203.8 

212.3 

289.2 

334.9 

475 

379.3 

196.9 

211.2 

204.3 

212.8 

289.9 

335.7 

476 

380.1 

197.4 

211.8 

204.9 

213.4 

290.6 

336.5 

477 

380.9 

197.9 

212.2 

205.3 

213.8 

291.3 

337.3 

478 

381.7 

198.5 

212.8 

205.9 

214.4 

292.0 

338.0 

479 

382.5 

199.0 

213.4 

206.5 

215.0 

292.7 

338.8 

480 

383.3 

199.5 

213.9 

207.0 

215.5 

293.3 

339.6 

481  * 

384.1 

200.1 

214.5 

207.6 

216.1 

294.0 

340.4 

482 

384.9 

200.5 

215.0 

208.0 

216.6 

294.7 

341.2 

483 

385.7 

201.1 

215.5 

208.6 

217.2 

295.4 

342.0 

484 

386.5 

201.7 

216.1 

209.2 

217.8 

296.1 

342.8 

485 

387.3 

202.2 

216.6 

209.7 

218.3 

296.7 

343.5 

486 

388.1 

202.7 

217.2 

210.2 

218.8 

297.4 

344.3 

487 

388.9 

203.2 

217.7 

210.7 

219.3 

298.1 

345.1 

488 

389.7 

203.8 

218.3 

211.3 

219.9 

298.8 

345.9 

489 

390.5 

204.3 

218.9 

211.9 

220.5 

299.5 

346.7 

490 

391.3 

204.8 

219.4 

212.4 

221.0 

300.1 

347.5 

491 

392.1 

205.4 

219.8 

212.9 

221.6 

300.8  . 

348.2 

492 

392.9 

205.9 

220.4 

213.4 

222.1 

301.5 

349.0 

493 

393.7 

206.5 

221.0 

214.0 

222.7 

302.2 

349.8 

494 

394.5 

207.0 

221.6 

214.6 

223.3 

302.9 

350.6 

495 

395.3 

207.5 

222.1 

215.1 

223.8 

303.5 

351.4 

496 

396.1 

208.1 

222.7 

215.7 

224.4 

304.2 

352.2 

497 

396.9 

208.6 

223.2 

216.2 

224.9 

304.9 

352.9 

498 

397.7 

209.2 

223.7 

216.7 

225.5 

305.6 

353.7 

499 

398.5 

209.7 

224.3 

217.3 

226.1 

306.3 

354.5 

500 

399.3 

210.2 

224.8 

217.8 

226.6 

306.9 

355.3 

501 

400.1 

210.8 

225.4 

218.4 

227.2 

307.6 

356.1 

502 

400.9 

211.3 

225.9 

218.9 

227.7 

308.3 

356.9 

503 

401.7 

211.9 

226.5 

219.5 

228.3 

309.0 

357.7 

504 

402.5 

212.5 

227.2 

220.1 

228.9 

309.7 

358.5 

505 

403.3 

213.0 

227.6 

220.6 

229.4 

310.3 

359.2 

506 

404.1 

213.6 

228.2 

221.2 

230.0 

311.0 

360.0 

507 

404.9 

214.0 

228.7 

221.6 

230.5 

311.7 

360.8 

508 

405.7 

214.6 

229.3 

222.2 

231.1 

312.4 

361.6 

509 

406.5 

215.2 

229.9 

222.8 

231.7 

313.1 

362.4 

510 

407.3 

215.7 

230.4 

223.3 

232.3 

313.7 

363.2 

511 

408.1 

216.3 

231.0 

223.9 

232.8 

314.4 

364.0 

512 

408.9 

216.8 

231.5 

224.4 

233.3 

315.1 

364.8 

513 

409.7 

217,4 

232.1 

225.0 

233.9 

315.8 

365.6 

514 

410.5 

218.0 

232.7 

225.6 

234.5 

316.5 

366.4 

515 

411.3 

218.5 

233.2 

226.1 

235.0 

317.1 

367.1 

516 

412.1 

219.1 

233.8 

226.7 

235.6 

317.8 

367.9 

517 

412.9 

219.6 

234.3 

227.2 

236.2 

318.5 

368.7 

518 

413.7 

220.2 

234.9 

227.8 

236.8 

319.2 

369.5 

519 

414.5 

220.8 

235.5 

228.4 

237.4 

319.9 

370.3 

SUGAR  TABLES 


61 


TABLE   16.     (Concluded.) 
50  c.c.  Fehling's  Solution. 


Copper 
oxide 
(CuO). 

Copper 

(Cu). 

Glucose. 

Fructose. 

Invert 
sugar. 

Galactose. 

Lactose 
CuH^Ou+HiO 

Maltose 
CuHjAi 

ings. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

520 

415.3 

221.3 

236.0 

228.9 

237.9 

320.6 

371.1 

521 

416.1 

221.9 

236.6 

229.5 

238.5 

321.3 

371.9 

522 

416.9 

222.4 

237.1 

230.0 

239.0 

321.9 

372.7 

523 

417.7 

223.0 

237.7 

230.6 

239.6 

322.6 

373.5 

524 

418.5 

223.6 

238.3 

231.2 

240.2 

323.3 

374.3 

525 

419.3 

224.2 

238.8 

231.7 

240.7 

323.9 

375.1 

526 

420.1 

224.7 

239.5 

232.4 

241.3 

324.7 

375.9 

527 

420.9 

225.2 

240.0 

233.0 

241.9 

325.4 

376.7 

528 

421.7 

225.8 

240.6 

233.5 

242.5 

326.1 

377.5 

529 

422.5 

226.4 

241.2 

234.1 

243.1 

326.8 

378.3 

530 

423.3 

227.0 

241.7 

234.6 

243.6 

327.4 

379.1 

531 

424.1 

227.6 

242.3 

235.2 

244.2 

328.1 

379.9 

532 

424.9 

228.1 

242.9 

235.8 

244.8 

328.9 

380.7 

533 

425.7 

228.7 

243.5 

236.4 

245.4 

329.6 

381.5 

534 

426.4 

229.2 

244.0 

236.9 

245.9 

330.2 

382.2 

535 

427.2 

229.7 

244.5 

237.4 

246.5 

330.9 

383.0 

536 

428.0 

230.3 

245.1 

238.0 

247.1 

331.6 

383.8 

537 

428.8 

230.9 

245.7 

238.6 

247.6 

332.2 

384.6 

538 

429.6 

231.5 

246.3 

239.2 

248.2 

332.9 

385.4 

539 

430.4 

232.1 

246.9 

239.8 

248.8 

333.7 

386.2 

540 

431.2 

232.6 

247.4 

240.3 

249.4 

334.4 

387.0 

541 

432.0 

233.2 

248.0 

240.9 

250.0 

335.1 

387.8 

542 

433.8 

233.8 

248.6 

241.5 

250.6 

335.7 

388.6 

543 

434.6 

234.4 

249.2 

242.1 

251.2 

336.4 

389.4 

62 


SUGAR  TABLES 


TABLE*  17. 

BROWN,  MORRIS  AND  MILLAR'S  TABLE  FOR  DETERMINING  GLUCOSE,  FRUCTOSE 

AND  INVERT  SUGAR. 


Milligrams 
of  sugar. 

Glucose. 

Fructose. 

Invert  sugar. 

%T 

Cupric 
oxide 
(CuO). 

?cT 

Cupric 
oxide 
(CuO). 

%T 

Cupric 
oxide 
(CuO). 

grams. 

grams. 

grams. 

grams. 

grams.  . 

grams. 

50 

0.1030 

0  1289 

0.0923 

0.1155 

0.0975 

0.1221 

55 

0.1134 

O!l422 

0.1027 

0.1287 

0.1076 

0.1349 

60 

0.1238 

0.1552 

0.1122 

0.1407 

0.1176 

0.1474 

65 

0.1342 

0.1682 

0.1216 

0.1524 

0.1275 

0.1598 

70 

0.1443 

0.1809 

0.1312 

0.1645 

0.1373 

0.1721 

75 

0.1543 

0.1935 

0.1405 

0.1761 

0.1468 

0.1840 

80 

0.1644 

0.2061 

0.1500 

0.1881 

0.1566 

0.1963 

85 

0.1740 

0.2187 

0.1590 

0.1993 

0.1662 

0.2084 

90 

0.1834 

0.2299 

0.1686 

0.2114 

0.1755 

0.2200 

95 

0.1930 

0.2420 

0.1774 

0.2224 

0.1848 

0.2317 

100 

0.2027 

0.2538 

0.1862 

0.2331 

0.1941 

0.2430 

105 

0.2123 

0.2662 

0.1952 

0.2447 

0.2034 

0.2550 

110 

0.2218 

0.2781 

0.2040 

0.2558 

0.2128 

0.2668 

115 

0.2313 

0.2900 

0.2129 

0.2669 

0.2220 

0.2783 

120 

0.2404 

0.3014 

0.2215 

0.2777 

0.2311 

0.2898 

125 

0.2496 

0.3130 

0.2303 

0.2887 

0.2400 

0.3009 

130 

0.2585 

0.3241 

0.2390 

0.2997 

0.2489 

0.3121 

135 

0.2675 

0.3354 

0.2477 

0.3106 

0.2578 

0.3232 

140 

0.2762 

0.3463 

0.2559 

0.3209 

0.2663 

0.3339 

145 

0.2850 

0.3573 

0.2641 

0.3311 

0.2750 

0.3448 

150 

0.2934 

0.3673 

0.2723 

0.3409 

0.2832 

0.3546 

155 

0.3020 

0.3787 

0.2805 

0.3517 

0.2915 

0.3655 

160 

0.3103 

0.3891 

0.2889 

0.3622 

0.3002 

0.3764 

165 

0.3187 

0.3996 

0.2972 

0.3726 

0.3086 

0  3869 

170 

0.3268 

0.4098 

0.3053 

0.3828 

0.3167 

0.3971 

175 

0.3350 

0.4200 

0.3134 

0.3930 

0.3251 

0.4076 

180 

0.3431 

0.4302 

0.3216 

0.4032  ' 

0.3331 

0.4177 

185 

0.3508 

0.4399 

0.3297 

0.4134 

0.3410 

0.4276 

190 

0.3590 

0.4501 

0.3377 

0.4234 

0.3490 

0.4376 

195 

0.3668 

0.4599 

0.3457 

0.4335 

0.3570 

0.4476 

200 

0.3745 

0.4689 

0.3539 

0.4431 

0.3650 

0.4570 

205 

0.3822 

0.4792 

0.3616 

0.4534 

0.3726 

0.4672 

*  See  "  Handbook,"  page  425. 


SUGAR  TABLES 


63 


TABLE*   18. 
DEFREN'S  TABLE  FOR  DETERMINING  GLUCOSE,  MALTOSE  AND  LACTOSE. 


Cupric 
oxide. 
(CuO). 

Glucose. 

Maltose. 

Lactose. 

Cupric 
oxide. 
(CuO). 

Glucose. 

Maltose. 

Lactose. 

nigs. 

nigs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

30 

13.2 

21.7 

18.8 

83 

36.8 

60.3 

52.4 

31 

13.7 

22.4 

19.5 

84 

37.2 

61.1 

53.0 

32 

14.1 

23.1 

20.1 

85 

37.7 

61.8 

53.6 

33 

14.6 

23.9 

20.7 

86 

38.1 

62.5 

54.3 

34 

15.0 

24.6 

21.4 

87 

38.5 

63.3 

54.9 

35 

15.4 

25.3 

22.0 

88 

39.0 

64.0 

55.5 

36 

15.9 

26.1 

22.6 

89 

39.4 

64.7 

56.2 

37 

16.3 

26.8 

23.3 

90 

39.9 

65.5 

56.8 

38 

16.8 

27.5 

23.9 

91 

40.3 

66.2 

57.4 

39 

17.2 

28.3 

24.5 

92 

40  .-8 

66.9 

58.1 

40 

17.6 

29.0 

25.2 

93 

41.2 

67.7 

58.7 

41 

18.1 

29.7 

25.8 

94 

41.7 

68.4 

59.3 

42 

18.5 

30.5 

26.4 

95 

42.1 

69.1 

60.0 

43 

19.0 

31.2 

27.1 

96 

42.5 

69:9 

60.6 

44 

19.4 

31.9 

27.7 

97 

43.0 

70.6 

61.2 

45 

19.9 

32.7 

28.3 

98 

43.4 

71.3 

61.9 

46 

20.3 

33.4 

29.0 

99 

43.9 

72.1 

62.5 

47 

20.7 

34.1 

29.6 

100 

44.4 

72.8 

63.2 

48 

21.2 

34.8 

30.2 

101 

44.8 

73.5 

63.8 

49 

21.6 

35.5 

30.8 

102 

45.3 

74.3 

64.4 

50 

22.1 

36.2 

31.5 

103 

45.7 

75.0 

65.1 

51 

22.5 

37.0 

32.1 

104 

46.2 

75.7 

65.7 

52 

23.0 

37.7 

32.7 

105 

46.6 

76.5 

66.3 

53 

23.4 

38.4 

33.3 

106 

47.0 

77.2 

67.0 

54 

23.8 

39.2 

34.0 

107 

47.5 

77.9 

67.6 

55 

24.2 

39.9 

34.6 

108 

48.0 

78.7 

68.2 

56 

24.7 

40.5 

35.2 

109 

48.4 

79.4 

68.9 

57 

25.1 

41.3 

35.9 

110 

48.9 

80.1 

69.5 

58 

25.5 

42.1 

36.5 

111 

49.3 

80.9 

70.1 

59 

26.0 

42.8 

37.1 

112 

49.8 

81.6 

70.8 

60 

26.4 

43.5 

37.8 

113 

50.2 

82.3 

71.4 

61 

26.9 

44.3 

38.4 

114 

50.7 

83.1 

72.0 

62 

27.3 

45.0 

39.0 

115 

51.1 

83.8 

72.7 

63 

27.8 

45.7 

39.7 

116 

51.6 

84.5 

73.3 

64 

28.2 

46.5 

40.3 

117 

52.0 

85.2 

74.0 

65 

28.7 

47.2 

40.9 

118 

52.4 

85.9 

74.6 

66 

29.1 

47.9 

41.6 

119 

52.9 

86.6 

75.2 

67 

29.5 

48.6 

42.2 

120 

53.3 

87.4 

75.9 

68 

30.0 

49.4 

42.8 

121 

53.8 

88.1 

76.6 

69 

30.4 

50.1 

43.5 

122 

54.2 

88.9 

77.2 

70 

30.9 

50.8 

44.1 

123 

54.7 

89.6 

77.9 

71 

31.3 

51.6 

44.7 

124 

55.1 

90.3 

78.5 

72 

31.8 

52.3 

45.4 

125 

55.6 

91.1 

79.1 

73 

32.2 

53.0 

46.0 

126 

56.0 

91.8 

79.8 

74 

32.6 

53.8 

46.6 

127 

56.5 

92.5 

80.4 

75 

33.1 

54.5 

47.3 

128 

56.9 

93.3 

81.1 

76 

33.5 

55.2 

47.9 

129 

57.3 

94.0 

81.7 

77 

34.0 

56.0 

48.5 

130 

57.8 

94.8 

82.4 

78 

34.4 

56.7 

49.2 

131 

58.2 

95.5 

83.0 

79 

34.9 

57.4 

49.8 

132 

58.7 

96.2 

83.6 

80 

35.4 

58.1 

50.5 

133 

59.1 

97.0 

84.2 

81 

35.9 

58.9 

51.1 

134 

59.6 

97.7 

84.9 

82 

36.3 

59.6 

51.7 

135 

60.0 

98.4 

85.5 

*  See  "  Handbook,"  page  425. 


64 


SUGAR  TABLES 


TABLE  18.     (Continued.) 


Cupric 
oxide 
(CuO)~ 

Glucose. 

Maltose. 

Lactose. 

Cupric 
oxide 
(CuO). 

Glucose. 

Maltose. 

Lactose. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

136 

60.5 

99.2 

86.1 

190 

84.9 

139.1 

121.0 

137 

60.9 

99.9 

86.8 

191 

85.4 

139.9 

121.7 

138 

61.3 

100.7 

87.4 

192 

85.9 

140.6 

122.3 

139 

61.8 

101.4 

88.1 

193 

86.3 

141.4 

123.0 

140 

62.2 

102.1 

88.7 

194 

86.8 

142.1 

123.6 

141 

62.7 

102.8 

89.3 

195 

87.2 

142.8 

124.3 

142 

63.1 

103.5 

90.0 

196 

87.7 

143.6 

124.9 

143 

63.6 

104.3 

90.6 

197 

88.1 

144.3 

125.6 

144 

64.0 

105.0 

91.3 

198 

88.6 

145.1 

126.2 

145 

64.5 

105.8 

91.9 

199 

89.0 

145.8 

126.9 

146 

64.9 

106.5 

92.6 

200 

89.5 

146.6 

127.5 

147 

65.4 

107.2 

93.2 

201 

89.9 

147.3 

128.2 

148 

65.8 

108.0 

93.9 

202 

90.4 

148.1 

128.8 

149 

66.3 

108.7 

94.5 

203 

90.8 

148.8 

129.5 

150 

66.8 

109.5 

95.2 

204 

91.3 

149.6 

130.1 

151 

67.3 

110.2 

95.8 

205 

91.7 

150.3 

130.8 

152 

67.7 

111.0 

96.5 

206 

92.2 

151.1 

131.5 

153 

68.3 

111.7 

97.1 

207 

92.6 

151.8 

132.1 

154 

68.7 

112.4 

97.8 

208 

93.1 

152.5 

132.8 

155 

69.2 

113.2 

98.4 

209 

93.5 

153.3 

133.4 

156 

69.6 

113.9 

99.1 

210 

94.0 

154.1 

134.1 

157 

70.0 

114.7 

99.7 

211 

04.4 

154.8 

134.7 

158 

70.5 

115.4 

100.4 

212 

94.9 

155.6 

135.4    ' 

159 

70.9 

116.1 

101.0 

213 

95.3 

156.3 

136.0 

160 

71.3 

116.9 

101.7 

214 

95.8 

157.1 

136.7 

161 

71.8 

117.6 

102.3 

215 

96.3 

157.8 

137.3 

162 

72.3 

118.4 

103.0 

216 

96.7 

158.6    ' 

138.0 

163 

72.7 

119.1 

103.6 

217 

97.2 

159.3 

138.6 

164 

73.2 

119.9 

104.3 

218 

97.6 

160.0 

139.3 

165 

73.6 

120.6 

104.9 

219 

98.1 

160.8 

139.9 

166 

74.1 

121.4 

105.6 

220 

98.6 

161.5 

140.6 

167 

74.5 

122.1 

106.2 

221 

99.0 

162.3 

141.2 

168 

74.9 

122.9 

106.9 

222 

99.5 

163.0 

141.9 

169 

75.4 

123.6 

107.5 

223 

99.9 

163.7 

142.5 

170 

75.8 

124.4 

108.2 

224 

100.4 

164.5 

143.2 

171 

76.3 

125.1 

108.8 

225 

100.9 

165.3 

143.8 

172 

76.8 

125.8 

109.5 

226 

101.3 

166.0 

144.5 

173 

77.3 

126.6 

110.1 

227 

101.8 

166.8 

145.1 

174 

77.7 

127.3 

110.8 

228 

102.2 

167.5 

145.8 

175 

78.2 

128.1 

111.4 

229 

102.7 

168.3 

146.4 

176 

78.6 

128.8 

112.0 

230 

103.1 

169.1 

147.0 

177 

79.1 

129.5 

112.6 

231 

103.6 

169.8 

147.7 

178 

79.5 

130.3 

113.3 

232 

104.0 

170.6 

148.3 

179 

80.0 

131.0 

113.9 

233 

104.5 

171.3 

149.0 

180 

80.4 

131.8 

114.6 

234 

105.0 

172.1 

149.6 

181 

80.8 

132.5 

115.2 

235 

105.4 

172.8 

150.3 

182 

81.3 

133.2 

115.8 

236 

105.9 

173.6 

150.9 

183 

81.8 

134.0 

116.5 

237 

106.3 

174.3 

151.6 

184 

82.2 

134.7 

117.1 

238 

106.8 

175.1 

152.2 

185 

82.7 

135.5 

117.8 

239 

107.2 

175.8 

152.9 

186 

83.1 

136.2 

118.4 

240 

107.7 

176.6 

153.5 

187 

83.5 

136.9 

119.1 

241 

108.1 

177.3 

154.2 

188 

84.0 

137.7 

119.7 

242 

108.6 

178.1 

154.8 

189 

84.4 

138.4 

120.4 

243 

109.0 

178.8 

155.5 

SUGAR   TABLES 


65 


TABLE   18.     (Concluded.') 


Cupric 
oxide 

Glucose. 

Maltose. 

Lactose. 

Cupric 
oxide 

Glucose. 

Maltose. 

Lactose. 

(CuO). 

(CuO). 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

244 

109.5 

179.6 

156.1 

283 

127.4 

209.0 

181,5 

245 

109.9 

180.3 

156.8 

284 

127.9 

209.8 

182.2 

246 

110.4 

181.1 

157.4 

285 

128.3 

210.5 

182.9 

247 

110.9 

181.8 

158.1 

286 

128.8 

211.3 

183.6 

248 

111.3 

182.6 

158.7 

287 

129.3 

212.1 

184.2 

249 

111.8 

183.3 

159.4 

288 

129.7 

212.8 

184.9 

250 

112.3 

184.1 

160.0 

289 

130.2 

213.6 

185.6 

251 

112.7 

184.8 

160.7 

290 

130.6 

214.3 

186.2 

252 

113.2 

185.5 

161.3 

291 

131.1 

215.1 

186.9 

253 

113.7 

186.3 

162.0 

292 

131.5 

215.9 

187.6 

254 

114.1 

187.1 

162.6 

293 

132.0 

216.6 

188.2 

255 

114.6 

187.8 

163.3 

294 

132.5 

217  A 

188.9 

256 

115.0 

188.6 

163.9 

295 

133.0 

218.2 

189.5 

257 

115.5 

189.3 

164.6 

296 

133.4 

218.9 

190.2 

258 

116.0 

190.1 

165.2 

297 

133.9 

219.7 

190.8 

259 

116.4 

190.8 

165.9 

298 

134.3 

220.4 

191.5 

260 

116.9 

191.6 

166.5 

299 

134.8 

221.2 

192.1 

261 

117.3 

192.4 

167.2 

300 

135.3 

221.9 

192.8 

262 

117.8 

193.1 

167.8 

301 

135.7 

222.7 

193.4 

263 

118.3 

193.9 

168.1 

302 

136.2 

223.5 

194.1 

264 

118.7 

194.6 

169.5 

303 

136.6 

224.2 

194.7 

265 

119.2 

195.4 

169.8 

304 

137.1 

225.0 

195.3 

266 

119.6 

196.1 

170.4 

305 

137.6 

225.8 

196.0 

267 

120.1 

196.9 

171.1 

306 

138.0 

226.5 

196.6 

268 

120.6 

197.7 

171.7 

307 

138.5 

227.3 

197.3 

269 

121.0 

198.4 

172.4 

308 

138.9 

228.1 

197.9 

270 

121.4 

199.2 

173.0 

309 

139.4 

228.8 

198.6 

271 

121.9 

199.9 

173.7 

310 

139.9 

229.6 

199.3 

272 

122.4 

200.7 

174.4 

311 

140.3 

230.4 

199.9 

273 

122.8 

201.5 

175.0 

312 

140.8 

231.1 

200.6 

274 

123.3 

202.2 

175.7 

313 

141.2 

231.9 

201.3 

275 

123.7 

203.0 

176.3 

314 

141.7 

232.7 

202.0 

276 

124.2 

203.7 

177.0 

315 

142.2 

233.4 

202.6 

277 

124.6 

204.5 

177.6 

316 

142.6 

234.2 

203.3 

278 

125.1 

205.2 

178.3 

317 

143.1 

234.9 

203.9 

279 

125.6 

206.0 

178.9 

318 

143.6 

235.7 

204.6 

280 

126.1 

206.8 

179.6 

319 

144.0 

236.5 

205.3 

281 

126.5 

207.5 

180.2 

320 

144.5 

237.2 

205.9 

282 

127.0 

208.3 

180.9 

66 


SUGAR  TABLES 


TABLE*  19. 

MUNSON  AND  WALKER'S  TABLE  FOR  DETERMINING  GLUCOSE,  INVERT  SUGAR 

ALONE,  INVERT  SUGAR  IN  THE  PRESENCE  OF  SUCROSE  (0.4  GRAM  AND 

2  GRAMS  TOTAL  SUGAR),  LACTOSE  AND  MALTOSE. 


1 

I 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

I 

S 

f 

1 

3 

1 

q 

q 

o 

a 

<t> 

Is 

^ 

+=  c 

0 

+ 

<5 

+ 

1 

§ 

1 

c 

1* 

el 

g  » 

u 

j 

• 
n 

2 

d> 

1 

1 

o 

B 

0 

m 

o 

0 

w 

0 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

10 

8.9 

4.0 

4.5 

1.6 

3.8 

4.0 

5.9 

6.2 

11 

9.8 

4.5 

5.0 

2.1 

4.5 

4.7 

6.7 

7.0 

12 

10.7 

4.9 

5.4 

2.5 



5.1 

5.4 

7.5 

7.9 

13 

11.5 

5.3 

5.8 

3.0 

5.8 

6.1 

8.3 

8.7 

14 

12^4 

5.7 

6.3 

3.4 

6.4 

Q.S 

9.1 

9.5 

15 

13.3 

6.2 

6.7 

3.9 

7.1 

7.5 

9.9 

10.4 

16 

14.2 

6.6 

7.2 

4.3 

7.8 

8.2 

10.6 

11.2 

17 

15.1 

7.0 

7.6 

4.8 

8.4 

8.9 

11.4 

12.0 

18 

16.0 

7.5 

8.1 

5.2 

9.5 

12.2 

12.9 

19 

7.9 

8.5 

5.7 

9.7 

10.2 

13.0 

13.7 

20 

17.8 

8  3 

8  9 

6  1 

10  4 

10  9 

13.8 

14  6 

21 

18.7 

8.7 

9.4 

6.6 

11.0 

11.6 

14.6 

15.4 

22 

19.5 

9.2 

9.8 

7.0 



11.7 

12.3 

15.4 

16.2 

23 

20.4 

9.6 

10.3 

7.5 



12.3 

13.0 

16.2 

17.1 

24 

21.3 

10.0 

10.7 

7.9 

13  0 

13.7 

17.0 

17.9 

25 

22  2 

10.5 

11.2 

8  4 

13  7 

14  4 

17.8 

18.7 

26 

23.1 

10.9 

11.6 

8.8 

14.3 

15.1 

18.6 

19.6 

27 

24.0 

11.3 

12.0 

9.3 

15.0 

15.8 

19.4 

20.4 

28 

24.9 

11.8 

12.5 

9.7 

15.6 

16  5 

20.2 

21.2 

29 

25.8 

12.2 

12.9 

10.2 

16.3 

17.1 

21.0 

22.1 

30 

26.6 

12.6 

13.4 

10.7 

4.3 

16.9 

17.8 

21.8 

22.9 

31 

27.5 

13.1 

13.8 

11.1 

4.7 

17.6 

18.5 

22.6 

23.7 

32 

28.4 

13.5 

14.3 

11.6 

5.2 

18.3 

19.2 

23.3 

24.6 

33 

29.3 

13.9 

14.7 

12.0 

5.6 

18.9 

19.9 

24.1 

25.4 

34 

30.2 

14.3 

15.2 

12.5 

6.1 

19.6 

20.6 

24.9 

26.2 

35 

31.1 

14.8 

15.6 

12.9 

6.5 

20.2 

21.3 

25.7 

27.1 

36 

32.0 

15.2 

16.1 

13.4 

7.0 

20.9 

22.0 

26.5 

27.9 

37 

32.9 

15.6 

16.5 

13.8 

7.4 

21.5 

22.7 

27.3 

28.7 

38 

33.8 

16.1 

16.9 

14.3 

7.9 

22.2 

23.4 

28.1 

29.6 

39 

34.6 

16.5 

17.4 

14.7 

8.4 

22.8 

24.1 

28.9 

30.4 

40 

35.5 

16.9 

17.8 

15.2 

8.8 

23.5 

24.8 

29.7 

31.3 

41 

36.4 

17.4 

18.3 

15.6 

9.3 

24.2 

25.4 

30.5 

32.1 

42 

37.3 

17.8 

18.7 

16.1 

9.7 

24.8 

26.1 

31.3 

32.9 

43 

38.2 

18.2 

19.2 

16.6 

10.2 

25.5 

26.8 

32.1 

33.8 

44 

39.1 

18.7 

19.6 

17.0 

10.7 

26.1 

27.5 

32.9 

34.6 

*  See  "  Handbook,"  page  426. 


SUGAR  TABLES 


67 


TABLE  19.     (Continued.') 


1 

1 

Invert  sugar, 
and  sucrose. 

Lactose. 

Maltose. 

€ 

s 

1 

1 

i 

1 

_ 

q 

q 

1 

1 

1 

3  . 

8:1 

•a 

4 

m 

4 

m 
+ 

| 

6 

I 

^e 

II 

ii 

w 

1 

H 

3 

o 

I 

1 

•* 
d 

M 

<M 

o 

:H 

0 

0 

0 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

45 

40.0 

19.1 

20.1 

17.5 

11.1 

26.8 

28.2 

33.7 

35.4 

46 

40.9 

19.6 

20.5 

17.9 

11.6 

27.4 

28.9 

34.4 

36.3 

47 

41.7 

20.0 

21.0 

18.4 

12.0 

28.1 

29.6 

35.2 

37.1 

48 

42.6- 

20.4 

21.4 

18.8 

12.5 

28.7 

30.3 

36.0 

37.9 

49 

43.5 

20.9 

21.9 

19.3 

12.9 

29.4 

31.0 

36.8 

38.8 

50 

44.4 

21.3 

22.3 

19.7 

13.4 

30.1 

31.7 

37.6 

39.6 

51 

45.3 

21.7 

22.8 

20.2 

13.9 

30.7 

32.4 

38.4 

40.4 

52 

46.2 

22.2 

23.2 

20.7 

14.3 

31.4 

33.0 

39.2 

41.3 

53 

47.1 

22.6 

23.7 

21.1 

14.8 

32.1 

33.7 

40.0 

42.1 

54 

48.0 

23.0 

24.1 

21.6 

15.2 

32.7 

34.4 

40.8 

42.9 

55 

48.9 

23.5 

24.6 

22.0 

15.7 

33.4 

35.1 

41.6 

43.8 

56 

49.7 

23.9 

25.0 

22.5 

16.2 

34.0 

35.8 

42.4 

44.6 

57 

50.6 

24.3 

25.5 

22.9 

16.6 

34.7 

36.5 

43.2 

45.4 

58 

51.5 

24.8 

25.9 

23.4 

17.1 

35.4 

37.2 

44.0 

46.3 

59 

52.4 

25.2 

26.4 

23.9 

17.5 

36.0 

37.9 

44.8 

47.1 

60 

53.3 

25.6 

26.8 

24.3 

18.0 

36.7 

38.6 

45.6 

48.0 

61 

54.2 

26.1 

27.3 

24.8 

18.5 

37.3 

39.3 

46.3 

48.8 

62 

55.1 

26.5 

27.7 

25.2 

18.9 

38.0 

40.0 

47.1 

49.6 

63 

56.0 

27.0 

28.2 

25.7 

19.4 

38.6 

40.7 

47.9 

50.5 

64 

56.8 

27.4 

28.6 

26.2 

19.8 

39.3 

41.4 

48.7 

51.3 

65 

57.7 

27.8 

29.1 

26.6 

20.3 

40.0 

42.1 

49.5 

52.1 

66 

58.6 

28.3 

29.5 

27.1 

20.8 

40.6 

42.8 

50.3 

53.0 

67 

59.5 

28.7 

30.0 

27.5 

21.2 

41.3 

43.5 

51.1 

53.8 

68 

60.4 

29.2 

30.4 

28.0 

21.7 

41.9 

44.2 

51.9 

54.6 

69 

61.3 

29.6 

30.9 

28.5 

22.2 

42.6 

44.8 

52.7 

55.5 

70 

62.2 

30.0 

31.3 

28.9 

22.  6 

43.3 

45.5 

53.5 

56.3 

71 

63.1 

30.5 

31.8 

29.4 

23.1 

43.9 

46.2 

54.3 

57.1 

72 

64.0 

30.9 

32.3 

29.8 

23.5 

44.6 

46.9 

55.1 

58.0 

73 

64.8 

31.4 

32.7 

30.3 

24.0 

45.2 

47.6 

55.9 

58.8 

74 

65.7 

31.8 

33.2 

30.8 

24.5 

45.9 

48.3 

56.7 

59.6 

75 

66.6 

32.2 

33.6 

31.2 

24.9 

46.6 

49.0 

57.5 

60.5 

76 

67.5 

32.7 

34.1 

31.7 

25.4 

47.2 

49.7 

58.2 

61.3 

77 

68.4 

33.1 

34.5 

32.1 

25.9 

47.9 

50.4 

59.0 

62.1 

78 

69.3 

33.6 

35.0 

32.6 

26.3 

48.5 

51.1 

59.8 

63.0 

79 

70.2 

34.0 

35.4 

33.1 

26.8 

49.2 

51.8 

60.6 

63.8 

80 

71.1 

34.4 

35.9 

33.5 

27.3 

49.9 

52.5 

61.4 

64.6 

81 

71.9 

34.9 

36.3 

34.0 

27.7 

50.5 

53.2 

62.2 

65.5 

82 

72.8 

35.3 

36.8 

34.5 

28.2 

51.2 

53.9 

63.0 

66.3 

83 

73.7 

35.8  . 

37.3 

34.9 

28.6 

51.8 

54.6 

63.8 

67.1 

84 

74.6 

36.2 

37.7 

35.4 

29.1 

52.5 

55.3 

64.6 

68.0 

68 


SUGAR  TABLES 


TABLE  19.     (Continued.} 


1 

1 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

^ 

B 

O 

Tl 

M 

"3 

- 

q 

q 

o 

! 

f 

•e 

3^. 

1  . 

S 

a 

i 

w 

1 

a 

| 

> 

o 

g  1 

II 

* 

q 

m 

°! 

Q. 

• 

bfi  m 

M 

O 

w 

0 

0 

d 

« 

<5 

0 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

85 

75.5 

36.7 

38.2 

35.8 

29.6 

53.1 

56.0 

65.4 

68.8 

86 

76.4 

37.1 

38.6 

36.3 

30.0 

53.8 

56.6 

66.2 

69.7 

87 

77.3 

37.5 

39.1 

36.8 

30.5 

54.5 

57.3 

67.0 

70.5 

88 

78.2 

38.0 

39.5 

37.2 

31.0 

55.1 

58.0 

67.8 

71.3 

89 

79.1 

38.4 

40.0 

37.7 

31.4 

55.8 

58.7 

68.5 

72.2 

90 

79.9 

38.9 

40.4 

38.2 

31.9 

56.4 

59.4 

69.3 

73.0 

91 

80.8 

39.3 

40.9 

38.6 

32.4 

57.1 

60.1 

70.1 

73.8 

92 

81.7 

39.8 

41.4 

39.1 

32.8 

57.8 

60.8 

70.9 

74.7 

93 

82.6 

40.2 

41,8 

39.6 

33.3 

58.4 

61.5 

71.7 

75.5 

94 

83.5 

40.6 

42.3 

40.0 

33.8 

59.1 

62.2 

72.5 

76.3 

95 

84.4 

41.1 

42.7 

40.5 

34.2 

59.7 

62.9 

73.3 

77.2 

96 

85.3 

41.5 

43.2 

41.0 

34.7 

60.4 

63.6 

74.1 

78.0 

97 

86.2 

42.0 

43.7 

41.4 

35.2 

61.1 

64.3 

74.9 

78.8 

98 

87.1 

42.4 

44.1 

41.9 

35.6 

61.7 

65.0 

75.7 

79.7 

99 

87.9 

42.9 

44.6 

42.4 

36.1 

62.4 

65.7 

76.5 

80.5 

100 

88.8 

43.3 

45.0 

42.8 

36.6 

63.0 

66.4 

77.3 

81.3 

101 

89.7 

43.8 

45.5 

43.3 

37.0 

63.7 

67.1 

78.1 

82.2 

102 

90.6 

44.2 

46.0 

43.8 

37.5 

64.4 

67.8 

78.8 

83.0 

103 

91.5 

44.7 

46.4 

44.2 

38.0 

65.0 

68.5 

79.6 

83.8 

104 

92.4 

45.1 

46.9 

44.7 

38.5 

65.7 

69.1 

80.4 

84.7 

105 

93.3 

45.5 

47.3 

45.2 

38.9 

66.4 

69.8 

81.2 

85.5 

106 

94.2 

46.0 

47.8 

45.6 

39.4 

67.0 

70.5 

82.0 

86.3 

107 

95.0 

46.4 

48.3 

46.1 

39.9 

67.7 

71.2 

82.8 

87.2 

108 

95.9 

46.9 

48.7 

46.6 

40.3 

68.3 

71.9 

83.6 

88.0 

109 

96.8 

47.3 

49.2 

47.0 

40.8 

69.0 

72.6 

84.4 

88.8 

110 

97.7 

47.8 

49.6 

47.5 

41.3 

69.7 

73.3 

85.2 

89.7 

111 

98.6 

48.2 

50.1 

48.0 

41.7 

70.3 

74.0 

86.0 

90.5 

112 

99.5 

48.7 

50.6 

48.4 

42.2 

71.0 

74.7 

86.8 

91.3 

113 

100.4 

49.1 

51.0 

48.9 

42.7 

71.6 

75.4 

87.6 

92.2 

114 

101.3 

49.6 

51.5 

49.4 

43.2 

72.3 

76.1 

88.4 

93.0 

115 

102.2 

50.0 

51.9 

49.8 

43.6 

73.0 

76.8 

89.2 

93.9 

116 

103.0 

50.5 

52.4 

50.3 

44.1 

73.6 

77.5 

90.0 

94.7 

117 

103.9 

50.9 

52.9 

50.8 

44.6 

74.3 

78.2 

90.7 

95.5 

118 

104.8 

51.4 

53.3 

51.2 

45.0 

75.0 

78.9 

91.5 

96.4 

119 

105.7 

51.8 

53.8 

51.7 

45.5 

75.6 

79.6 

92.3 

97.2 

120 

106.6 

52.3 

54.3 

52.2 

46.0 

76.3 

80.3 

93.1 

98.0 

121 

107.5 

52.7 

54.7 

52.7 

46.5 

76.9 

81.0 

93.9 

98.9 

122 

108.4 

53.2 

55.2 

53.1 

46.9 

77.6 

81.7 

94.7 

99.7 

123 

109.3 

53.6 

55.7 

53.6 

47  .4 

78.3 

82.4 

95.5 

100.5 

124 

110.1 

54.1 

56.1 

54.1 

47.9 

78.9 

83.1 

96.3 

101.4 

SUGAR  TABLES 


69 


TABLE  19.     (Continued.) 


5 

1 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

g 

x 

g 

£ 

9) 

"3 

5 

T 

1 

3 

3 

q 

q 

o 

1 

I 

1 

Is 

«s 

°s 

H 

J 

+ 

1 

6 

£ 

£ 

|f 

1  1 

a 

a 

Si 

1 

§• 

Q 

•f 

a 

0 

W 

cf 

o 

0 

<N 

u 

<5 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

125 

111.0 

54.5 

56.6 

54.5 

48.3 

79.6 

83.8 

97.1 

102.2 

126 

111.9 

55.0 

57.0 

55.0 

48.8 

80.3 

84.5 

97.9 

103.0 

127 

112.8 

55.4 

57.5 

55.5 

49.3 

80.9 

85.2 

98.7 

103.9 

128 

113.7 

55.9 

58.0 

55.9 

49.8 

81.6 

85.9 

99.4 

104.7 

129 

114.6 

56.3 

58.4 

56.4 

50.2 

82.2 

86.6 

100.2 

105.5 

130 

115.5 

56.8 

58.9 

56.9 

50.7 

82.9 

87.3 

101.0 

106.4 

131 

116.4 

57.2 

59.4 

57.4 

51.2 

83.6 

88.0 

101.8 

107.2 

132 

117.3 

57.7 

59.8 

57.8 

51.7 

84.2 

88.7 

102.6 

108.0 

133 

118.1 

58.1 

60.3 

58.3 

52.1 

84.9 

89.4 

103.4 

108.9 

134 

119.0 

58.6 

60.8 

58.8 

52.6 

85.5 

90.1 

104.2 

109.7 

135 

119.9 

59.0 

61.2 

59.3 

53.1 

86.2 

90.8 

105.0 

110.5 

136 

120.8 

59.5 

61.7 

59.7 

53.6 

86.9 

91.5 

105.8 

111.4 

137 

121.7 

60.0 

62.2 

60.2 

54.0 

87.5 

92.1 

106.6 

112.2 

138 

122.6 

60.4 

62.6 

60.7 

54.5 

88.2 

92.8 

107.4 

113.0 

139 

123.5 

60.9 

63.1 

61.2 

55.0 

88.9 

93.5 

108.2 

113.9 

140 

124.4 

61.3 

63.6 

61.6 

55.5 

89.5 

94.2 

109.0 

114.7 

141 

125.2 

61.8 

64.0 

62.1 

55.9 

90.2 

94.9 

109.8 

115.5 

142 

126.1 

62.2 

64.5 

62.6 

56.4 

90.8 

95.6 

110.5 

116.4 

143 

127.0 

62.7 

65.0 

63.1 

56.9 

91.5 

96.3 

111.3 

117.2 

144 

127.9 

63.1 

65.4 

63.5 

57.4 

92.2 

97.0 

112  1 

118.0 

145 

128.8 

63.6 

65.9 

64.0 

57.8 

92.8 

97.7 

112.9 

118.9 

146 

129.7 

64.0 

66.4 

64.5 

58.3 

93.5 

98.4 

113.7 

119.7 

147 

130.6 

64.5 

66.9 

65.0 

58.8 

94.2 

99.1 

114.5 

120.5 

148 

131.5 

65.0 

67.3 

65.4 

59.3 

94.8 

99.8 

115.3 

121.4 

149 

132.4 

65.4 

67.8 

65.9 

59.7 

95.5 

100.5 

116.1 

122.2 

150 

133.2 

65.9 

68.3 

66.4 

60.2 

96.1 

101.2 

116.9 

123.0 

151 

134.1 

66.3 

68.7 

66.9 

60.7 

96.8 

101.9 

117.7 

123.9 

152 

135.0 

66.8 

69.2 

67.3 

61.2 

97.5 

102.6 

118.5 

124.7 

153 

135.9 

67.2 

69.7 

67.8 

61.7 

98.1 

103.3 

119.3 

125.5 

154 

136.8 

67.7 

70.1 

68.3 

62.1 

98.8 

104.0 

120.0 

126.4 

155 

137.7 

68.2 

70.6 

68.8 

62.6 

99.5 

104.7 

120.8 

127.2 

156 

138.6 

68.6 

71.1 

69.2 

63.1 

100.1 

105.4 

121.6 

128.0 

157 

139.5 

69.1 

71.6 

69.7 

63.6 

100.8 

106.1 

122.4 

128.9 

158 

140.3 

69.5 

72.0 

70.2 

64.1 

101.5 

106.8 

123.2 

129.7 

159 

141.2 

70.0 

72.5 

70.7 

64.5 

102.1 

107.5 

124.0 

130.5 

160 

142.1 

70.4 

73.0 

71.2 

65.0 

102.8 

108.2 

124.8 

131.4 

161 

143.0 

70.9 

73.4 

71.6 

65.5 

103.4 

108.9 

125.6 

132.2 

162 

143.9 

71.4 

73.9 

72.1 

66.0 

104.1 

109.6 

126.4 

133.0 

163 

144.8 

71.8 

74.4 

72.6 

66.5 

104.8 

110.3 

127.2 

133.9 

164 

145.7 

72.3 

74.9 

73.1 

66.9 

105.4 

111.0 

128.0 

134.7 

70 


SUGAR  TABLES 


TABLE   19.     (Continued.) 


i 

f 

Invert  sugar, 
and  sucrose. 

Lactose. 

Maltose. 

5 

,_; 

g 

S 

! 

O 
8 

3 
"si 

3, 

I 

1   . 

1 

^ 

g 

i 

q 

0. 

5 

® 

> 

S   M 

aa  oS 

q 

~h 

s 

~t 

I 

a 

| 

£ 

B 

<J 

w 

i 

§* 

1 

•W 

H 

o 

B 

0 

^ 

o 

0 

o* 

u 

0 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

165 

146.6 

72.8 

75.3 

73.6 

67.4 

106.1 

111.7 

128.8 

135.5 

166 

147.5 

73.2 

75.8 

74.0 

67.9 

106.8 

112.4 

129.6 

136.4 

167 

148.3 

73.7 

76.3 

74.5 

68.4 

107.4 

113.1 

130.3 

137.2 

168 

149.2 

74.1 

76.8 

75.0 

68.9 

108.1 

113.8 

131.1 

138.0 

169 

150.1 

74.6 

77.2 

75.5 

69.3 

108.8 

114.5 

131.9 

138.9 

170 

151.0 

75.1 

77.7 

76.0 

69.8 

109.4 

115.2 

132.7 

139.7 

171 

151.9 

75.5 

78.2 

76.4 

70.3 

110.1 

115.9 

133.5 

140.5 

172 

152.8 

76.0 

78.7 

76.9 

70.8 

110.8 

116.6 

134.3 

141.4 

173 

153.7 

76.4 

79.1 

77.4 

71.3 

111.4 

117.3 

135.1 

142.2 

174 

154.6 

76.9 

79.6 

77.9 

71.7 

112.1 

118.0 

135.9 

143.0 

175 

155.5 

77.4 

80.1 

78.4 

72.2 

112.8 

118.7 

136.7 

143.9 

176 

156.3 

77.8 

80.6 

78.8 

72.7 

113.4 

119.4 

137.5 

144.7 

177 

157.2 

78.3 

81.0 

79.3 

73.2 

114.1 

120.1 

138.3 

145.5 

178 

158.1 

78.8 

81.5 

79.8 

73.7 

114.8 

120.8 

139.1 

146.4 

179 

159.0 

79.2 

82.0 

80.3 

74.2 

115.4 

121.5 

139.8 

147.2 

180 

159.9 

79.7 

82.5 

80.8 

74.6 

116.1 

122.2 

140.6 

148.0 

181 

160.8 

80.1 

82.9 

81.3 

75.1 

116.7 

122.9 

141.4 

148.9 

182 

161.7 

80.6 

83.4 

81.7 

75.6 

117.4 

123.6 

142.2 

149.7 

183 

162.6 

81.1 

83.9 

82.2 

76.1 

118.1 

124.3 

143.0 

150.5 

184 

163.4 

81.5 

84.4 

82.7 

76.6 

118.7 

125.0 

143.8 

151.4 

185 

164.3 

82.0 

84.9 

83.2 

77.1 

119.4 

125.7 

144.6 

152.2 

186 

165.2 

82.5 

85.3 

83.7 

77.6 

120.1 

126.4 

145.4 

153.0 

187 

166.1 

82.9 

85.8 

84.2 

78.0 

120.7 

127.1 

146.2 

153.9 

188 

167.0 

83.4 

86.3 

84.6 

78.5 

121.4 

127.8 

147.0 

154.7 

189 

167.9 

83.9 

86.8 

85.1 

79.0 

122.1 

128.5 

147.8 

155.5 

190 

168.8 

84.3 

87.2 

85.6 

79.5 

122.7 

129.2 

148.6 

156.4 

191 

169.7 

84.8 

87.7 

86.1 

80.0 

123.4 

129.9 

149.3 

157.2 

192. 

170.5 

85.3 

88.2 

86.6 

80.5 

124.1 

130.6 

150.1 

158.0 

193 

171.4 

85.7 

88.7 

87.1 

81.0 

124.7 

131.3 

150.9 

158.9 

194 

172.3 

86.2 

89.2 

87.6 

81.4 

125.4 

132.0 

151.7 

159.7 

195 

173.2 

86.7 

89.6 

88.0 

81.9 

126.1 

132.7 

152.5 

160.5 

196 

174.1 

87.1 

90.1 

88.5 

82.4 

126.7 

133.4 

153.3 

161.4 

197 

175  0 

87.6 

90.6 

89.0 

82.9 

127.4 

134.1 

154.1 

162.2 

198 

175.9 

88.1 

91.1 

89.5 

83.4 

128.1 

134.8 

154.9 

163.0 

199 

176.8 

88.5 

91.6 

90.0 

83.9 

128.7 

135.5 

155.7 

163.9 

200 

177.7 

89.0 

92.0 

90.5 

84.4 

129.4 

136.2 

156.5 

164.7 

201 

178.5 

89.5 

92.5 

91.0 

84.8 

130.0 

136.9 

157.3 

165.5 

202 

179.4 

89.9 

93.0 

91.4 

85.3 

130.7 

137.6 

158.1 

166.4 

203 

180.3 

90.4 

93.5 

91.9 

85.8 

131.4 

138.3 

158.8 

167.2 

204 

181.2 

90.9 

94.0 

92.4 

86.3 

132.0 

139.0 

159.6 

168.0 

SUGAR  TABLES 


71 


TABLE   19.     (Continued.) 


I 

i 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

g 

f 

•rj 

g 

•T 

B 

1      ' 

1 

1 

3 

g 

s 

1 

0 

1 

g  S 

03  03 

4 

I 

6 

£ 

a 

i§ 

1* 

w 

o 

*! 

<f 

1 

Q 

•# 

1°° 

0 

i 

0 

u 

0 

O> 

0 

u 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

205 

182.1 

91.4 

94.5 

92.9 

86.8 

132.7 

139.7 

160.4 

168.9 

206 

183.0 

91.8 

94.9 

93.4 

87.3 

133.4 

140.4 

161.2 

169.7 

207 

183.9 

92.3 

95.4 

93.9 

87.8 

134.0 

141.1 

162.0 

170.5 

208 

184.8 

92.8 

95.9 

94.4 

88.3 

134.7 

141.8 

162.8 

171.4 

209 

185.6 

93.2 

96.4 

94.9 

88.8 

135.4 

142.5 

163.6 

172.2 

210 

186.5 

93.7 

96.9 

95.4 

89.2 

136.0 

143.2 

164.4 

173.0 

211 

187.4 

94.2 

97.4 

95.8 

89.7 

136.7 

143.9 

165.2 

173.8 

212 

188.3 

94.6 

97.8 

96.3 

90.2 

137.4 

144.6 

166.0 

174.7 

213 

189.2 

95.1 

98.3 

96.8 

90.7 

138.0 

145.3 

166.8 

175.5 

214 

190.1 

95.6 

98.8 

97.3 

91.2 

138.7 

146.0 

167.5 

176.4 

215 

191.0 

96.1 

99.3 

97.8 

91.7 

139.4 

146.7 

168.3 

177.2 

216 

191.9 

96.5 

99.8 

98.3 

92.2 

140.0 

147.4 

169.1 

178.0 

217 

192.8 

97.0 

100.3 

98.8 

92.7 

140.7 

148.1 

169.9 

178.9 

218 

193.6 

97.5 

100.8 

99.3 

93.2 

141.4 

148.8 

170.7 

179.7 

219 

194.5 

98.0 

101.2 

99.8 

93.7 

142.0 

149.5 

171.5 

180.5 

220 

195.4 

98.4 

101.7 

100.3 

94.2 

142.7 

150.2 

172.3 

181.4 

221 

196.3 

98.9 

102.2 

100.8 

94.7 

143.4 

150.9 

173.1 

182.2 

222 

197.2 

99.4 

102.7 

101.2 

95.1 

144.0 

151.6 

173.9 

183.0 

223 

198.1 

'99.9 

103.2 

101.7 

95.6 

144.7 

152.3 

174.7 

183.9 

224 

199.0 

100.3 

103.7 

102.2 

96.1 

145.4 

153.0 

175.5 

184.7 

225 

199.9 

100.8 

104.2 

102.7 

96.6 

146.0 

153.7 

176.2 

185.5 

226 

200.7 

101.3 

104.6 

103.2 

97.1 

146.7 

154.4 

177.0 

186.4 

227 

201.6 

101.8 

105.1 

103.7 

97.6 

147.4 

155.1 

177.8 

187.2 

228 

202.5 

102.2 

105.6 

104.2 

98.1 

148.0 

155.8 

178.6 

188.0 

229 

203.4 

102.7 

106.1 

104.7 

98.6 

148.7 

156.5 

179.4 

188.8 

230 

204.3 

103.2 

106.6 

105.2 

99.1 

149.4 

157.2 

180.2 

189.7 

231 

205.2 

103.7 

107.1 

105.7 

99.6 

150.0 

157.9 

181.0 

190.5 

232 

206.1 

104.1 

107.6 

106.2 

100.1 

150.7 

158.6 

181.8 

191.3 

233 

207.0 

104.6 

108.1 

106.7 

100.6 

151.4 

159.3 

182.6 

192.2 

234 

207.9 

105.1 

108.6 

107.2 

101.1 

152.0 

160.0 

183.4 

193.0 

235 

208.7 

105.6 

109.1 

107.7 

101.6 

152.7 

160.7 

184.2 

193.8 

236 

209.6 

106.0 

109.5 

108.2 

102.1 

153.4 

161.4 

184.9 

194.7 

237 

210.5 

106.5 

110.0 

108.7 

102.6 

154.0 

162.1 

185.7 

195.5 

238 

211.4 

107.0 

110.5 

109.2 

103.1 

154.7 

162.8 

186.5 

196.3 

239 

212.3 

107.5 

111.0 

109.6 

103.5 

155.4 

163.5 

187.3 

197.2 

240 

213.2 

108.0 

111.5 

110.1 

104.0 

156.1 

164.3 

188.1 

198.0 

241 

214.1 

108.4 

112.0 

110.6 

104.5 

156.7 

165.0 

188.9 

198.8 

242 

215.0 

108.9 

112.5 

111.1 

105.0 

157.4 

165.7 

189.7 

199.7 

243 

215.8 

109.4 

113.0 

111.6 

105.5 

158.1 

166.4 

190.5 

200.5 

244 

216.7 

109.9 

113.5 

112.1 

106.0 

158.7 

167.1 

191.3 

201.3 

72 


SUGAR  TABLES 


TABLE  19.     (Continued.) 


1 

! 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

1 

| 

"M 

1 

1. 

1 

3 

! 

§ 

i         0 

1 

^ 

I 

S  t 

3 

3 

4 

•f 

3 

O 

o 

d 

c3  & 

s  ^ 

M 

M 

Q 

! 

g 

3°° 

B 

0 

w 

u= 

a 

0 

Q 

0 

* 

0 

c5 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

245 

217.6 

110.4 

114.0 

112.6 

106.5 

159.4 

167.8 

192.1 

202.2 

246 

218.5 

110.8 

114.5 

113.1 

107.0 

160.1 

168.5 

192.9 

203.0 

247 

219.4 

111.3 

115.0 

113.6 

107.5 

160.7 

169.2 

193.6 

203.8 

248 

220.3 

111.8 

115.4 

114.1 

108.0 

161.4 

169.9 

194.4 

204.7 

249 

221.2 

112.3 

115.9 

114.6 

108.5 

162.1 

170.6 

195.2 

205.5 

250 

222.1 

112.8 

116.4 

115.1 

109.0 

162.7 

171.3 

196.0 

206.3 

251 

223.0 

113.2 

116.9 

115.6 

109.5 

163.4 

172.0 

196.8 

207.2 

252 

223.8 

113.7 

117.4 

116.1 

110.0 

164.1 

172.7 

197.6 

208.0 

253 

224.7 

114.2 

117.9 

116.6 

110.5 

164.7 

173.4 

198.4 

208.8 

254 

225.6 

114.7 

118.4 

117.1 

111.0 

165.4 

174.1 

199.2 

209.7 

255 

226.5 

115.2 

118.9 

117.6 

111.5 

166.1 

174.8 

200.0 

210.5 

256 

227.4 

115.7 

119.4 

118.1 

112.0 

166.8 

175.5 

200.8 

211.3 

257 

228.3 

116.1 

119.9 

118.6 

112.5 

167.4 

176.2 

201.6 

212.2 

258 

229.2 

116.6 

120.4 

119.1 

113.0 

168.1 

176.9 

202.3 

213.0 

259 

230.1 

117.1 

120.9 

119.6 

113.5 

168.8 

177.6 

203.1 

213.8 

260 

231.0 

117.6 

121.4 

120.1 

114.0 

169.4 

178.3 

203.9 

214.7 

261 

231.8 

118.1 

121.9 

120.6 

114.5 

170.1 

179.0 

204.7 

215.5 

262 

232.7 

118.6 

122  .4 

121.1 

115.0 

170.8 

179.8 

205.5 

216.3 

263 

233.6 

119.0 

122.9 

121.6 

115.5 

171.4 

180.5 

206.3 

217.2 

264 

234.5 

119.5 

123.4 

122.1 

116.0 

172.1 

181.2 

207.1 

218.0 

265 

235.4 

120.0 

123.9 

122.6 

116.5 

172.8 

181.9 

207.9 

218.8 

266 

236.3 

120.5 

124.4 

123.1 

117.0 

173.5 

182.6 

208.7 

219.7 

267 

237.2 

121.0 

124.9 

123.6 

117.5 

174.1 

183.3 

209.5 

220.5 

268 

238.1 

121.5 

125.4 

124.1 

118.0 

174.8 

184.0 

210.3 

221.3 

269 

238.9 

122.0 

125.9 

124.6 

118.5 

175.5 

184.7 

211.0 

222.1 

270 

239.8 

122.5 

126.4 

125.1 

119.0 

176.1 

185.4 

211.8 

223.0 

271 

240.7 

122.9 

126.9 

125.6 

119.5 

176.8 

186.1 

212.6 

223.8 

272 

241.6 

123.4 

127.4 

126.2 

120.0 

177.5 

186.8 

213.4 

224.6 

273 

242.5 

123.9 

127.9 

126.7 

120.6 

178.1 

187.5 

214.2 

225.5 

274 

243.4 

124.4 

128.4 

127.2 

121.1 

178.8 

188.2 

215.0 

226.3 

275 

244.3 

124.9 

128.9 

127.7 

121.6 

179.5 

188.9 

215.8 

227.1 

276 

245.2 

125.4 

129.4 

128.2 

122.1 

180.2 

189.6 

216.6 

228.0 

277 

246.1 

125.9 

129.9 

128.7 

122.6 

180.8 

190.3 

217.4 

228.8 

278 

246.9 

126.4 

130.4 

129.2 

123.1 

181.5 

191.0 

218.2 

229.6 

279 

247.8 

126.9 

130.9 

129.7 

123.6 

182.2 

191.7 

218.9 

230.5 

280 

248.7 

127.3 

131.4 

130.2 

124.1 

182.8 

192.4 

219.7 

231.3 

281 

249.6 

127.8 

131.9 

130.7 

124.6 

183.5 

193.1 

220.5 

232.1 

282 

250.5 

128.3 

132.4 

131.2 

125.1 

184.2 

193.9 

221.3 

233.0 

283 

251.4 

128.8 

132.9 

131.7 

125.6 

184.8 

194.6 

222.1 

233.8 

284 

252.3 

129.3 

133.4 

132.2 

126.1 

185.5 

195.3 

222.9 

234.6 

SUGAR  TABLES 


73 


TABLE   19.     (Continued.) 


§ 

x. 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

0 

3 

g 

j3 

"5b 

1 

"3  ' 

•a 

d 

q 

'§ 
1 

1 

i 

c 

J! 

I1 

B 

« 
0 

a 

3 

no»H«o 

a 

u 

H 

° 

<M 

0 

o 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

285 

253.2 

129.8 

133.9 

132.7 

126.6 

186.2 

196.0 

223.7 

235.5 

286 

254.0 

130.3 

134.4 

133.2 

127.1 

186.9 

196.7 

224.5 

236.3 

287 

254.9 

130.8 

134.9 

133.7 

127.6 

187.5 

197.4 

225.3 

237.1 

288 

255.8 

131.3 

135.4 

134.3 

128.1 

188.2 

198.1 

226.1 

238.0 

289 

256.7 

131.8 

135.9 

134.8 

128.6 

188.9 

198.8 

226.9 

238.8 

290 

257.6 

132.3 

136.4 

135.3 

129.2 

189.5 

199.5 

227.6 

239.6 

291 

258.5 

132.7 

136.9 

135.8 

129.7 

190.2 

200.2 

228.4 

240.5 

292 

259.4 

133.2 

137.4 

136.3 

130.2 

190.9 

200.9 

229.2 

241.3 

293 

260.3 

133.7 

137.9 

136.8 

130.7 

191.5 

201.6 

230.0 

242.1 

294 

261.2 

134.2 

138.4 

137.3 

131.2 

192.2 

202.3 

230.8 

242.9 

295 

262.0 

134.7 

138.9 

137.8 

131.7 

192.9 

203.0 

231.6 

243.8 

296 

262.9 

135.2 

139.4 

138.3 

132.2 

193.6 

203.7 

232.4 

244.6 

297 

263.8 

135.7 

140.0 

138.8 

132.7 

194.2 

204.4 

233.2 

245.4 

298 

264.7 

136.2 

140.5 

139.4 

133.2 

194.9 

205.1 

234.0 

246.3 

299 

265.6 

136.7 

141.0 

139.9 

133.7 

195.6 

205.8 

234.8 

247.1 

300 

266.5 

137.2 

141.5 

140.4 

134.2 

196.2 

206.6 

235.5 

247.9 

301 

267.4 

137.7 

142.0 

140.9 

134.8 

196.9 

207.3 

236.3 

248.8 

302 

268.3 

138.2 

142.5 

141.4 

135.3 

197.6 

208.0 

237.1 

249.6 

303 

269.1 

138.7 

143.0 

141.9 

135.8 

198.3 

208.7 

237.9 

250.4 

304 

270.0 

139.2 

143.5 

142.4 

136.3 

198.9 

209.4 

238.7 

251.3 

305 

270.9 

139.7 

144.0 

142.9 

136.8 

199.6 

210.1 

239.5 

252.1 

306 

271.8 

140.2 

144.5 

143.4 

137.3 

200.3 

210.8 

240.3 

252.9 

307 

272.7 

140.7 

145.0 

144.0 

137.8 

201.0 

211.5 

241.1 

253.8 

308 

273.6 

141.2 

145.5 

144.5 

138.3 

201.6 

212.2 

241.9 

254.6 

309 

274.5 

141.7 

146.1 

145.0 

138.8 

202.3 

212.9 

242.7 

255.4 

310 

275.4 

142.2 

146.6 

145.5 

139.4 

203.0 

213.7 

243.5 

256.3 

311 

276.3 

142.7 

147.1 

146.0 

139.9 

203.6 

214.4 

244.2 

257.1 

312 

277.1 

143.2 

147.6 

146.5 

140.4 

204.3 

215.1 

245.0 

257.9 

313 

278.0 

143.7 

148.1 

147.0 

140.9 

205.0 

215.8 

245.8 

258.8 

314 

278.9 

144.2 

148.6 

147.6 

141.4 

205.7 

216.5 

246.6 

259.6 

315 

279.8 

144.7 

149.1 

148.1 

141.9 

206.3 

217.2 

247.4 

260.4 

316 

280.7 

145.2 

149.6 

148.6 

142.4 

207.0 

217.9 

248.2 

261.2 

317 

281.6 

145.7 

150.1 

149.1 

143.0 

207.7 

218.6 

249.0 

262.1 

318 

282.5 

146.2 

150.7 

149.6 

143.5 

208.4 

219.3 

249.8 

262.9 

319 

283.4 

146.7 

151.2 

150.1 

144.0 

209.0 

220.0 

250.6 

263.7 

320 

284.2 

147.2 

151.7 

150.7 

144.5 

209.7 

220.7 

251.3 

264.6 

321 

285.1 

147.7 

152.2 

151.2 

145.0 

210.4 

221.4 

252.1 

265.4 

322 

286.0 

148.2 

152.7 

151.7 

145.5 

211.0 

222.2 

252.9 

266.2 

323 

286.9 

148.7 

153.2 

152.2 

146.0 

211.7 

222.9 

253.7 

267.1 

324 

287.8 

149.2 

153.7 

152.7 

146.6 

212.4 

223.6 

254.5 

267.9 

74 


SUGAR  TABLES 


TABLE   19.     (Continued.) 


§ 
g 

i 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

0 

o 

1 

1 

R 

3 

"S 

3 

q 

q 

1 

1 

1 

1 

+a     . 

g  a 

°   K- 

4 

+ 

4 

+ 

1 

8 

I 

1 

1! 

•«*< 
d 

I1 

e<i 

i 

| 

oa 

a 

0= 

i 

0 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

325 

288.7 

149.7 

154.3 

153.2 

147.1 

213.1 

224.3 

255.3 

268.7 

326 

289.6 

150.2 

154.8 

153.8 

147.6 

213.7 

225.0 

256.1 

269.6 

327 

290.5 

150.7 

155.3 

154.3 

148.1 

214.4 

225.7 

256.9 

270.4 

328 

291.4 

151.2 

155.8 

154.8 

148.6 

215.1 

226.4 

257.7 

271.2 

329 

292.2 

151.7 

156.3 

155.3 

149.1 

215.8 

227.1 

258.5 

272.1 

330 

293.1 

152.2 

156.8 

155.8 

149.7 

216.4 

227.8 

259.3 

272.9 

331 

294.0 

152.7 

157.3 

156.4 

150.2 

217.1 

228.5 

260.0 

273.7 

332 

294.9 

153.2 

157.9 

156.9 

150.7 

217.8 

229.2 

260.8 

274.6 

333 

295.8 

153.7 

158.4 

157.4 

151.2 

218.4 

230.0 

261.6 

275.4 

334 

296.7 

154.2 

158.9 

157.9 

151.7 

219.1 

230.7 

262.4 

276.2 

335 

297.6 

154.7 

159.4 

158.4 

152.3 

219.8 

231.4 

263.2 

277.0 

336 

298.5 

155.2 

159.9 

159.0 

152.8 

220.5 

232.1 

264.0 

277.9 

337 

299.3 

155.8 

160.5 

159.5 

153.3 

221.1 

232.8 

264.8 

278.7 

338 

300.2 

156.3 

161.0 

160.0 

153.8 

221.8 

233.5 

265.6 

279.5 

339 

301.1 

156.8 

161.5 

160.5 

154.3 

222.5 

234.2 

266.4 

280.4 

340 

302.0 

157.3 

162.0 

161.0 

154.8 

223.2 

234.9 

267.1 

281.2 

341 

302.9 

157.8 

162.5 

161.6 

155.4 

223.8 

235.6 

267.9 

282.0 

342 

303.8 

158.3 

163.1 

162.1 

155.9 

224.5 

236.3 

268.7 

282.9 

343 

304.7 

158.8 

163.6 

162.6 

156.4 

225.2 

237.0 

269.5 

283.7 

344 

305.6 

159.3 

164.1 

163.1 

156.9 

225.9 

237.8 

270.3 

284.5 

345 

306.5 

159.8 

164.6 

163.7 

157.5 

226.5 

238.5 

271.1 

285.4 

346 

307.3 

160.3 

165.1 

164.2 

158.0 

227.2 

239.2 

271.9 

286.2 

347 

308.2 

160.8 

165.7 

164.7 

158.5 

227.9 

239.9 

272.7 

287.0 

348 

309.1 

161.4 

166.2 

165.2 

159.0 

228.5 

240.6 

273.5 

287.9 

349 

310.0 

161.9 

166.7 

165.7 

159.5 

229.2 

241.3 

274.3 

288.7 

350 

310.9 

162.4 

167.2 

166.3 

160.1 

229.9 

242.0 

275.0 

289.5 

351 

311.8 

162.9 

167.7 

166.8 

160.6 

230.6 

242.7 

275.8 

290.4 

352 

312.7 

163.4 

168.3 

167.3 

161.1 

231.2 

243.4' 

276.6 

291.2 

353 

313.6 

163.9 

168.8 

167.8 

161.6 

231.9 

244.1 

277.4 

292.0 

354 

314.4 

164.4 

169.3 

168.4 

162.2 

232.6 

244.8 

278.2 

292.8 

355 

315.3 

164.9 

169.8 

168.9 

162.7 

233.3 

245.6 

279.0 

293.7 

356 

316.2 

165.4 

170.4 

169.4 

163.2 

233.9 

246.3 

279.8 

294.5 

357 

317.1 

166.0 

170.9 

170.0 

163.7 

234.6 

247.0 

280.6 

295.3 

358 

318.0 

166.5 

171.4 

170.5 

164.3 

235.3 

247.7 

281.4 

296.2 

359 

318.9 

167.0 

171.9 

171.0 

164.8 

236.0 

248.4 

282.2 

297.0 

360 

319.8 

167.5 

172.5 

171.5 

165.3 

236.7 

249.1 

282.9 

297.8 

361 

320.7 

168.0 

173.0 

172.1 

165.8 

237.3 

249.8 

283.7 

298.7 

362 

321.6 

168.5 

173.5 

172.6 

166.4 

238.0 

250.5 

284.5 

299.5 

363 

322.4 

169.0 

174.0 

173.1 

166.9 

238.7 

251.2 

285.3 

300.3 

364 

323.3 

169.6 

174.6 

173.7 

167.4 

239.4 

252.0 

286.1 

301.2 

SUGAR  TABLES 


75 


TABLE  19.    (Continued.) 


i 

i 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

0 

x. 

§ 

c 

0} 

1 

0 

i 

i 

1. 

1 

3 

. 

g, 

0 

1 

1 

|> 

-.     *H 

S  °5 

Sj 

4 

+ 

S 

+ 

I 

6 

| 

A 

3   W> 

&s 

*  3 

H 

a 

i 

w 

4 

i 

8 

-*< 

0 

a 

o* 

O 

0= 

0 

B 

O 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

365 

324.2 

170.1 

175.1 

174.2 

167.9 

240.0 

252.7 

286.9 

302.0 

366 

325.1 

170.6 

175.6 

174.7 

168.5 

240.7 

253.4 

287.7 

302.8 

367 

326.0 

171.1 

176.1 

175.2 

169.0 

241.4 

254.1 

288.5 

303.6 

368 

326.9 

171.6 

176.7 

175.8 

169.5 

242.1 

254.8 

289.3 

304.5 

369 

327.8 

172.1 

177.2 

176.3 

170.0 

242.7 

255.5 

290.0 

305.3 

370 

328.7 

172.7 

177.7 

176.8 

170.6 

243.4 

256.2 

290.8 

306.1 

371 

329.5 

173.2 

178.3 

177.4 

171.1 

244.1 

256.9 

291.6 

307.0 

372 

330.4 

173.7 

178.8 

177.9 

171.6 

244.8 

257.7 

292.4 

307.8 

373 

331.3 

174.2 

179.3 

178.4 

172.2 

245.4 

258.4 

293.2 

308.6 

374 

332.2 

174.7 

179.8 

179.0 

172.7 

246.1 

259.1 

294.0 

309.5 

375 

333.1 

175.3 

180.4 

179.5 

173.2 

246.8 

259.8 

294.8 

310.3 

376 

334.0 

175.8 

180.9 

180.0 

173.7 

247.5 

260.5 

295.6 

311.1 

377 

334.9 

176.3 

181.4 

180.6 

174.3 

248.1 

261.2 

296.4 

312.0 

378 

335.8 

176.8 

182.0 

181.1 

174.8 

248.8 

261.9 

297.2 

312.8 

379 

336.7 

177.3 

182.5 

181.6 

175.3 

249.5 

262.6 

297.9 

313.6 

380 

337.5 

177.9 

183.0 

182.1 

175.9 

250.2 

263.4 

298.7 

314.5 

381 

338.4 

178.4 

183.6 

182.7 

176.4 

250.8 

264.1 

299.5 

315.3 

382 

339.3 

178.9 

184.1 

183.2 

176.9 

251.5 

264.8 

300.3 

316.1 

383 

340.2 

179.4 

184.6 

183.8 

177.5 

252.2 

265.5 

301.1 

316.9 

384 

341.1 

180.0 

185.2 

184.3 

178.0 

252.9 

266.2 

301.9 

317.8 

385 

342.0 

180.5 

185.7 

184.8 

178.5 

253.6 

266.9 

302.7 

318.6 

386 

342.9 

181.0 

186.2 

185.4 

179.1 

254.2 

267.6 

303.5 

319.4 

387 

343.8 

181.5 

186.8 

185.9 

179.6 

254.9 

268.3 

304.2 

320.3 

388 

344.6 

182.0 

187.3 

186.4 

180.1 

255.6 

269.0 

305.0 

321.1 

389 

345.5 

182.6 

187.8 

187.0 

180.6 

256.3 

269.8 

305.8 

321.9 

390 

346.4 

183.1 

188.4 

187.5 

181.2 

256.9 

270.5 

306.6 

322.8 

391 

347.3 

183.6 

188.9 

188.0 

181.7 

257.6 

271.2 

307.4 

323.6 

392 

348.2 

184.1 

189.4 

188.6 

182.3 

258.3 

271.9 

308.2 

324.4 

393 

349.1 

184.7 

190.0 

189.1 

182.8 

259.0 

272.6 

309.0 

325.2 

394 

350.0 

185.2 

190.5 

189.7 

183.3 

259.6 

273.3 

309.8 

326.1 

395 

350.9 

185.7 

191.0 

190.2 

183.9 

260.3 

274.0 

310.6 

326.9 

396 

351.8 

186.2 

191.6 

190.7 

184.4 

261.0 

274.7 

311.4 

327.7 

397 

352.6 

186.8 

192.1 

191.3 

184.9 

261.7 

275.5 

312.1 

328.6 

398 

353.5 

187.3 

192.7 

191.8 

185.5 

262.3 

276.2 

312.9 

329.4 

399 

354.4 

187.8 

193.2 

192.3 

186.0 

263.0 

276.9 

313.7 

330.2 

400 

355.3 

188.4 

193.7 

192.9 

186.5 

263.7 

277.6 

314.5 

331.1 

401 

356.2 

188.9 

194.3 

193.4 

187.1 

264.4 

278.3 

315.3 

331.9 

402 

357.1 

189.4 

194.8 

194.0 

187.6 

265.0 

279.0 

316.1 

332.7 

403 

358.0 

189.9 

195.4 

194.5 

188.1 

265.7 

279.7 

316.9 

333.6 

404 

358.9 

190.5 

195.9 

195.0 

188.7 

266.4 

280.4 

317.7 

334.4 

76 


SUGAR  TABLES 


TABLE   19.     (Continued.} 


q 

x, 

Invert  sugar, 
and  sucrose. 

Lactose. 

Maltose. 

g 

x 

o 

ii 

0 

L 

_3 

"ti 
2, 

1 

1 

1 

q 

q 

0 

I 

1 

6  5 

**  j 

00  & 

| 

+ 

1 

+ 

1 

§ 

I 

^c 

|| 

« 

3 

2 

1 

8 

I 

•<* 

o 

C<l 

O 

B 

2 

0 

0 

3 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

405 

359.7 

191.0 

196.4 

195.6 

189.2 

267.1 

281.1 

318.5 

335.2 

406 

360.6 

191.5 

197.0 

196.1 

189.8 

267.8 

281.9 

319.2 

336.0 

407 

361.5 

192.1 

197.5 

196.7 

190.3 

268.4 

282.6 

320.0 

336.9 

408 

362.4 

192.6 

198.1 

197.2 

190.8 

269.1 

283.3 

320.8 

337.7 

409 

363.3 

193.1 

198.6 

197.7 

191.4 

269.8 

284.0 

321.6 

338.5 

410 

364.2 

193.7 

199.1 

198.3 

191.9 

270.5 

284.7 

322.4 

339.4 

411 

365.1 

194.2 

199.7 

198.8 

192.5 

271.2 

285.4 

323.2 

340.2 

412 

366.0 

194.7 

200.2 

199.4 

193.0 

271.8 

286.2 

324.0 

341.0 

413 

366.9 

195.2 

200.8 

199.9 

193.5 

272.5 

286.9 

324.8 

341.9 

414 

367.7 

195.8 

201.3 

200.5 

194.1 

273.2 

287.6 

325.6 

342.7 

415 

368.6 

196.3 

201.8 

201.0 

194.6 

273.9 

288.3 

326.3 

343.5 

416 

369.5 

196.8 

202.4 

201.6 

195.2 

274.6 

289.0 

327.1 

344.4 

417 

370.4 

197.4 

202.9 

202.1 

195.7 

275.2 

289.7 

327.9 

345.2 

418 

371.3 

197.9 

203.5 

202.6 

196.2 

275.9 

290.4 

328.7 

346.0 

419 

372.2 

198.4 

204.0 

203.2 

196.8 

276.6 

291.2 

329.5 

346.8 

420 

373.1 

199.0 

204.6 

203.7 

197.3 

277.3 

291.9 

330.3 

347.7 

421 

374.0 

199.5 

205.1 

204.3 

197.9 

277.9 

292.6 

331.1 

348.5 

422 

374.8 

200.1 

205.7 

204.8 

198.4 

278.6 

293.3 

331.9 

349.3 

423 

375.7 

200.6 

206.2 

205.4 

198.9 

279.3 

294.0 

332.7 

350.2 

424 

376.6 

201.1 

206.7 

205.9 

199.5 

280.0 

294.7 

333.4 

351.0 

425 

377.5 

201.7 

207.3 

206.5 

200.0 

280.7 

295.4 

334.2 

351.8 

426 

378.4 

202.2 

207.8 

207.0 

200.6 

281.3 

296.2 

335.0 

352.7 

427 

379.3 

202.8 

208.4 

207.6 

201.1 

282.0 

296.9 

335.8 

353.5 

428 

380.2 

203.3 

208.9 

208.1 

201.7 

282.7 

297.6 

336.6 

354.3 

429 

381.1 

203.8 

209.5 

208.7 

202.2 

283.4 

298.3 

337.4 

355.1 

430 

382.0 

204.4 

210.0 

209.2 

202.7 

284.1 

299.0 

338.2 

356.0 

431 

382.8 

204.9 

210.6 

209.8 

203.3 

284.7 

299.7 

339.0 

356.8 

432 

383.7 

205.5 

211.1 

210.3 

203.8 

285.4 

30CK5 

339.7 

357.6 

433 

384.6 

206.0 

211.7 

210.9 

204.4 

286.1 

301.2 

340.5 

358.5 

434 

385.5 

206.5 

212.2 

211.4 

204.9 

286.8 

301.9 

341.3 

359.3 

435 

386.4 

207.1 

212.8 

212.0 

205.5 

287.5 

302.6 

342.1 

360.1 

436 

387.3 

207.6 

213.3 

212.5 

206.0 

288.1 

303.3 

342.9 

361.0 

437 

388.2 

208.2 

213.9 

213.1 

206.6 

288.8 

304.0 

343.7 

361.8 

438 

389.1 

208.7 

214.4 

213.6 

207.1 

289.5 

304.7 

344.5 

362.6 

439 

390.0 

209.2 

215.0 

214.2 

207.7 

290.2 

305.5 

345.3 

363.4 

440 

390.8 

209.8 

215.5 

214.7 

208.2 

290.9 

306.2 

346.1 

364.3 

441 

391.7 

210.3 

216.1 

215.3 

208.8 

291.5 

306.9 

346.8 

365.1 

442 

392.6 

210.9 

216.6 

215.8 

209.3 

292.2 

307.6 

347.6 

365.9 

443 

393.5 

211.4 

217.2 

216.4 

209.9 

292.9 

308.3 

348.4 

366.8 

444 

394.4 

212.0 

217.8 

216.9 

210.4 

293.6 

309.0 

349.2 

367.6 

SUGAR   TABLES 


77 


TABLE   19.     (Continued.} 


i 

1 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

u 

X 

§ 

si 

1 

o 

f 

S 

"g 

q 

q 

i 

1 

5 

t; 

o 

1   . 

Is 

O 

+ 

Jl 

B 

• 

0. 

o 

> 

&  S 

a 

\« 

Cl 

~£ 

§ 

3 

£ 

c 

i  =? 

B 

o 

B 

Q* 

I 

i 

bfi  w 

s 

u 

J 

s 

s? 

° 

0 

<M 

O 

o1 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

mgs. 

445 

395.3 

212.5 

218.3 

217.5 

211.0 

294.2 

309.7 

350.0 

368.4 

446 

396.2 

213.1 

218.9 

218.0 

211.5 

294.9 

310.5 

350.8 

369.3 

447 

397.1 

213.6 

219.4 

218.6 

212.1 

295.6 

311.2 

351.6 

370.1 

448 

397.9 

214.1 

220.0 

219.1 

212.6 

296.3 

311.9 

352.4 

370.9 

449 

398.8 

214.7 

220.5 

219.7 

213.2 

297.0 

312.6 

353.2 

371.7 

450 

399.7 

215.2 

221.1 

220.2 

213.7 

297.6 

313.3 

353.9 

372.6 

451 

400.6 

215.8 

221.6 

220.8 

214.3 

298.3 

314.0 

354.7 

373.4 

452 

401.5 

216.3 

222.2 

221.4 

214.8 

299.0 

314.7 

355.5 

374.2 

453 

402.4 

216.9 

222.8 

221.9 

215.4 

299.7 

315.5 

356.3 

375.1 

454 

403.3 

217  A 

223.3 

222.5 

215.9 

300.4 

316.2 

357.1 

375.9 

455 

404.2 

218.0 

223.9 

223.0 

216.5 

301.1 

316.9 

357.9 

376.7 

456 

405.1 

218.5 

224.4 

223.6 

217.0 

301.7 

317.6 

358.7 

377.6 

457 

405.9 

219.1 

225.0 

224.1 

217.6 

302.4 

318.3 

359.5 

378.4 

458 

406.8 

219.6 

225.5 

224.7 

218.1 

303.1 

319.0 

360.3 

379.2 

459 

407.7 

220.2 

226.1 

225.3 

218.7 

303.8 

319.8 

361.0 

380.0 

460 

408.6 

220.7 

226.7 

225.8 

219.2 

304.5 

320.5 

361.8 

380.9 

461 

409.5 

221.3 

227.2 

226.4 

219.8 

305.1 

321.2 

362.6 

381.7 

462 

410.4 

221.8 

227.8 

226.9 

220.3 

305.8 

321.9 

363.4 

382.5 

463 

411.3 

222.4 

228.3 

227.5 

220.9 

306.5 

322.6 

364.2 

383.4 

464 

412.2 

222.9 

228.9 

228.1 

221  A 

307.2 

323.4 

365.0 

384.2 

465 

413.0 

223.5 

229.5 

228.6 

222.0 

307.9 

324.1 

365.8 

385.0 

466 

413.9 

224.0 

230.0 

229.2 

222.5 

308.6 

324.8 

366.6 

385.9 

467 

414.8 

224.6 

230.6 

229.7 

223.1 

309.2 

325.5 

367.3 

386.7 

468 

415.7 

225.1 

231.2 

230.3 

223.7 

309.9 

326.2 

368.1 

387.5 

469 

416.6 

225.7 

231.7 

230.9 

224.2 

310.6 

326.9 

368.9 

388.3 

470 

417.5 

226.2 

232.3 

231.4 

224.8 

311.3 

327.7 

369.7 

389.2 

471 

418.4 

226.8 

232.8 

232.0 

225.3 

312.0 

328.4 

370.5 

390.0 

472 

419.3 

227.4 

233.4 

232.5 

225.9 

312.6 

329.1 

371.3 

390.8 

473 

420.2 

227.9 

234.0 

233.1 

226.4 

313.3 

329.8 

372.1 

391.7 

474 

421.0 

228.5 

234.5 

233.7 

227.0 

314.0 

330.5 

372.9 

392.5 

475 

421.9 

229.0 

235.1 

234.2 

227.6 

314.7 

331.3 

373.7 

393.3 

476 

422.8 

229.6 

235.7 

234.8 

228.1 

315.4 

332.0  - 

374.4 

394.2 

477 

423.7 

230.1 

236.2 

235.4 

228.7 

316.1 

332.7 

375.2 

395.0 

478 

424.6 

230.7 

236.8 

235.9 

229.2 

316.7 

333.4 

376.0 

395.8 

479 

425.5 

231.3 

237.4 

236.5 

229.8 

317.4 

334.1 

376.8 

396.6 

480 

426.4 

231.8 

237.9 

237.1 

230.3 

318.1 

334.8 

377.6 

397.5 

481 

427.3 

232.4 

238.5 

237.6 

230.9 

318.8 

335.6 

378.4 

398.3 

482 

428.1 

232.9 

239.1 

238.2 

231.5 

319.5 

336.3 

379.2 

399.1 

483 

429.0 

233.5 

239.6 

238.8 

232.0 

320.1 

337.0 

380.0 

400.0 

484 

429.9 

234.1 

240.2 

239.3 

232.6 

320.8 

337.7 

380.7 

400.8 

78 


SUGAR  TABLES 
TABLE   19.    (Concluded.} 


q 

| 

Invert  sugar 
and  sucrose. 

Lactose. 

Maltose. 

g 

I 

3 
1 

i 
i 

1 

3 

a 

| 

i 

s: 

O 

1 

I 

1 

B  £ 
II 

il 

1 

i 

3 

q 

g 

« 

o 

I 

0 

w 

0 

i 

mgs. 

485 

mgs. 

430.8 

mgs. 

234.6 

mgs. 

240.8 

mgs. 

239.9 

mgs. 

233.2 

mgs. 

321.5 

mgs. 

338.4 

mgs. 

381.5 

mgs. 

401.6 

486 

431.7 

235.2 

241.4 

240.5 

233.7 

322.2 

339.1 

382.3 

402.4 

487 

432.6 

235.7 

241.9 

241.0 

234.3 

322.9 

339.9 

383.1 

403.3 

488 

433.5 

236.3 

242.5 

241.6 

234.8 

323.6 

340.6 

383.9 

404.1 

489 

434.4 

236.9 

243.1 

242.2 

235.4 

324.2 

341.3 

384.7 

404.9 

490 

435.3 

237.4 

243.6 

242.7 

236.0 

324.9 

342.0 

385.5 

405.8 

SUGAR  TABLES 


79 


TABLE*  20. 

BERTRAND'S  TABLE  FOR  DETERMINING  INVERT  SUGAR,  GLUCOSE,  GALACTOSE, 
MALTOSE,  AND  LACTOSE. 


Milligrams  of 
sugar. 

Milligrams  of  copper  corresponding  to 

Invert  sugar. 

Glucose. 

Galactose. 

Maltose. 

Lactose. 

10 

20.6 

20.4 

19.3 

11.2 

14.4 

11 

22.6 

22.4 

21.2 

12.3 

15.8 

12 

24.6 

24.3 

23.0 

13.4 

17.2 

13 

26.5 

26.3 

24.9 

14.5 

18.6 

14 

28.5 

28.3 

26.7 

15.6 

20.0 

15 

30.5 

30.2 

28.6 

16.7 

21.4 

16 

32.5 

32.2 

30.5 

17.8 

22.8 

17 

34.5 

34.2 

32.3 

18.9 

24.2 

18 

36.4 

36.2 

34.2 

20.0 

25.6 

19 

38.4 

38.1 

36.0 

21.1 

27.0 

20 

40.4 

40.1 

37.9 

22.2 

28.4 

21 

42.3 

42.0 

39.7 

23.3 

29.8 

22 

44.2 

43.9 

41.6 

24.4 

31.1 

23 

46.1 

45.8 

43.4 

25.5 

32.5 

24 

48.0 

47.7 

45.2 

26.6 

33.9 

25 

49.8 

49.6 

47.0 

27.7 

35.2   . 

26 

51.7 

51.5 

48.9 

28.9 

36.6 

27 

53.6 

53.4 

50.7 

30.0 

38.0 

28 

55.5 

55.3 

52.5 

31.1 

39.4 

29 

57.4 

57.2 

54.4 

32.2 

40.7 

30 

59.3 

59.1 

56.2 

33.3 

42.1 

31 

61.1 

60.9 

58.0 

34.4 

43.4 

32 

63.0 

62.8 

59.7 

35.5 

44.8 

33 

64.8 

64.6 

61.5 

36.5 

46.1 

34 

66.7 

66.5 

63.3 

37.6 

47.4 

35 

68.5 

68.3 

65.0 

38.7 

48.7 

36 

70.3 

70.1 

66.8 

39.8 

50.1 

37 

72.2 

72.0 

68.6 

40.9 

51.4 

38 

74.0 

73.8 

70.4 

41.9 

52.7 

39 

75.9 

75.7 

72.1 

43.0 

54.1 

40 

77.7 

77.5 

73.9 

44.1 

55.4 

41 

79.5 

79.3 

75.6 

45.2 

56.7 

42 

81.2 

81.1 

77.4 

46.3 

58.0 

43 

83.0 

82.9 

79.1 

47.4 

59.3 

44 

84.8 

84.7 

80.8 

48.5 

60.6 

45 

86.5 

86.4 

82.5 

49.5 

61.9 

46 

88.3 

88.2 

84.3 

50.6 

63.3 

47 

90.1 

90.0 

86.0 

51.7 

64.6 

48 

91.9 

91.8 

87.7 

52.8 

65.9 

49 

93.6 

93.6 

89.5 

53.9 

67.2 

60 

95.4 

95.4 

91.2 

55.0 

68.5 

51 

97.1 

97.1 

92.9 

56.1 

69.8 

52 

98.8 

98.9 

94.6 

57.1 

71.1 

53 

100.6 

100.6 

96.3 

58.2 

72.4 

54 

102.2 

102.3 

98.0 

59.3 

73.7 

55 

104.0 

104.1 

99.7 

60.3 

74.9 

56 

105.7 

105.8 

101.5 

61.4 

76.2 

57 

107.4 

107.6 

103.2 

62.5 

77.5 

58 

109.2 

109.3 

104.9 

63.5 

78.8 

59 

110.9 

111.1 

106.6 

64.6 

80.1 

*  See  "  Handbook,"  page  426. 


80 


SUGAR  TABLES 
TABLE  20.     (Concluded.) 


Milligrams  of 
sugar. 

Milligrams  of  copper  corresponding  to 

Invert  sugar. 

Glucose. 

Galactose. 

Maltose. 

Lactose. 

60 

112.6 

112.8 

108.3 

65.7 

81.4 

61 

114.3 

114.5 

110.0 

66.8 

82.7 

62 

115.9 

116.2 

111.6 

67.9 

83.9 

63 

117.6 

117.9 

113.3 

68.9 

85.2 

64 

119.2 

119.6 

115.0 

70.0 

86.5 

65 

120.9 

121.3 

116.6 

71.1 

87.7 

66 

122.6 

123.0 

118.3 

72.2 

89.9 

67 

124.2 

124.7 

120.0 

73.3 

.      90.3 

68 

125.9 

126.4 

121.7 

74.3 

91.6 

69 

127.5 

128.1 

123.3 

75.4 

92.8 

70 

129.2 

129.8 

125.0 

76.5 

94.1 

71 

130.8 

131.4 

126.6 

77.6 

95.4 

72 

132.4 

133.1 

128.3 

78.6 

96.9 

73 

134.0 

134.7 

130.0 

79.7 

98.0 

74 

135.6 

136.3 

131.5 

80.8 

99.1 

75 

137.2 

137.9 

133.1 

81.8 

100.4 

76 

138.9 

139.6 

134.8 

82.9 

101.7 

77 

140.5 

141.2 

136.4 

84.0 

102.9 

78 

142.1 

142.8 

138.0 

85.1 

104.2 

79 

143:7 

144.5 

139.7 

86.1 

105.4 

80 

145.3 

146.1 

141.3 

87.2 

106.7 

81 

146.9 

147.7 

142.9 

88.3 

107.9 

82 

148.5 

149.3 

144.6 

89.4 

109.2 

83 

150.0 

150.9 

146.2 

90.4 

110.4 

84 

151.6 

152.5 

147.8 

91.5 

111  7 

85 

153.2 

154.0 

149.4 

92.6 

112.9 

86 

154.8 

155.6 

151.1 

93.7 

114.1 

87 

156.4 

157.2 

152.7 

94.8 

115.4 

88 

157.9 

158.8 

154.3 

95.8 

116  6 

89 

159.5 

160.4 

156.0 

96.9 

117.9 

90 

161.1 

162.0 

157.6 

98.0 

119.1 

91 

162.6 

163.6 

159.2 

99.0 

120.3 

92 

164.2 

165.2 

160.8 

100.1 

121.6 

93 

165.7 

166.7 

162.4 

101.1 

122.8 

94 

167.3 

168.3 

164.0 

102.2 

124.0 

95 

168.8 

169.9 

165.6 

103.2 

125.2 

96 

170.3 

171.5 

167.2 

104.2 

126.5 

97 

171.9 

173.1 

168.8 

105.3 

127.7 

98 

173.4 

174.6 

170.4 

106.3 

128.9 

99 

175.0 

176.2 

172.0 

107.4 

130.2 

100 

176.5 

177.8 

173.6 

108.4 

131.4 

SUGAR  TABLES 


81 


TABLE*  21. 

HERZFELD'S  TABLE  FOR  DETERMINING  INVERT  SUGAR  IN  RAW  SUGARS  (INVERT 
SUGAR  NOT  TO  EXCEED  1.5%.) 


Oogjr. 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 

sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

Coppe, 

Invert 
sugar. 

mgs. 

per  cent. 

mgs. 

per  cent. 

mgs. 

per  cent. 

mgs. 

per  cent. 

50 

0.050 

101 

0.305 

152 

0.574 

203 

0.863 

51 

0.054 

102 

0.310 

153 

0.580 

204 

0.869 

52 

0.058 

103 

0.315 

154 

0.586 

205 

0.874 

53 

0.062 

104 

0.320 

155 

0.592 

206 

0.880 

54 

0.066 

105 

0.325 

156 

0.598 

207 

0.885 

55 

0.070 

106 

0.330 

157 

0.604 

208 

0.891 

56 

0.074 

107 

0.335 

158 

0.609 

209 

0.896 

57 

0.078 

108 

0.340 

159 

0.615 

210 

0.902 

58 

0.082 

109 

0.346 

160 

0.621 

211 

0.907 

59 

0.086 

110 

0.351 

161 

0.627 

212 

0.913 

60 

0.090 

111 

0.356 

162 

0.633 

213 

0.918 

61 

0.094 

112 

0.361 

163 

0.639 

214 

0.924 

62 

0.098 

113 

0.366 

164 

0.645 

215 

0.929 

63 

0.103 

114 

0.371 

165 

0.651 

216 

0.935 

64 

0.108 

115 

0.376 

166 

0.657 

217 

0.940 

65 

0.113 

116 

0.381 

167 

0.663 

218 

0.946 

66 

0.118 

117 

0.386 

168 

0.669 

219 

0.951 

67 

0.123 

118 

0.392 

169 

0.675 

220 

0.957 

68 

0.128 

119 

0.397 

170 

0.680 

221 

0.962 

69 

0.133 

120 

0.402 

171 

0.686 

222 

0.968 

70 

0.138 

121 

0.407 

172 

0.692 

223 

0.973 

71 

0.143 

122 

0.412 

173 

0.698 

224 

0.979 

72 

0.148 

123 

0.417 

174 

0.704 

225 

0.984 

73 

0.152 

124 

0.423 

175 

0.709 

226 

0.990 

74 

0.157 

125 

0.428 

176 

0.715 

227 

0.996 

75 

0.162 

126 

0.433 

177 

0.720 

228 

1.001 

76 

0.167 

127 

0.438 

178 

0.726 

229 

.007 

77 

0.172 

128 

0.443 

179 

0.731 

230 

.013 

78 

0.177 

129 

0.448 

180 

0.737 

231 

.018 

79 

0.182 

130 

0.453 

181 

0.742 

232 

.024 

80 

0.187 

131 

0.458 

182 

0.748 

233 

.030 

81 

0.192 

132 

0.463 

183 

0.753 

234 

.036 

82 

0.197 

133 

0.468 

184 

0.759 

235 

.041 

83 

0.202 

134 

0.473 

185 

0.764 

236 

1.047 

84 

0.208 

135 

0.478 

186 

0.770 

237 

1.053 

85 

0.213 

136 

0.483 

187 

0.775 

238 

1.058 

86 

0.219 

137 

0.488 

188 

0.781 

239 

1.064 

87 

0.225 

138 

0.493 

189 

0.786 

240 

1.070 

88 

0.231 

139 

0.498 

190 

0.792 

241 

1.076 

89 

0.236 

140 

0.503 

191 

0.797 

242 

1.081 

90 

0.242 

141 

0.509 

192 

0.803 

243 

1.087 

91 

0.248 

142 

0.515 

193 

0.808 

244 

1.093 

92 

0.254 

143 

0.521 

194 

0.814 

245 

1.099 

93 

0.260 

144 

0.527 

195 

0.819 

246 

1.104 

94 

0.265 

145 

0.533 

196 

0.825 

247 

1.110 

95 

0.271 

146 

0.538 

197 

0.830 

248 

1.116 

96 

0.277 

147 

0.544 

198 

0.836 

249 

1.122 

97 

0.283 

148 

0.550 

199 

0.841 

250 

1.127 

98 

0.288 

149 

0.556 

200 

0.847 

251 

1.133 

99 

0.294 

150 

0.562 

201 

0.852 

252 

1.139 

100 

0.300 

151 

0.568 

202 

0.858 

253 

1.144 

*  See  "  Handbook,"  page  428. 


82 


SUGAR  TABLES 


TABLE  21.     (Concluded.) 


Copper. 

(Cu). 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

Ogpe, 

Invert 
sugar. 

Copper. 

(Cu). 

Invert 
sugar. 

nigs. 

per  cent. 

mgs. 

per  cent. 

mgs. 

per  cent. 

mgs. 

per  cent. 

254 

1.150 

270 

.242 

286 

1.334 

302 

1.425 

255 

1.156 

271 

.248 

287 

1.339 

303 

1.431 

256 

1.162 

272 

.253 

288 

1.345 

304 

1.437 

257 

1.167 

273 

.259 

289 

1.351 

305 

1.443 

258 

1.173 

274 

.265 

290 

1.357 

306 

1.448 

259 

1.179 

275 

1.271 

291 

1.362 

307 

1.454 

260 

1.185 

276 

1.276 

292 

1.368 

308 

.460 

261 

1.190 

277 

1.282 

293 

.374 

309 

.466 

262 

1.196 

278 

1.288 

294 

.380 

310 

.471 

263 

1.202 

279 

1.294 

295 

.385 

311 

.477 

264 

1.207 

280 

1.299 

296 

.391 

312 

.483 

265 

1.213 

281 

1.305 

297 

.397 

313 

.489 

266 

1.219 

282 

1.311 

298 

.403 

314 

.494 

267 

1.225 

283 

1.317 

299 

.408 

315 

1.500 

268 

1.231 

284 

1.322 

300 

.414 

269 

1.236 

285 

1.328 

301 

.420 

SUGAR  TABLES 


83 


TABLE  *  22. 
KROBER'S  TABLE  FOR  DETERMINING  PENTOSES  AND  PENTOSANS. 


Furfural 
phloroglu- 
cide. 

Furfural. 

Arabinose. 

Araban. 

Xylose. 

Xylan. 

Pentose. 

Pentosan. 

grams. 

grams. 

grams. 

grams. 

grams. 

grama. 

grams. 

grams. 

0.030 

0.0182 

0.0391 

0.0344 

0.0324 

0.0285 

0.0358 

0.0315 

.031 

.0188 

.0402 

.0354 

.0333 

.0293 

.0368 

.0324 

.032 

.0193 

.0413 

.0363 

.0342 

.0301 

.0378 

.0333 

.033 

.0198 

.0424 

.0373 

.0352 

.0309 

.0388 

.0341 

.034 

.0203 

.0435 

.0383 

.0361 

.0317 

.0398 

.0350 

.035 

.0209 

.0446 

.0393 

.0370 

.0326 

.0408 

.0359 

.036 

.0214 

.0457 

.0402 

.0379 

.0334 

.0418 

.0368 

.037 

.0219 

.0468 

.0412 

.0388 

.0342 

.0428 

.0377 

.038 

.0224 

.0479 

.0422 

.0398 

.0350 

.0439 

.0386 

.039 

.0229 

.0490 

.0431 

.0407 

.0358 

.0449 

.0395 

.040 

.0235 

.0501 

.0441 

.0416 

.0366 

.0459 

.0404 

.041 

.0240 

.0512 

.0451 

.0425 

.0374 

.0469 

.0413 

.042 

.0245 

.0523 

.0460 

.0434 

.0382 

.0479 

.0422 

.043 

.0250 

.0534 

.0470 

.0443 

.0390 

.0489 

.0431 

.044 

.0255 

.0545 

.0480 

.0452 

.0398 

.0499 

.0440 

.045 

.0260 

.0556 

.0490 

.0462 

.0406 

.0509 

.0448 

.046 

.0266 

.0567 

.0499 

.0471 

.0414 

.0519 

.0457 

.047 

.0271 

.0578 

.0509 

.0480 

.0422 

.0529 

.0466 

.048 

.0276 

.0589 

.0519 

.0489 

.0430 

.0539 

.0475 

.049 

.0281 

.0600 

.0528 

.0498 

.0438 

.0549 

.0484 

.050 

.0286 

.0611 

.0538 

.0507 

.0446 

.0559 

.0492 

.051 

.0292 

.0622 

.0548 

.0516 

.0454 

.0569 

.0501 

.052 

.0297 

.0633 

.0557 

.0525 

.0462 

.0579 

.0510 

.053 

.0302 

.0644 

.0567 

.0534 

.0470 

.0589 

.0519 

.054 

.0307 

.0655 

.0576 

.0543 

.0478 

.0599 

.0528 

.055 

.0312 

.0666 

.0586 

.0553 

.0486 

.0610 

.0537 

.056 

.0318 

.0677 

.0596 

.0562 

.0494 

.0620 

.0546 

.057 

.0323 

.0688 

.0605 

.0571 

.0502 

.0630 

.0555 

.058 

.0328 

.0699 

.0615 

.0580 

.0510 

.0640 

.0564 

.059 

.0333 

.0710 

.0624 

.0589 

.0518 

.0650 

.0573 

.060 

.0338 

.0721 

.0634 

.0598 

.0526 

.0660 

.0581 

.061 

.0344 

.0732 

.0644 

.0607 

.0534 

.0670 

.0590 

.062 

.0349 

.0743 

.0653 

.0616 

.0542 

.0680 

.0599 

.063 

.0354 

.0754 

.0663 

.0626 

.0550 

.0690 

.0608 

.064 

.0359 

.0765 

.0673 

.0635 

.0558 

.0700 

.0617 

.065 

.0364 

.0776 

.0683 

.0644 

.0567 

.0710 

.0625 

.066 

.0370 

0787 

.0692 

.0653 

.0575 

.0720 

.0634 

.067 

.0375 

.0798 

.0702 

.0662 

.0583 

.0730 

.0643 

.068 

.0380 

.0809 

.0712 

.0672 

.0591 

.0741 

.0652 

.069 

.0385 

.0820 

.0721 

.0681 

.0599 

.0751 

.0661 

.070 

.0390 

.0831 

.0731 

.0690 

.0607 

.0761 

.0670 

.071 

.0396 

.0842 

.0741 

.0699 

.0615 

.0771 

.0679 

.072 

.0401 

.0853 

.0750 

.0708 

.0623 

.0781 

.0688 

.073 

.0406 

.0864 

.0760 

.0717 

.0631 

.0791 

.0697 

.074 

.0411 

.0875 

.0770 

.0726 

.0639 

.0801 

.0706 

*  See  "  Handbook,"  page  450. 


84 


SUGAR  TABLES 


TABLE  22.     (Continued.) 


Furfural 
phloroglu- 
cide. 

Furfural. 

Arabinose. 

Araban. 

Xylose. 

Xylan. 

Pentose. 

Pentosan. 

grams. 

0.075 

grains. 

0.0416 

grams. 
0.0886 

grams. 

0.0780 

grams. 

0.0736 

grams. 

0.0647 

grams. 

0.0811 

grams. 

0.0714 

.076 

.0422 

.0897 

.0789 

.0745 

.0655 

.0821 

.0722 

.077 

.0427 

.0908 

.0799 

.0754 

.0663 

.0831 

.0731 

.078 

.0432 

.0919 

.0809 

.0763 

.0671 

.0841 

.0740 

.079 

.0437 

.0930 

.0818 

.0772 

.0679 

.0851 

.0749 

.080 

.0442 

.0941 

.0828 

.0781 

.0687 

.0861 

.0758 

.081 

.0448 

.0952 

.0838 

.0790 

.0695 

.0871 

.0767 

.082 

.0453 

.0963 

.0847 

.0799 

.0703 

.0881 

.0776 

.083 

.0458 

.0974 

.0857 

.0808 

.0711 

.0891 

.0785 

.084 

.0463 

.0985 

.0867 

.0817 

.0719 

.0901 

.0794 

.085 

.0468 

.0996 

.0877 

.0827 

.0727 

.0912 

.0803 

.086 

.0474 

.1007 

.0886 

.0836 

.0735 

.0922 

.0812 

.087 

.0479 

.1018 

.0896 

.0845 

.0743 

.0932 

.0821 

.088 

.0484 

.1029 

.0906 

.0854 

.0751 

.0942 

.0830 

.089 

.0489 

.1040 

.0915 

.0863 

.0759 

.0952 

.0838 

.090 

.0494 

.1051 

.0925 

.0872 

.0767 

.0962 

.0847 

.091 

.0499 

.1062 

.0935 

.0881 

.0775 

.0972 

.0856 

.092 

.0505 

.1073 

.0944 

.0890 

.0783 

.0982 

.0865 

.093 

.0510 

.1084 

.0954 

.0900 

.07;91 

.0992 

.0874 

.094 

.0515 

.1095 

.0964 

.0909 

.0800 

.1002 

.0883 

.095 

.0520 

.1106 

.0974 

.0918 

.0808 

.1012 

.0891 

.096 

.0525 

.1117 

.0983 

.0927 

.0816 

.1022 

.0899 

.097 

.0531 

.1128 

.0993 

.0936 

.0824 

.1032 

.0908 

.098 

.0536 

.1139 

.1003 

.0946 

.0832 

.1043 

.0917 

.099 

.0541 

.1150 

.1012 

.0955 

.0840 

.1053 

.0926 

.100 

.0546 

.1161 

.1022 

.0964 

.0848 

.1063 

.0935 

.101 

.0551 

.1171 

.1032 

.0973 

.0856 

.1073 

.0944 

.102 

.0557 

.1182 

.1041 

.0982 

.0864 

.1083 

.0953 

.103 

.0562 

.1193 

.1051 

.0991 

.0872 

.1093 

.0962 

.104 

.0567 

.1204 

.1060 

.1000 

.0880 

.1103 

.0971 

.105 

.0572 

.1215 

.1070 

.1010 

.0888 

.1113 

.0979 

.106 

.0577 

.1226 

.1080 

.1019 

.0896 

.1123 

.0988 

.107 

.0582 

.1237 

.1089 

.1028 

.0904 

.1133 

.0997 

.108 

.0588 

.1248 

.1099 

.1037 

.0912 

.1143 

.1006 

.109 

.0593 

.1259 

'.1108 

.1046 

.0920 

.1153 

.1015 

.110 

.0598 

.1270 

.1118 

.1055 

.0928 

.1163 

.1023 

.111 

.0603 

.1281 

.1128 

.1064 

.0936 

.1173 

.1032 

.112 

.0608 

.1292 

.1137 

.1073 

.0944 

.1183 

.1041 

.113 

.0614 

.1303 

.1147 

.1082 

.0952 

.1193 

.1050 

.114 

.0619 

.1314 

.1156 

.1091 

.0960 

.1203 

.1059 

.115 

.0624 

.1325 

.1166 

.1101 

.0968 

.1213 

.1067 

.116 

.0629 

.1336 

.1176 

.1110 

.0976 

.1223 

.1076 

.117 

.0634 

.1347 

.1185 

.1119 

.0984 

.1233 

.1085 

.118 

.0640 

.1358 

.1195 

.1128 

.0992 

.1243 

.1094 

.119 

.0645 

.1369 

.1204 

.1137 

.1000 

.1253 

.1103 

SUGAR  TABLES 


85 


TABLE  22.     (Continued.) 


Furfural 
phloroglu- 
cide. 

Furfural. 

Arabinose. 

Araban. 

Xylose. 

Xylan. 

Pentose. 

Pentosan. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

0.120 

0.0650 

0.1380 

0.1214 

0.1146 

0.1008 

0.1263 

0.1111 

.121 

.0655 

.1391 

.1224 

.1155 

.1016 

.1273 

.1120 

.122 

.0660 

.1402 

.1233 

.1164 

.1024 

.1283 

.1129 

.123 

.0665 

.1413 

.1243 

.1173 

.1032 

.1293 

.1138 

.124 

.0671 

.1424 

.1253 

.1182 

.1040 

.1303 

.1147 

.125 

.0676 

.1435 

.1263 

.1192 

.1049 

.1314 

.1156 

.126 

.0681 

.1446 

1272 

.1201 

.1057 

.1324 

.1165 

.127 

.0686 

.1457 

.1282 

.1210 

.1065 

.1334 

.1174 

.128 

.0691 

.1468 

.1292 

.1219 

.1073 

.1344 

.1183 

.129 

.0697 

.1479 

.1301 

.1228 

.1081 

.1354 

.1192 

.130 

.0702 

.1490 

.1311 

.1237 

.1089 

.1364 

.1201 

.131 

.0707 

.1501 

.1321 

.1246 

.1097 

.1374 

.1210 

.132 

.0712 

.1512 

.1330 

.1255 

.1105 

.1384 

.1219 

.133 

.0717 

.1523 

.1340 

.1264 

.1113 

.1394 

.1227 

.134 

.0723 

.1534 

.1350 

.1273 

.1121 

.1404 

.1236 

.135 

.0728 

.1545 

.1360 

.1283 

.1129 

.1414 

.1244 

.136 

.0733 

.1556 

.1369 

.1292 

.1137 

.1424 

.1253 

.137 

.0738 

.1567 

.1379 

.1301 

.1145 

.1434 

.1262 

.138 

.0743 

.1578 

.1389 

.1310 

.1153 

.1444 

.1271 

.139 

.0748 

.1589 

.1398 

.1319 

.1161 

.1454 

.1280 

.140 

.0754 

.1600 

.1408 

.1328 

.1169 

.1464 

.1288 

.141 

.0759 

.1611 

.1418 

.1337 

.1177 

.1474 

.1297 

.142 

.0764 

.1622 

.1427 

.1346 

.1185 

.1484 

.1306 

.143 

.0769 

.1633 

.1437 

.1355 

.1193 

.1494 

.1315 

.144 

.0774 

.1644 

.1447 

.1364 

.1201 

.1504 

.1324 

.145 

.0780 

.1655 

.1457 

.1374 

.1209 

.1515 

.1333 

.146 

.0785 

.1666 

.1466 

.1383 

.1217 

.1525 

.1342 

.147 

.0790 

.1677 

.1476 

.1392 

.1225 

.1535 

.1351 

.148 

.0795 

.1688 

.1486 

.1401 

.1233 

.1545 

.1360 

.149 

.0800 

.1699 

.1495 

.1410 

.1241 

.1555 

.1369 

.150 

.0805 

.1710 

.1505 

.1419 

.1249 

.1565 

.1377 

.151 

.0811 

.1721 

.1515 

.1428 

.1257 

.1575 

.1386 

.152 

.0816 

.1732 

.1524 

.1437 

.1265 

.1585 

.1395 

.153 

.0821 

.1743 

.1534 

.1446 

.1273 

.1595 

.1404 

.154 

.0826 

.1754 

.1544 

.1455 

.1281 

.1605 

.1413 

.155 

.0831 

.1765 

.1554 

.1465 

.1289 

.1615 

.1421 

.156 

.0837 

.1776 

.1563 

.1474 

.1297 

.1625 

.1430 

.157 

.0842 

.1787 

.1573 

.1483 

.1305 

.1635 

.1439 

.158 

.0847 

.1798 

.1583 

.1492 

.1313 

.1645 

.1448 

.159 

.0852 

.1809 

.1592 

.1501 

.1321 

.1655 

.1457 

.160 

.0857 

1820 

.1602 

.1510 

.1329 

.1665 

.1465 

.161 

.0863 

.1831    .1612 

.1519 

.1337 

.1675 

.1474 

.162 

.0868 

1842    .  1621 

.1528 

.1345 

.1685 

.1483 

163 

0873 

.  1853    .  1631 

.1537 

.1353 

.1695 

.1492 

".164 

.0878 

.  1864    .  1640 

.1546 

.1361 

.1705 

.1501 

86 


SUGAR  TABLES 


TABLE  22.     (Continued.) 


Furfural 
phloroglu- 
cide. 

Furfural. 

Arabinose. 

Araban. 

Xylose. 

Xylan. 

Pentose. 

Pentosan. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

0.165 

0.0883 

0.1875 

0.1650 

0.1556 

0.1369 

0.1716 

0.1510 

.166 

.0888 

.1886 

.1660 

.1565 

.1377 

.1726 

.1519 

.167 

.0894 

.1897 

.1669 

.1574 

.1385 

.1736 

.1528 

.168 

.0899 

.1908 

.1679 

.1583 

.1393 

.1746 

.1537 

.169 

.0904 

.1919 

.1688 

.1592 

.1401 

.1756 

.1546 

.170 

.0909 

.1930 

.1698 

.1601 

.1409 

.1766 

.1554 

.171 

.0914 

.1941 

.1708 

.1610 

.1417 

.1776 

.1563 

.172 

.0920 

.1952 

.1717 

.1619 

.1425 

.1786 

.1572 

.173 

.0925 

.1963 

.1727 

.1628 

.1433 

.1796 

.1581 

.174 

.0930 

.1974 

.1736 

.1637 

.1441 

.1806 

.1590 

.175 

.0935 

.1985 

.1746 

.1647 

.1449 

.1816 

.1598 

.176 

.0940 

.1996 

.1756 

.1656 

.1457 

.1826 

.1607 

.177 

.0946 

.2007 

.1765 

.1665 

.1465 

.1836 

.1616 

.178 

.0951 

.2018 

.1775 

.1674 

.1473 

.1846 

.1625 

.179 

.0956 

.2029 

.1784 

.1683 

.1481 

.1856 

.1634 

.180 

.0961 

.2039 

.1794 

.1692 

.1489 

.1866 

.1642 

.181 

.0966 

.2050 

.1804 

.1701 

.1497 

.1876 

.1651 

.182 

.0971 

.2061 

.1813 

.1710 

.1505 

.1886 

.1660 

.183 

.0977 

.2072 

.1823 

.1719 

.1513 

.1896 

.1669 

.184 

.0982 

.2082 

.1832 

.1728 

.1521 

.1906 

.1678 

.185 

.0987 

.2093 

.1842 

.1738 

.1529 

.1916 

.1686 

.186 

.0992 

.2104 

.1851 

.1747 

.1537 

.1926 

.1695 

.187 

.0997 

.2115 

.  1861 

.1756 

.1545 

.1936 

.1704 

.188 

.1003 

.2126 

.1870 

.1765 

.1553 

.1946 

.1712 

.189 

.1008 

.2136 

.1880 

.1774 

J561 

.1955 

.1721 

.190 

.1013 

.2147 

.1889 

.1783 

.1569 

.1965 

.1729 

.191 

.1018 

.2158 

.1899 

.1792 

.1577 

.1975 

.1738 

.192 

.1023 

.2168 

.1908 

.1801 

.1585 

.1985 

.1747 

.193 

.1028 

.2179 

.1918 

.1810 

.1593 

.1995 

.1756 

.194 

.1034 

.2190 

.1927 

.1819 

.1601 

.2005 

.1764 

.195 

.1039 

.2201 

.1937 

.1829 

.1609 

.2015 

.1773 

.196 

.1044 

.2212 

.1946 

.1838 

.1617 

.2025 

.1782 

.197 

.1049 

.2222 

.1956 

.1847 

.1625 

.2035 

.1791 

.198 

.1054 

.2233 

.1965 

.1856 

.1633 

.2045 

.1800 

.199 

.1059 

.2244 

.1975 

.1865 

.1641 

.2055 

.1808 

.200 

.1065 

.2255 

.1984 

.1874 

.1649 

.2065 

.1817 

.201 

.1070 

.2266 

.1994 

.1883 

.1657 

.2075 

.1826 

.202 

.1075 

.2276 

.2003 

.1892 

.1665 

.2085 

.1835 

.203 

.1080 

.2287 

.2013 

.1901 

.1673 

.2095 

.1844 

.204 

.1085 

.2298 

.2022 

.1910 

.1681 

.2105 

.1853 

.205 

.1090 

.2309 

.2032 

.1920 

.1689 

.2115 

.1861 

.206 

.1096 

.2320 

.2041 

.1929 

.1697 

.2125 

.1869 

.207 

.1101 

.2330 

.2051 

.  1938 

.1705 

.2134 

.1878 

.208 

.1106 

.2341 

.2060 

.1947 

.1713 

.2144 

.1887 

.209 

.1111 

.2352 

.2069 

.1956 

.1721 

.2154 

.1896 

SUGAR  TABLES 


87 


TABLE  22.     (Continued.) 


Furfural 
phloroglu- 
cide. 

Furfural. 

Arabinose. 

Araban. 

Xylose. 

Xylan. 

Pentose. 

Pentosan. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

0.210 

0.1116 

0.2363 

0.2079 

0.1965 

0.1729 

0.2164 

0.1904 

.211 

.1121 

.2374 

.2089 

.1975 

.1737 

.2174 

.1913 

.212 

.1127 

.2384 

.2098 

.1984 

.1745 

.2184 

.1922 

.213 

.1132 

.2395 

.2108 

.1993 

.1753 

.2194 

.1931 

.214 

.1137 

.2406 

.2117 

.2002 

.1761 

.2204 

.1940 

.215 

.1142 

.2417 

.2127 

.2011 

.1770 

.2214 

.1948 

.216 

.1147 

.2428 

.2136 

.2020 

.1778 

.2224 

.1957 

.217 

.1152 

.2438 

.2146 

.2029 

.1786 

.2234 

.1966 

.218 

.1158 

.2449 

.2155 

.2038 

.1794 

.2244 

.1974 

.219 

.1163 

.2460 

.2165 

.2047 

.1802 

.2254 

.1983 

.220 

.1168 

.2471 

.2174 

.2057 

.1810 

.2264 

.1992 

.221 

.1173 

.2482 

.2184 

.2066 

.1818 

.2274 

.2001 

.222 

.1178 

.2492 

.2193 

.2075 

.1826 

.2284 

.2010 

.223 

.1183 

.2503 

.2203 

.2084 

.1834 

.2294 

.2019 

.224 

.1189 

.2514 

.2212 

.2093 

.1842 

.2304 

.2028 

.225 

.1194 

.2525 

.2222 

.2102 

.1850 

.2314 

.2037 

.226 

.1199 

.2536 

.2232 

.2111 

.1858 

.2324 

.2046 

.227 

.1204 

.2546 

.2241 

.2121 

.1866 

.2334 

.2054 

.228 

.1209 

.2557 

.2251 

.2130 

.1874 

.2344 

.2063 

.229 

.1214 

.2568 

.2260 

.2139 

.1882 

.2354 

.2072 

.230 

.1220 

.2579 

.2270 

.2148 

.1890 

.2364 

.2081 

.231 

.1225 

.2590 

.2280 

.2157 

.1898 

.2374 

.2089 

.232 

.1230 

.2600 

.2289 

.2166 

.1906 

.2383 

.2097 

.233 

.1235 

.2611 

.2299 

.2175 

.1914 

.2393 

.2106 

.234 

.1240 

.2622 

.2308 

.2184 

.1922 

.2403 

.2115 

.235 

.1245 

.2633 

.2318 

.2193 

.1930 

.2413 

.2124 

.236 

.1251 

.2644 

.2327 

.2202 

.1938 

.2423 

.2132 

.237 

.1256 

.2654 

.2337 

.2211 

.1946 

.2433 

.2141 

.238 

.1261 

.2665 

.2346 

.2220 

.1954 

.2443 

.2150 

.239 

.1266 

.2676 

.2356 

.2229 

.1962 

.2453 

.2159 

.240 

.1271 

.2687 

.2365 

.2239 

.1970 

.2463 

.2168 

.241 

.1276 

.2698 

.2375 

.2248 

.1978 

.2473 

.2176 

.242 

.1281 

.2708 

.2384 

.2257 

.1986 

.2483 

.2185 

.243 

.1287 

.2719 

.2394 

.2266 

.1994 

.2493 

.2194 

.244 

.1292 

.2730 

.2403 

.2275 

.2002 

.2503 

.2203 

.245 

.1297 

.2741 

.2413 

.2284 

.2010 

.2513 

.2212 

.246 

.1302 

.2752 

.2422 

.2293 

.2018 

.2523 

.2220 

.247 

.1307 

.2762 

.2432 

.2302 

.2026 

.2533 

.2229 

.248 

.1312 

.2773 

.2441 

.2311 

.2034 

.2543 

.2238 

.249 

.1318 

.2784 

.2451 

.2320 

.2042 

.2553 

.2247 

.250 

.1323 

.2795 

.2460 

.2330 

.2050 

.2563 

.2256 

.251 

.1328 

.2806 

.2470 

.2339 

.2058 

.2573 

.2264 

.252 

.1333 

.2816 

.2479 

.2348 

.2066 

.2582 

.2272 

.253 

.1338 

.2827 

.2489 

.2357 

.2074 

.2592 

.2281 

.254 

.1343 

.2838 

.2498 

.2366 

.2082 

.2602 

.2290 

88 


SUGAR  TABLES 
TABLE  22.     (Concluded.) 


Furfural 
phloroglu- 
cide. 

Furfural. 

Arabinose. 

Araban. 

Xylose. 

Xylan. 

Pentose. 

Pentosan. 

grams. 

grams. 

grams.  - 

grams. 

grams. 

grams. 

grams. 

grams. 

0.255 

0.1349 

0.2849 

0.2508 

0.2375 

0.2090 

0.2612 

0.2299 

.256 

1354 

.2860 

.2517 

.2384 

.2098 

.2622 

.2307 

.257 

.1359 

.2870 

.2526 

.2393 

.2106 

.2632 

.2316 

.258 

.1364 

.2881 

.2536 

.2402 

.2114 

.2642 

.2325 

.259 

.1369 

.2892 

.2545 

.2411 

.2122 

.2652 

.2334 

.260 

.1374 

.2903 

.2555 

.2420 

.2130 

.2662 

2342 

.261 

.1380 

.2914 

.2565 

.2429 

.2138 

.2672 

.2351 

-  .262 

.1385 

.2924 

.2574 

.2438 

.2146 

.2681 

.2359 

.263 

.1390 

.2935 

.2584 

.2447 

.2154 

.2691 

.2368 

.264 

.1395 

.2946 

.2593 

.2456 

.2162 

.2701 

.2377 

.265 

.1400 

.2957 

.2603 

.2465 

.2170 

.2711 

.2385 

.266 

.1405 

..2968 

.2612 

.2474 

.2178 

.2721 

.2394 

.267 

.1411 

.2978 

.2622 

.2483 

.2186 

.2731 

.2403 

.268 

.1416 

.2989 

.2631 

.2492 

.2194 

.2741 

.2412 

.269 

.1421 

.3000 

.2641 

.2502 

.2202 

.2751 

.2421 

.270 

.1426 

.3011 

.2650 

.2511 

.2210 

.2761 

.2429 

.271 

.1431 

.3022 

.2660 

.2520 

.2218 

.2771 

.2438 

.272 

.1436 

.3032 

.2669 

.2529 

.2226 

.2781 

.2447 

.273 

.1442 

.3043 

.2679 

.2538 

.2234 

.2791 

.2456 

.274 

.1447 

.3054 

.2688 

.2547 

.2242 

.2801 

.2465 

.275 

.1452 

.3065 

.2698 

.2556 

.2250 

.2811 

.2473 

.276 

.1457 

.3076 

.2707 

.2565 

.2258 

.2821 

.2482 

.277 

.1462 

.3086 

.2717 

.2574 

.2266 

.2830 

.2490 

.278 

.1467 

.3097 

.2726 

.2583 

.2274 

.2840 

.2499 

.279 

.1473 

.3108 

.2736 

.2592 

.2282 

.2850 

.2508 

.280 

.1478 

.3119 

.2745 

.2602 

.2290 

.2861 

.2517 

.281 

.1483 

.3130 

.2755 

.2611 

.2298 

.2871 

.2526 

.282 

.1488 

.3140 

.2764 

.2620 

.2306 

.2880 

.2534 

.283 

.1493 

.3151 

.2774 

.2629 

.2314 

.2890 

.2543 

,284 

.1498 

.3162 

.2783 

.2638 

.2322 

.2900 

.2552 

.285 

.1504 

.3173 

.2793 

.2647 

.2330 

.2910 

.2561 

.286 

.1509 

.3184 

.2802 

.2656 

.2338 

.2920 

.2570 

.287 

.1514 

.3194 

.2812 

.2665 

.2346 

.2930 

.2578 

.288 

.1519 

.3205 

.2821 

.2674 

.2354 

.2940 

.2587 

.289 

.1524 

.3216 

.2831 

.2683 

.2362 

.2950 

.2596 

.290 

.1529 

.3227 

.2840 

.2693 

.2370 

.2960 

.2605 

.291 

.1535 

.3238 

.2850 

.2702 

.2378 

.2970 

.2614 

.292 

.1540 

.3248 

.2859 

.2711 

.2386 

.2980 

.2622 

.293 

.1545 

.3259 

.2868 

.2720 

.2394 

.2990 

.2631 

.294 

.1550 

.3270 

.2878 

.2729 

.2402 

.3000 

.2640 

.295 

.1555 

.3281 

.2887 

.2738 

.2410 

.3010 

.2649 

.296 

.1560 

.3292 

.2897 

.2747 

.2418 

.3020 

.2658 

.297 

.1566 

.3302 

.2906 

.2756 

.2426 

.3030 

.2666 

.298 

.1571 

.3313 

.2916 

.2765 

.2434 

.3040 

.2675 

.299 

.1576 

.3324 

.2925 

.2774 

.2442 

.3050 

.2684 

.300 

.1581 

.3335 

.2935 

.2784 

.2450 

.3060 

.2693 

SUGAR  TABLES 


89 


TABLE*  23. 

TOLLENS,  ELLET,  AND  MAYER'S  TABLE  FOR  DETERMINING  METHYLPENTOSES 
AND  METHYLPENTOSANS. 


Methylfurfural 
phloroglucide. 

Fucose. 

Fucosan 

(fucoseX0.89). 

1 

Rhamnose. 

Rhamnosan 
(rhamnose 
X0.8). 

Methylpentosan 
(average  of  fucosan 
and  rharnnosan)  . 

grams. 

grams. 

grams. 

grams. 

grams. 

grams. 

0.010 

0.0260 

0.0231 

0.0266 

0.0213 

0.0222 

0.011 

0.0284 

0.0253 

0.0279 

0.0223 

0.0238 

0.012 

0.0307 

0.0274 

0.0295 

0.0236 

0.0255 

0.013 

0.0331 

0.0295 

0.0311 

0.0249 

0.0272 

0.014 

0.0354 

0.0315 

0.0327 

0.0262 

0.0288 

0.015 

0.0377 

0.0336 

0.0343 

0.0274 

0.0305 

0.016 

0.0400 

0.0356 

0.0359 

0.0287 

0.0321 

0.017 

0.0423 

0.0376 

0.0375 

0.0300 

0.0338 

0.018 

0.0445 

0.0396 

0.0391 

0.0313 

0.0354 

0.019 

0.0467 

0.0416 

0.0407 

0.0326 

0.0371 

0.020 

0.0489 

0.0435 

0.0423 

0.0338 

0.0386 

0.021 

0.0510 

0.0454 

0.0438 

0.0350 

0.0402 

0.022 

0.0532 

0.0473 

0.0454 

0.0363 

0.0418 

0.023 

0.0553 

0.0492 

0.0469 

0.0375 

0.0433 

0.024 

0.0574 

0.0511 

0.0485 

0.0388 

0.0449 

0.025 

0.0594 

0.0529 

0.0500 

0.0400 

0.0462 

0.026 

0.0614 

0.0547 

0.0516 

0.0413 

0.0480 

0.027 

0.0634 

0.0565 

0.0531 

0.0425 

0.0495 

0.028 

0.0654 

0.0583 

0.0547 

0.0438 

0.0510 

0.029 

0.0674 

0.0600 

0.0562 

0.0450 

0.0525 

0.030 

0.0693 

0.0617 

0.0578 

0.0462 

0.0539 

0.031 

0.0712 

0.0634 

0.0593 

0.0474 

0.0554 

0.032 

0.0731 

0.0651 

0.0609 

0.0487 

0.0569 

0.033 

0.0750 

0.0668 

0.0624 

0.0499 

0.0584 

0.034 

0.0768 

0.0684 

0.0639 

0.0511 

0.0598 

0.035 

0.0786 

0.0700 

0.0655 

0.0524 

-      0.0612 

0.036 

0.0804 

0.0716 

0.0670 

0.0536 

0.0626 

0.037 

0.0822 

0.0732 

0.0685 

0.0548 

0.0640 

0.038 

0.0839 

0.0747 

0.0700 

0.0560 

0.0654 

0.039 

0.0857 

0.0764 

0.0716 

0.0573 

0.0668 

0.040 

0.0874 

0.0778 

0.0731 

0.0585 

0.0681 

0.041 

0.0890 

0.0792 

0.0747 

0.0598 

0.0695 

0.042 

0.0907 

0.0807 

0.0761 

0.0609 

0.0708 

0.043 

0.0923 

0.0821 

0.0775 

0.0620 

0.0721 

0.044 

0.0939 

0.0836 

0.0790 

0.0632 

0.0734 

0.045 

0.0954 

0.0850 

0.0803 

0.0644 

0.0747 

0.046 

0.0970 

0.0863 

0.0820 

0.0656 

0.0759 

0.047 

0.0985 

0.0877 

0.0835 

0.0668 

0.0772 

0.048 

0.1000 

0.0890 

0.0849 

0.0679 

0.0785 

0.049 

0.1015 

0.0903 

0.0864 

0.0691 

0.0797 

0.050 

0.1029 

0.0916 

0.0879 

0.0703 

0.0809 

*  See  "Handbook,"  page  456. 


90 


SUGAR  TABLES 


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TABLE  25. 
RECIPROCALS  OF  NUMBERS  FROM  1  TO  100. 


Number. 

Reciprocal. 

Number. 

Reciprocal. 

Number. 

Reciprocal. 

Number. 

Reciprocal. 

1 

1.0000 

'    26 

0.0385 

51 

0.0196 

76 

0.0132 

2 

0.5000 

27 

0.0370 

52 

0.0192 

77 

0.0130 

3 

0.3333 

28 

0.0357 

53 

0.0189 

78 

0.0128 

4 

0.2500 

29 

0.0345 

54 

0.0185 

79 

0.0127 

5 

0.2000 

30 

0.0333 

55 

0.0182 

80 

0.0125 

6 

0.1667 

31 

0.0323 

56 

0.0179 

81 

0  0123 

7 

0.1429 

32 

0.0313 

57 

0.0175 

82 

0.0122 

8 

0.1250 

33 

0.0303 

58 

0.0172 

83 

0.0120 

9 

0.1111 

34 

0.0294 

59 

0.0169 

84 

0.0119 

10 

0.1000 

35 

0.0286 

60 

0.0167 

85 

0.0118 

11 

0.0909 

36 

0.0278 

61 

0.0164 

86 

0.0116 

12 

0.0833 

37 

0.0270 

62 

0.0161 

87 

0.0115 

13 

0.0769 

38 

0.0263 

63 

0.0159 

88 

0.0114 

14 

0.0714 

39 

0.0256 

64 

0.0156 

89 

0.0112 

15 

0.0667 

40 

0.0250 

65 

•    0.0154 

90 

0.0111 

16 

0.0625 

41 

0.0244 

66 

0.0152 

91 

0.0110 

17 

0.0588 

42 

0.0238 

67 

0.0149 

92 

0.0109 

18 

0.0555 

43 

0.0233 

68 

0.0147 

93 

0.0108 

19 

0.0526 

44 

0.0227 

69 

0.0145 

94 

0.0106 

20 

0.0500 

45 

0.0222 

70 

0.0143 

95 

0.0105 

21 

0.0476 

46 

0.0217 

71 

0.0141 

96 

0.0104 

22 

0.0455 

47 

0.0213 

72 

0.0139 

97 

0.0103 

23 

0.0435 

48 

0.0208 

73 

0.0137 

98 

0.0102 

24 

0.0417 

49 

0.0204 

74 

0.0135 

99 

0.0101 

25 

0.0400 

50 

0.0200 

75 

0.0133 

100 

0.0100 

INDEX 

Abbe  ref lactometer,  53-61. 

adjustment,  59-61. 
compensator,  57,  58. 
Geerligs's  table  for,  65;  Appendix,  22. 
illumination,  58. 

Main's  table  for,  64;  Appendix,  17. 
temperature  regulation,  58,  59. 
theory  of,  53-57. 

"Absatz"  method  of  Tollens,  344,  345. 
Absorption  error  of  bone  black,  220,  221,  284,  285 
of  moisture  by  raw  sugars,  7,  8. 
spectra  (see  Spectra). 
Accessories  of  polariscopes,  146-171. 
Acetaldehyde,  reaction  with  sugars,  368. 

sugar  alcohols,  766 
Acetals  of  sugar  alcohols,  766. 
Acetates  of  lead,  207,  208  (see  Lead). 
Acetic  acid,  inverting  power,  273,  663. 

method  for  decomposing  saccharates,  250. 
anhydride,  reaction  with  sugars,  369. 
Acetol,  536. 
Acetylcarbinol,  536. 
Acetylene  lamps,  152. 
Acetylmethylcarbinol,  537. 
Achroodextrin,  577,  686. 

Acidity  of  sugar  products,  determination,  496,  497. 
Acids,  color  reactions  with  sugars,  340,  341. 
influence  on  activity  of  diastase,  691. 
invertase,  671. 
pancreatin,  694. 
Clerget  factor,  269. 
rotation  of  sugars,  185,  186. 
inverting  power,  662-666. 
organic,  for  invert  polarization,  273. 
products  from  heating  sugars  with,  340,  341. 
relation  of  affinity,  inverting  power  and  conductivity, 
Acids  of  the  sugars,  529,  772-787. 

dibasic,  778-787. 

dehydration,  781. 
double  lactones,  780. 
formation,  778. 
xiii 


xiv  INDEX 

Acids  of  the  sugars: 

dibasic, 

hydrazides,  782. 
lactone  acids,  779. 
nomenclature,  778-779. 
properties,  779. 
reduction,  782,  783. 
salts,  783,  784. 
monobasic,  772-778. 

hydrazides,  777. 

lactones,  773,  774  (see  Lactones). 
molecular  rearrangement,  775. 
nomenclature,  773. 
oxidation,  778. 
salts,  777,  778. 
synthesis,  772,  773. 
Acorn  sugar  (see  Quercite). 
a-  and  £-Acrose,  623. 
Adonite,  dibenzal,  770. 
occurrence,  559. 
oxidation  to  d,  1-ribose,  559. 

ketopentose,  562. 
properties,  767. 
Affining,  646. 

Affinity  and  inverting  power  of  acids,  663. 
Agar-agar,  preparation  of  d-galactose  from,  603. 
Alcohol  (ethyl),  digestion  methods  (see  Sugar  beets), 
extraction  methods  (see  Sugar  beets), 
influence  on  rotation  of  sugars,  181,  182. 

activity  of  invertase,  674,  675. 
lamps,  152. 
precipitate,  determination  in  fruit  products,  520. 

honey,  521. 

use  of  in  purification  of  sirups,  550. 

Alcoholic  fermentation,  581,  582,  604,  619,  651,  701,  702,  714  738. 
Alcohols,  reaction  with  sugars,  367. 
Alcohols  of  the  sugars,  529,  530,  764-772. 

compounds  with  metals,  765. 
formation  during  fermentation,  764,  765. 
nomenclature,  766. 
oxidation  by  bacteria,  771,  772. 

chemical  means,  770,  771. 
properties,  765-770. 
reactions  with  acetaldehyde,  766. 

benzaldehyde,  766,  769,  770. 
borax  and  boric  acid,  765. 
formaldehyde,  766. 
rotation,  765-768. 

influence  of  boric  acid  on,  765,  766. 
molybdic  acid  on,  766. 


INDEX  XV 

Alcohols  of  the  sugars. 

rotation,  influence  of  tungstic  acid  on,  766. 
synthesis,  764. 

table  of  classification,  etc.,  767,  768. 
Aldehyde  reactions  of  sugars,  333-387,  527. 
Aldehydes,  reaction  with  sugars,  368. 
Aldoses,  conversion  into  ketoses,  355, 

distinguishing  from  ketoses,  340,  354,  363,  380. 
group,  527. 

oxidation  with  bromine,  363. 
Aldoheptoses,  633-637. 
Aldohexoses,  570-612. 
Aldopentoses,  545-560. 
Aldotetroses,  540-542. 
Aldotrioses,  538. 

Alkalies,  action  upon  d-galactose,  603,  604. 
d-glucose,  586,  587. 
lactose,  712,  713. 
maltose,  701. 

reducing  sugars,  303,  339,  340. 
color  reactions  with  sugars,  339. 
influence  on  activity  of  invertase,  671. 
diastase,  691. 
pancreatin,  694 
mutarotation,  190. 
rotation  of  sucrose,  183. 
products  from  heating  sugars  with,  339,  340. 
saccharates  of,  676,  677. 
Alkaline  earths,  influence  on  rotation  of  sucrose,  183. 

saccharates  of,  677. 

Alkalinity  of  sugar  products,  determination,  496,  497. 
Alkaloids,  use  in  resolving  d,  1-acids,  786,  787. 

Allen's  method  for  determining  glucose,  maltose  and  dextrin,  486-488 
Allihn's  method  for  determining  glucose,  403;  Appendix,  30. 
application  to  other  sugars,  420,  421. 
modification  by  Koch  and  Ruhsam,  420;  Appendix,  35. 

Pfliiger,  419;  Appendix,  33. 
Allylphenylhydrazine,  346. 
Allomucic  acid,  781. 
[a]D  and  [a]j,  meaning  of  symbols,  172. 
Alum  as  a  clarifying  agent,  223. 
Alumina  cream,  preparation,  222,  223. 
Aluminum  hydroxide  for  clarifying,  222,  223. 
Amines,  reaction  with  sugars,  367. 
Amino  compounds,  influence  on  Clerget  factor,  270. 
Amino  sugars,  751-754. 

Ammonium  nitrate  method  for  decomposing  saccharates,  251. 
Amygdalin,  572. 
Amygdalinbiose,  730. 
Amylases  (see  under  Conversion  of  starch). 


xvi  INDEX 

Amylocellulose,  688. 

Amylodextrin,  577,  686,  706. 

Amylodextrinase,  686. 

Amyloglucase,  691. 

Amylomaltase,  686. 

Amylopectin,  688. 

Amylose,  688. 

Amylphenylhydrazine,  346. 

d-Amylphenylhydrazine,  use  in  resolving  racemic  sugars,  362. 

Analytical  balance,  39,  162. 

Analyzer,  82-84. 

Angular  rotation,  calculation  to  saccharimeter  degrees,  145. 

determination  of  sugars  from,  194,  195. 
Aniline  acetate  test  for  artificial  invert  sugar,  620. 
furfural,  374-375. 
methylfurfural,  377. 
test-paper,  375. 
Animal  cellulose,  579. 

gum,  579. 
Antiarin,  569. 
Antiarose,  569. 
Apiin,  544. 

hydrolysis  to  glucoapiose,  643. 
Apiose,  544,  644. 

Apparatus,  care  of  polariscopic,  169-171. 

Araban,  determination,  450-452;  Appendix,  83  (see  also  under  Pentosans). 
hydrolysis  to  1-arabinose,  548. 
occurrence,  546-548. 
properties,  546,  547. 
Arabic,  gum,  547. 
Arabinic  acid,  547,  601. 
d-Arabinose,  545. 

formation  from  galactoarabinose,  644. 
1-menthylhydrazone,  362,  545,  551. 
synthesis  of  glucosamine  from,  754. 

from  d-glucose,  365. 
1-Arabinose,  546-551. 

absorption  spectra  with  a-naphthol,  379. 
phloroglucin,  384. 
resorcin,  381. 
calorific  value,  319. 
conversion  to  1-glucose,  592. 
1-mannose,  597. 
1-ribose,  777. 

determination,  450-452;  Appendix,  83  (see  also  under  Pentoses). 
as  diphenylhydrazone,  469. 
in  presence  of  fructose,  482. 

xylose,  482. 
fermentation,  550,  551. 

action  of  different  yeasts,  714. 


INDEX  xvii 


1-Arabinose,  formation  by  hydrolysis  from  arabans,  548. 

diarabinose,  643. 
mutarotation,  187. 

occurrence,  546. 

preparation  from  cherry  gum,  548-550. 
properties,  550,  551. 
reducing  ratio  to  glucose,  421. 
specific  rotation,  174-192,  550. 
tests,  551. 

value  of  Ventzke  degree,  200,  201. 
yield  of  furfural  from,  449. 
d,  1-Arabinose,  551. 

resolution  of,  362. 
d-Arabite,  545,  557,  767. 
1-Arabite,  551,  767. 

calorific  value,  319. 
monobenzal,  770- 
Arabogalactans,  599. 
d-Araboketose,  561. 
1-Araboketose,  561. 
d-Arabonic  acid,  545. 

oxidation  to  d-erythrose,  540. 
1-Arabonic  acid,  551. 

conversion  to  1-ribonic  acid,  559,  775. 
rotation  of  lactone,  551,  774. 
oxidation  to  1-erythrose,  541 . 
Arbutin,  571. 

Armstrong  on  enzymic  synthesis  of  sugars,  704,  705. 
Arrhenius's  hypothesis  of  inversion,  664. 

viscosity  equation,  310. 

Asbestos,  preparation  for  filter-tubes  and  Gooch  crucibles,  406. 
Ash,  analysis  of  for  determining  origin  of  sugars,  519. 
determination  by  direct  incineration,  495. 

ignition  with  sulphuric  acid,  495. 
in  commercial  dextrins,  509. 

sugar  products,  495. 
of  maple  sugar,  composition,  519. 

muscovado  sugar,  composition,  519. 
preparation  for  quantitative  analysis,  495,  496. 
soluble  and  insoluble,  495. 
Asparagine  error  in  sugar  beet  analysis,  245,  246. 
Aspergillus  niger,  action  upon  gentianose,  743. 

lactose,  715. 
melezitose,  742. 
raffinose,  738. 
trehalose,  720. 
Aspergillus  oryzae,  692. 
Assimilation,  532,  533. 
Association  of  Official  Agricultural  Chemists, 

method  for  clarifying  milk,  447. 


xviii  INDEX 

Association  of  Official  Agricultural  Chemists: 

method  for  determining  alcohol  precipitate,  520. 
ash,  495. 
dextrin,  301. 
moisture,  16,  18. 
preparing  alumina  cream,  223. 

standard  invert  sugar,  390. 
modification  of  Sachsse's  method  for  starch,  439. 

Soxhlet's  method  for  reducing  sugars,  390» 
Tollens's  method  for  galactan,  459,  460. 
reports  of  Referees  on  sugar,  224,  254. 
Astragalose,  729. 
Asymmetric  carbon  atom,  530. 

Atmospheric  pressure,  influence  on  copper  reduction,  418. 
Atomizer  for  removing  foam,  205. 
Autoclave,  439,  440. 
Autolysis  of  yeast,  669. 

Baeyer's  theory  of  photosynthesis  of  sugars,  533. 
Bacillus  gummosus,  653. 
lactis  acidi,  583. 
levaniformans,  615. 
suavolens,  586. 
Bacterium  gummosum,  653. 
oxydans,  702. 

pediculatum,  584,  652,  653. 
xylinum,  (Sorbose  bacterium): 

action  upon  alcohols  of  sugars,  771,  772. 
1-arabite,  562. 
i-erythrite,  542. 
d-galactose,  604. 
d-glucose,  585. 
glycerol,  539. 
d-mannite,  617. 
perseite,  637. 
d-sorbite,  624. 
sucrose,  654. 

Bagasse  (see  under  Sugar  cane). 
Balance,  analytical,  39,  162. 
metric  solution,  163. 
sugar,  162. 

Westphal  (Mohr's  specific  gravity),  40-42. 
Balling's  specific  gravity  table,  29. 

Bang's  copper  bicarbonate  method  for  determining  glucose,  434. 
Barbituric  acid  for  precipitating  furfural,  454. 

methylfurfural,  457. 

Bardach  and  Silberstein's  method  for  destroying  optical  activity  of  sugars,  304. 
Barfoed's  copper  acetate  solution,  336,  432. 
Barium  monosaccharate,  680. 

process  of  recovering  sucrose,  680. 


INDEX 


xix 


Barium  raffinosate,  739. 
Bates's  saccharimeter,  139-143. 

principle  of,  140-142. 
zero-point  error  of,  142. 
Baumann's  reaction,  370. 
Baume  hydrometer  scale,  48,  49. 

old  and  new  degrees,  48,  49;  Appendix,  6. 
Beckmann's  apparatus  for  determining  depression  of  freezing  point,  327,  328. 

elevation  of  boiling  point,  331,  332. 
Benzaldehyde,  reaction  with  sugar  alcohols,  766. 

use  in  liberating  sugars  from  hydrazones,  348. 
Benzals  of  sugar  alcohols,  766,  769,  770. 

table  of  formulae,  properties,  etc.,  770. 
Benzoyl  chloride,  reaction  with  sugars,  369,  370. 
Benzylphenylhydrazine,  346. 
Bertrand's  method  for  determining  galactose,  glucose,  invert  sugar,  kctose  and 

maltose,  426;  Appendix,  79. 
Bertrand's  reaction  for  xylose,  555,  556. 
Betite,  756. 

Bial's  orcin  test  for  pentoses  and  glucuronic  acid,  382. 
Bichromate  light  filter,  115-117. 
Biot's  polariscope,  84. 
Birotation  (see  Mutarotation) . 
Bismuth  solution,  Nylander's,  338. 
Blankit,  221. 
Block,  Maquenne's,  357. 
Boiling  point  of  sucrose  solutions,  651. 
Boiling  point  of  sugar  solutions,  determination  of,  by  Beckmann's  method,  331. 

application  to  molecular  weight  determinations,  332. 
Bomb  calorimeter  (see  Calorimeter). 
Bone  black,  absorption  error  in  sucrose  polarization,  220,  221. 

raffinose  polarization,  284,  285. 
purification  of,  219. 

use  in  decolorizing  sugar  solutions,  219,  277. 
Boot's  pycnometer,  38. 
Borax  and  boric  acid,  influence  on  rotation  of  sugar  alcohols,  765,  766. 

reaction  with  sugar  alcohols,  765. 
Boring  rasp,  Keil's,  226. 
Bornesite,  762. 
Brix  hydrometer,  44,  45. 

specific  gravity  table,  29;  Appendix,  6. 
Bromine,  oxidation  of  sugars  with,  363,  772. 

test  for  aldoses  and  ketoses,  363. 
Bromomethy If urf ural,  62 1 . 
p-Bromophenylhydrazine,  347. 

test  for  d-glucuronic  acid,  376. 
Brown,  Morris  and  Millar's  method  for  determining  glucose,  fructose  and  invert 

sugar,  425;  Appendix,  62. 

Brown,  Morris  and  Millar's  theory  of  diastatic  conversion,  686,  687. 
Browne's  diagram  of  temperature  corrections,  258. 


XX  INDEX 

Browne's  formulae  for  analyzing  sugar  mixtures,  477-483. 
method  for  determining  dextrin  in  honey,  521. 

commercial  glucose  in  honey,  294. 
of  vacuum  drying,  23,  24. 
Bryan's  results  on  action  of  clarifying  agents,  224. 

precipitation  of  sugars  by  basic  lead,  216,  444. 
Bryan,  Given,  and  Straughn's  method  for  extracting  sugarsj  446. 
Butyric  fermentation,  583,  584,  652,  715,  716. 

Cabinet,  for  constant  temperature  polarization,  169. 

portable  polariscope,  170. 
Calc  spar,  80. 
Calcium  bisaccharate,  677. 

monosaccharate,  677. 
raffinosate,  739. 
trisaccharate,  678. 
Cald well's  crucible,  415. 
Calibration  of  polariscope  tubes,  155,  156. 

by  Landolt's  gauge,  155. 
of  sugar  flasks,  166-168. 
Calories,  313-321. 

calculation  from  formula  of  sugars,  320,  321. 
definitions,  313. 

centuple,  313. 
gram-molecular,  318. 
large  or  kilogram,  313. 
small  or  gram,  313. 
determination,  314-318. 
table  of  values  for  different  sugars,  319. 
Calorimeter,  bomb,  313-318. 

description  and  operation,  314,  315. 
hydrothermal  value,  315,  316. 
radiation  correction,  316. 
Cane  sugar  (see  Sucrose) . 
Caps,  Wiley's  desiccating,  160,  161. 

Capillary  tube  method  for  determining  melting  points,  356,  357. 
Capsules  for  drying  sugar  products,  16,  19. 
Caramel,  Ehrlich's  colorimetric  method  for  estimating,  467. 
preparation,  655. 
properties,  656. 
Caramelane,  656. 
Caramelene,  656. 
Carameline,  656. 
Carbohydrates,  528,  529. 

formation  in  nature,  532,  533. 
Carbon  dioxide,  method  for  decomposing  saccharates,  250. 

estimation  of  in  fermentation  methods,  460-464. 
Carbonatation,  646. 

Care  of  polariscopic  apparatus,  169-171. 
Carob  beans,  preparation  of  d-mannose  from,  596. 


INDEX  xxi 

Carr's  vacuum  oven,  22,  23. 
Cellobiose  (see  Cellose). 
Cellose,  726-728. 

octacetate,  727. 

preparation  from  cellulose,  726,  727. 
properties,  727,  728. 
Celloxin,  376. 
Cellulose,  575. 

conversion  to  cellose,  726,  727. 
formation  by  bacteria,  654,  655. 
hydrolysis  to  d-glucose,  580. 
Cellulosic  fermentation,  654. 
Centrifugals,  laboratory  hand,  502. 
Cerasinose,  560. 
Cerealose  (see  Maltose). 

Chandler  and  Ricketts's  method  of  high  temperature  polarization,  289-291. 
Cherry-gum,  method  of  hydrolyzing,  548-550. 
Chips,  sugar  beet  (see  under  Sugar  beet). 
Chitin,  752. 

hydrolysis,  752. 
occurrence,  752. 
Chitonic  acid,  755,  782. 
Chitosan,  752. 

formation  from  chitin,  752. 
hydrolysis,  752. 
Chitose,  754,  755. 

formation  from  d-glucosamine,  754. 
properties,  754. 
reactions,  755. 

oxidation  to  chitonic  acid,  755. 

Chocolate,  determination  of  sucrose  and  lactose  in,  280,  281. 
Chondroglucose,  631. 

Cider  vinegar,  determination  of  d-glucose  and  d-fructose  in,  479. 
Cinchona  bases,  use  in  resolving  d,  1-acids,  786,  787. 
Citric  fermentation,  585,  655,  702. 
Citromyces  glaber,  655. 

Pfefferianus,  702. 
Clarification,  of  milk,  447. 

of  raw-sugars,  204,  207-225. 

errors  in,  207-225. 

change  in  rotation  of  sugars,  216,  217. 
precipitation  of  sugars,  215,  216. 
volume  of  precipitate,  209-215. 
method  of  Herles,  218,  219. 
Home,  212-214. 
Sachs,  210,  211. 
Scheibler,  209,  210. 
Zamaron,  218. 
of  solutions  for  chemical  methods,  443,  444. 

animal  substances,  447. 


xxii  INDEX 

Clarification  of  solutions  for  chemical  methods: 

plant  substances,  443. 

Clerget  methods,  276-278  (see  also  Clarifying  Agents). 
Clarifying  agents,  207-225. 

comparative  value  of  different,  223-225. 
errors  in  use  of,  209-225. 
list  of,  alum,  223. 

alumina  cream,  222,  223. 
basic  lead  nitrate,  218,  219. 
bone  black,  219,  220,  277. 
dry  lead  subacetate,  212-215. 
hydrosulphites,  221,  222. 
hypochlorite,  218. 
lead  acetate,  neutral,  207. 
nitrate,  basic,  218,  219. 
subacetate,  dry,  212-215. 

solution,  207,  208. 
mercuric  nitrate,  447. 
sulphites,  278. 
zinc  dust,  278. 
Clerget  method  of  inversion,  264-286. 

application  of,  to  determination  of  raffmose,  281-286. 

sugars  in  presence  of  sucrose,  279- 

281. 
factor  for,  influence  of  acids,  269. 

amino  compounds,  270. 
concentration,  267,  268. 
fructose,  270. 
modification  for  impure  products,  271-276. 

invertase  method,  274-276. 
neutral  polarization,  271. 
urea  method,  271-273. 
use  of  organic  acids,  273,  274. 
modification  of  Andrlik  and  Stanek,  271-273. 
Herzfeld,  266-268. 
Hudson,  275. 
Ogilvie,  274. 

O'Sullivan  and  Tompson,  274. 
Tolman,  269 
principle  of,  263,  264. 
reliability  of  results,  278,  279. 
Clostridium  butyricum,  584. 
Coefficient  of  purity,  494,  495. 
Colloidal  water,  229,  230,  246. 
Color  reactions  of  sugars,  339-345,  378-386. 

d-glucuronic  acid,  381-383. 

ketoses,  378-381. 

methylpentoses,  385,  386. 

pentoses,  381-383. 

use  of  spectroscope  in  studying,  342-345. 


INDEX  xxiii 

Color  reactions  of  sugars: 

with  acids,  340,  341. 
alkalies,  339. 
phenols,  341. 

a-naphthol,  378-379. 
naphthoresorcin,  381,  383. 
orcin,  382. 

phloroglucin,  381,  382. 
resorcin,  380,  381. 
Colorimeter,  Duboscq's,  464-467. 
Stammer's,  467-469. 
Colorimetric  methods  for  determining  caramel,  467. 

sugars,  464-469. 

Combined  methods  for  analyzing  sugar  mixtures  (see  under  Mixtures). 
Commercial  glucose,  determination  by  high  temperature  polarization,  289-296. 

method  of  Browne,  294,  295. 

Chandler  and  Ricketts,  28&-291. 
Leach,  291-293. 
estimation  in  honey,  294-296. 
polarizations  of,  293. 

mixtures  with  honey,  296. 
process  of  manufacture,  698. 
Compensation,  of  optical  activity,  molecular,  531. 
quartz-wedge,  108-112. 

double,  110-112. 
single,  108-110. 

Compensator  of  refractometer,  57,  58. 
Composition  of  osazones  of  sugars,  371. 
Compound  sugars,  528. 
Concentrating  sugar  solutions,  448. 
Concentration,  effect  on  Clerget  factor,  267. 

rotation  of  sugars,  174-177. 

equations  for  expressing,  174-177. 
viscosity  of  sugar  solutions,  310. 
Concentric  field,  93. 

half -wave  plate,  93. 

Conductivity  and  inverting  power  of  acids,  663. 
Coniferin,  571. 
Contraction  of  sugar  and  water  mixtures,  32-34. 

volume  during  inversion,  662. 
Control-tube,  122-125. 
Control-wedge,  110-112. 
Convallamarin,  599. 

sugar,  631. 
Convallarin,  599. 

Conversion  factors,  for  polariscope  scales,  145,  1 96-201 o 
Conversion  of  starch,  685-698. 

by  acids,  697,  698. 

formation  of  dextrin,  697. 
maltose,  697. 


INDEX 

Conversion  of  starch  by  acids: 

formation  of  reversion  products,  697. 
technical  processes,  698. 
by  enzymes,  685-696. 

malt  diastase,  685-692. 

influence  of  acids,  alkalies,  etc.,  691,  692. 

temperature,  690. 
restriction  of,  690,  691. 
steps  of  process,  686. 
theory  of  Brown  and  coworkers,  686,  687. 
Maquenne  and  Roux,  687-689. 
pancreatin,  693-696. 

activation  of,  694. 

converting  power  of  highly  active,  696. 

influence  of  acids  and  alkalies,  694. 

concentration  of  starch,  695. 
temperature,  695,  696. 
ptyalin,  693. 
takadiastase,  692,  693. 
Convolvulin,  567,  569. 
Coomb's  drip  sampler,  10,  11. 
Copper,  ferrocyanide  test,  392-394. 

method  of  Ross,  393,  394. 
method  of  Wiley,  393. 
hydrobromic  acid  test,  410. 
methods  of  determining,  403-417. 

by  electrolysis,  406-410. 

from  nitric  acid,  407. 

sulphuric  acid,  406,  407. 
sulphuric  and  nitric  acids,  407. 
tartrate  solution,  409,  410. 

by  reduction  of  cuprous  oxide  in  hydrogen,  403-405. 
by  titration,  410-415. 

volumetric  cyanide  method,  415. 

iodide  method,  411-414. 
modification  of  Kendall,  412,  413. 
Low,  411,  412. 
Peters,  413,  414. 
permanganate  method,  410,  411. 
thiocyanate  method,  414,  415. 
by  weighing  as  cupric  acid,  415,  416. 

cuprous  oxide,  416. 
comparison  of  methods,  416,  417. 
Copper-reducing  power  of  sugars,  421-423. 
Copper  reduction,  factors  influencing,  417-419. 

atmospheric  pressure,  418,  419. 
dilution  of  solutions,  417,  418. 
purity  of  reagents,  417. 
surface  area  of  solution,  419. 
temperature,  418,  419. 


INDEX  xxv 

Copper  reduction,  factors  influencing: 

time  of  boiling,  417,  418. 

Copper-reduction  methods  for  determining  sugars,  388-435. 
method  of  Allihn,  403. 

Bang,  434,  435. 
Barfoed,  432. 
Bertrand,  426. 

Brown,  Morris  and  Millar,  425. 
Defren,  425,  426. 
Fehling,  389. 
Herzfeld,  428. 
Kendall,  435. 

Kjeldahl  and  Woy,  424,  425. 
Koch  and  Ruhsam,  420. 
Meissl,  423. 

Meissl  and  Hiller,  430,  431. 
Meissl  and  Wein,  428-430. 
Munson  and  Walker,  426,  432. 
Ost,  433,  434. 
Pavy,  395-397. 
Pfliiger,  419,  420. 
Reischauer  and  Kruis,  398,  399. 
Soldaini,  432. 
Soxhlet,  389-391,  424. 
Violette,  393-395. 
Wein,  423. 

Corrections,  temperature  (see  under  Temperature). 
Cottonseed  meal,  preparation  of  raffinose  from,  733,  734. 
Cover-glasses  for  polariscope  tubes,  156. 
Creydt's  formula  for  estimating  raffinose,  282. 
Crystal  content  of  raw  sugars,  determination  of,  498-506. 

method  of  Herzfeld  and  Zimmermann,  503-506. 
Koydl,  501,  502. 
Payen,  499. 
Scheibler,  499-501. 
Crystalline  forms  of  sodium  ammonium  tartrate,  785. 

sucrose,  647,  648. 
Cubic  centimeter,  27,  28. 

metric,  28. 
Mohr,  28. 
reputed,  28. 

Cupric  oxide,  determination  of  copper  by  weighing,  415,  416. 
Cuprous  oxide,  contamination  of,  416,  417. 

determination  of  copper  by  weighing,  416. 
method  of  filtering,  404. 
reduction  in  hydrogen,  403-406. 
Cyanhydrine  reaction  of  sugars,  365,  366. 
Cyanide  metnod  for  determining  unreduced  copper,  415. 
Cyclamose,  560. 
Cy closes,  755-763. 


xxvi  INDEX 

Cylinders,  for  filtering  sugar  solutions,  168. 

determining  specific  gravity,  45. 
Cytase,  686. 

d-  and  d,  1-,  meaning  of  prefix,  532. 

Dambonite,  762. 

Dambose  (see  i-Inosite). 

Decolorization  of  sugar  solutions  (see  Clarification  and  Clarifying  agents). 

Decoses,  642. 

Decrolin,  70. 

Defecation  (see  Clarification  and  Clarifying  agents). 

Defren's  method  for  determining  glucose,  lactose  and  maltose,  425,  426;  Appendix,  63. 

Dehydration  of  hexose  dibasic  acids,  781. 

Dehydromucic  acid,  781,  782. 

formation  of  furfural  from,  782. 
reaction  for  hexose  dibasic  acids,  781. 
test  of  Tollens  and  Yoder  for,  781. 
Deleading  sugar  solutions,  276,  277. 
Depression  of  freezing  point  (see  Freezing  point). 
Desiccating  caps,  Wiley's,  160,  161. 

Destruction  of  optical  activity  of  reducing  sugars,  302-306. 
by  alkalies,  302. 

method  of  Bardach  and  Silberstein,  304,  305. 
Dubrunfaut,  302,  303. 
Jolles,  304. 

Lobry  de  Bruyn  and  van  Ekenstein,  303. 
by  alkalies  and  hydrogen  peroxide,  305,  306. 

method  of  Pellet  and  Lemeland,  305. 
by  alkalies  and  mercuric  cyanide,  306. 

method  of  Wiley,  306. 
Deterioration  of  raw  sugars,  14. 
Dextran,  578,  584,  653,  654. 
calorific  value,  319. 
formation  by  bacteria,  584,  653,  654. 
influence  on  polarization  of  sugar  products,  654. 
properties,  584. 
Dextrin,  577,  686-691. 

commercial,  composition  of,  510. 

methods  of  analysis,  508-510. 
process  of  manufacture,  577. 
viscosity  of  solutions,  508,  510. 
determination  by  Fehling's  solution,  442. 
fermentation,  301,  302. 
precipitation  with  alcohol,  490. 
Wiley's  method,  490. 
in  fruit  products,  301,  302. 
honey,  521-523. 

presence  of  glucose  and  maltose,  486-488,  490-492. 
formation  during  conversion  of  starch,  686-691. 
plant-,  578. 


INDEX  xxvii 

Dextrin,  researches  of  Brown  and  Millar  on,  687. 

Dextrinase,  686. 

Dextrinomaltase,  686. 

a-  and  /3-Dextro-metasaccharin,  587. 

Dextrose  (see  d-Glucose). 

Dhurrin,  573. 

Diarabinose,  643. 

Diastase,  683-685. 

action  on  starch  (see  under  Conversion). 

formation  during  germination  of  barley,  683. 

method  for  determining  starch,  440-442. 

occurrence,  683. 

preparation  from  malt,  685. 

properties,  685. 
Diastatic-power,  methods  of  determining,  511-515. 

method  of  Lintner  for  diastases,  513. 

malt  and  malt  extracts,  511-513. 
method  of  Sherman,  Kendall  and  Clark,  513-515. 
Sykes  and  Mitchell,  513. 
Wohlgemuth,  515. 

Digestion  methods  for  polarizing  sugar  beets  (see  Sugar  beets). 
Digitalin,  570. 
Digitalose,  570. 
Digitonin,  599. 
Digitoxin,  544. 
Digitoxose,  543,  544. 
Dihexose  saccharides,  645-730. 
Dilution,  double,  209,  210. 

effect  on  copper-reduction,  417,  418. 

of  solutions  in  determining  refractive  index,  66-69. 

specific  gravity,  35. 
Dimethyldioses,  537. 
Dimethylglycolose,  537. 
Dimethylketol,  537. 
Dimethyltetroses,  543,  544. 
Dioses,  535. 

Dioxyacetone,  538,  539. 
Dipentose  saccharides,  643. 
Diphenylhydrazine,  346. 
Disaccharides,  643-730. 

variability  in  reducing  power  of,  402. 
Dissociation  and  inverting  power  of  acids,  663-666. 

salts,  666-668. 
Double  dilution,  method  of  Scheibler,  209,  210. 

Wiley  and  Ewell,  253. 
Double-field,  89-94. 
Double  hydrazides,  782. 
Double  lactones,  780. 
Double  quartz  plate,  Soleil's,  86-88. 
Double  refraction,  80. 


xxviii  INDEX 

Double-wedge  system,  110-112. 

Dry  lead  subacetate,  212-214. 

Dry  substance  (see  Total  solids). 

Dubois's  method  of  determining  lactose  and  sucrose,  280,  281. 

Duboscq's  colorimeter,  464r-466. 

saccharimeter,  132,  135. 

Dubrunfaut's  method  of  destroying  optical  activity  of  sugars,  302. 
Dulcite,  calorific  value,  319. 

dibenzal,  770. 

formation  by  reducing  d-galactose,  606. 

occurrence,  606. 

oxidation  to  d,  1-galactose,  607. 

properties,  768. 
Dutch  standard,  498. 

Ehrlich's  colorimetric  method  for  estimating  caramel,  467. 
Einhorn's  fermentation  saccharometer,  462,  463. 
Electric  lamp,  Schmidt  and  Haensch,  153. 

stereopticon,  152. 
Electrolytic  apparatus  of  Leach,  407-409. 

determination  of  copper  (see  under  Copper). 
Elementary  composition  of  osazones,  371. 
Eliett  and  Tollens's  method  for  determining  methylpentoses  and  methylpentosans, 

456-458;   Appendix,  89. 
Elution  process  of  Scheibler,  678. 
Emulsin,  action  upon  glucosides,  amygdalin,  572. 

dhurrin,  573. 
a-  and  /3-glucosides,  591. 
prulaurasin,  572. 
salicin,  571. 
sambunigrin,  572. 
saccharides,  cellose,  727. 

galactosido-galactose,  728. 
gentiobiose,  726. 
glucosido-galactose,  728. 
isomaltose,  705. 
raffinose,  737. 
occurrence,  572. 

synthetic  action  upon  d-glucose,  704,  705. 
Engler's  viscosimeter,  308. 
Enzymes,  acting  upon  glucosides, 

emulsin,  571-573,  591. 
indimulsin,  571. 
maltase,  591. 
myrosin,  573. 
tannase,  573. 
acting  upon  saccharides, 

amylases,  683-696. 

cytase,  686. 

diastase,  683,  685-692. 


INDEX  xxix 

Enzymes,  acting  upon  saccharides: 

dextrinase,  686. 
emulsin,  726-728,  737. 
inulase,  615. 

invertase,  651,  668-676,  737,  743,  748. 
lactase,  713,  714. 

maltase  (maltoglucase),  686,  701,  702. 
melibiase,  723. 
pancreatin,  693-696. 
ptyalin,  693. 
takadiastase,  692,  693. 
trehalase,  720. 
zymase,  582 

Enzymic  synthesis,  704,  705 
d-Erythrite,  542,  767. 
1-Erythrite,  542,  767. 
i-Erythrite  (mesoerythrite),  541,  767. 
calorific  value,  319. 
dibenzal,  770. 
occurrence,  541. 
oxidation  to  d,  1-erythrose,  541. 
Erythrodextrin,  577,  686. 
d-Erythrose,  540,  541. 
1-Erythrose,  541. 
d,  1-Erythrose,  541,  542. 
d-Erythrulose,  542,  543. 
d,  1-Erythrulose,  543. 
Ester  fermentation,  586. 
Ether,  atomizer,  205. 

use  in  purification  of  sirups,  550. 
Ethylphenylhydrazine,  346. 
Evaporation  of  moisture  from  raw  sugars,  8,  9. 

sugar  solutions  in  vacuum,  549-550. 
Extraction,  determination  of,  496. 
Extraction  of  sugars,  alcoholic,  233,  446. 

method  of  Bryan,  Given  and  Straughn,  446. 

Scheibler,  233-235. 
aqueous,  with  cold  water,  445 

with  hot  water  (Zamaron),  235-238." 
Expression  of  juice,  227-230. 

errors  of  method,  229. 
hydraulic  press  for,  227,  228. 

Fehling's  copper  solution,  335,  389-444. 

composition,  335,  389. 

factors  influencing  results  (see  under  Copper  reduction). 

gravimetric  methods  employing,  399-443. 

products  obtained  by  action  on  sugars,  335,  336. 

reducing  action  of  sucrose  on,  427. 

use  in  determining  dextrin,  442. 


xxx  INDEX 

Fehling's  copper  solution: 

use  in  determining  glycogen,  443. 
starch,  438-442. 
sucrose,  436-438. 

volume  reduced  by  different  sugars,  391. 
volumetric  methods  employing,  389-399. 
Fermentation,  alcoholic,  581,  582,  651. 
butyric,  583,  584,  652. 
cellulosic,  654,  655. 
citric,  585,  655. 
ester,  586. 
gluconic  acid,  585. 
lactic,  583,  652. 
mannitic,  653,  654. 
oxalic,  585. 
viscous,  584,  652. 
Fermentation  flask,  300. 
Fermentation  methods  for  determining  sugars,  299-302,  460-464. 

by  Einhorn's  saccharometer,  462,  463. 
Lohnstein's  saccharometer,  463,  464. 
weighing  carbon  dioxide,  461,  462. 
resolving  racemic  mixtures,  787. 
Fermentation  of  raw  sugars,  14. 
Fermentations  of  sugars:  1-arabinose,  550,  551. 
d-fructose,  619. 
d-galactose,  604. 

gentianose,  743. 
d-glucose,  581-586. 
isomaltose,  707. 
lactose,  713-716. 
maltose,  701-703. 
mannatrisaccharide,  745. 
d-mannononose,  641. 
d-mannose,  596,  597. 
melibiose,  723. 
raffinose,  738. 
rhamnose,  565. 
d-sorbose,  625. 
stachyose,  748. 
sucrose,  651-655. 
trehalose,  720. 
1-xylose,  555. 

Ferrocyanide  test  for  copper,  392,  393. 
Fiber,  determination  in  bagasse,  248. 

sugar  beets,  228,  229. 

Field  of  vision  in  polariscopes :  concentric,  93. 

double,  89-94. 
fringed,  100. 
quadruple,  97,  98. 
triple,  97,  98. 


INDEX  xxxi 

Fillmass,  646  (see  Massecuite) . 
Filter-press  cake,  polarization  of,  249-251. 

in  absence  of  saccharate,  249,  250. 
presence  of  saccharate,  250,  251. 

acetic  acid  method,  250. 
ammonium  nitrate  method,  251. 
carbon  dioxide  method,  250. 
zinc  nitrate  method,  251. 
Filter-tube,  Knorr's,  393. 
Wiley's,  393. 

Filtration  of  sugar  solutions,  205. 

Fischer's  hydrazone  and  osazone  reaction  of  sugars,  345-362. 
method  of  oxidizing  alcohols  to  sugars,  770,  771. 

reducing  lactones  to  sugars,  776. 
synthesis  of  d-fructose,  355,  622,  623. 
d-galactose,  602. 
d-glucose,  580. 
isomaltose,  705. 
d-mannose,  596. 
methyl  glucosides,  590. 
Flasks,  calibration  of,  166-168. 
for  fermentation,  300. 

polariscopic  analysis,  163-168. 
solution  by  weight,  164. 
volumetric  use,  165. 
specifications  for,  166. 
Formaldehyde,  reaction  with  sugar  alcohols,  766. 

use  in  liberating  sugars  from  hydrazones,  348. 
Formals  of  sugar  alcohols,  766. 
Formation  of  carbohydrates  in  nature,  532-534. 
Formose,  629,  630. 
/3-Formose,  630. 
Frangulin,  563. 
Fraunhofer's  lines,  343,  384. 
Freezing  point  of  sugar  solutions,  325-331. 

application  to  determining  molecular  weights  of  sugars,  329-331. 

rate  of  inversion,  331. 
molecular  depression  of,  329. 
Raoult's  method  for  determining  depression  of,  327-331. 

by  Beckmann's  apparatus,  328. 
relation  to  vapor  and  osmotic  pressure,  326,  327. 
French  sugar  scale,  112,  113. 

value  in  circular  and  Ventzke  degrees,  145. 
Fric's  saccharimeter,  138,  139. 

illuminating  device  of,  137. 
Fringes,  interference,  100. 
d-Fructose,  612-622. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381,  384. 
action  of  alkalies  on,  339,  340. 


. 

xxxii  INDEX 

•* 
d-Fructose,  calorific  value,  319. 

color  reactions,  378,  619. 

Seliwanoff 's  resorcin  test,  380. 
decomposition  into  oxymethylfurfural,  620. 
determination,  as  methylphenylosazone,  470. 

by  copper   reduction   methods,    424,    425     (see    under 

Copper  reduction), 
by  polarization  at  high  temperature,  296-298. 

Sieben's  method,  470,  471. 
in  cider  vinegar,  479. 

presence  of  1-arabinose,  482. 
d-galactose,  481. 
d-glucose,  477-479. 
d-glucose  and  d-galactose,  484. 
d-glucose  and  sucrose,  485,  489. 
of  moisture  in  fructose  products,  20. 
effect  of  temperature  on  polarization,  179,  297,  478. 
fermentation,  619. 

action  of  different  yeasts,  714. 
formation  by  hydrolysis  from  gentianose,  743. 

inulin,  618. 
lupeose,  749. 
melezitose,  742. 
raffinose,  736,  737. 
secalose,  746. 
stachyose,  748. 
sucrose,  617,  660. 
turanose,  725. 
verbascose,  750. 

influence  on  Clerget  factor,  270. 
methylphenylosazone  reaction,  621,  622. 
mutarotation,  187,  618. 
normal  weight,  197. 
occurrence,  612-616. 
osazone,  354,  622  (see  d-Glucose-osazone). 

influence  of  lactose,  maltose  and  sucrose  on  formation  of,  352, 

353. 

oxidation  with  bromine,  363,  619. 
precipitation  by  basic  lead  salts,  216. 
preparation  from  inulin,  618. 

sucrose,  617,  618. 
properties;  618. 

protective  action  on  invertase,  675,  676. 
reaction  with  hydrobromic  acid,  621. 
reducing  ratio  to  glucose,  391,  421. 
reducing  reactions,  621. 
reduction  to  d-mannite  and  d-sorbite,  619. 
specific  rotation,  173-192,  618. 

influence  of  acids  on,  185,  186. 
alcohol  on,  181,  182. 


INDEX  xxxiii 

d-Fructose,  specific  rotation,  influence  of  lead  subacetate  on,  185,  217. 

urea  on,  272. 
synthesis  from  d-glucose  and  d-mannose  by  action  of  alkalies,  303. 

reduction   of   osones,    355, 

616. 

d-mannite,  617. 
tests,  619-622. 

value  of  Ventzke  degree,  200,  201. 
yield  of  levulinic  acid  from,  373. 
1-Fructose,  622. 
d,  1-Fructose,  622,  623. 

synthesis  from  acrolein  dibromide,  623. 
Fruit  products,  determination  of  alcohol  precipitate  in,  520. 
Fuconic  acid,  566-568. 
Fucosan,  565. 

determination,  457;  Appendix,  89  (see  also  under  Methylpentosans). 
Fucose,  565,  566. 

calorific  value,  319. 

determination,  456,  457;  Appendix,  89  (see  also  under  Methylpentoses). 
mutarotation,  187,  566. 
occurrence,  565. 
preparation,  565,  566. 
properties,  566. 

racemic  combination  with  rhodeose,  568. 
specific  rotation,  566. 
tests,  566. 

yield  of  methylfurfural  from,  377. 
Funnels  for  filtering  sugar  solutions,  168. 

transferring  sugars,  203. 
Furaloid,  453. 

Furfural,  apparatus  for  distilling,  450,  451. 
determination,  449-455. 
formation  from  d-glucuronic  acid,  375,  376. 
oxycellulose,  376,  377. 
pentoses  and  pentosans,  374. 

method  for  determining  pentoses  and  pentosans,  449-455. 
phenylhydrazone,  375. 
phloroglucide,  375,  451. 

factors  for  converting  to  pentoses  and  pentosans,  452. 
precipitation  with  ammonia,  449. 

barbituric  acid,  454. 
phenylhydrazine,  449. 
phloroglucin,  451. 
reaction  for  pentoses  and  pentosans,  374,  375. 

limitations  of,  375-377. 
yield  from  pentoses,  374. 
Furfuran,  755. 
Furfuroids,  453. 


' 
xxxiv  INDEX 

Galactan,  599,  600. 

determination,  459,  460. 
Galactoaraban,  599,  600. 
Galactoarabinose,  644. 
Galactomannan,  600. 
Galacto-metasaccharins,  604. 
d-Galactonic  acid,  conversion  to  lactone,  774. 

d-talonic  acid,  611,  775. 
oxidation  to  d-lyxose,  557. 
lactone  of,  rotation,  774. 
1-Galactonic  acid,  606. 
d,  1-Galactonic  acid,  608. 

resolution  of,  608,  787. 
d-Galactose,  598-606. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 

action  of  alkalies  on,  603,  604,  625,  626. 
calorific  value,  319. 
conversion  to  a-  and  /3-galaheptose,  636. 

d-tagatose  and  1-sorbose,  626. 
d-talose,  611,  777. 
determination  by  copper  reduction,  426. 

mucic  acid  method,  459. 
in  presence  of  d-fructose,  481. 
d-glucose,  480. 

d-fructose  and  d-glucose,  484. 
effect  of  temperature  on  polarization,  179,  480. 
fermentation,  604. 

action  of  different  yeasts,  714. 
formation  by  hydrolysis  from  galactans,  599,  600. 

lactose,  602,  713. 
lactosinose,  746. 
lupeose,  749. 
mannatrisaccharide,  744. 
pectins,  601. 
raffinose,  736. 
rhamninose,  732. 
stachyose,  748. 
verbascose,  750. 
hydrazones,  605. 
modifications,  192,  603. 
mucic  acid  reaction,  459,  460,  604,  605. 
mutarotation,  187,  603. 
occurrence,  599-602. 
osazone,  605. 

oxidation  with  bromine,  363,  606. 
preparation  from  agar-agar,  603. 

milk-sugar,  602,  603. 
properties,  603. 
reducing  ratio  to  glucose,  421. 


INDEX  xxxv 

d-Galactose,  reduction  to  dulcite,  606. 

specific  rotation,  173-192,  603. 
synthesis,  602. 

value  of  Ventzke  degree,  200,  201. 
variability  in  reducing  power,  400. 
yield  of  levulinic  acid  from,  373. 

mucic  acid  from,  459. 
1-Galactose,  606,  607. 
d,  1-Galactose,  607,  608. 
Galactosido-galactose,  728. 
Galactosido-glucoheptose,  730. 
Galactoxylan,  600. 
Galaheptite,  768. 

a-Galaheptonic  acid  lactone,  rotation  of,  774. 
a-Galaheptose,  636. 
/3-Galaheptose,  636. 
Galaoctite,  768. 

a-Galaoctonic  acid  lactone,  rotation  of,  774. 
a-Galaoctose,  639,  640. 
Galtose,  628,  629. 
Gas  lamps,  152. 

Gas  pressure,  relation  to  osmotic  pressure,  323. 
Gauge  for  calibrating  polariscope  tubes,  155. 
Gaultherin,  571. 

Gedda  gum,  hydrolysis  to  diarabinose,  643. 
Geerlig's  refractometer  table,  65;  Appendix,  22. 

researches  upon  inverting  power  of  invert  sugar  and  salts,  667,  668. 
theory  of  melassigenic  action,  650,  651. 
Gentianose,  726,  742-744. 

action  of  enzymes  on,  743. 
configuration,  743. 
fermentation,  743. 
hydrolysis,  726,  743. 
occurrence,  742. 
preparation,  742. 
properties,  743. 
Gentiobiose,  726,  743. 

formation  from  gentianose,  726,  743. 
preparation  and  properties,  726. 

German  or  Ventzke  sugar  scale,  113-115  (see  also  under  Scales). 
Glan  prism,  82. 
Glucase,  591,  683,  701,  702. 
Glucoapiose,  643,  644. 

formation  from  apiin,  643,  644. 
hydrolysis  to  apiose  and  d-glucose,  644. 
a-Glucodecite,  642. 
a-Glucodecose,  642. 
Glucogalactan,  599. 
Glucoheptite,  768 

monobenzal,  770. 


xxxvi  INDEX 

a-  and  /3-Glucoheptonic  acids,  633,  634. 

rotation  of  lactones,  774. 
a-Glucoheptose,  633. 

action  of  different  yeasts  upon,  714. 
conversion  to  a-glucooctose,  638. 
0-Glucoheptose,  634. 

d-Gluconic  acid,  conversion  to  d-mannonic  acid,  775. 
fermentation,  585. 
formation  from  d-glucose  by  oxidation  by  bacteria,  585. 

with  bromine,  590. 
lactone,  rotation  of,  590,  774. 
oxidation  to  d-arabinose,  545. 
1-Gluconic  acid,  synthesis  from  1-arabinose,  592. 
a-Glucononite,  641,  768. 
a-Gluconononic  acid,  641. 
a-Glucononose,  640,  641. 

conversion  to  a-glucodecose,  642. 
a-Glucooctite,  638,  768. 
a-  and  j8-Glucooctonic  acids,  638. 

rotations  of  lactones,  774. 
a-Glucooctose,  638. 

action  of  different  yeasts  upon,  714. 
conversion  to  a-glucononose,  641. 
/3-Glucooctose,  638. 
Gluco-proteids,  579. 
d-Glucosamine,  751-754. 

chloride,  753. 

formation  from  chitin,  752. 

mucins,  752. 
occurrence,  751. 

preparation  from  lobster  shells,  752. 
properties,  753. 

synthesis  from  d-arabinose,  754. 
tests,  753. 
d-Glucose,  570-591. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 

action  of  alkalies  on,  339,  340,  586,  587. 
calorific  value,  319. 
commercial  (see  Commercial  glucose), 
conversion  to  d-arabinose,  365. 

d-glucoheptose,  365. 
dehydration  of,  25. 

determination  by  copper  reduction,  389-435  (see  under  Copper  reduction), 
in  cider  vinegars,  479. 
in  presence  of  d-fructose,  477-479. 
d-galactose,  480. 
d-fructose  and  d-galactose,  484, 
d-fructose  and  sucrose,  485,  489. 
maltose  and  dextrin,  486,  490. 


INDEX  xxxvii 

d-Glucose,  fermentations  of,  581-586. 

formation  by  hydrolysis  from: 

cellose,  727. 

cellulose,  580. 

gentianose,  743. 

gentiobiose,  726. 

glucosides,  563,  570-573. 

glycogen,  579. 

isomaltose,  705. 

lactose,  713. 

maltose,  701. 

mannatrisaccharide,  744. 

melezitose,  725,  742. 

melibiose,  723. 

raffinose,  736. 

stachyose,  748. 

starch,  580. 

sucrose,  581. 

trehalose,  720. 

turanose,  725. 

verbascose,  750. 
hydrazones,  589. 
influence  of  sucrose  on  reducing  power,  427. 

urea  on  polarization,  272. 
manufacture  of,  698. 
modifications,  192,  581. 
mutarotation,  187-193,  581. 
normal  weight,  197-199. 
occurrence,  570-580. 
osazone,  348-354,  589,  590. 

influence  of  lactose,  maltose,  raffinose  and  sucrose  on  formation 

of,  351,  352. 
oxidation  to  d-gluconic  acid,  585,  590. 

with  bromine,  363. 
precipitation  by  basic  lead  salts,  216. 
preparation  from  cellulose,  580. 
honey,  580. 
starch,  580. 
sucrose,  581. 
properties,  581. 
reactions,  362-370,  587-591. 
reduction  to  d-sorbite,  590. 
saccharic  acid  test,  587,  588. 
specific  rotation,  173-192,  581. 
synthesis,  580. 
tests,  587-590. 

value  of  Ventzke  degree,  200,  201. 
variability  in  reducing  power,  400. 
yield  of  levulinic  acid  from,  373. 
1-Glucose,  592,  593. 


xxxviii  INDEX 

d,  1-Glucose,  593. 

Glucose  ratio,  496. 

Glucose  reduction  equivalents  of  sugars,  421,  476. 

Glucosides,  glucose-yielding,  570-573. 

preparation  from  plant  substances,  574. 
rhamnose-yielding,  563,  564. 
synthetic,  590,  591. 
Glucosido-galactose,  728. 
Glucosido-glucoheptose,  730. 
Glucosuria,  571,  578. 
Glucotannin,  573. 

d-Glucuronic  acid,  color  reactions  with  naphthoresorcin,  383. 

orcin,  382. 
phloroglucin,  382. 
conversion  to  1-xylose,  375. 
formation  from  d-saccharic  ajcid,  608,  783. 
occurrence  in  urine,  375,  783. 
production  of  furfural  from,  375,  783. 
reaction  with  p-bromophenylhydrazine,  376. 
Glutose,  629. 

occurrence  in  cane  molasses,  629. 
Glyceric  aldehyde  (see  d,  1-Glycerose) . 
Glycerol,  538,  767. 

monobenzal,  770. 

oxidation  by  Bacterium  xylinum,  539. 
to  dioxyacetone,  539. 
d,  1-glycerose,  538. 
d,  1-Glycerose,  538. 

antipodal  forms  of,  530. 
Glycogen,  578,  579. 

calorific  value,  319. 

determination  by  Fehling's  solution,  443. 
occurrence,  578. 
preparation,  578,  579. 
properties,  579. 
vegetable-,  578. 
Glycol,  535,  767. 
Glycolaldehyde,  535. 
Glycolose,  535. 
Gooch  crucible,  404,  415. 
Gossypose  (see  Raffinose). 
Graduation  of  hydrometers,  43-49. 

saccharimeter  scales,  117-119. 
Gram-molecular  calories  (see  Calories). 
Graminin,  615. 
Grape  sugar  (see  d-Glucose). 

Gravimetric  methods  for  determining  sugars,  399-445. 
d-Gulonic  acid,  conversion  to  d-idonic  acid,  610. 

formation  from  d-saccharic  acid,  608. 
oxidation  to  d-xylose,  552. 


INDEX  xxxix 

d-Gulonic  acid,  rotation  of  lactone,  609,  774. 
1-Gulonic  acid,  conversion  to  1-idonic  acid,  775. 

formation  from  1-xylose,  609. 
d,  1-Gulonic  acid,  610. 

hemihedry  of  lactone  crystals,  610,  786. 
d-Gulose,  608,  609. 

conversion  to  d-idose,  610,  777. 
1-Gulose,  609,  610. 

action  of  different  yeasts  upon,  714. 
d,  1-Gulose,  610. 
Gums,  solution  of  in  digesting  sugar  beets,  245. 

Half-shadow,  angle,  89-92,  94-96. 

polarimeters,  89-98,  101-106. 
saccharimeters,  132-145. 
Half -wave  plate,  Laurent's,  91-93. 
Hayduck's  nutritive  salt  solution,  299. 

Hay  wood's  modification  for  determining  methylpentoses,  458,  459. 
Heat  of  combustion  (see  Calories). 
Hederose,  631. 
Helianthenin,  615. 

Hemicelluloses,  439,  441,  534,  546,  553,  575,  593,  599. 
Hemihedral  crystals,  of  d,  1-gulonic  lactone,  610,  786. 

sodium  ammonium  d,  1-tartrate,  785. 
surfaces  of  sucrose  crystals,  647. 
Heptoses,  633-637. 
Herles's  basic  lead  nitrate  method  of  clarification,  218,  219. 

raffinose  formula  for  variations  in  temperature,  283,  284. 
Herzfeld's  method  for  determining  acidity  and  alkalinity,  496,  497.  • 

invert  sugar  in  raw  sugars,  428;  Appendix,  81. 
raffinose,  282,  283. 

method  of  alcoholic  digestion  and  extraction,  247,  248. 
hot-water  digestion,  244. 
preparing  maltose,  699. 
modification  of  Clerget's  method,  266-268. 

Herzfeld  and  Zimmermann's  method  for  determining  crystal  content,  503-506. 
Hesperidin,  563. 

Hexose  groups,  levulinic  acid  reaction  for,  372-374. 
Hexose-heptose  saccharides,  730. 
Hexoses,  570-631. 
" High-polarizing"  sugar,  658,  659. 
Hinks's  oil  and  gas  lamps,  151. 
Honey,  579,  580,  616. 

detection  of  artificial  invert  sugar  in,  620. 

commercial  glucose  in,  523. 
determination  of  commerical  glucose  in,  294-296. 

dextrin  in,  521-523. 

dextrorotation  at  87°  C.  after  inversion,  293,  294. 
occurrence  of  fructose,  glucose  and  sucrose  in,  616. 
polarization  of  varieties,  294. 


xl  INDEX 

Honey,  polarization  of  varieties  containing  commercial  glucose,  296. 
preparation  of  d-glucose  from,  580. 
table  of  composition,  522. 
Honey-dew,  522. 

occurrence  of  melezitose  in,  740. 
Home's  method  of  dry  defecation,  212-215. 
Hortvet's  method  for  measuring  lead  precipitate,  516,  517. 
Hiibener's  refractometer  table,  74;  Appendix,  24. 
Hudson's  constant  temperature  water  bath,  160. 
equation  for  inversion  of  sucrose,  672. 
modification  of  Clerget's  method,  275. 
researches  upon  invertase,  669-676. 
lactose,  710,  711. 
rotation  of  lactones,  774,  775. 
Humus  substances,  340. 
" Hundred  polarization,"  125,  126. 
Hydraulic  laboratory  press,  227,  228. 
Hydrazides  of  dibasic  acids,  782. 

monobasic  acids,  777. 
Hydrazines,  optically  active,  for  resolving  d,  1-sugars,  361,  362,  551. 

substituted,  346,  347. 
Hyclrazone  reaction  of  sugars,  345,  346. 
Hydrazones,  analysis  of,  370,  371. 

decomposition  of,  with  benzaldehyde,  348. 
formaldehyde,  348. 
hydrochloric  acid,  347. 

determination  of  sugars  from  weight  of,  469,  470. 
identification,  356-360,  370. 
melting  point  of  (see  Melting  points), 
optical  activity  of,  360. 
separation  of  sugars  from,  347,  348. 
table  of  melting  points  and  properties,  Appendix,  90 
Hydrobromic  acid,  relative  inverting  power  of,  663. 
test  for  unreduced  copper,  410. 
Hydrochloric  acid,  decomposition  products  of  sugars  with,  340,  372-378. 

relative  inverting  power  of,  663. 

Hydrocyanic  acid,  action  upon  reducing  sugars,  365,  366. 
Hydrogen,  reduction  of  cuprous  oxide  in,  403-406. 
Hydrolysis  of  sugar-yielding  substances,  Tollens's  method,  548-550. 
Hydrometers,  42-49. 

according  to  Baume,  48. 
Brix,  44-46. 
Langen,  47,  48. 
Volquartz,  46,  47. 
Vosatka,  47. 

standardization  of,  43,  44. 
"sweet-water,"  47,  48. 
Hydrosulphites  as  decolorizing  agents,  221,  222. 

errors  due  to  use  of,  222. 
Hydrothermal  value,  315,  316. 


INDEX  xli 

Hydroxylamine,  action  upon  reducing  sugars,  364,  365. 

standard  solution  for  titrating  copper,  434r-435. 
Hypochlorite  as  a  decolorizing  agent,  218. 

i-,  meaning  of  prefix,  532. 
d-Idite,  610,  767. 
1-Idite,  611,  768. 
d-Idonic  acid,  610. 
1-Idonic  acid,  611. 

conversion  to  1-gulonic  acid,  775. 
d-Idose,  610. 
1-Idose,  611. 
Illumination  of  polariscopes,  146-153  (see  under  Lamps). 

refractometers,  58 
Imbibition  water,  229-230,  246. 
Immersion  refractometer,  70-75. 

adjustment  of,  72-74. 
Hiibener's  table  for,  74;  Appendix,  24. 
principle  of,  71,  72. 
tempering  bath  for,  74,  75. 

Imperial  German  Commission,  sucrose  specific  gravity  table,  30;  Appendix,  1. 
Incrusting  substances,  553,  575. 
Index  of  refraction  (see  Refractive  index). 
Indican,  571. 
Inosinic  acid,  558. 
Inosites,  757-763. 

isomeric  forms,  757,  758. 
d-Inosite,  758,  759. 

preparation  from  pinite,  758. 
properties  and  tests,  758. 
1-Inosite,  759. 

preparation  from  quebrachite,  759. 
properties  and  tests,  759. 
d,  1-Inosite,  760. 
i-Inosite,  760-763. 

formation  from  bornesite,  762. 
dambonite,  762. 
phytin,  762,  763. 
occurrence,  760. 
preparation  from  meat,  760. 

walnut  leaves,  761 
properties  and  tests,  761,  762. 
Interference  fringes,  100. 
International  Commission,  method  for  determining  moisture,  16. 

rules  for  polarizing  sugars,  201,  202. 
Inulase,  615. 
Inulenin,  615. 
Inulin,  613-615. 

calorific  value,  319. 

hydrolysis  to  d-fructose,  615,  618. 


xlii  INDEX 

' 
Inulin,  occurrence,  613. 

preparation  of,  613,  614. 
preparation  of  d-fructose  from,  618. 
properties,  614. 
sphere-crystals,  614. 
Inversion  of  sucrose,  263-279,  659-676. 

by  acids,  263-279,  659-666. 

invertase,  668-676  (see  Invertase). 
salts,  666-668. 

Clerget's  method  (see  Clerget). 
early  investigations,  659,  660. 
hypothesis  of  Arrhenius,  664. 
law  of,  263,  264. 
rate  of,  660-667,  671-674. 

determination  by  freezing  point  method,  331. 

polariscope,  661,  662. 
influence  of  concentration,  665. 

organic  substances,  666. 
salts,  665. 
temperature,  664. 
urea,  272,  273. 
Wilhelmy's  law,  660,  661. 
relative  power  of  acids  in,  663. 
Invert  sugar,  artificial,  620. 

color  reactions  for,  620. 
decolorization  of  solutions,  277,  278. 
determination  by  copper  reduction,  423-432   (see  Copper-reduction 

methods) . 

determination  by  polarization  at  high  temperature,  287-289. 
in  presence  of  d-glucose  and  d-fructose,  478. 

sucrose,  428-432. 

influence  on  inverting  power  of  salts,  667,  668. 
normal  weight,  197. 
preparation  of  standard  solution,  390. 
reducing  ratio  to  glucose,  391,  421. 
specific  rotation,  174-192. 

influence  of  acids  on,  185,  186. 
alcohol  on,  181,  182. 
concentration  on,  177. 
lead  subacetate  on,  185. 
temperature  on,  179,  180. 
urea  on,  272. 

temperature  of  optical  inactivity,  287,  288. 
value  of  Ventzke  degree,  200,  201. 
variability  in  reducing  power,  400 
Invertase,  action  upon  gentianose,  743,  744. 
raffinose,  737,  738. 
stachyose,  748. 
sucrose,  668-676. 
verbascose,  750. 


INDEX 

Invert ase,  conditions  affecting  activity  of,  670-676. 

influence  of  acids,  671. 

alcohol,  674,  675. 

alkalies,  671. 

concentration  of  invertase,  673. 

sucrose,  673,  674. 
temperature,  674. 
occurrence,  668,  669. 
preparation,  669,  670. 
properties,  670. 

protective  action  of  fructose  and  sucrose  on,  675,  676. 
researches  of  Hudson,  669-676. 
use  in  Clerget's  method,  274,  275. 
Inverting  action  of  honey,  13,  616. 
power  of  acids,  662-666. 
salts,  666-668. 

Iodide  methods  for  determining  copper,  411-414  (see  under  Copper), 
lonization  and  inverting  power  of  acids,  663-666. 

salts,  666-668. 
Irisin,  615. 

Isatin  reaction  for  dehydromucic  acid,  781. 
Isodulcite  (see  Rhamnose). 
Isolactose,  718. 
Isomaltose,  705-707. 

action  of  emulsin  on,  705. 
preparation,  705. 
properties,  707. 

theories  regarding  formation,  706,  707. 
tests,  707. 
Isorhamnonic  acid,  568. 

rotation  of  lactone,  568,  774. 
Isorhamnose,  568. 
Isorhodeose,  569. 
Isosaccharic  acid,  755,  782. 
Isosaccharin,  713. 
Isosaccharinic  acid,  712,  713. 
Isotonic  sugar  solutions,  326,  327. 
Isotrehalose,  728,  729. 
Ivory  nuts,  preparation  of  d-mannose  from,  595 

Jellet-Cornu  prism,  89-91,  133. 
Jellet  half -shadow  polariscope,  89. 

Jolles's  method  for  destroying  optical  activity  of  sugars,  304. 
determining  methylpentoses,  457. 

pentoses,  454,  455. 
Juice,  bottle  for  weighing,  24. 

composition  of  from  different  cane-mills,  232. 

determination  of  moisture  in,  18-25. 

distribution  in  tissues  of  sugar  cane,  231. 

hydraulic  press  for  expressing,  227-229. 


I 

xliv  INDEX 

Juice,  methods  of  polarizing,  205,  206. 
normal,    497. 
sampling,  10,  11. 

Kahlenberg,  Davis  and  Fowler's  researches  on  inversion,  331,  666,  667. 
Kefir,  714. 

ferment  of,  715,  718. 
Keil's  boring  rasp,  226. 
Kendall's  copper-salicylate  method  for  determining  sugars,  435. 

iodide  method  for  determining  copper,  412,  413. 
Ketoses,  characteristic  group  of,  527. 

reactions,  340,  341,  354,  363,  364,  378-381. 

color  reactions  of  (see  Color  reactions). 

conversion  of  aldoses  into,  355. 

distinguishing  from  aldoses  (see  Aldoses). 

methylphenylhydrazine  reaction,  354. 

oxidation  with  bromine,  363. 

nitric  acid,  364. 
Ketoheptoses,  637. 
Ketohexoses,  612-630. 
Ketopentoses,  560-562. 
Ketotetroses,  542,  543. 
Ketotrioses,  538,  539. 
Kjeldahl  and  Woy's  method  for  determining  d-fructose,  d-glucose,  invert  sugar, 

lactose  and  maltose,  424,  425;  Appendix,  44. 
Knapp's  mercury  solution,  338,  435. 

mercuric  cyanide  method  for  determining  sugars,  435. 
Knorr's  filter  tube,  393. 

Koch  and  Ruhsam's  method  for  determining  glucose,  420;  Appendix,  35. 
Koydl's  method  for  determining  crystal  content,  501,  502. 
Krober's  factors  for  calculating  pentoses  and  pentosans,  452. 

table  for  calculating  pentoses  and  pentosans,  Appendix,  83. 
Kriiger's  automatic  pipette,  240,  241. 

cold  water  digestion  process,  240-242. 
Kumiss,  714. 

1-,  meaning  of  prefix,  532. 
Lactase,  713-715. 

preparation,  715. 
Lactic  aldehyde,  535,  536. 

fermentation,  583,  652,  715. 
Lactobionic  acid,  644,  712. 
Lactones  of  dibasic  sugar  acids,  779,  780. 

double  lactones,  780. 
lactone  acids,  779,  780. 
reduction  of,  782,  783. 
monobasic  sugar  acids,  773-776. 

reduction  to  sugars,  776. 
specific  rotation  of,  774. 

relation  of,  to  configuration,  774,  775. 


INDEX  xlv 

Lactones  of  monobasic  sugar  acids: 

transformation  into  acids,  773. 
Lactose,  708-718. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 
action  of  acids  on,  713. 

alkalies  on,  712,  713. 
enzymes  on,  714. 
calorific  values,  319. 
compounds,  716,  717. 

acetates,  716,  717. 
lactosates,  717. 
nitrates,  716. 
osazone,  716. 
configuration,  717. 

•      conversion  to  galactoarabinose,  644. 
dehydration,  25. 
determination  by  copper-reduction,  424-426  (see  Copper  reduction  methods). 

polariscopic  methods,  252-255. 
in  milk,  252-255. 

milk  chocolate,  280,  281. 
milk  sugar,  255. 
fermentations,  713-716. 

action  of  different  yeasts,  714. 
formation  of  isosaccharin  from,  712,  713. 

mucic  acid  from,  712. 
hydrolysis  of,  713. 

influence  on  osazone  formation  of  fructose  and  glucose,  352. 
modifications,  709-711. 
inutarotation,  187,  709-711. 
normal  weight,  197,  198. 
occurrence,  708. 
oxidation  products,  712. 
preparation,  708,  709. 
preparation  of  d-galactose  from,  602,  603. 
properties,  709-711. 
reactions,  711-713. 
reducing  ratio  to  glucose,  391,  422. 
reduction  products,  711. 
specific  rotation,  173-192,  709-711. 
tests,  717. 

value  of  Ventzke  degree,  200,  201 . 
variability  in  reducing  power,  402. 
Lactosinose  (Lactosin),  745,  746. 
occurrence,  745. 
preparation,  745. 
•  properties,  745,  746. 

Lamps  for  polariscopes,  146-153. 

sodium  light,  147-151. 

Landolt's,  148. 


INDEX 

Lamps  for  polariscopes : 

sodium  light, 

Pribram's,  148. 
Zeiss's,  148,  149. 
white  light,  151-153. 

acetylene,  152. 
alcohol,  152. 
electric,  152,  153. 
gas,  152. 
oil,  151. 

Landolt's  concentration  formula  for  rotation  of  sucrose,  118,  177. 
gauge  for  calibrating  tubes,  155,  156. 
polarimeters,  104-106. 
polariscope  tube,  157. 
sodium  lamp,  105,  148. 
Langen's  sweet-water  spindle,  48. 
Laurent's  half-shadow  polarimeter,  91-93,  101,  102. 

saccharimeter,  133-135. 
half-wave  plate,  91-93. 

principle  of,  92,  93. 

Leach's  apparatus  for  high-temperature  polarization,  291,  292. 
electrolytic  apparatus,  407-409. 
method  of  determining  commercial  glucose,  291-293 
Lead,  acetates  of,  207. 

acetate  solution,  neutral,  207. 
basic  nitrate,  clarification  with,  218,  219. 
number  of  Winton,  517,  518. 
precipitate,  errors  due  to,  209. 

Hortvet's  method  of  measuring,  516,  517. 
raffinosate,  740. 

removal  from  solutions  (deleading),  276,  277. 
saccharates,  681. 
subacetate,  action  on  rotation  of  fructose,  217. 

invert  sugar,  185. 
sucrose,  216,  217. 

amount  necessary  for  clarification,  204. 
precipitating  action  upon  sugars,  215,  216,  444. 
preparation  of  solutions,  207,  208. 
use  of  dry  salt  for  clarifying,  212-215. 
Least  squares,  method  of,  175,  401. 

Leffmann  and  Beam's  method  for  determining  lactose  in  milk,  253,  254. 
Leuconostoc  mesenterioides,  584,  652,  653,  716. 
Levan,  615. 

influence  on  polarization  of  sugar  products,  654. 
Levosin,  615. 
LevuLan,  615. 
/S-Levulin  (see  Lecalose). 
Levulinic  acid,  reaction  for  hexose  groups,  372-374. 

yield  from  fructose,  galactose  and  glucose,  373. 
Levulose  (see  d-Fructose). 


INDEX  xlvii 

Lichenin,  578. 

Light,  dispersion  of,  51. 

effect  of  kind  of  on  rotation  of  sugars,  173,  174. 
polarization  of,  76-82. 
sodium,  lamps  for,  147-149. 

purification  of,  149-151. 
white,  lamps  for,  151-153. 
Light-filter,  bichromate,  115-117. 

Lippich's,  150,  151. 
Light-wave,  theory  of,  76,  77. 
Linimarin,  573. 

Lintner's  method  for  determining  diastatic  power  of  diastases,  513. 

malt,  511-513. 

preparing  soluble  starch,  577. 
pressure  bottle,  439,  440. 
scale  of  diastatic  power,  512. 

Lippich's  half-shadow  polarimeter,  94-98,  104-106. 
light  filter,  150,  151. 
polarizer,  94-98. 

principle  of,  95-98. 

Lobry  de  Bruyn's  method  of  drying  sugars,  25,  26. 
Lobry  de  Bruyn  and  van  Ekenstein's  method  of  destroying  optical  activity  of 

sugars,  303. 
Lobster  shells,  occurrence  of  chitin  in,  752. 

preparation  of  d-glucosamine  from,  752,  753 
Locaose,  631. 

Lohnstein's  fermentation  saccharometer,  463,  464. 
Low's  iodide  method  for  determining  copper,  411-413. 
Lupeose,  748,  749. 
Lycerose,  630. 
d-Lyxonic  acid,  557. 

rotation  of  lactone,  557,  774. 
d-Lyxose,  557. 

Main's  refractometer  table,  64;  Appendix,  17. 
Malt,  determination  of  diastatic  power  of,  511-513. 
preparation  of  diastase  from,  685. 
process  of  manufacturing,  684. 
Malt  extracts,  action  on  starch,  685-691. 
analysis  of,  510,  511. 

determination  of  diastatic  power  of,  511-513. 
preparation  of,  440,  441. 
restriction  of,  690,  691. 
Malt  sugar  (see  Maltose). 
Maltase,  701,  702. 

action  upon  d-glucose,  705. 

a-  and  /8-glucosides,  591. 
maltose,  705. 

Maltobionic  acid,  700,  701. 
Maltobiose  (see  Maltose). 

, 

• 


xlviii  INDEX 

Maltodextrin,  577,  686,  706. 
Maltoglucase  (see  Maltase). 
Maltose,  682-705. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 
action  of  acids  on,  701. 

alkalies  on,  701. 
enzymes  on,  701-702,  705. 
calorific  value,  319. 
compounds,  703. 

maltosates,  703. 
octacetate,  703. 
osazone,  703. 
configuration,  704. 
copper-reducing  power,  422. 
dehydration,  25. 
determination  by  copper  reduction,  423-426  (see  Copper-reduction  methods) . 

polariscopic  methods,  194-201. 
in  presence  of  glucose  and  dextrin,  486-492. 

starch  conversion  products,  486-492,  507,  508. 
fermentations,  701-703. 

action  of  different  yeasts,  714. 
formation  from  starch  by  acids,  697-699. 

enzymes,  683-696. 
hydrolysis  of,  701. 

influence  on  osazone  formation  of  fructose  and  glucose,  351,  352. 
mutarotation,  187,  700. 
normal  weight,  197,  198. 
.  occurrence,  682,  683. 
oxidation  products,  700,  701. 
preparation,  699. 
properties,  699,  700. 
reactions,  700,  701. 
reducing  ratio  to  glucose,  391,  422. 
specific  rotation,  173-192,  700. 
synthesis,  704,  705. 
tests,  703,  704. 

value  of  Ventzke  degree,  200,  201. 
variability  in  reducing  power,  402. 
Maltose  carboxylic  acid,  703. 
Manna,  597,  740,  744. 
Mannans,  593-595. 

Mannatetrasaccharide  (see  Stachyose). 
Mannatrionic  acid,  745. 
Mannatrisaccharide,  744,  745. 

formation  from  stachyose,  748. 
hydrolysis,  744. 
occurrence,  744. 

preparation  and  properties,  744. 
d-Mannite,  calorific  value,  319. 


INDEX  xlix 

d-Mannite,  formation  during  fermentation,  653,  654,  764,  765. 
occurrence,  597. 
oxidation  by  chemical  means,  770,  771. 

bacteria,  771. 
to  d-fructose,  617. 
d-mannose,  596. 
properties,  597,  767. 
reaction  with  acetaldehyde,  766. 

benzaldehyde,  766-769. 
borax  and  boric  acid,  765,  766. 
formaldehyde,  766. 
tribenzal,  770. 
1-Mannite,  767. 
Mannogalactans,  599. 
d-Mannoheptite,  identity  with  perseite,  634-635. 

properties,  635. 
1-Mannoheptite,  635,  768. 
d-Mannoheptonic  acid,  634. 

rotation  of  lactone,  774. 
d-Mannoheptose,  634,  635. 

conversion  to  d-mannooctose,  639. 
reduction  to  d-mannoheptite,  634. 
synthesis  from  d-mannose,  634. 
1-Mannoheptose,  635. 
d,  1-Mannoheptose,  635,  636. 
d-Mannonic  acid,  597. 

conversion  to  d-gluconic  acid,  775. 
rotation  of  lactone,  597,  774. 
1-Mannonic  acid,  597,  598. 

conversion  to  1-gluconic  acid,  775. 
d,  1-Mannonic  acid,  598. 

resolution  by  means  of  strychnine  salts,  598,  786. 
d-Mannonononic  acid,  641. 
d-Mannononose,  641. 
d-Mannooctite,  639,  768. 
d-Mannooctonic  acid,  639. 

rotation  of  lactone,  774. 
d-Mannooctose,  639. 

conversion  to  d-mannononose,  641. 
synthesis  from  d-mannoheptose,  639. 
d-Mannosaccharic  acid,  597. 

double  lactone  of,  597,  780. 
1-Mannosaccharic  acid,  598. 

double  lactone  of,  598. 
d-Mannose,  593-597. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 

action  of  alkalies  upon,  339,  340. 
conversion  to  d-mannoheptose,  634. 
determination  as  phenylhydrazone,  469,  470. 


1  INDEX 

d-Mannose,  fermentation,  596,  597. 

action  of  different  yeasts,  714. 

formation  from  methyl  mannorhamnoside,  645. 

hydrazone,  597. 

mutarotation,  596. 

occurrence,  593-595. 

oxidation,  597. 

osazone,  353,  354,  597. 

preparation,  from  Carob  beans,  596. 
ivory  nuts,  595. 

properties,  596,  597. 

reduction,  596,  597. 

specific  rotation,  596. 

synthesis,  596. 

tests,  597. 
1-Mannose,  597,  598. 

action  of  yeasts  upon,  714. 
d,  1-Mannose,  598. 

Maple  sugar,  composition  of  ash,  519. 
lead  number  of,  518. 
volume  of  lead  precipitate  from,  517. 
Maquenne's  block,  357-359. 

test  for  methylfurfural,  377,  378. 

Maquenne  and  Roux's  theory  of  diastatic  conversion,  687-689. 
Marc,  determination,  228,  229. 

variation  of  content  in  beets,  246. 

Marcker's  diastase  method  for  determining  starch,  440,  441. 
Mashing  at  high  and  low  temperature,  690. 
Massecuite,  646. 

determination  of  moisture  in,  18-20. 

methods  for  polarizing,  205,  206. 
Mazun,  714. 

Meat,  preparation  of  i-inosite  from,  760. 

Meissl's  method  for  determining  invert  sugar,  423;  Appendix,  38. 
Meissl  and  Killer's  method  for  determining  invert  sugar  in  presence  of  sucrose,  430, 

431. 
Meissl  and  Wein's  method  for  determining  invert  sugar  in  presence  of  sucrose,  428- 

430. 
Melassigenic  action  of  salts,  648-650. 

Geerligs's  theory  of,  650. 
in  beet  molasses,  649. 
cane  molasses,  650. 
Melezitose,  740-742. 

fermentation,  742. 

hendecacetate,  742. 

hydrolysis,  741. 

occurrence,  740,  741. 

preparation,  741. 

properties,  741. 

reactions,  741.' 


INDEX  li 

Melibiase,  723. 
Melibiose,  721-724. 

absorption  of,  by  bone  black,  284,  285. 
fermentation,  723. 
formation  from  raffinose,  737,  738, 
hydrolysis,  by  acids,  723. 

melibiase,  723. 
occurrence,  721. 

preparation  from  raffinose,  721,  722. 
properties,  722. 
reactions,  722,  723. 
synthesis,  724. 
tests,  723,  724. 
Melibiotite,  722. 
Melitriose  (see  Raffinose). 
Melting  points  of  hydrazones  and  osazones,  356-359;  Appendix,  90. 

comparison  of  methods  for  determining,  359. 
determination  by  capillary  tube,  356,  357. 

Maquenne's  block,  357-359. 
variability  in,  359,  360. 
Meniscus,  adjustment  of,  167. 
1-Menthylhydrazine,  362. 

use  of  in  resolving  d,  1-sugars,  362,  551. 
Mercaptals,  367,  368. 

Mercaptans,  reactions  of  sugars  with,  367,  368. 
Mercury,  acid  nitrate  solution  for  clarifying,  252,  447. 
iodide  solution  for  clarifying,  252. 
Knapp's  alkaline  cyanide  solution  for  determining  reducing  sugars,  338, 

435,  436. 

Sachsse's  alkaline  iodide  solution  for  determining  reducing  sugars,  436,  474. 
Mesoerythrite  (see  i-Erythrite). 
Metal  polariscope  tubes,  157-159. 

with  jacket,  158,  159. 
Metallic  salt  solutions  for  testing  sugars,  334-339   (see  under  Bismuth,   Copper. 

Mercury  and  Silver), 
miscellaneous  solutions,  339. 
Metabolism  of  sugars  in  plants,  534. 
Metapectic  acid,  601. 
Metapectin,  601. 
Metaraban,  547. 
Metarabin,  548. 
Metasaccharins,  587,  604. 

Methyl  alcohol,  use  of,  in  separating  raffinose  and  sucrose,  734. 
Methyl  a-  and  /3-glucosides,  590,  591. 

mannorhamnoside,  645. 
Methylarbutin,  571. 
Methyldioses,  535,  536. 
Methylerythrite,  543,  767. 
Methylfurfural,  absorption  spectra,  384-386. 
color  reactions,  377,  378. 


Hi  INDEX 

Methylfurfural,  determination,  456-459. 

in  presence  of  furfural,  458,  459. 

formation  from  methylpentoses  and  methylpentosans,  377,  378. 
method  for  determining  methylpentoses  and  methylpentosans,  456- 

459;  Appendix,  89. 
phloroglucide,  457. 

factors  for  converting  to  methylpentoses  and  methyl- 
pentosans, 457. 
precipitation  with  barbituric  acid,  457. 

phloroglucin,  456,  457. 
reaction  for  methylpentose  groups,  377. 
yield  from  methylpentoses,  377. 
Methylglycerose,  539. 
Methylglycolose,  535. 
Methylglyoxal,  378,  537,  539. 
Methylheptoses,  637,  638. 
Methylhexoses,  631-633. 
Methyloctoses,  640. 

Methylpentosans,  determination  of,  456-459;  Appendix,  89  (see  also  under  Methyl- 
pentoses). 

Methylpentose-hexose  saccharides,  644,  645,  731,  732. 
Methylpentoses,  563-570. 

color  reactions,  384-386. 
determination,  456-459;  Appendix,  89. 

by  method  of  Tollens  and  Ellett,  456-458. 

Haywood's  modification,  458. 
in  presence  of  pentoses,  458,  459. 

methylfurfural  reactions,  377,  378  (see  also  under  Methylfurfural). 
Methylphenylhydrazine,  346. 

reaction  for  d-fructose,  621,  622. 

ketoses,  354. 

use  of  in  determining  d-fructose,  470. 
Methyltetroses,  543. 
Methyltrioses,  539. 
Metric  cubic  centimeter,  28. 

normal  weight,  113,  114,  163,  203. 
standard  in  saccharimetry,  113-115. 
Metric  solution  scale,  163. 
Microorganisms,  action  upon  samples,  13,  14. 
Midzu  ame,  analysis  of,  491. 
Milk,  clarification  of,  447. 

determination  of  lactose  in,  252-254. 
percentages  of  lactose  in  different  kinds  of,  708. 
polarization  of,  252-254. 
Milk  sugar  (see  Lactose). 

Milling,  effect  on  composition  of  cane  juice,  232. 
Mitscherlich's  polariscope,  85,  86. 
Mixtures  of  sugars,  analysis  of,  279-286,  472-493. 

by  combined  polariscopic  methods,  472,  473. 
reduction  methods,  473,  474. 


INDEX  liii 

Mixtures  of  sugars,  analysis  of,  by  combined  polariscopic  and  reduction  methods, 

475-493. 
determinations  of  two  sugars  in,  475-483. 

arabinose  and  fructose,  482. 

xylose,  482,  483. 
fructose  and  galactose,  481. 

glucose,  477-479. 
galactose  and  glucose,  480,  481. 
glucose  and  sucrose,  279. 

xylose,  300,  301. 
lactose  and  sucrose,  280,  281. 
methylpentoses  and  pentoses,  458,  459. 
raffinose  and  sucrose,  282-285. 
determinations  of  three  sugars  in,  484-492. 

dextrin,  glucose  and  maltose,  486,  490. 
fructose,  galactose  and  sucrose,  484,  485. 

glucose  and  sucrose,  485,  489. 
determinations  of  four  sugars  in,  492,  493. 
formulae  for  analyzing,  477. 
racemic,  532. 

resolution  of,  361,  362,  784-787. 
Mohr  cubic  centimeter,  28. 

normal  weight,  113,  163. 
standard  in  saccharimetry,  113. 
Mohr's  specific  gravity  balance,  40-42. 
Moisture,  absorption  of  by  raw  sugars,  7-9. 

determination  by  drying  in  air,  16-20. 

vacuum,  20-24. 
on  sand,  19. 

pumice  stone,  18>  19. 
method  of  A.  O.  A.  C.,  16-18. 
Browne,  23,  24. 
Carr  and  Sanborn,  21-23. 
International  Commission,  16. 
Lobry  de  Bruyn,  25,  26. 
Pellet,  19,  20. 
in  commerical  dextrin,  508. 

fructose  and  its  products,  20-24. 
glucose,  25. 
lactose,  25. 
maltose,  25. 
raw  sugars,  15-18. 
sirups,  molasses,  etc.,  18-26. 
starch  products,  26. 

estimation  from  refractive  index,  50-75. 
specific  gravity,  27-49. 
evaporation  of  from  raw  sugars,  7-9. 

Molasses,  calculation  of  composition  and  purity  in  raw  sugars,  506. 
comparison  of  methods  for  determining  solids  in,  69. 
determination  of  moisture  in,  18-25. 


liv  INDEX 

Molasses,  determination  of  refractive  index,  66-70. 

by  clarification,  69,  70. 
dilution  with  water,  66-68. 
sirup,  68,  69. 
specific  gravity,  38. 

dextrorotation  at  87°  C.  after  inversion,  296. 
effect  of  clarifying  agents  on  polarization,  224,  225. 
methods  for  polarizing,  205,  206. 
occurrence  of  glutose  in  cane-,  629. 
preparation  of  raffinose  from  beet-,  734,  735. 
Molecular  depression  of  freezing  point,  329. 

elevation  of  boiling  point,  331,  332. 

heat  of  combustion,  318. 

rearrangements  of  sugars,  303,  625,  626,  628,  629. 

sugar  acids,  775. 
weight  determinations  of  sugars,  322-332. 

by  boiling  point  method,  331,  332. 
freezing  point  method,  327-331. 
osmotic  pressure,  322-324. 
plasmolysis,  324,  325. 
Molybdates,  color  reactions  of  sugars  with,  682. 

influence  of,  on  rotation  of  sugar  alcohols,  766. 
Monnier's  formula  for  calculating  rendement,  498. 
Monosaccharides,  535-642. 

classification,  528. 

relationship  to  alcohols  and  acids,  529,  530. 
variability  in  reducing  power,  400. 
Morfose,  630. 
Moulds,  non-inverting,  651. 

occurrence  of  chitin  in,  752. 
Mounting  polariscopes,  169,  170. 
polariscope  tubes,  154. 
Mucic  acid,  605. 

configuration,  605. 

conversion  to  allomucic  acid,  781. 

dehydromucic  acid,  605,  781. 
formation  from  galactose,  364,  459,  460,  604,  605. 

lactose,  712. 
properties,  605. 

reaction  for  galactose  group,  364,  459,  460,  604,  605. 
reduction,  783. 
yield  from  galactose,  459. 
Mucins,  751,  752. 
Mucor  circinelloides,  651. 
Mucose,  631. 

Multirotation  (see  Mutarotation) . 
Munson  and  Walker's  method  for  determining  d-glucose,  invert  sugar,  lactose  and 

maltose,  426;  Appendix,  66. 

method  for  determining  invert  sugar  in  presence  of  sucrose 
432;  Appendix,  66. 


INDEX  1? 

Munson  and  Walker's  method  for  preparing  asbestos,  406. 
Muscovado  sugar,  composition  of  ash,  519. 

lead  number  of,  518. 
Mushrooms,  occurrence  of  chitin  in,  752. 

trehalose  in,  718. 
Mushroom  sugar  (see  Trehalose). 
Mutarotation,  187-193. 

influence  of  acids  on,  189,  190. 
alkalies  on,  190. 
salts  on,  190. 
.    solvent  on,  190,  191. 
temperature  on,  188. 
occurrence  during  inversion,  671-673. 
of  d-glucose,  189. 

lactose,  709-711. 
theories  of,  191-193. 
velocity  of,  188. 
Mycose  (see  Trehalose). 
Myrosin,  573. 
Myrticolorin,  599. 

a-Naphthol,  absorption  spectra  of  sugars  with,  379. 

color  reaction  of  sugars  with,  341,  378,  379. 
test  for  sucrose,  341,  681. 

Naphthoresorcin,  absorption  spectra  of  glucuronic  acid  with,  383-385. 

pentoses  with,  383-385. 
sugars  with,  381. 

test  for  glucuronic  acid  in  urine,  383-385. 

Nasini  and  Villavecchia's  concentration  formula  for  specific  rotation  of  sucrose,  176. 
Naphthylhydrazine,  347. 
Nectar,  composition  of,  616. 
Net  analysis,  498. 

Neutral  polarization  of  inverted  solutions,  271. 
New  York  Sugar  Trade  Laboratory,  constant  temperature  cabinet,  169. 

methods  of  polarization,  202-205,  261. 
refrigerating  equipment,  261,  262. 
New  York  Sugar  Trade  method  of  sampling  sugar,  6. 
Nicol  prism,  81-84. 
Nitric  acid,  inverting  power  of,  663. 

oxidation  of  sugar  alcohols  with,  770,  771. 

sugars  with,  364. 
p-Nitrophenylhydrazine,  347. 
Nomenclature  of  sugar  acids,  dibasic,  778. 

monobasic,  773. 
sugar  alcohols,  766. 
sugars,  528,  531,  532. 
Non-inverting  yeasts  and  moulds,  651. 
Nonoses,  640,  641. 

Non-reducing  sugars,  reactions  of,  386,  387, 
Non-sugar,  496. 


Ivi  INDEX 

Non-sugar,  organic,  496. 

"Nori,"565,  606. 

Normal  juice,  497. 

Normal  weight  of  sucrose  for  saccharimeters,  112-119. 

for  French  scale,  112,  113. 

Ventzke  or  German  Scale,  113-115. 

metric  cc.  standard,  113,  114,  163. 
Mohr  cc.  standard,  113,  163. 
U.  S.  Coast  Survey  standard,  114,  115. 
Normal  weights  of  sugars,  197-201. 

definition,  197,  199. 
methods  of  calculating,  197,  198. 
tables  of,  197,  198. 

use  of  a  single  weight  for  all  sugars,  200,  201. 
Norrenberg's  polariscope,  78-80. 

Noyes's  modified  diastase  method  for  determining  starch,  442. 
Nucite  (see  i-Inosite). 

Nucleic  acids,  occurrence  of  pentose  group  in,  558. 
Nutritive  salt  solution  for  yeast,  299. 
Nylander's  bismuth  solution,  338. 

Oak  sugar  (see  Quercite). 

Octoses,  638-640. 

Optical  activity  of  sugars,  methods  of  destroying,  302-306. 

relation  to  asymmetric  carbon  atom,  530. 
Optical  inactivity  of  sugars,  531. 
Optically  inactive  sugar  from  sucrose,  659. 
Organic  matter,  determination  of,  496. 
Organic  non-sugars,  determination  of,  496. 
Osazones  of  sugars,  analysis  of,  370,  371. 

conversion  into  osones,  354,  355. 

elementary  composition,  371. 

^identification,  356-361,  370,  371. 

limitation  of  reactions  for,  353,  354. 

melting  point  (see  Melting  points). 

purification,  353. 

rotation  of,  360,  361. 

table  of  formulae,  descriptions,  melting  points,  and  solubilities, 

Appendix,  90. 

yield  and  time  of  formation,  350-353. 
Osmose  process,  649,  650. 
Osmotic  pressure  of  sugar  solutions,  321-332. 

application  to  molecular  weight  determinations,  324. 
determination  by  Pfeffer's  method,  322-324. 

plasmolysis,  324,  325. 
relation  to  boiling  point,  326,  327. 
freezing  point,  326,  327. 
gas  pressure,  323. 
vapor  pressure,  326,  327. 
Osones,  formation  from  osazones,  354,  355. 


INDEX  Ivii 

Ost's  copper  bicarbonate  method  for  determining  reducing  sugars,  433,  434. 
O'Sullivan's  copper  reducing  factors,  421,  422. 

solution  factors,  31. 
O'Sullivan  and  Tompson's  yeast  method  of  inversion,  274. 

Ogilvie's  modification,  274. 
Oven,  Carr's  vacuum,  22,  23. 

Soxhlet's,  16,  17. 

Wiesnegg's,  17,  18. 
Oxalic  acid,  inverting  power  of,  663. 

use  in  Clerget  method,  273,  274 
Oxalic  fermentation,  585. 
Oxidizing  agents,  action  upon  sugars,  363,  364. 
Oxime  reaction  of  sugars,  364,  365. 
Oxycellulose,  production  of  furfural  from,  376. 
Oxymethylfurfural,  formation  from  d-fructose,  620. 
Oxymethyltetroses,  544. 

Pancreatin,  693-696  (see  under  Conversion  of  Starch). 
Paper-stock,  determination  of  pentosans  in,  456. 
Paradextran,  578. 
Parapectic  acid,  601. 
Parasaccharose,  729. 

Pasteur's  methods  of  resolving  racemic  mixtures,  785-787. 
researches  upon  alcoholic  fermentation,  582. 

tartaric  acid,  784-787. 

Pavy's  volumetric  method  for  determining  reducing  sugars,  395-397. 
Payen's  method  for  determining  crystal  content,  499. 
Pectase,  601. 
Pectic  acids,  601. 
Pectinase,  601. 
Pectins,  600-602. 
Pectose,  601. 
Pectosinase,  601. 
Pellet's  drying  capsules,  19. 

method  of  aqueous  digestion,  239,  240. 

with  cold  water,  239. 
hot  water,  240. 
determining  moisture,  19,  20. 
tube  for  continuous  polarization,  158,  159. 
Pellet  and  Lemeland's  method  for  destroying  optical  activity  of  reducing  sugars, 

305,  306. 
Pellin's  polarimeter,  102,  103. 

saccharimeter,  135. 

Penicillium  glaucum,  selective  action  on  d,  1-acids,  787. 

Pentosans,  methods  of  determining,  449-456;  Appendix,  83  (see  also  under  Pentoses). 
occurrence,  properties,  etc.  (see  under  Araban  and  Xylan), 
percentages  in  paper  and  paper  stock,  456. 
Pentose-hexose  saccharides,  643,  644. 
Pentoses,  545-562. 

apparatus  for  determining,  450,  451. 


Iviii  INDEX 

Pentoses,  color  and  spectral  reactions,  381-386. 

with  naphthoresorcin,  383-385. 
orcin,  382,  383. 
phloroglucin,  381,  382,  384. 
determination  from  yield  of  furfural,  449-456. 

by  barbituric  acid  method,  454. 
phloroglucin  method,  451,  452. 
titration  with  bisulphite,  454, 455. 
factors  for  calculating  from  phloroglucide,  452. 
furfural  reaction  for,  374-377  (see  under  Furfural). 
Krober's  table  for  determining,  451;  Appendix,  83. 
limitations  of  methods  for  estimating,  375-377,  452,  453. 
Permanganate  volumetric  method  for  determining  copper,  410,  411. 
Perseite,  634,  635  (see  also  d-Mannoheptite) . 
conversion  to  perseulose,  637 
dibenzal,  770. 
occurrence,  634,  635. 
properties,  635,  767. 
Perseulose,  637. 
Peters' s  saccharimeter,  138. 
Peter's  electrolytic  method  for  determining  copper,  409,  410. 

iodide  method  for  determining  copper,  413,  414. 
Pfeffer's  researches  on  osmotic  pressure  of  sucrose  solutions,  322-324. 
Pfliiger's  method  of  determining  glucose,  419;  Appendix,  33. 

glycogen,  443. 
Pharbitose,  729. 
Phaseolunatin,  573. 
Phaseomannite  (see  i-Inosite). 
Phenols,  color  reactions  with  sugars,  341,  378-386. 

reactions  of  sugars  with,  368. 
Phenylhydrazides  (see  Hydrazides). 
Phenylhydrazine,  reaction  with  acids,  777,  782. 

reaction  with  sugars,  345-362  (see  also  under  Hydrazones). 
substituted  derivatives  of,  346,  347,  361,  362. 
use  in  determining  d-mannose,  469,  470. 
Phenylhydrazones  (see  Hydrazones) . 
Phlein,  615. 
Phloridzin,  571,  578. 
Phloroglucide,  furfural,  375,  451,  452. 

methylfurfural,  456,  457. 

Phloroglucin,  color  reactions  with  pentoses,  381,  382,  384. 
purification  of,  451. 
use  in  precipitating  furfural,  451,  452. 

methylfurfural,  456,  457. 
Photosynthesis,  533. 
Phytase,  763. 
Phytin,  762,  763. 
Pinite,  758,  759. 

occurrence,  758,  759. 

preparation  of  d-inosite  from,  758. 


INDEX  lix 

Finite,  properties,  759. 
Pipette,  Kruger's  automatic,  240,  241. 
Sachs-Le  Docte  automatic,  243. 
Spencer's  sucrose,  205. 
viscosity,  307. 

Plant  tissues,  distribution  of  water  in,  230-232. 
" Plaque  type,"  135. 
Plasmolysis,  324,  325. 

application  to  molecular  weight  determinations,  325. 
Plate,  concentric  half -wave,  93. 

Laurent's  half -wave,  91-93. 
Savart's  98. 

Soleil's  double  quartz,  86,  88. 

Plates,  standard  quartz,  for  calibrating  polariscope  scales,  119,  120,  135. 
Polarimeters  (angular  degree  Polariscopes),  76-107  (see  also  under  Polariscopes). 
apparatus  of  Biot,  84,  85. 
Jellet,  89. 
Landolt,  104-106. 
Laurent,  91-93,  101,  102. 
Lippich,  94-98,  104. 
Mitscherlich,  85,  86. 
Norrenberg,  78-80. 
Pellin,  102,  103. 
Robiquet,  86-88. 
Wild,  98-101. 
construction  of,  82-101. 

factor  for  converting  readings  into  sugar  degrees,  145. 
half -shadow  instruments,  89-98. 

description  of  modern  types,  101-106. 
scales  and  method  of  reading,  85-87. 
tint  instruments,  86-88. 
verification  of  scale  readings,  106,  107. 

Polariscopes,  76-145  (see  more  especially  under  Polarimeters  and  Saccharimeters) . 
accessories  of,  146-171. 
analyzer  of,  82-84. 
angular  degree  (see  Polarimeters). 
cabinets  for  (see  Cabinet), 
care  of,  169-171. 
field  of  vision  (see  Field), 
illumination  of,  146-153. 
mounting  of,  169,  170. 
polarizer  of,  82-84. 
quartz-wedge  (see  Saccharimeters). 
sugar  degree  (see  Saccharimeters). 
theory  of,  76-101. 
tubes  for  (see  Tubes). 

Polariscopic  methods,  employing  direct  polarization,  194-262. 

double  polarization,  263-286. 
special  processes,  286-306. 
for  analyzing  sugar  mixtures,  472,  473,  475-493. 


lx  INDEX 

Polariscope  methods  for  determining  velocity  of  inversion,  661,  662. 

(see  under   Filter-press  cake,  Honey,   Milk,  Molasses, 
Raw  sugars,  Sugar  beets,  etc.,  for  particular  methods). 
Polaristrobometer  of  Wild,  98-101. 
Polarization  at  constant  temperature,  261,  262. 

equipment  for,  169,  262. 
Polarization  at  high  temperature,  287-299. 

for  determining  commercial  glucose,  289-296. 
fructose,  296-299. 
invert  sugar,  287-289. 
method  of  Chandler  and  Ricketts,  289-291. 
Leach,  291-293. 
Wiley,  296-298. 
Polarization  of  light,  76-84. 

by  double  refraction,  80-84. 

reflection,  78-80. 
theory  of,  76-84. 
Polarizer,  82-84. 

of  Jellet,  89. 

Cornu's  modification,  89-91. 
of  Lippich,  94-98. 
of  Schmidt  and  Haensch,  89. 
Polysaccharides,  528,  574-579. 
Populin,  571. 

Precipitation  of  sugars  by  basic  lead  salts,  215,  216. 
Precipitate  error,  in  polarizing  milk  products,  253,  254. 

sugar  products,  209,  215. 
methods  of  correcting,  209-215. 

by  Home's  method,  212,  213. 
Sachs's  method,  210,  211. 
Scheibler's  method,  209,  210. 
Press,  hydraulic,  for  laboratory  use,  227,  228. 

"  Sans  Pareille,"  239. 
Pressure  bottle,  Lintner's,  439,  440. 
Pressure  methods  for  dissolving  starch,  439,  506. 
Pressure,  osmotic  (see  Osmotic  pressure). 
Pfibram's  sodium  lamp,  148. 
Prism,  Glan,  82. 

Jellet-Cornu,  89. 
Nicol,  81,  82. 
Protagon,  602. 
Prulaurasin,  572,  573. 
Prunose,  560. 
Pseudinulin,  615. 
Pseudofructose,  629. 
Pseudostrophanthobiose,  729. 
Ptyalin,  693. 

Purification  of  bone  black,  219. 
osazones,  353. 
sirups  in  preparing  sugars,  550. 


INDEX  bd 

Purification  of  sodium  light,  149-151. 
Purity,  coefficient  of,  494,  495. 

determination  in  molasses  of  raw  sugars,  506. 
Purity  of  reagents,  influence  on  copper  reduction,  417. 
Pycnometer,  Boot's,  38. 

types  of,  36-39. 
Pyromucic  acid,  782. 

Quadruple  field,  97,  98. 

Qualitative  methods  for  examining  sugars,  333-387. 

Quartz,  rotation  of,  compared  with  sucrose,  116,  117. 

temperature  coefficient  for  rotation  of,  126,  127. 
Quartz  plates,  for  verifying  polariscope  scales,  119,  120. 

"plaque  type,"  135. 
Quartz  wedge,  compensation,  108-112. 

double,  110-112. 
single,  108-110. 
Quebrachite,  759. 
Quercinite,  762. 
Quercite,  756,  757. 

occurrence,  756. 
properties  and  tests,  757. 
Quercitrin,  563. 
Quinovin,  568. 
Quinovose,  568,  569. 

Racefoliobiose,  730. 
Racemic  mixtures,  532. 

resolution  of  d,  1-acids,  784-787. 

by  crystalline  form,  785,  786. 

optically  active  bases,  786,  787. 
selective  fermentation,  787. 
resolution  of  d,  1-sugars,  551,  593,  598,  607,  623. 

by  optically  active  hydrazines,  361,  362. 

selective  fermentation,  787. 
Radiation  correction  in  calorimetry,  316. 
Raffinose,  732-740. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 
action  of  emulsin  on,  737,  738. 

invertase  on,  737,  738. 
calorific  values,  318,  319. 
compounds,  738-740. 

hendecacetate,  738,  739. 

octobenzoate,  739. 

raffinosates  of  barium,  calcium,  strontium,  lead  and  sodium, 

739-740. 

configuration,  738,  740. 
dehydration,  25. 


Ixii  INDEX 

Raffinose,  determination,  by  double  polarization,  281-286. 

Creydt's  method,  282. 
Herzf eld's  method,  282,  283. 
error  from  bone-black  absorption,  284,  285. 
reliability  of  methods,  285,  286. 
temperature  correction  for,  283,  284. 
fermentation,  738. 

formation  of  melibiose  from,  721,  722. 
hydrolysis,  by  acids,  736,  737. 

enzymes,  737,  738. 

influence  on  crystalline  form  of  sucrose,  735,  736. 
formation  of  d-glucose-osazone,  352. 
molecular  weight  determination  by  plasmolysis,  325. 
normal  weight  of,  197,  198. 
occurrence,  732,  733. 
preparation  from  beet  molasses,  734,  735. 

cotton-seed  meal,  733,  734. 
properties,  735. 
reactions,  736-738. 
separation  from  sucrose,  734,  735. 
solubility,  735. 

specific  rotation,  173,  174,  736. 
tests,  740. 

value  of  Ventzke  degree,  200,  201. 

Raoult's  method  for  determining  molecular  depression  of  freezing  point,  327-331. 
Rapp-Degener  method  of  alcoholic  digestion,  238. 
Rate  of  inversion,  660-662. 

Raw  sugars,  clarification  of  solutions,  .204,  207-215,  276-278. 
composition,  259,  260. 
deterioration  of  samples,  14. 
determination  of  moisture  in,  15-18,  65. 
effect  of  clarifying  agents  on  polarization,  224. 
polarization,  201-205. 

method  of  New  York  Sugar  Trade,  202-205. 
rules  of  International  Commission,  201,  202. 
sampling,  method  of  New  York  Sugar  Trade,  5,  6. 

U.  S.  Treasury  Dept.,  5,  6. 
shaker  for  dissolving,  203,  204. 
Reciprocals,  table  of,  398;  Appendix,  101. 
"Redo,"  221. 
Reducing  action  of  sugars,  law  of,  400,  401. 

sucrose  on  Fehling's  solution,  427,  428. 
agents,  reaction  of  sugars  with,  362,  363. 
power,  relative  copper,  421-423. 

variability  in,  of  disaccharides,  402. 

monosaccharides,  400. 
ratio  of  sugars,  glucose  equivalent,  391,  421. 

maltose  equivalent,  422. 

Reducing  sugars,  determination  (see  Copper  reduction  methods), 
glucose  equivalents  of,  427,  476. 


INDEX  Ixiii 

Reducing  sugars,  precipitation  by  basic  lead  salts,  215,  216,  444. 
reactions,  333-386. 

volume  of  Fehling's  solution  reduced  by,  391. 

Reduction  methods,  combined,  for  analyzing  sugar  mixtures,  473-475. 
Reduction  tables  of  sugars,  calculation  of,  401. 
Refining  of  raw  sugar,  646,  647. 
Refining  value,  498  (see  Rendement). 
Reflection,  principle  of  total,  52,  53. 
Refraction,  law  of,  50,  51. 
Refractive  index  of  sugar  solutions,  50-75. 

calculation  of  dissolved  solids  from,   51-75. 
clarification  of  solutions  for,  69,  70. 
determination  by  Abbe's  refractemeter,  53-70. 

immersion  refractometer,  70-75. 
dilution  of  solutions  for,  66-68. 
influence  of  impurities  on,  66-70. 

temperature  on,  58,  59. 
relation  of  to  specific  gravity,  62. 
Tischtschenko's  method  of  determining,  68,  69. 
Refractometer,  Abbe  (see  Abbe  refractometer) . 

immersion  (see  Immersion  refractometer). 
Refractometer  tables  for  sugar  solutions,  61-65. 

table  of  Geerlig's,  65;  Appendix,  22. 
Hubener,  74;  Appendix,  24. 
Main,  64;  Appendix,  17. 
Schonrock,  64. 
Stanek,  64;  Appendix,  21. 
Stolle,  62. 
Strohmer,  61. 
Tolman  and  Smith,  62,  63. 

Refrigerating  machine  for  constant  temperature  polarization,  262. 
Reischaur  and  Kruis's  method  for  determining  glucose,  398,  399;  Appendix,  27. 
Rendement,  methods  for  calculating,  498. 
Reputed  cubic  centimeter,  28. 

Resorcin,  absorption  spectra  of  sugars  with,  381,  384. 
color  reactions  of  sugars  with,  380,  381. 
test  for  ketoses,  380. 
Restriction  of  malt  extracts,  690,  691. 
Reversion  products,  formation  from  starch,  488,  697. 
Revertose,  704,  730. 
Rhamninase,  731. 
Rhamninite,  731. 
Rhamninose,  731,  732. 

hydrolysis,  732. 

occurrence  and  preparation,  731. 
oxidation,  731,  732. 
properties  and  reactions,  731,  732. 
Rhamninotrionic  acid,  732. 
Ilhamnite,  565,  767. 
Rhamnodulcite  (see  Rhamnose). 


Ixiv  INDEX 

Rhamnoheptonic  acid,  637. 

rotation  of  lactone,  774. 
Rhamnoheptose,  637,  638. 

conversion  to  rhamnooctose,  640. 
a-Rhamnohexite,  631,  768. 
a-Rhamnohexonic  acid,  631. 

rotation  of  lactone,  774. 
/S-Rhamnohexonic  acid,  632. 

rotation  of  lactone,  774. 
a-Rhamnohexose,  631,  632. 

conversion  to  rhamnoheptose,  637. 
/3-Rhamnohexose,  632. 
Rhamnonic  acid*,  565. 

rotation  of  lactone,  565,  774. 
Rhamnooctonic  acid,  640. 

rotation  of  lactone,  774. 
Rhamnooctose,  640. 
Rhamnose,  563-565. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 
calorific  values,  319. 
conversion  to  isorhamnose,  568,  777. 

rhamnohexose,  631. 

determination,  456,  457;  Appendix,  89. 
fermentation,  565. 

action  of  different  yeasts,  714 
formation  from  glucosides,  563,  564. 

mannorhamnoside,  645. 
rhamninose,  732. 
glucosides  of,  563,  564. 
modifications,  564. 
mutarotation,  187,  564. 
occurrence,  563,  564. 
oxidation  with  bromine,  363,  565. 
preparation  from  quercitrin,  564. 
properties,  564,  565. 
specific  rotation,  173-192,  564. 

influence  of  alcohol  on,  182,  565. 
tests,  565  (see  also  under  Methylpentoses) . 
yield  of  methylfurfural  from,  377. 
Rhamnosan,  457. 

determination,  456, 457;  Appendix,  89  (see  also  under  Methylpentosans) 
a-Rhodeohexose,  632. 
0-Rhodeohexose,  633. 
Rhodeonic  acid,  567,  568. 

rotation  of  lactone,  568,  774. 
Rhodeose,  566-568. 

conversion  to  rhodeohexose,  632,  633. 

occurrence,  567. 

preparation  from  convolvulin,  567. 


INDEX  Ixv 

Rhodeose,  properties,  567. 

racemic  combination  with  fucose,  568. 
tests,  567,  568. 
1-Ribonic  acid,  558,  559. 

conversion  to  1-arabonic  acid,  775. 

rotation  of  lactone,  774. 
d-Ribose,  558. 
1-Ribose,  558,  559. 

d,  1-Ribose,  formation  from  adonite,  559. 
Robiquet's  polariscope,  86-88. 
Rolfe's  method  for  calculating  composition  of  acid  hydrolyzed  starch  products,  507. 

researches  on  acid  conversion  of  starch,  698,  699. 
Rolfe  and  Faxon's  method  of  drying  starch  products,  26. 
"Rongalite,"  222. 

Ross's  method  of  testing  for  unreduced  copper,  393,  394. 
Rotation  dispersion  of  sugars,  115,  173,  196. 
Rotation,  specific  (see  Specific  rotation). 
Ruberythric  acid,  572. 

Saccharan,  467,  656. 

Ehrlich's  colorimetric  method  for  estimating,  467. 

Saccharate,  polarization  of,  in  filter-press  cake  (see  under  Filter-press  cake). 
Saccharates,  676-681. 

barium  monosaccharate,  680. 
calcium  bisaccharate,  677. 

monosaccharate,  677. 
trisaccharate,  678. 
lead  saccharate,  681. 
potassium  saccharate,  676. 
sodium  saccharate,  676. 
strontium  bisaccharate,  679,  680. 

monosaccharate,  678,  679. 
Saccharic  acid,  587-589. 

acid  lactone  of,  779,  780. 
test  for  d-glucose  groups,  587-589. 
Saccharides  (see  under  Mono-,  Di-,  Tri-,  Tetra-,  and  Polysaccharides) . 

hydrolytic  methods  of  determining  higher,  436-443. 
Saccharimeters  (Quartz-wedge  polariscopes),  108-145. 
apparatus  of  Bates,  139-143. 

Chandler  and  Ricketts,  290,  291. 
Ducboscq-Pellin,  135. 
Fric,  138,  139. 
Jellet-Cornu,  133. 
Laurent,  133-135. 
Peters,  138. 

Schmidt  and  Haensch,  136-138. 
Soleil-Duboscq,  132. 
Soleil-Ventzke-Scheibler,  131. 
Stammer,  144. 
construction  of,  108-112. 


INDEX 

Saccharimeters,  conversion  factors  for  scales  of,  145. 

of  readings  to  angular  rotations,  145,  196. 
weights  of  sugars,  199-201. 
correction  of  readings  for  concentration,  118,  119. 

temperature,  255-262. 
graduation  of  scales,  117-119. 

for  variable  temperatures,  129,  130. 
half-shadow  instruments,  132-145. 
normal  weight  (see  Normal  weight), 
quartz-wedge  compensation  (see  Quartz-wedge), 
scales,  111,  112. 

method  of  reading,  111. 
temperature  corrections,  by  method  of  Browne,  258-261. 

U.S.  Treasury  Dept.,  256,  257. 
Wiley,  256. 

error  of  methods,  257-261. 
.      for  beet  products,  258,  260. 

cane  products,  258,  259,  261. 
temperature,  effect  on  scale  readings,  126-130. 
tint  instruments,  131,  132. 
use  of  bichromate  light  filter,  115-117. 
verification  of  scale  readings,  119-126. 

by  control  tube,  122-125. 

"hundred  polarization,"  125,  126. 
quartz  plates,  119,  120. 
sucrose,  121,  122. 
with  magnified  scale,  143,  144. 

variable  sensibility,  139-143. 
Saccharimetry,  special  methods  of,  287-306. 

technical  methods  of,  201-286. 
Saccharin,  586,  587. 
Saccharinic  acid,  586,  587. 
Saccharometer,  Einhorn's  fermentation,  462. 

Lohnstein's  fermentation,  463,  464. 
Saccharomyces  apiculatus,  651. 

cerevisise,  582,  714. 
ellipsoideus,  714. 
Marxianus,  704,  705,  714. 
membransefaciens,  714. 
octosporus,  651. 
productivus,  714. 
Saccharose  (see  Sucrose). 

Sachs's  method  of  determining  lead  precipitate  error,  210,  211. 
Sachs-Le  Docte  automatic  pipette, -243. 

process  of  water  digestion,  242-244. 
Sachsse's  method  for  determining  reducing  sugars  with  mercuric  iodide  solution, 

436,  474. 

for  determining  starch,  439. 
Salep  mannan,  594. 
Salicin,  571. 


INDEX  Ixvii 

Saline  quotient,  496. 

Saliva,  determination  of  diastatic  power  of,  515t 

Salts,  influence  on  activity  of  diastase,  691. 

pancreatin,  694. 
inverting  power  of  acids,  665. 
rotation  of  reducing  sugars,  184,  185. 

sucrose,  183,  184. 

inverting  action  upon  sucrose,  666-668. 
Sambunigrin,  572. 
Sampler,  Coomb's  drip,  10,  11. 
Samples,  changes  in  composition  of,  12-14. 

by  absorption  and  evaporation  of  moisture,  12,  13. 
action  of  enzymes,  13. 

microorganisms,  13,  14. 
deterioration  of,  13,  14. 
mixing  of,  5,  9. 
preservation  of,  14. 
segregation  of  molasses  in,  9. 

sugar  crystals  in,  11,  12. 

Sampling  of  juices,  molasses  and  sirups,  10,  11. 
raw  sugars,  3-10. 

change  in  moisture  content  during,  6-9. 
introduction  of  trash  during,  9. 
method  of  New  York  Sugar  Trade,  6. 
U.  S.  Treasury  Dept.,  5,  6 
triers  for,  4-6. 
sugar  and  sugar  products,  3-14. 

errors  in,  6-12. 
sugar  beets,  225-227. 
"Sans  Pareille"  press,  239. 
Saporubrose,  631. 
Savart  plate,  98. 
Scale,  metric  solution,  163. 
Scales  of  polarimeters,  85-87. 

method  of  reading,  85-87. 
verification,  106. 
zero-point  determination,  106. 
snccharimeters,  110-130. 

conversion  factors  for,  145. 
French  sugar  scale,  112,  113. 
German  or  Ventzke  scale,  113-115. 

for  metric  c.c.,  113,  114. 

Mohr  c.c.,  113. 
graduation,  117. 
magnified,  143,  144, 
method  of  reading,  111. 
verification,    119-126 

(see  also  under  Polarimeters  and  Saccharimeters). 
Scammonose,  631. 
Scheibler's  elution  pj  ocess,  67. 


Ixviii  INDEX 

Scheibler's  method  of  alcoholic  extraction,  233-235. 

determining  crystal  content,  499-501. 
double  dilution,  209,  210. 
"hundred  polarization,"  125,  126 
saccharimeter,  131. 
specific  gravity  tables  for  sucrose,  29. 
strontium  process,  679,  680. 
Scherer's  test  for  inosite,  758. 
Schiff's  reaction  for  furfural,  374. 
Schmidt  and  Haensch  polariscope  tube,  157. 
polarizer,  89. 

saccharimeters,  136,  137,  153. 
Schmitz's  concentration  formula  for  rotation  of  sucrose,  118,  176. 

table  for  correcting  saccharimeter  readings,  118. 
Schonrock's  formula  for  temperature  coefficient  of  saccharimeters,  120. 

table  of  refractive  indices  of  sucrose  solutions,  64. 
Scillin,  615. 
Secalose,  746. 

Seliwanoff's  resorcin  test  for  d-fructose  and  ketoses,  380,  384,  619. 
Semicarbazone  reaction  of  sugars,  366. 
Seminose  (see  d-Mannose). 

Shaking  machine  for  dissolving  sugars,  203,  204. 
Sherman's  researches  on  pancreatin,  693-696. 
scale  of  diastatic  power,  514,  515. 

Sherman,  Kendall  and  Clark's  method  for  determining  diastatic  power,  513-515. 
Sherman  and  Williams's  results  on  time  of  osazone  formation,  351-353. 
Sidersky's  specific  gravity  tables,  30. 
Sieben's  method  for  estimating  fructose,  470,  471 
Silver  solution  of  Tollens,  337,  338. 
Simple  sugars  (see  Monosaccharides). 
Sinalbin,  573. 

Single  wedge  system,  108,  109. 
Sinigrin,  573. 
Sinistrin,  615. 
Sirups,  methods  for  polarizing,  205,  206. 

purification  of,  in  separating  sugars,  550. 
Skimminose,  631.' 
Sodium  light,  77,  116,  173. 

lamps  for,  147-151. 
purification  of,  149-151. 
wave  length  of,  150. 

Sodium  hydrosulphite,  as  a  decolorizer,  221. 
raffinosate,  739. 
saccharate,  676. 
sulphite,  as  a  decolorizer,  278. 
Solanose,  631. 

Soldaini's  copper  solution,  337,  432. 
Soleil's  double-quartz  plate,  86-88. 

quartz  wedge  compensation,  108. 
saccharimeters,  131,  132. 


INDEX  Ixix 


Solubility  of  sucrose  in  water,  at  different  temperatures,  649. 

influence  of  salts  on,  648-650. 

Soluble  matter,  determination  in  commercial  dextrin,  509. 
Soluble  starch,  determination  in  commercial  dextrin,  509. 

Lintner's  method  of  preparing,  577. 
Solution  by  weight,  flasks  for,  164. 
Solution  factors,  31,  32. 

use  in  analysis  of  starch-conversion  products,  487. 
Solution  scale,  metric,  163. 
Solutions,  sugar,  boiling  point  of,  331,  332. 
concentration  of,  448. 
freezing  point  of,  327-331. 
isotonic,  326,  327. 
osmotic  pressure  of,  321-327. 
preparation  of,  from  animal  substances,  447. 

plant  substances,  445,  446. 
refractive  index  of,  50-75. 
specific  gravity  of,  27-48. 
vapor  pressure  of,  326,  327. 
viscosity  of,  307-313. 

Solvent,  influence  on  rotation  of  sugars,  181,  182. 
Sophorin,  563. 
d-Sorbinose  (see  d-Sorbose). 
d-Sorbite,  dibenzal,  770. 

formation  by  reducing  d-fructose,  619. 
occurrence,  624. 

oxidation  by  Bacterium  xylinum,  624. 
properties,  767. 

reaction  with  benzaldehyde,  769. 
1-Sorbite,  627,  767. 
d-Sorbose,  623-625. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 
calorific  value,  319. 
fermentation,  625. 
occurrence,  623,  624. 
preparation  from  d-sorbite,  624. 
properties,  624,  625. 
specific  rotation,  181,  625. 
tests,  625. 
1-Sorbose,  625-627. 

properties,  626. 

synthesis  from  d-galactose,  625,  626. 
tests,  627. 
d,  1-Sorbose,  627. 

Sorbose  bacterium  (see  Bacterium  xylinum). 
Soxhlet's  autoclave,  439,  440. 
drying  oven,  16,  17. 
extractor,  234. 

^'uller's  modification  of,  234. 


Ixx  INDEX 

Soxhlet's  method  for  analyzing  sugar  mixtures,  473,  474. 

determining  lactose,  424;  Appendix,  42. 
reducing  sugars,  389-391. 

modifications  of,  391,  392. 
Specific  gravity  balance,  40-42. 
bottles,  36-39. 

Specific  gravity  of  impure  sugar  solutions,  35,  36. 
lead  precipitates,  211,  212. 
starch-conversion  products,  31,  487. 
sucrose  solutions,  28-34. 

influence  of  impurities  on,  35,  36. 

temperature  on,  30,  31. 
relation  to  refractive  index,  62. 
table  of  Balling,  29. 

Brix,  29;  Appendix,  6. 

Gerlach,  29. 

German    Imperial    Commission,    30; 

Appendix,  1. 
Scheibler,  29. 
Sidersky,  30. 
sugar  solutions,  27-49. 

calculation  of  solids  from,  27-36. 

by  solution  factors,  31,  32. 

tables,  28-31. 
errors  in,  35,  36. 
methods  of  determining,  36-49. 
Specific  heat  of  combustion  (see  Calories). 
Specific  rotation  of  lactones,  774,  775. 

determination  of  configuration  from,  774,  775. 
Specific  rotation  of  starch  conversion  products,  31,  507. 

calculation  of  ingredients  from,  507,  508. 
Specific  rotation  of  sugars,  172-193. 

calculation  of,  172,  173,  194. 
determination  of  concentrations  from,  194. 

normal  weights  from,  197,  198. 
effect  of  acids  on,  185,  186. 

concentration  on,  174-177. 
foreign  optically  active  substances  on,  186,  187. 
kind  of  light  on,  173. 
mineral  impurities  on,  183-185. 
solvent  on,  181,  182. 
temperature  on,  178-181. 
influence  of  mutarotation  on,  187-193. 
Specifications  for  sugar  flasks,  166-168. 
Spectra,  absorption,  for  identifying  sugars,  342-345,  378-386. 

diagram  of  characteristic,  384. 
methods  of  studying,  344,  345,  378-386. 
(see  under  Glucuronic  acid,  Methylpen- 
toses,  Pentoses,  and  the  different  sugars 
for  individual  spectral  reactions). 


INDEX  Ixxi 

Spectroscope,  direct-vision,  342-344. 

applications  to  study  of  color  and  spectral  reactions,  344,  345,  378-386. 
Spencer's  sucrose  pipette,  205,  206. 
Stachyose,  747,  748. 

fermentation,  748. 
hydrolysis  of,  748. 
occurrence,  747. 
preparation,  747. 
properties,  747,  748. 
Stammer's  colorimeter,  467-469. 

saccharimeter  with  magnified  scale,  144. 
Standardization  of  hydrometers,  43-45. 

polariscope  tubes,  155,  156. 
refractometers,  59-61,  72-74. 
saccharimeter  scales,  119-126. 
sugar  flasks,  166-168. 

Stanek's  zinc  nitrate  method  for  decomposing  saccharate,  251. 
Starch,  575-577. 

action  of  acids  on  (see  under  Conversion). 

enzymes  on  (see  under  Conversion), 
calorific  value,  319. 
conversion  (see  Conversion), 
determination  by  Fehling's  solution,  438-442. 

Sachsse's  method,  439. 
solution  under  pressure,  439. 

with  diastase,  440,  441. 

modification  of  Noyes,  442. 
polariscopic  methods,  506,  507. 

by  solution  under  pressure,  506. 

with  hydrochloric  acid,  506,  507. 
in  commercial  dextrins,  509. 
formation  of  isomaltose  from,  706. 

maltose  from,  683,  699,  706. 
formula  of,  687. 

hydrolysis  (see  under  Conversion), 
microscopic  appearance,  576. 
molecular  weight,  686,  687. 
occurrence,  575,  576. 
preparation  of,  576. 

of  d-glucose  from,  580. 

maltose  from,  699. 
properties,  576. 

soluble,  Lintner's  method  for  making,  577. 

Starch-conversion  products,  calculation  of  composition  from  specific  rotation,  507. 
determination  of  moisture  in,  26. 
solution  factors  of,  31,  487. 

relation  to  specific  rotation,  487. 
Steffens's  trisaccharate  process,  678. 
Stereopticon  electric  lamp,  152. 
Stolle's  refractometer  table,  62. 


Ixxii  INDEX 

Strohmer's  refractometer  table,  61,  62. 


Strontium  bisaccharate,  679,  680. 

process,  679,  680. 
use  in  isolating  sucrose,  647. 
monosaccharate,  678,  679. 
raffinosate,  739. 
Strophanthin,  645. 

Strychnos  alkaloids,  use  in  resolving  d,  1-acids,  786,  787. 
Sucrose,  645-682. 

absorption  spectra  with  a-naphthol,  379. 

resorcin,  381. 
action  of  acids  upon  (see  Inversion). 

heat  on  solutions  of,  656-659. 
invertase  upon  (see  under  Invertase). 
active  and  inactive  molecules,  664. 
boiling  point  of  solutions,  651. 
calorific  value,  317-319. 
compounds,  676-681. 

concentration,  influence  on  activity  of  invertase,  674. 
specific  rotation,  174-177. 
saccharimeter  readings,  118,  119. 
configuration,  682. 

contraction  of  volume  with  water  mixtures,  32-36. 
crystalline  form,  647,  648. 

influence  of  raffinose  on,  735,  736. 
decomposition  by  heat,  655-659. 
determination  by  chemical  methods,  436-438. 
direct  polarization,  194r-262. 
invert  polarization,  263-281. 
in  presence  of  fructose  and  glucose,  485,  489. 

raffinose,  282-286. 
fermentations,  651-655. 

action  of  different  yeasts,  714. 

non-inverting  organisms,  651. 
freezing  point  of  solutions,  325-330. 
high  polarizing  derivative,  658,  659. 
influence  on  action  of  invertase,  673,  674. 

formation  of  osazones,  352,  353. 
reducing  power  of  glucose,  427,  428. 
inversion  of  (see  Inversion), 
ions,  hypothesis,  of,  665. 
melting  point,  648. 

molecular  weight  determination,  322-332. 
normal  weight  (see  Normal  weight), 
occurrence,  645-647. 
optically  inactive  derivative,  659. 
osmotic  pressure  of  solutions,  322-324. 
plasmolysis  by  solutions  of,  324,  325. 
polarizing  power  compared  with  quartz,  116,  117. 
preparation,  from  plant  substances,  647. 


TNDEX  Ixxiii 

Sucrose,  preparation,  manufacturing  processes,  646. 

refining,  646,  647. 

preparation  of  d-fructose  from,  617. 
d-glucose  from,  581. 
properties,  647,  648. 

protective  action  upon  invertase,  675,  676. 
purification  for  standardizing  saccharimeters,  121. 
reducing  action  upon  Fehling's  solution,  427,  428. 
rotation  dispersion  of,  116,  173. 
solubility,  648-650. 

in  beet  molasses,  649. 
cane  molasses,  650. 
water,  649. 

influence  of  salts  on,  649-650. 
specific  gravity,  648. 

of  solutions  (see  under  Specific  gravity), 
specific  rotation,  173-184,  651  (see  also  Specific  rotation), 
technical  processes  for  recovering,  678-680. 

temperature  influence  on  saccharimetric  determination,  126-130,  255-262. 
specific  gravity  of  solutions,  30,  31. 
specific  rotation,  178,  179. 
tests  for,  681,  682. 
value  of  Ventzke  degree,  200,  201. 
verification  of  saccharimeters  by  means  of,  121,  122. 
viscosity  of  solutions,  307-313. 
Sucrose  pipette,  Spencer's,  205,  206. 
Sugar  acids  (see  under  Acids). 
Sugar  alcohols  (see  under  Alcohols). 
Sugar  balance,  162. 
Sugar  beets,  colloidal  water  in,  229,  230. 

determination  of  juice  in,  227,  230. 
marc  in,  228,  229. 
sucrose  in,  227-246. 

by  digestion  with  alcohol,  238,  239. 
Rapp-Degener  method,  238. 
digestion  with  cold  water,  239. 
Kriiger's  method,  240-242. 
Pellet's  method,  239. 
Sachs-Le  Docte's  method,  242-244. 
digestion  with  hot  water,  240. 
Herzfeld's  method,  244. 
Pellet's  method,  240. 
Sachs-Le  Docte's  method,  243, 244, 
expression  of  juice,  227-229. 
extraction  with  alcohol,  232-235. 
Scheibler's  method,  233-235. 
determination  of  sucrose  in  spent  chips,  247. 
by  expression  method,  247. 

Herzfeld's  alcoholic  digestion  and  extraction  method,  247,  248. 
sampling  of,  225. 


Ixxiv  INDEX 

Sugar  beets,  sampling  of,  by  Keil's  boring  rasp,  226. 
Sugar-beet  molasses,  composition  of,  260,  649. 

solubility  of  sucrose  in,  649. 
Sugar-beet  products,  composition  of,  260. 

influence  of  temperature  on  polarization  of,  258-260 
Sugar  cane,  composition  of  mill  pressings  from  232. 
distribution  of  water  in,  231. 
determination  of  fibre  in,  248. 

sucrose  in,  235-238. 

by  Zamaron's  extractor,  235-238. 
determination  of  sucrose  in  bagasse  of,  248,  249. 

by  hot-water  digestion,  248,  249. 
tissues  of,  231. 
Sugar  cane  molasses,  composition  of,  259,  650. 

solubility  of  sucrose  in,  650. 
Sugar  cane  products,  composition  of,  259. 

influence  of  temperature  on  polarization  of,  258-261. 
Sugar  flasks,  165-168. 
Sugar  scale  (see  under  Scales). 
Sulphitation,  646. 
Sulphuric  acid,  color  reactions  of  sugars  with,  340,  341. 

inverting  power  of,  663. 

Surface  area  of  solution,  influence  on  copper  reduction,  419. 
Sweet-water  spindles,  47,  48. 

Sykes  and  Mitchell's  method  for  determining  diastatic  power,  513. 
Synanthrin,  615. 

Synthesis  of  sugars,  by  cyanhydrine  reaction,  365,  366. 
enzymic  action,  704,  705,  718. 
molecular  rearrangement,  355,  625,  626. 
oxidation  of  alcohols,  770-772. 
reduction  of  lactones,  776,  777. 

d-Tagatose,  626-628. 

properties  and  tests,  627. 
synthesis  from  d-galactose,  626,  627. 
1-Tagatose,  628. 
d,  1-Tagatose,  628. 
Takadiastase,  692,  693. 
d-Talite,  611,  768. 

tribenzal,  770. 
d,  1-Talite,  768. 
d-Talomucic  acid,  611. 
d-Talonic  acid,  611,  775. 
d-Talose,  611,  612. 

action  of  different  yeasts  upon,  714. 
1-Talose,  612. 
Tannase,  573. 
Tanret's  researches  on  modifications  of  sugars,  191,  192. 

d-galactose,  192,  603. 
d-glucose,  192,  581. 


INDEX  Ixxv 

Tanret's  researches  on  modifications  of  lactose,  192,  710. 

rhamnose,  192,  565. 
Tartar  emetic,  784. 
Tartaric  acid,  784-787. 

isomeric  forms,  784. 

Pasteur's  methods  for  resolving  racemic  acid,  784-787     (see  under 

Pasteur). 
Tartrate,  sodium  ammonium,  785. 

hemihedral  forms  of,  785. 
Technical  methods  of  saccharimetry,  201-255. 
Temperature,  adjustment  of  saccharimeters  at  variable,  129,  130. 
coefficient  for  polarization  of  quartz,  126,  127. 

sucrose,  127. 
sugars,  127-129. 

saccharimeter  readings,  255-262. 
specific  rotation  of  sugars,  178-181. 
corrections  in  Clerget's  method,  264-269. 
determining  fructose,  478. 
galactose,  480. 
raffmose,  283,  284. 
refractive  index,  64;  Appendix,  21. 
specific  gravity,  30,  31 ;  Appendix,  5,  16. 
specific  rotation,  178-181. 
polarizing  sugars,  255-262. 

errors  in  use  of,  257-261. 

for  beet  products,  260. 
cane  products,  259. 
method  of  Browne,  258-261. 

U.  S.  Treasury  Dept.,  256,  257. 
Wiley,  256. 

equations  for  specific  rotation  of  sugars,  178-181. 
influence  on  activity  of  diastase,  690,  691. 
invertase,  674. 
pancreatin,  695,  696. 
copper-reducing  power  of  sugars,  418. 
length  of  polariscope  tubes,  158. 
saccharimeter  scales,  126. 
specific  rotation  of  sugars,  178-181. 
speed  of  inversion,  269,  664. 
viscosity  of  sugar  solutions,  311. 
of  optical  inactivity  of  invert  sugar,  287-289. 
polarization  at  constant  (see  under  Polarization). 

high  (see  under  Polarization), 
regulation  of  refractometers,  58,  59,  73,  74. 
water  regulators  for  constant,  59,  60,  159,  160. 
Tetrasaccharides,  528,  574,  747-750. 
Tetroses,  540-543. 

reaction  for,  378. 

Thiocyanate  method  for  determining  copper,  414,  415. 
Thiosemicarb,".zone  reaction  of  sugars,  366. 


Ixxvi  INDEX 

d-Threose,  542. 
1-Threose,  542. 

Time  of  boiling,  influence  upon  copper  reduction,  417,  418. 
Tint  polarimeters,  86,  88. 
Tint  saccharimeters,  131,  132. 

Tischtschenko's  method  for  determining  refractive  index,  68,  69. 
Tollens's  "absatz"  method  for  studying  absorption  spectra,  344,  345. 
apparatus  for  hydrolysis,  548,  549. 

vacuum  evaporation,  549,  550. 

concentration  formula  for  specific  rotation  of  sucrose,  176. 
furfural  reaction  for  pentose  groups,  374,  375. 
levulinic  acid  reaction  for  hexose  groups,  372,  373. 
method  for  determining  galactose  and  galactan,  459,  460. 
pentoses  and  pentosans,  449-453. 

naphthoresorcin  test  for  pentoses  and  glucuronic  acid,  383-385. 
silver  solution,  337. 
Tollens  and  Ellett's  method  for  determining  rhamnose  and  rhamnosan,  456,  457; 

Appendix,  89. 

Gans's  saccharic  acid  test  for  glucose  groups,  588. 
Krober's  method  for  determining  pentoses  and  pentosans,  449-452 ; 

Appendix,  83. 
Mayer's  method  for  determining  fucose  and  fucosan,  456,  457;  Appendix, 

89. 

Oshima's  test  for  methylfurfural,  386. 
Wheeler's  method  for  preparing  xylan,  553. 
Widtsoe's  test  for  methylfurfural,  385. 
Yoder's  test  for  dehydromucic  acid,  781. 

Tolman's  modification  of  Clerget's  method  by  inverting  at  ordinary  temperature,  269. 
Tolman  and  Smith's  refractometer  table,  62,  63. 

Total  solids  of  sugar  solutions,  determination  by  methods  of  drying,  15-26. 

estimation  from  refractive  index,  50-75. 
specific  gravity,  27-49. 

results  compared  by  different  methods,  67-69. 
Traganthose,  560. 
Trehabiose  (see  Trehalose). 
Trehala-manna,  718,  719. 
Trehalase,  720. 
Trehalose,  718-721. 

configuration,  721. 
fermentation,  .720. 
occurrence,  718. 

preparation  and  properties,  719. 
reactions,  719,  720. 
tests,  720,  721. 
Trehalum,  718,  719. 
Trier  for  sampling  sugar,  4-6. 

dimensions  of,  5. 
Trihexose  saccharides,  732-746. 
Trimethyltrioses,  540. 
Trioses,  538,  539. 


INDEX  Ixxvii 

Trioses,  reactions  for,  378. 
Trioxyglutaric  acids,  529,  551,  556,  559. 
Triple  field,  97,  98. 
Trisaccharides,  528,  574,  731-746. 
Triticin,  615. 

Tubes,  filter  (see  Filter  tubes), 
polariscope,  153-161. 

calibration  of,  155,  156. 
cover  glasses  and  washers  for,  156. 
desiccating  caps  for,  160,  161. 
expansion  coefficients  of,  158. 
form  of  Landolt  (sliding  caps),  157. 

Pellet  (continuous  polarization),  158,  159. 
Schmidt  and  Haensch  (enlarged  end),  157. 
Yoder  (volumetric),  161. 
mounting  of,  154,  155. 
of  glass,  153-157. 

metal,  157,  158. 
with  water-jacket,  158,  159. 
Tungstates,  reaction  with  sugar  alcohols,  766. 
Tunicin,  579. 
Turanose,  725,  726. 

formation  from  melezitose,  741. 
hydrolysis,  725,  742. 
preparation  and  properties,  725. 

Unified  copper-reduction  methods,  424-426  (see  under  Copper-reduction). 

United  States  Coast  Survey  Sugar  Scale,  114,  115. 

United  States  Treasury  Department  regulations  for  sampling  molasses,  10. 

sugars,  5. 
temperature    corrections    for   saccharimeters, 

256,  257. 

Units  of  heat  (see  Calories). 
Units  of  volume  (see  Cubic  centimeter). 
Urea,  action  upon  sugars,  366. 

influence  on  rate  of  inversion,  272. 

rotation  of  fructose,  glucose  and  invert  sugar,  272. 
use  in  Clerget's  method  of  inversion,  271-273. 
Ureide  reaction  of  sugars,  366. 

Vacuum,  evaporation  of  sugar  solutions  in,  549,  550. 

methods  of  drying  sugar  products,  20-26. 

Van't  Hoff  and  Le  Bel's  theory  of  the  asymmetric  carbon  atom,  530,  758. 
Variability  in  reducing  power  of  sugars,  400-402. 
Vegetable-glycogen,  578. 
Velocity  of  inversion  (see  under  Inversion). 

mutarotation  (see  under  Mutarotation). 
Ventzke  sugar  scale  (see  under  Scales). 
Verbascose,  749,  750. 

occurrence,  749. 


Ixxviii  INDEX 

Verbascose,  preparation,  749,  750. 

properties,  750. 
Verification  of  polarimeter  readings  (see  under  Polarimeters) . 

saccharimeter  readings  (see  under  Saccharimeters). 
Violette's  volumetric  method  for  determining  reducing  sugars,  393-395. 
Viscosimeter,  apparatus  of  Engler,  308. 

principle  of,  309 
Viscosity,  coefficient  of,  309. 

of  dextrin  solutions,  508,  510. 
sucrose  solutions,  307-313. 

diagram  of  curves,  311. 
influence  of  concentration,  310. 
impurities,  311,  312. 
temperature,  310,  311. 
pipette,  307,  308. 

Viscous  fermentation  of  sugars,  584,  652,  653. 
Volemite,  636,  768. 
Volemose,  636,  637. 
Volquartz's  hydrometer,  46,  47. 
Volume  of  precipitate  error,  209-215. 
Volume,  units  of,  27,  28  (see  Cubic  centimeter). 
Volumetric  methods  for  determining  copper,  410-415. 

reducing  sugars,  389-399. 

conversion  tables  for,  397,  398. 
Volumetric  polariscope  tube,  161. 
Volumetric  sugar  flasks,  165-168. 
Vosatka's  hydrometer,  47. 

Walnut  leaves,  preparation  of  i-inosite  from,  761. 
Washers  for  polariscope  tubes,  156. 
Water,  colloidal  or  imbibition,  229,  230,  246. 
digestion  (see  under  Sugar  beet), 
distribution  in  plant  tissues,  230-232. 

sugar  cane,  231. 

Water-baths  for  constant  temperature,  159,  160. 
Water-heater  and  pressure  regulator,  59,  60. 
Wave  length  of  light,  77. 

influence  on  rotation  of  sugars,  173,  174. 

zero  point  of  saccharimeters,  109,  110. 
length  for  sodium  light,  116,  150. 

white  light,  116. 
Wave  theory  of  light,  76,  77. 
Wedge  system  of  saccharimeters,  108-112. 

control,  111,  112. 
double,  110-112. 
single,  108-110. 
working,  111,  112. 
Weighing  bottle  for  solutions,  24. 

sugars,  16. 
capsules,  16. 


INDEX  Ixxix 

Weighing  dish  for  sugars,  203. 

Weight  in  vacuo,  38,  40,  164,  165. 

Weight,  normal  (see  Normal  weight). 

Wein's  method  for  determining  maltose,  423;  Appendix,  40. 

Welsbach  lamps,  152. 

W'estphal's  specific  gravity  balance,  40-42. 

White  light,  lamps  for,  151-153. 

mean  wave  lengths  of,  116. 

Wheeler  and  Tollens's  method  for  preparing  xylan,  553. 
Wiesnegg's  hot-air  oven,  17,  18. 
Wild's  polaristrobometer,  98-100. 
Wilhelmy's  law  of  mass  action,  660. 
Wiley's  desiccating  caps  for  polariscope  tubes,  160,  161. 

filter  tube,  393. 

method  for  destroying  optical  activity  of  reducing  sugars,  306. 
determining  dextrin,  306,  490. 

fructose  by  polarization  at  high  temperature,  296- 
298. 

temperature  correction  table  for  saccharimeters,  256. 
Wiley  and  EwelPs  method  for  determining  lactose  in  milk,  253. 
Winter's  cylinder  for  determining  specific  gravity,  45,  46. 
Winton's  lead  number,  517,  518. 

Wohlgemuth's  method  for  determining  diastatic  power,  515. 
Wood  gum  (see  Xylan). 
Wood  sugar  (see  1-Xylose). 
Working  wedge,  111,  112. 
Worts,  composition  of,  690. 


Xanthorhamnin,  564,  599. 

Xylan,  determination,  450-452;  Appendix,  83  (see  also  under  Pentosans). 
hydrolysis,  553,  554. 
occurrence,  553. 
preparation,  553. 
properties,  553. 
Xylite,  556,  767. 

dibenzal,  770. 

oxidation  to  d,  1-xylose,  556. 
Xylogalactans,  599. 
d,  1-Xyloketose,  562. 
d-Xylonic  acid,  552. 

cadmium  double  salt  of,  552. 
1-Xylonic  acid,  555. 

cadmium  double  salt  of,  555. 
conversion  to  d-lyxonic  acid,  775. 
oxidation  to  1-threose,  542. 
rotation  of  lactone,  774. 
d-Xylose,  552. 
1-Xylose,  552-556. 

Bertrand's  reaction  for,  555,  556. 


Ixxx  INDEX 

1-Xylose,  calorific  value,  319. 

conversion  to  1-gulose,  609. 

1-idose,  611. 

determination,  450-453;  Appendix,  83  (see  under  Pentoses). 
in  presence  of  1-arabinose,  482. 

d-glucose,  300,  301. 
diformal,  556. 
fermentation,  555. 

formation  from  d-glucuronic  acid,  375,  532. 
mutarotation,  187,  555. 
occurrence,  552—554. 
oxidation  to  1-xy Ionic  acid,  556. 

with  bromine,  363. 
preparation  from  straw,  etc.,  554,  555. 

xylan,  554. 
properties,  555. 

reducing  ratio  to  glucose,  421,  476. 
reduction  to  xylite,  556. 
specific  rotation,  173-191,  555. 
tests,  555,  556  (see  also  under  Pentoses). 
value  of  Ventzke  degree,  200,  201. 
yield  of  furfural  from,  449. 
d,l-Xylose,  556. 
Xylo-proteids,  554. 


Yeast,  action  of  pure  cultures  on  different  sugars,  299,  714. 
autolysis  of,  669. 
extract,  preparation  of,  300. 
mannan,  594. 
method  of  O'  Sullivan  and  Tompson  for  inversion,  274. 

Ogilvie's  modification,  274 
microscopic  appearance,  582. 
non-inverting  varieties  of,  651. 
nutritive  salt  solution  for,  299. 
occurrence  of  zymase  in,  582. 
preparation  of  invertase  from,  669,  670. 
maltoglucase  from,  702. 
top-  and  bottom-fermentation  varieties  of,  723. 

action  on  melibiose,  723. 
raffinose,  738. 

use  in  resolving  racemic  sugars,  787  (see  also  under  Saccharomyces) . 
Yoder's  volumetric  polariscope  tube,  161. 
Yoder  and  Tollens's  test  for  dehydromucic  acid,  781. 


Zamaron's  hypochlorite  method  of  clarification,  218. 
method  of  hot-water  extraction,  235-238. 

Zeiss's  immersion  refractometer  (see  Immersion  refractometer). 
sodium  lamp,  148,  149. 


INDEX  Ixxxi 


Zeiss's  spiral  heater  and  water  pressure  regulator,  59,  60. 
Zero-point  determination  of  polarimeters,  106,  107. 

saccharimeters,  109-112. 
error  for  Bates's  saccharimeter,  140-142. 
Zinc  dust  as  a  decolorizing  agent,  278. 
Zinc  nitrate  method  for  decomposing  saccharate,  251. 
Zymase,  582. 
Zymogen,  683. 


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